JHM Rotors - who has? Anyone have pulsation issues when new.

[alrightroad]

I purchased all 4 lightweight ones for my allroad project which has all 4 new RS6 calipers, hubs, bearings, uprights, etc. etc. Bed-in procedure was done properly following the recommended famous Stasis article referred to many times (even by JHM themselves).

Within about 15 miles after bed-in, I noticed I've got major pulsation with awesome wobbly steering wheel. They are warped. I've tested the rears only use p-brake and they are also warped but only slightly. I've been in touch with JHM and it's not going well. I've done many brake jobs prior and never experienced anything like this. JHM is saying the bed-in procedure was done wrong and I have pad deposits on the rotors causing the pulsation. I have several emails from JHM dealing with this but quote is my favorite: "There are no such thing as “warped rotors” it is just a misconception."

Before I blast JHM publicly for not standing behind their product and at least trying to work with me (they are denying anything is wrong with their product), is anyone running these and what has your experience been? I know there have been reports of these rotors getting warped after track use or beating on them with daily driving.

To prove a point, I have installed full set of OEM RS6 rotors, followed the bed-in procedure exactly as I did before... no issues at all on the OEM set. I was hoping to put the OEM set on my RS6 and leave the JHM ones on the allroad. argh!

Input from the brain trust appreciated.

[RSoverAll]

Well, that's disappointing to hear. Hopefully they get you all squared away and make it right.

Have you mic'd the rotors and sent the recordings to JHM? I was eyeing their rotors for my 6 as well....

Have they offered any solution at all?

[hahnmgh63]

A couple of others on the list here used or are using them and with the same results. If you do a Google search you will find many B7 RS4 owners un-happy with them also.

[s8prtotype]

Did the rotor hat bolts come loose?

Lots of threads over on AZ say not to trust these. Cracks after one track day.

[DHall1]

Damn that sucks. Did you use the same pads for each test? Which pads? I cant really think of anything else you did wrong..

Start cleaning the shotgun.

[hahnmgh63]

A previous member, "Brav", I think had a set and once he had them surfaced they were supposedly better.

[Corbett]

I purchased all 4 lightweight ones for my allroad project which has all 4 new RS6 calipers, hubs, bearings, uprights, etc. etc. Bed-in procedure was done properly following the recommended famous Stasis article referred to many times (even by JHM themselves).

Within about 15 miles after bed-in, I noticed I've got major pulsation with awesome wobbly steering wheel. They are warped. I've tested the rears only use p-brake and they are also warped but only slightly. I've been in touch with JHM and it's not going well. I've done many brake jobs prior and never experienced anything like this. JHM is saying the bed-in procedure was done wrong and I have pad deposits on the rotors causing the pulsation. I have several emails from JHM dealing with this but quote is my favorite: "There are no such thing as “warped rotors” it is just a misconception."

Before I blast JHM publicly for not standing behind their product and at least trying to work with me (they are denying anything is wrong with their product), is anyone running these and what has your experience been? I know there have been reports of these rotors getting warped after track use or beating on them with daily driving.

To prove a point, I have installed full set of OEM RS6 rotors, followed the bed-in procedure exactly as I did before... no issues at all on the OEM set. I was hoping to put the OEM set on my RS6 and leave the JHM ones on the allroad. argh!

Input from the brain trust appreciated.

I have these on the front and rear. When I first installed them I had major shaking as well after properly bedding them. I was using EBC Yellow pads. I talked to JHM and they told me I needed to run HAWK ceramic pads. I ended up having to get the rotors resurfaced and I bed them in again with new Hawk ceramic pads and they were better but not 100% not shaking. But still the build up on them is terrible and they look horrible with all that pad wear on them. I've never seen rotors act like this on any car I have owned ever. I plan on changing them out completely to a different brand when my car is back on the road this year.

[Bigglezworth]

The JHM rotors are junk. Nuff said...

[alrightroad]

Hat bolts are solid. I checked/torqued them all before install. Funny thing is I am using Hawk HPS. Same pads on the RS6 setup. Pads only have ~100 miles on them between both rotor sets. I'm sure there are some pad deposits (not see by eye but expected to be there) on the JHM rotors but not enough to make waffling horrid like I have. I'm going to give it one more go with resurfacing and non-ceramic pads which will prevent the possibility of deposits. If still waffling after this I'll report back and then go silent with my JHM efforts. I don't like public blasting but I do like everyone to know the truth about vendors, products and service providers. I'll post replies from JHM after my next testing for reference.

[hahnmgh63]

Between those of you on here and all of the B5 S4 and B7 RS4, you can't all be wrong. JHM needs to make it right.

[mrdave]

http://www.rs6.com/showthread.php/23121-Tackling-my-vibration-issue

[lswing]

Holy crap...I've been looking and asking about these for years. There have been a few sporadic reports of warping, but this ends that. Sorry to hear of the warped rotors, I hope they can stand by their product and refund your money. I will never get near them, best of luck.

[essexmetal]

I build a lot of custom brake components and systems. Custom hats for rotor upgrades, special caliper mounts, etc. Have lived through a wide range of diagnosing issues from improper bedding to poor mounting to billet disc hats that "settle" and go out of round. From what I have read here, especially several notes that say "after the discs were resurfaced they improved" it leads me to the rotors that are going out of true after a few heat cycles. Good practice to indicate a new rotors run out and see if there is a delta in the numbers after bedding.

I do understand their use of the word "misconception" when referring to the term warped because they probably have a lot of calls with issues of "pick up" from both improper bedding and a poor pad choice. There are many times where both those issues manifest themselves at the same time. Pad pickup certainly feels like a warped rotor but that is easy to correct by cleaning the rotor surface or a pad compound change and a couple of conscientious stops. I don't see this as a pick up issue since there are too many people with the problem.

Putting an indicator on the rotor will confirm the run out and give you direct data to go back to vendor with. From what information is presented it seems that their rotors have some residual stresses that release after some in service heat cycling. This is a manufacturing issue that I have come across occasionally, even on OEM production rotors and almost always rectified with a resurface after they "settle in". If they refuse to step up and you get stuck with the rotors take them to an automotive machine shop and have them surfaced on a flywheel grinder. Do not turn them. Grinding leaves a unidirectional pattern that aides in bedding and if the rotors have been in service for a while, it will cut through the hard spots. When you turn a rotor the cutter leaves radial grooves as well as the cutter skipping over the hard spots. Neither help in pad bedding. If I get OEM spec rotors in here that have not got a ground surface I put them on the grinder and put the pattern on the surface before they go on the car. Many times they are not as flat as they should be even though the are new and this shows up on the grinder.

Just to state the obvious......... the hub surface needs to perfectly flat and clean. A few microns out at the brake hat can create a noticeable run out at the outer diameter of the rotor. I always try to stay away from brand bashing because auto parts are so application specific but I have never had any luck with Hawk pads. This has been observed with heavier cars under track use conditions, all the German brands. Issues with pad pickup, glazing, and high pad wear. This across their full range of compounds.
Rick

[lswing]

Always liked Hawk pads...

[DHall1]

Great information ^^ essex

How does the flywheel grinder get both sides of the rotor? How does that work on a blanchard type grinder? Any chatter when the disc is airborne?

[Corbett]

Here are my JHM rotors after about 1,500 miles of use. Immediately started hard shaking after proper bedding.

http://i.imgur.com/RCjRLSO.jpg

Here they are after resurfacing.

http://i.imgur.com/7dNGnhh.jpg

And here they are after another 1,500 mile or so with Hawk ceramic pads.

http://i.imgur.com/gK5NsKo.jpg

[s8prtotype]

Well you're correct on how they look after brief use! ew.

[nistah]

For the record I ran a set of JHM front rotors which i removed to revert back to stock rotor application.

[essexmetal]

A flywheel grinder is basically a small Blanchard grinder without a magnetic table. Flywheels / rotors are bolted down with a piloted center. To do the opposite surface you have to flip the rotor. To the chatter, yes you can if you push too hard with a big cut, otherwise no issue. Instead of segment stones like a Blanchard they use cup wheels of different abrasive media. Media choice is dictated by the material being ground, steel, cast iron, etc.

First time I have seen the JHM rotor setup. I don't know if all they do is machine the hat and use someone else's rotor or cast their cast their own discs. Chances are they purchase rotors from one of the known suppliers. These look to have an even pattern, bad pattern but even. That shows that the rotor is running true. The last shot of the resurfaced rotors on the car shows that the pads are not making a full contact with the rotor. Hard to say the root cause from a picture but it is a pad or caliper issue not the rotor creating that pattern. I am assuming that the pads are not narrower since they had full coverage on the previous picture.

Corbett, Other than a unidirectional grind to assist in bedding, (just my preference, turned rotors bed in just fine much of the time) I would try some different pads. You are getting very uneven pickup. In theory, the purpose of bedding pads imbeds a layer of pad material into the rotor. The pad creates friction against this layer. If I saw this pattern the first thing I would do would be to change from an organic pad compound to a ceramic material. Since you are already running a ceramic compound I could only guess that a brand change would be an option. Just never had good luck with hawk pads, but again a personal observation, you mielage may very.It would be interesting to do a back to back with the same pad compound on an OEM rotor and these JHM ???
Rick

[lswing]

No problems with OEM, no problem with Zimmerman's...on all sorts of pads, 10-15 types at least. I'd say that you could tiptoe around the JHM rotors and try and find what works, but there is clearly a quality/compatibility issue that no end user should have to deal with. If it's a pad issue then JHM should know this by now and recommend what to use. I couldn't see getting near their product myself.

[essexmetal]

That says it all. From a distance it is hard to define product problems, real world input and from several sources pretty well confirms they have an product issue. Agree 100% that no end user should ever worry about it. That engineering is the responsibility of the vendor, these parts should be plug and play.

[alrightroad]

Essex, great input here... thank you. I'm going to experiment with different pad material and resurfacing of rotors each time. So far, my conversations with JHM have yielded not 1% of assumption of engineering issue on their end.

Anyone have a new or very lightly used set of OEM pads? I'll start there.

[scottmandu]

The Phaeton W12 rotors are or were at one time considered to be an upgrade for the RS6.

[G2]

From my first observation driving those rotors they were warped. No pad deposits, hot or chill spots. Worst I've felt so far on Audi.

Machine shop wasn't happy with the big lip, hat to rotor step down.

Really curious about who makes the rotors. Not seeing anyone beating OEM quality at this point...

[v8a6]

I ran 350mm JHM lightweight rotors on my S6 for two years and about 15k miles, and they worked flawlessly. Used with Hawk Ceramic pads and Brembo 18z calipers from a Porsche.

Mine definitely look cleaner than Corbett's
http://ep1.pinkbike.org/p4pb11080554/p4pb11080554.jpg
http://ep1.pinkbike.org/p4pb11080551/p4pb11080551.jpg
http://ep1.pinkbike.org/p4pb11080550/p4pb11080550.jpg

Mine were perfectly fine with the Hawk Ceramic's (unlike Corbett's).


These look to have an even pattern, bad pattern but even. That shows that the rotor is running true. The last shot of the resurfaced rotors on the car shows that the pads are not making a full contact with the rotor. Hard to say the root cause from a picture but it is a pad or caliper issue not the rotor creating that pattern.


What you are saying makes perfect sense. And since my car ran for two years with the Hawk Ceramics, we can rule out a compatibility issue (unless Hawk changed the formula on their Ceramics in the last two years).

So, does that mean that it must have been a caliper issue or install error on Corbett's car, since we have ruled out everything else?

[lswing]

Or the rotors can't handle the weight and power of the RS6? Much more force applied.

[v8a6]

Or the rotors can't handle the weight and power of the RS6? Much more force applied.

Weight of the RS6 and S6 Avant is negligible in this situation. Force applied to bring a car equal in weight, to a stop from 200 km/h isnt any different if the car is making 100hp or 1000hp. In fact, with a 365mm rotor vs a 350mm rotor, it should be less force (all else being equal).

If the car was tracked alot, well OK, then maybe that caused an issue with excessive heat. I was just chatting with a buddy of mine about tracking a car. He is a Porsche guy, and and described the expenses of a weekend track session:

After 3 track days, my costs were $1500 for the track days, $2000 in tires, and about $4000 in brakes (discs/pads/labour/brake fluid), not to mention increased wear and tire on my clutch.

If you are going to track the car, then you can't expect things to last forever. Things wear down quick and brake when tracking a heavy car. I am not saying that is what caused the problem. I don't even know if Corbett participates in track events. But you can see from my car that is equal in weight, I had no issues and a much cleaner rotor.

[v8a6]

Or the rotors can't handle the weight and power of the RS6? Much more force applied.

Also, let's stick to the facts. The rotors have already been ruled out as root cause by a brake expert, upon his examination of the pad residue pattern. So, if you are still blaming the rotors, then dispute what he said with a logical argument.

[v8a6]

Vibration could also be caused by a whole bunch of other things. I have owned four C5s including an RS6, and all of them had vibration issues. Wheels, control arms, bearings, tires, driveshafts, engine problems, transmission issues etc. can all cause vibration to occur. Maybe for some reason it was just amplified under braking.

[Corbett]

So, does that mean that it must have been a caliper issue or install error on Corbett's car, since we have ruled out everything else?


Wtf are you talking about? Installation error? On a rotor? Seriously? I never had any of these issues on my previous rotors (MTM 180mm) And to have the same results twice with the JHM rotors? Not to mention the other people in here and across other forums bitching about similar issues? Just more typical JHM fanboy BS of blaming the car of the cars owner lol. There are 4 different people complaining about the JHM rotors in this thread alone, not to mention other threads and other forums lol

[v8a6]

Wtf are you talking about? Installation error? On a rotor? Seriously? I never had any of these issues on my previous rotors (MTM 180mm) And to have the same results twice with the JHM rotors? Not to mention the other people in here and across other forums bitching about similar issues? Just more typical JHM fanboy BS of blaming the car of the cars owner lol.

I am not talking about other people asshole. I am talking about your case. I deal with one case at a time.

You uploaded pics. Pics show even wear on the rotor. You still have vibration.


These look to have an even pattern, bad pattern but even. That shows that the rotor is running true...it is a pad or caliper issue not the rotor creating that pattern.

Maybe you have problems understanding what Essex is saying. Ill translate it for you. The rotors are true. The problem is YOU. LOL

[Corbett]

I am not talking about other people asshole. I am talking about your case. I deal with one case at a time.

You uploaded pics. Pics show even wear on the rotor. You still have vibration.



Maybe you have problems understanding what Essex is saying. Ill translate it for you. The rotors are true. The problem is YOU. LOL

yep, resurfaced rotors with 2 different sets pads. No previous issues like this on the car. Multiple people bitching about the same issue on these rotors only. But yes, let's take the anonymous guys input who has 14 posts as the final authority here.

[v8a6]

yep, resurfaced rotors with 2 different sets pads. No previous issues like this on the car. Multiple people bitching about the same issue on these rotors only. But yes, let's take the anonymous guys input who has 14 posts as the final authority here.

OK, so now you are disputing what Essex is saying? It is him you are talking about when you refer to the guy with 14 posts, right? I will admit, I am not an expert in car brake systems at all. But, from what I can tell from Essex' posts, he seems quite knowledgeable, and helpful too.

So, you have resurfaced the rotors, and gone through two sets of pads. You still have vibration, and the problem is still with the rotors, right? Is that what you are saying?

Seriously, do you want to fix your problem with logical troubleshooting, or was your intent simply to come here and bash JHM's product even though your very own pics prove that the rotors are true, and not the root cause of the vibration?

[Corbett]

I'm not trying to fix a problem. I'm sharing my experience with these rotors. Not sure why you find that so irritating. I've spent too much time on these rotors already, like many others here have as well. They are going in the trash.

[v8a6]

I'm not trying to fix a problem. I'm sharing my experience with these rotors. Not sure why you find that so irritating. I've spent too much time on these rotors already, like many others here have as well. They are going in the trash.

Where did I say that you were irritating? You came on here in a flash calling me names, the second I posted some comments about possible root cause of your issue. Prior to that, the only time I have conversed with you is on Audizine, where I posted some compliments about your car and wheels (which used to be running and on the road, remember way back then?)

Thank you for sharing your experience. By posting pics you have provided the proof that the rotors are perfectly fine and true. The fact that you continue to blame the rotors for your vibration problem, even after they have been proven to be perfectly true, is telling. It leads me to believe that you have other motivating factors with your posts. Or maybe you just don't understand cars that well. Or maybe you are stubborn. I don't know.

The only thing I do know is that your JHM rotors are fine. And I would guess that is why you have continued to run them and NOT thrown them in the trash, despite what you say.

Good Luck Corbett. I had heard that your car was running really well at one point. What is happening with it now?

[Corbett]

Where did I say that you were irritating? You came on here in a flash calling me names, the second I posted some comments about possible root cause of your issue. Prior to that, the only time I have conversed with you is on Audizine, where I posted some compliments about your car and wheels (which used to be running and on the road, remember way back then?)

Anyone that hangs out on AR is a JHM fanboy. Thats not namecalling. Calling someone an asshole is. Thank you for the complements on my wheels, I appreciate it.




Thank you for sharing your experience. By posting pics you have provided the proof that the rotors are perfectly fine and true. The fact that you continue to blame the rotors for your vibration problem, even after they have been proven to be perfectly true, is telling. It leads me to believe that you have other motivating factors with your posts. Or maybe you just don't understand cars that well. Or maybe you are stubborn. I don't know.

Ya like I said, if you are going to say case closed based on one new users input on these forums, then I don't know what to say. I've never had issues like this on any other rotor Ive ever owned on any car.



The only thing I do know is that your JHM rotors are fine. And I would guess that is why you have continued to run them and NOT thrown them in the trash, despite what you say.

Good Luck Corbett. I had heard that your car was running really well at one point. What is happening with it now?[/QUOTE]


The rotors are not fine. As shown by multiple people in this thread alone. I dont run them now. The car has had the motor out for the past 6 months due to JHMs inability to properly tune e85. The rotors will be in the trash when the car is back up and running.

[lswing]

I am not talking about other people asshole. I am talking about your case. I deal with one case at a time.

You uploaded pics. Pics show even wear on the rotor. You still have vibration.



Maybe you have problems understanding what Essex is saying. Ill translate it for you. The rotors are true. The problem is YOU. LOL

I really can't believe any of your thoughts on this with such childish input. Appreciate the feedback, but clearly many have had issues with these and this should be known and made aware by JHM.

[lswing]

Weight of the RS6 and S6 Avant is negligible in this situation. Force applied to bring a car equal in weight, to a stop from 200 km/h isnt any different if the car is making 100hp or 1000hp. In fact, with a 365mm rotor vs a 350mm rotor, it should be less force (all else being equal).

If the car was tracked alot, well OK, then maybe that caused an issue with excessive heat. I was just chatting with a buddy of mine about tracking a car. He is a Porsche guy, and and described the expenses of a weekend track session:

After 3 track days, my costs were $1500 for the track days, $2000 in tires, and about $4000 in brakes (discs/pads/labour/brake fluid), not to mention increased wear and tire on my clutch.

If you are going to track the car, then you can't expect things to last forever. Things wear down quick and brake when tracking a heavy car. I am not saying that is what caused the problem. I don't even know if Corbett participates in track events. But you can see from my car that is equal in weight, I had no issues and a much cleaner rotor.

Your track argue quote is also pointless, way off base with the numbers. These are having problems under light tracking for a $500 weekend, it's pretty simple.

[fukinavit]

[QUOTE=v8a6;270355]Weight of the RS6 and S6 Avant is negligible in this situation. Force applied to bring a car equal in weight, to a stop from 200 km/h isnt any different if the car is making 100hp or 1000hp. In fact, with a 365mm rotor vs a 350mm rotor, it should be less force (all else being equal).


no, not really, The RS6 has a lot more power than the S6 so often you will be braking from a higher speed, weight may be the same but speed will not, so hence more braking force more often.

[v8a6]

Anyone that hangs out on AR is a JHM fanboy. Thats not namecalling. Calling someone an asshole is. Thank you for the complements on my wheels, I appreciate it.

No problem, asshole.



Ya like I said, if you are going to say case closed based on one new users input on these forums, then I don't know what to say. I've never had issues like this on any other rotor Ive ever owned on any car.

I side with the person who presents a logical argument, is impartial, and seems to know what the hell he is talking about. Above all, I look at the proof.

If we are going to base it on when people joined the forum, well you only joined in 2013. I've been on here since 2006. Does that mean I should disregard anything you say? That argument makes no sense.



The car has had the motor out for the past 6 months due to JHMs inability to properly tune e85.

It is JHM's tune that blew up your car? LOL. Sure buddy. Now this is starting to make a lot more sense. So, you purchased the JHM rotors, and they were non-stop issues, to the point where you are ready to throw them in the trash and be out way over a thousand bucks. So then you decided to get them to tune your car? Of course, that makes perfect sense.

Good luck with your car man. Let everyone know if it ever makes it back on the road. If you ever part it out let me know, as I might be interested in the wheels.

[v8a6]

[QUOTE=v8a6;270355]Weight of the RS6 and S6 Avant is negligible in this situation. Force applied to bring a car equal in weight, to a stop from 200 km/h isnt any different if the car is making 100hp or 1000hp. In fact, with a 365mm rotor vs a 350mm rotor, it should be less force (all else being equal).


no, not really, The RS6 has a lot more power than the S6 so often you will be braking from a higher speed, weight may be the same but speed will not, so hence more braking force more often.

Valid point if you are tracking the car on a road course. For daily driving, unless you are constantly beating the hell out of your car, it should be equal.

Which is why I brought up the track comments. I don't track my cars, but from what I understand it is costly in the brakes department.

[Corbett]

No problem, asshole.



I side with the person who presents a logical argument, is impartial, and seems to know what the hell he is talking about. Above all, I look at the proof.

If we are going to base it on when people joined the forum, well you only joined in 2013. I've been on here since 2006. Does that mean I should disregard anything you say? That argument makes no sense.



It is JHM's tune that blew up your car? LOL. Sure buddy. Now this is starting to make a lot more sense. So, you purchased the JHM rotors, and they were non-stop issues, to the point where you are ready to throw them in the trash and be out way over a thousand bucks. So then you decided to get them to tune your car? Of course, that makes perfect sense.

Good luck with your car man. Let everyone know if it ever makes it back on the road. If you ever part it out let me know, as I might be interested in the wheels.


Your ignorance is showing through. If you think I decided to go with JHM to tune after I had rotor issues then you are just showing how little you know about the situation. When JHMs "calibrator" is requesting around 7.6AFRs or something silly like that on e85, its a clear indication he has no clue how to properly tune e85

[v8a6]

Your track argue quote is also pointless, way off base with the numbers. These are having problems under light tracking for a $500 weekend, it's pretty simple.

How can my numbers be way off base, when they are a quote of what my buddy spent after a three day track session? That is what he spent, period. Maybe these users weekend of what you are calling "light tracking" (never heard of light tracking before) should have spent more than $500, and purchased replacement rings after the weekend. That is exactly the point.

Light tracking a 4000 pound tuned, twin turbo AWD car? LOL, OK.

[v8a6]

Your ignorance is showing through. If you think I decided to go with JHM to tune after I had rotor issues then you are just showing how little you know about the situation. When JHMs "calibrator" is requesting around 7.6AFRs or something silly like that on e85, its a clear indication he has no clue how to properly tune e85

OK, so you are saying that you didn't go to get your car tuned for e85 by JHM AFTER you had rotor issues. So, you got it tuned by JHM for e85 BEFORE you had rotor issues?

So, how did you get so much time on the car, enough to go through two sets of pads and have the rotors resurfaced, and experience all kinds of problems with the rotors, all after a bad e85 tune that supposedly caused your engine to blow up?

Again, if the e85 tune was bad and it blew your engine, then when did you have all this time to have problems with JHM rotors AFTER that?

[Corbett]

OK, so you are saying that you didn't go to get your car tuned for e85 by JHM AFTER you had rotor issues. So, you got it tuned by JHM for e85 BEFORE you had rotor issues?

So, how did you get so much time on the car, enough to go through two sets of pads and have the rotors resurfaced, and experience all kinds of problems with the rotors, all after a bad e85 tune that supposedly caused your engine to blow up?

Again, if the e85 tune was bad and it blew your engine, then when did you have all this time to have problems with JHM rotors AFTER that?

You need an exact timeline here? What's the point?

[v8a6]

You need an exact timeline here? What's the point?

Your stories don't line up and make sense. No one who has had a terrible experience with a company's products goes back for more.

We started with your rotor experience, and your own pics show that they are perfectly true. Then, you reported that JHM blew up your engine, but now you say that it happened BEFORE you had problems with their rotors. That doesnt make sense either. If they blew your engine then how could you spend so much time after that on the rotors, as you have reported.
I've spent too much time on these rotors already

When the engine is blown, the last thing you would be worrying about is your brake rotors.

When things don't add up, then they usually aren't true. I, along with many others, have had nothing but great experiences with JHM and their products. I had their lightweight brake kit, and it performed flawlessly. I have been assisted on multiple occasions with my cars by a few of the guys at JHM.

So, when someone is publicly bashing the company with a story that seems to have holes in it, then I am interested in getting to the facts.

[s8prtotype]

What does his car not running currently have anything to do with this thread? Have you ever had these rotors on an RS6? Do you have any experience with these rotors at all? Do you even have an RS6??

[v8a6]

For those experiencing vibration issues with their rotors (JHM or other) check out this post. It may help you sort out your issues.

http://audirevolution.net/forum/index.php?topic=169.0

[v8a6]

Stoptech on warping rotors

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

[Corbett]

Your stories don't line up and make sense. No one who has had a terrible experience with a company's products goes back for more.

I'm sorry if you cant follow along. Have fun playing internet detective.


We started with your rotor experience, and your own pics show that they are perfectly true.

Again, you wouldnt know what a "perfectly true" rotor looks like. You are just reading what one person said on the internet and running with it. Pathetic.


Then, you reported that JHM blew up your engine, but now you say that it happened BEFORE you had problems with their rotors.
Wrong again. You asked what was up with my car and I answered.



That doesnt make sense either. If they blew your engine then how could you spend so much time after that on the rotors, as you have reported.
When the engine is blown, the last thing you would be worrying about is your brake rotors.


Again, I'm not worried about the rotors. I shared my experience and you came in guns blazing.



So, when someone is publicly bashing the company with a story that seems to have holes in it, then I am interested in getting to the facts.

Holes? Seriously? Just because you dont understand exactly when things took place doesnt mean i have holes in my story. Get a life dude. You sound like every other AR loser who has nothing better to do than play JHM customer support online.

[Corbett]

What does his car not running currently have anything to do with this thread? Have you ever had these rotors on an RS6? Do you have any experience with these rotors at all? Do you even have an RS6??


He posted pics of these rotors on his A6. They worked great for him so CLEARLY everyone else on the internet is a moron.

[SteveKen]

So the above references suggest that the JHM rotors could suffer from an unfavorable metallurgy in comparison to the stock rotors or other manufacturers, as they may be more susceptible to carbide precipitates. It's hard to say without cutting them up and doing a microstructural and chemistry analysis.

I've heard it both ways with regards to brake vibration: Too much heat, not enough heat, not enough cooling, too much cooling. I dunno

[Corbett]

Ya I mean if people want to try to say my issue was installation error or something that's fine. Not true but that's fine if they want to say thay. But then you have th explain all these other people's having similar issues as well with the same product

[hahnmgh63]

A friend down the street with a B7 RS4 is also one of the guys on Quattroworld that had problems with his JHM rotors. I think they use the same rotor and a different rotor hat for the RS6 (same diameter rotor). He used the recommended Hawk pads and JHM also told him that he must have installed them wrong. This was a couple of years ago and he was given the option or returning them for his money back or an exchange. He took the money back as there were plenty of other B7 RS4 guys just starting to have problems with them. Went back to stock and he's still driving the car today. He did a few DE events with the car but like a lot of us we also do that with the OEM rotors. Besides metalurgy the one thing that has always bothered me about JHM is the weight savings claimed. I can only think they save almost all of it off the disc as the stock hat (although non-replaceable) is aluminum so they can't be saving a lot there. Also in their claim, the stock rotor is over exagerated by one pound. Not much but an error. Also and error by about the same on the RS4 rotors according to my friend?

[Bigglezworth]

Oh my..... lol

[alrightroad]

A friend down the street with a B7 RS4 is also one of the guys on Quattroworld that had problems with his JHM rotors. I think they use the same rotor and a different rotor hat for the RS6 (same diameter rotor). He used the recommended Hawk pads and JHM also told him that he must have installed them wrong. This was a couple of years ago and he was given the option or returning them for his money back or an exchange. He took the money back as there were plenty of other B7 RS4 guys just starting to have problems with them. Went back to stock and he's still driving the car today. He did a few DE events with the car but like a lot of us we also do that with the OEM rotors. Besides metalurgy the one thing that has always bothered me about JHM is the weight savings claimed. I can only think they save almost all of it off the disc as the stock hat (although non-replaceable) is aluminum so they can't be saving a lot there. Also in their claim, the stock rotor is over exagerated by one pound. Not much but an error. Also and error by about the same on the RS4 rotors according to my friend?

Hahn, please pm me. thx.

[MaxRS6]

I really can't believe any of your thoughts on this with such childish input. Appreciate the feedback, but clearly many have had issues with these and this should be known and made aware by JHM.

+1- Nuff said




After 3 track days, my costs were $1500 for the track days, $2000 in tires, and about $4000 in brakes (discs/pads/labour/brake fluid), not to mention increased wear and tire on my clutch.



I've tracked the RS6 a few times. My costs are not near the above amounts. I also track a 996 (a Porsche) and I assure you my cost do not approach those quoted amounts. For example, my Hoosiers are about to make their 5th track weekend (10 days), brake pads have been used on 10 track days with 85% life remaining. Many of my track friends would not be out there if the cost were that high. Of course, one can "elect" to throw money at anything.

I wish Lil Sis were hear to add some Uuuuummph to the argument..;0

edit: Just noticed that was the 2500th post. I must know something...LOL

[essexmetal]

Wow, has this ever got blown out of range. First off I was pretty careful to include disclaimers "it is hard to tell from a distance" . In an initial post I suggested that to go from a subjective assessment on run out to fact based one you need to put an indicator on the hub, then the new (or resurfaced rotor) then on one that has been run and one that had developed issues. If the run out is within spec something else is causing the pulsations. If that proves out good, then next is uneven pad pickup. This can show up looking like the patchy spots on a rotor or be hard to see signs of it. The pulsation which feels like a warped rotor are the pads getting various rates of grip as the disc goes through a rotation. This can be a rotor and pad compatibility issue. To be specific on one of my posts that started this rant fest I noted that the rotor looked to be true because the patchiness was even around the rotor. That just meant the rotor was true, could easily have other material issues. The note about the caliper was in reference to incomplete coverage, radial pattern on the rotor. Again all this is hard to definitively diagnose from a distance.

Corbett, I understand your frustration. I have had to deal similar problems where the best result was found by multiple defined combinations only to fluke upon a combination that was the fix. The one thing that I certainly agree on is there is seldom coincidences. If several people have problems with a similar product you can bet the product has an issue and not the person. As for your comment on me, lets face it, this is the internet and anyone can build themselves up to be a super genius. I would like to think my posts are specific and detailed when it comes to mechanical components. You will not see me expounding which carbonfiber gearshift knob someone should buy. Your comment on some anonymous guy with only 14 posts made you look like a Twat !!
You should not be surprised that other forum people responded to you the way they did. I would think with all the time you spend on the form you would have a better understanding of quality over quantity.

[v8a6]

Corbett...Your comment on some anonymous guy with only 14 posts made you look like a Twat !!
You should not be surprised that other forum people responded to you the way they did.

x2

Corbett has a history of bashing JHM and fabricating stories to defame the company, as we have seen above. Without getting into another battle with him, I would suggest to anyone reading his posts that you disregard his "experience" when it comes to anything with the JHM logo on it, as he is far from impartial when it comes to JHM. There is sufficient evidence from his very own pics, that the rotors are not warped.

Essex, your approach to determine root cause of the problem that some people are experiencing seems well thought out and logical. I can tell by your comments that you have experience in troubleshooting this type of problem (even though you have less than 20 posts! LOL). I am sure if OP was close to you he could pay you to investigate the issue and determine root cause.

OP, if you really want to figure out what root cause of the problem is, then youll have to do some further investigating. It sounds like JHM is trying to help you with that. I also posted a couple links (one from AudiRevolution and one from Stoptech) that deal with cases of vibration/pulsation. Check them out and see if they help. If you could find a guy like Essex close by, then that would be excellent too.

If you disregard Corbett's account, then aside from OP there is only one actual user account on this thread that is detailed from the person having the problem (not a third party reporting it, without any proof). That is Brav, as MrDave posted the link (http://www.rs6.com/showthread.php/23121-Tackling-my-vibration-issue). If you read Brav's thread, it seems his issues was resolved when he turned the rotors AND had the control arms replaced. So, whatever the initial problem was, it was fixed by one of those items. He continued to experience vibration after that, but was not attributing it to the rotors.

OP, good luck in finding the root cause of your issue. I can tell you that I loved the JHM rotors on my car, and I am sure if you get things sorted you will too.

[essexmetal]

V8a6, thank you for your comments. Even though there are 5 Audi's in our fleet there is really little need to participate on the forum. Some of the other German car forums get a bit more activity. Guess I need to drive the RS6's more to have more problems pop up. I have been involved with performance chassis and driveline systems for 30 years. Track based and (due to my proximity to the Motorcity) for production vehicles. As it applies to brake systems, I have the ability to CNC custom brake hats, grind rotors and balance them to under a gram. That said, never worry to get them that close. Most of these parts are to upgrade capacity and many are for performance Porsche street and track cars. I have seen and struggled with just about every problem noted on this post. Some were real battles that were remedied by a shear fluke.

Some observations. Brakes are one of the simplest systems on a vehicle, usually easy to remedy issues. When there is a problem it usually falls into two categories, mechanical accuracy ( runout, parallelism, force application, component rigidity) and friction.... rotor surface and pads. Mechanical is an easy diagnose, everything is a measurable. Friction is the science part where you end up with a harder to determine tangible. Easy to visually see the rotor but the pad has the magic. If you can't find the mechanical problem then it usually ends up a pad issue, or specifically ( if we trust the pad manufacturer got it right ) a compatibility issue. Hard to beat OEM pads, they have to do everything, good initial bite, good wear, low noise, function in a wide temperature range. As soon as you need to raise the performance of any of those categories you diminish or compromise the function of the others. I have had big problems with certain pad manufacturers but so many others love there products and have used them successfully for years. As you get outside the OEM's wide bandwidth, pads get into a narrower range of function and that is where issues with compatibility can pop up. Glazing, low friction / high pedal force , hot spots etc. The above point applies to rotors too. Several people have had an issue and many successful applications. That means there is a variable so more investigation is required before you can find fault with the product, application, or installation.

Point is, once you get out side the OEM validated product there may be some trail and error to perfect function. To this thread, if a rotor does not run out then the only problem area is the disc surface. If it is fresh, especially with unidirectional grind then it is down to proper bedding and the ability for the pad to bed without glazing or pick up. There could be another full page of finer details but in the big picture most issues are pad related. Bad rotors, crack, run out, and pit. All easy to detect.

Not sure a $150.00 slab of cast iron is worth losing stomach lining over especially when it is normally not the primary cause of most of issues.

[lswing]

Very good info. Just a few things; the stock pads are poor, heavy dust and sensor pins that eat into rotors at about 50% wear. This is the second car I've run Hawk HPS plus pads on and been very happy. Are you referring the $150 to our rotors? They are around $600-900 per front pair. Cheers!

[v8a6]

Great post Essex!

If someone really wanted to get to the bottom of their issues, it sounds like it should be fairly straight forward to troubleshoot if they knew what they were doing.

As LS pointed out, the OEM RS6 rotors are quite pricey. One of the cool things about the JHM rotors is that after your first set wears out, you can get replacement rings for $450. So in the long run they should be cheaper than OEM.

[essexmetal]

When I mentioned OEM Pads it is a generic mention across the industry, nothing specific, and the $150 is a standard no hat universal rotor like the JHM's. I have lived through the pain of the RS6 rotor purchase. At the time a bit cheaper through my wholesaler than they are today.

I run stock rotors on one of my track Porsches and they are a gift by comparison but a hard three day track event and the rotors crack through the cross holes enough to require replacement. Based on those replacement intervals, the stock RS6 rotor cost is not that bad. If an RS6 was pounded as hard the replacement interval would rise just a quick. The biggest problem I have with the stock composite rotor is the "ping click" while they are cooling down. Rotors should not be driven or mounted on Popsicle sticks.

[nistah]

For the record I ran a set of JHM front rotors which i removed to revert back to stock rotor application.


Since this is lively topic let me expand on my experience: I removed my JHM front rotors because they produced an unpleasant vibration and became warped prematurely, rather than troubleshoot I simply replaced with a new set of OEM rotors which have held up fine.

[v8a6]

Since this is lively topic let me expand on my experience: I removed my JHM front rotors because they produced an unpleasant vibration and became warped prematurely, rather than troubleshoot I simply replaced with a new set of OEM rotors which have held up fine.

Thanks for adding your experience. To be clear, I think it is almost impossible that they became warped (see the articles linked below), but there was obviously some issue with them that caused vibration
http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths
http://audirevolution.net/forum/index.php?topic=169.0

Do you happen to still have them?

[Corbett]

x2

Corbett has a history of bashing JHM and fabricating stories

Sigh. I have never fabricated any story about JHM. Sorry but nice try. I have however posted my personal experiences as well as a lot of insight as to the truth behind some lies being spread over at AudiRevolution. I have no beef with JHM.

I cant help it if you cant handle me sharing my personal experiences with these rotors in particular. I never once said they are warped. What I did say was that I have never had any issues with rotors on my RS6 or any other car the way I have with JHM rotors.

Dru has reached out to me to work on a solution. So plus one to JHM.

If anyone is serious about purchasing a set of JHM rotors, I suggest they use their time wisely and do their research. Not just the multiple people in this thread complaining, but also over on Audizine and Quattroworld. I wouldnt take the opinions of AR very seriously as that site is clearly in place to prop up JHM and JHM only.

[Corbett]

First off I was pretty careful to include disclaimers "it is hard to tell from a distance".......Again all this is hard to definitively diagnose from a distance.

The one thing that I certainly agree on is there is seldom coincidences. If several people have problems with a similar product you can bet the product has an issue and not the person.

Thank you. It seems v8a6 just wanted to pick and choose what you said and run with it. Its good to see people so level headed about the situation.



As for your comment on me, lets face it, this is the internet and anyone can build themselves up to be a super genius.

Thank you. I do appreciate your input and you do seem like you know what you are talking about. It was not my intent whatsoever to put you down. You'll have to excuse my skepticism regarding internet experts as I've seen people on AR and from AR use multiple accounts to try to sound like they are someone important when really its just someone using a fake account. I appreciate your input on the rotors!

[lswing]

Since this is lively topic let me expand on my experience: I removed my JHM front rotors because they produced an unpleasant vibration and became warped prematurely, rather than troubleshoot I simply replaced with a new set of OEM rotors which have held up fine.

Obviously another case of user error:) Regardless of warping or buildup it comes down to the manufacturer warning the buyer about this and suggesting a pad if that's the issue, and I don't see anything on their website. If the rotor material is good I would suspect the way they bolt to the hats, who knows.

OEM and OEM spec Zimmerman's have been tried and tested true with a variety of pads. I think we all know the safe bet.

Corbett, good to see the input, sounds like a hassle.

Edit 2; my own concern (valid or not) with these was always the lighter/thinner rotor. These cars produce so much stress under braking. I just couldn't pull the trigger on these as nice as the look.

[v8a6]

They definitely are pretty. These were mine when brand spanking new (350mm version)

http://ep1.pinkbike.org/p4pb9559143/p4pb9559143.jpg

[v8a6]

Corbett, just looking at yours and I see a difference... did they not come with washers on the bolts like mine?

http://i.imgur.com/7dNGnhh.jpg

[Corbett]

Corbett, just looking at yours and I see a difference... did they not come with washers on the bolts like mine?

http://i.imgur.com/7dNGnhh.jpg

Guess not. When did you get yours? I originally got mine back in August 2013.

[v8a6]

Mine were purchased in May 2013. They are 350mm rotors, not RS6 ones.

However, on the JHM site the pic of the RS6 rotors, which it says all after Aug 2012 should look like, definitely has the washers on the outside
https://jhmotorsports.com/products/pictures/LWrotors/JHM_LW_Rotor_Update.jpg

This is alrightroad's pic from QW. His fronts look like yours. Maybe that is just how the RS6 ones are. I cant tell if his has small washers, or not.
https://lh5.googleusercontent.com/-tJUVj3vwpnU/U8spYyn6p0I/AAAAAAAACds/ccnN8HXcQKI/s800/IMG_1225.JPG
https://lh3.googleusercontent.com/-S_TyYQMXNNI/U8spZKlTFKI/AAAAAAAACdw/HAK4zZyxEZw/s800/IMG_1226.JPG

[v8a6]

Probably has nothing to do with the issue, but every other pic I can find of JHM rotors except for the ones from you two guys, has the washers. Even the replacement rotors look like they come with bolts and washers.

https://jhmotorsports.com/products/pictures/LWrotors/JHM_B7-RS4_365mm_Front_Rotor_Ring_Kit.jpg

Anyway, something to ask Dru about when you talk to him.

[s8prtotype]

Mine were purchased in May 2013. They are 350mm rotors, not RS6 ones.




This is alrightroad's pic from QW. His fronts look like yours. Maybe that is just how the RS6 ones are. I cant tell if his has small washers, or not.

https://lh3.googleusercontent.com/-S_TyYQMXNNI/U8spZKlTFKI/AAAAAAAACdw/HAK4zZyxEZw/s800/IMG_1226.JPG

There is washers on those they're just the same size as the bolt head. Hard to tell.

[v8a6]

There is washers on those they're just the same size as the bolt head. Hard to tell.

I was wondering if that was the case.

[v8a6]

Starting today, remove “warped rotor” from your vocabulary...
http://www.brakeandfrontend.com/warped-rotors-myth/

That mentality is troublesome when it comes to servicing brakes — saying a rotor is warped easily puts the blame on an ineffective part that needs to be replaced when that isn’t the case. Understanding that a warped rotor is a myth is to understand that there are other causes for the braking condition and additional work is needed to do the job right. This may seem like a matter of semantics, but mischaracterizing the root problems of pulsation just perpetuates the myth.

[MaxRS6]

^I can find anything on the interweb. I have definitely had warped rotors verified through independent reviews of the rotors. I have the Alcon BBK on my RS6, and I can tell you they warped under track conditions. I have purchased (and bed) multiple sets of the Alcon rotors without issue. It was not pad build up, improper bedding, it wasn't a fairy shaking the front-end, it wasn't worn suspension parts- The Rotors were WARPED. I was so ticked, I had them examined. STaSis verified they were warped when I sent them back- and STaSis replaced them. I put the new rotors on the car (same pads, same suspension, same everything) and all was good for many many miles.

I guess I can go to the chalkboard and if I write it enuff times maybe I'll believe too...

"There is no such thing as Warped Rotors"
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Bummer- it didn't work- I still believe in Warped Rotors

[v8a6]

^I can find anything on the interweb. I have definitely had warped rotors verified through independent reviews of the rotors. I have the Alcon BBK on my RS6, and I can tell you they warped under track conditions. I have purchased (and bed) multiple sets of the Alcon rotors without issue. It was not pad build up, improper bedding, it wasn't a fairy shaking the front-end, it wasn't worn suspension parts- The Rotors were WARPED. I was so ticked, I had them examined. STaSis verified they were warped when I sent them back- and STaSis replaced them. I put the new rotors on the car (same pads, same suspension, same everything) and all was good for many many miles.

I guess I can go to the chalkboard and if I write it enuff times maybe I'll believe too...

"There is no such thing as Warped Rotors"
"There is no such thing as Warped Rotors"
"There is no such thing as Warped Rotors"
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"There is no such thing as Warped Rotors"
"There is no such thing as Warped Rotors"
"There is no such thing as Warped Rotors"
"There is no such thing as Warped Rotors"

Bummer- it didn't work- I still believe in Warped Rotors

I cannot argue with your chalkboard argument, or anything else you write that has absolutely nothing to do with the design of braking systems on modern automobiles. That being said, I am sure it makes perfect sense to you and some other members of this board, who do not believe in using logic and known facts to troubleshoot problems.

As for your Stasis rotors, I cannot say what the deal was. And since you don't have the rotors and Stasis is no longer in business, I would say we will never know with certainty what caused your issues of pulsation. This is a quote from the article I just posted:

Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible.

This makes more sense to me than your chalkboard argument. Do you have a scientific explanation of how your rotors became warped following track use? Or were they 'magic' rotors that defied the laws of physics?

[SteveKen]

Playing devil's advocate here, the article might start another myth that the rotor is never the problem.

Then we should all just buy the cheapest rotors we can find.

I wonder what the author of that article thinks about cryo treating?

Now some speculation on my part:

I'd be inclined to disassemble the rotors to see if they were assembled correctly. The stock rotors have a different floating design from the JHM ones. It's a factor in why I'm partial to the VAG design, even though they don't use this design on the B7 RS4, which is is a story for another opinionated rant, I guess.

Improper 'floating' due to over torquing the bolts could affect the hats as well as the rotors.

[MaxRS6]

I only have a trusted independent brake shop that inspected the rotors. They did not have a dog in the hunt as they were only inspecting the rotors. I certainly had tried to re-bed the rotors and clear pad-deposits. It did not work.

The independent brake shop was not going to make a sale for a rotors. Thus; they had nothing in it but their inspection and reputation. STaSis agreed after they received the rotors and inspected. This was not the Space Shuttle. Thus; there was no in-depth analysis of why they warped. Heck- that inspection probably would be far more than the cost of the rotors. They were warped according to a few inspections and that was good enuff for me when STaSis sent me replacement rotors.

Maybe defective, maybe the monkey driver, maybe the fairy...all I know is they were warped and replaced.

[SteveKen]

Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible.

This makes more sense to me than your chalkboard argument. Do you have a scientific explanation of how your rotors became warped following track use? Or were they 'magic' rotors that defied the laws of physics?

Thinking that nothing can metallurgically happen to the rotors between room temperature and the casting temperature is quite frankly, idiotic.

It's common knowledge to me but you can search the ASM's library if you're curious.

[v8a6]

Corbett has JHM rotors that he believes are causing pulsation, and he is planning to throw in the trash bin. Nistah may have a set too (to be confirmed by him) that it sounds like he will never use again.

I am willing to reimburse for shipping charges out of my own pocket to send either (or both) set(s) to Essex for examination to see if he can confirm what the problem is, or rule out the rotor as the source of the issue. Of course, this would only be if Essex agrees.

Ideally, it sounds like the car with the vibration would be brought to a guy like Essex, but geographically, I am not sure where you guys are.

Let's settle this once, and for all

[4everRS]

I cannot argue with your chalkboard argument, or anything else you write that has absolutely nothing to do with the design of braking systems on modern automobiles. That being said, I am sure it makes perfect sense to you and some other members of this board, who do not believe in using logic and known facts to troubleshoot problems.

As for your Stasis rotors, I cannot say what the deal was. And since you don't have the rotors and Stasis is no longer in business, I would say we will never know with certainty what caused your issues of pulsation. This is a quote from the article I just posted:

Rotors are cast in extreme heat — three to five times greater than the most aggressive braking situation. Physically “warping” a rotor would require a similar application of extreme heat, which is impossible.

This makes more sense to me than your chalkboard argument. Do you have a scientific explanation of how your rotors became warped following track use? Or were they 'magic' rotors that defied the laws of physics?

I can understand there is not likely a "scientific" explanation for a warped rotor. This denies the factor of other variables such as poor casting conditions, or foreign material during the casting process. These can make a significant influence in the strength of the finished product, as is well documented in the foundry business. Quality control is very important, and mistakes happen.

[hahnmgh63]

Your right though Steve, the authors assumption that the rotor would have to get to casting temperature for anything to have an effect on the Cast Iron (fairly weak metal) is a Joke. I don't have to melt a piece of any metal to be able to bend it or for it to change shape.
With that said I will say most of the time (probably 90%+) it is pad transference of material to the disc that causes the pulsation feeling. Also with that said the term "Warped" has been used for many years and what actually/usually happens when it does occur is that the disc itself doesn't actually warp but the unsupported disc surface (between the cooling vanes on vented brakes) collapses somewhat giving an uneven surface the pad runs over to give the warping feeling. I've had a few discussions on Braking system with Bob Chemelka with Brembo Brakes who shows up every year at a Tech session up here in the great NW at Maxrpm motorsports. An engineer background and very knowledgeable in braking systems.

[v8a6]

Great info hahnmgh63! So, you and the Engineer from Brembo also agree that there is no such thing as a warped rotor. It is a term that is being used inaccurately. 90+% of the time (your estimate, before people start attacking that number), the term "warped" is being used for the condition where a rotor experiences uneven pad transference of material to the disc.

In the remainder of the cases where the rotor is being called warped, the rotor is not still not actually warped, but instead there is a partial collapse of the disc in the unsupported area between the cooling vanes. I would be interested to know if in these particular cases the collapse is always accompanied by cracks in the rotor were the collapse is occurring. If that was the case, it would be easier to identify rotors with this condition visually

[lswing]

Great info hahnmgh63! So, you and the Engineer from Brembo also agree that there is no such thing as a warped rotor. It is a term that is being used inaccurately. 90+% of the time (your estimate, before people start attacking that number), the term "warped" is being used for the condition where a rotor experiences uneven pad transference of material to the disc.

In the remainder of the cases where the rotor is being called warped, the rotor is not still not actually warped, but instead there is a partial collapse of the disc in the unsupported area between the cooling vanes. I would be interested to know if in these particular cases the collapse is always accompanied by cracks in the rotor were the collapse is occurring. If that was the case, it would be easier to identify rotors with this condition visually

Really man, stop beating a dead horse. You just made two contradictory statements, it's making my brain hurt (or the bourbon from last night).

If a rotor has collapse between the vanes, it could easily be termed "warped", as in uneven surface.

How the hell can you say that it would be easily identifiable visually, when everything stated so far refers to microscopic measurements of unevenness or buildup causing issues.

I just fail to understand your unabashed support and pushing of these ideas in defense of a problematic product. All I figure is that you work for JHM or really just love their products, which is fine.

This thread has brought up some good info from all sides at least. Again, your car and rotors are different to begin with so even though it's close, it's different, meaning a direct comparison to the RS6 can't be made, it just can't.

[SteveKen]

It's all splitting hairs here and "depends on your what your definition of 'is' is" to quote slick Willy.

Are the rotors allrightroad's problem or not? Can't say 100% for sure, but I'm not a fan of the JHM design. Disclaimer, I've never had any problems with he JHM stuff I've purchased, either.

Corbett's discoloration, whether it's heat staining or impregnation that's causing the problem is unclear, but whatever it is, it's not on the outer 20mm of the diameter of the rotor surface. Why not? Is the pad different at this point? That doesn't make sense. Is there less heat at this point? I'd guess it's heat related due to the rotor design.

https://jhmotorsports.com/products/pictures/LWrotors/JHM_B7-RS4_325mm_Rear_Rotors_Better_Center_Cooling.jpg

There's just not enough 'heat sink' in comparison to the stock rotors. They say better cooling, but the rotor has to be moving to get the cooling. Where does the heat go when the cooling effect breaks down? To the hats?

Also, all the floating rotors I've seen that bolt to the hats use a special sleeved nut that ensures that the hat is decoupled from the rotor and the rotor can float. The JHM nuts, socket head cap screws and washers look generic in comparison to Brembo's and Centric/Stoptech equivalents.

[v8a6]

Really man, stop beating a dead horse. You just made two contradictory statements, it's making my brain hurt (or the bourbon from last night).

If a rotor has collapse between the vanes, it could easily be termed "warped", as in uneven surface.

How the hell can you say that it would be easily identifiable visually, when everything stated so far refers to microscopic measurements of unevenness or buildup causing issues.

I just fail to understand your unabashed support and pushing of these ideas in defense of a problematic product. All I figure is that you work for JHM or really just love their products, which is fine.

This thread has brought up some good info from all sides at least. Again, your car and rotors are different to begin with so even though it's close, it's different, meaning a direct comparison to the RS6 can't be made, it just can't.

Why would you be so against figuring out the actual root cause of the problem? If I seem intent to figure it out, well, that is probably just my nature. My professional position involves investigating recurring issues of unknown root cause. So, as it may seem like I am being argumentative, I am not trying to be. It is just difficult to relay tone on in web discussions. My purpose is to find out the root cause of the issue. So, if your head hurts from reading the thread, then don't read anymore (or lay off the damn bourbon, unless of course you are willing to share)

Ill say this... From the evidence I have seen so far, I think the reported issues of "warped" rotors are likely mainly issues of uneven pad transference. 90+% of the time seems reasonable. The rest of the occurrences we can call "unknown" at this point. We really would have to see each instance to determine the problem.

So, when I offered to pay for shipping of the rotors to Essex, it was to attempt to get to root cause. Unrelenting persistence to determine root cause of a problem is what makes me so good at my job. You guys are getting tired after a week. Try managing a problem investigation for a year or more, if you want to see your head hurt LOL This is honestly a cake walk.

So, is the purpose of this thread simply to bash a JHM product and leave it at that, or is it to get to the root cause of the problem and determine a solution? I would say that for many on here, the purpose was to bash JHM, and that is probably why those same people get uncomfortable when the the actual root cause is trying to be determined.

Is there any other reason why you would not want root cause of this, apparently recurring issue to be determined?

[v8a6]

Interesting points Steve. We probably need to have the rotors in hand to run some tests and determine the exact root cause of his issue. I think if Corbett would donate his rotors to the investigation, instead of throwing them in the trash, then we could probably figure out exactly what root cause is.

[v8a6]

Oh yeah, and yes, I love JHM products. Who wouldn't? LOL

[hahnmgh63]

It would be nice to compare the rotors side by side with an IR temp gun to check the heat differential in different areas. On this one I would have to lean with Steve again. JHM's look like they have opened up the air gap channels ("to get better airflow") but they are cutting the weight a lot. Less heat sink and less metal support. SHW rotors of the same design as our OEM were used on all of the later Porsche GT3's up until they switched to Carbon Ceramic rotors and I would say Porsche knows Brakes.
15882
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[s8prtotype]

I don't know why you're specifically going after Corbett when there is multiple guys in this thread with REAL WORLD experience of having these JHM rotors on an actual RS6

You don't have any experience with this car or this situation at all. So I'm not sure why you're even here copy and pasting different sections of the internet, let alone putting up a fight.

At the end of the day I'm only going to believe ALL of these guys with them on their car. EXPERIENCE.

Cue the link to bedding in pads like no one here knows how to do it.... No one here has changed set-ups multiple times since they all own this super car and drive it like grannys. Might wanna read what you're copy and pasting from the internet because you contradicted yourself. Don't believe everything you read.

[v8a6]

I am not specifically going after anyone. I will reimburse the shipping charges to anyone with the problem willing to donate their rotors to investigate root cause. That is if Essex agrees to examine them.

You are mistaking an investigation for a fight. And I dont have to own an RS6 in order to investigate the reported issues with JHM rotors.

If you have no interest in ever purchasing a set of JHM rotors, and you dont own any at the moment, then just fuck off out of here. You arent ever going to buy them anyway, so what do you care what other people talk about? Seriously, what the fuck do you care what other people are discussing if you have no interest in the product?

[hahnmgh63]

Part of the reason for these automotive forums are for enthusiasts and DIY'ers and others to learn about their cars, improvements and modifications and to share experiences. Even if I don't plan on buying a set of their rotors I would be interested/curious to learn why so many have had problems? Is there a fault in the design, metallurgy, pad recommendation, installations? It may help others make informed choices thinking about Brake upgrades. Other than stock their are not a lot of choices, and those that are out there are not cheap. JHM, C6 RS6 rotors w/C5 caliper adaptes, C6 RS6 Brakes w/C6 calipers, Brembo Rotor & Calipers, Stoptech, etc...

[v8a6]

Thank you Hahnmgh63. You fucking get it LOL

[s8prtotype]

I am not specifically going after anyone.

Yes you are.


I dont have to own an RS6 in order to investigate the reported issues with JHM rotors.

Yes you do.


If you have no interest in ever purchasing a set of JHM rotors, and you dont own any at the moment, then just fuck off out of here. You arent ever going to buy them anyway, so what do you care what other people talk about? Seriously, what the fuck do you care what other people are discussing if you have no interest in the product?

What, Are you 12? You don't even own the car, Why are you even here?? You're simply ignorant to this fact, and I HOPE not employed by JHM. Because if so you're diminishing there credibility with every post.

I have nothing against them, and I probably would have bought the rotors if it wasn't for other real world experience from multiple members who actually own the car.

It's big, fast and It's heavy. These rotors are not up to the task for this car. Pretty simple.

[v8a6]

What, Are you 12? You don't even own the car, Why are you even here?? You're simply ignorant to this fact, and I HOPE not employed by JHM. Because if so you're diminishing there credibility with every post.

I have nothing against them, and I probably would have bought the rotors if it wasn't for other real world experience from multiple members who actually own the car.




LOL, no I am not a JHM employee, and I would agree if a company planted an unidentified employee in ANY internet discussions then I would lose all respect for that company.

If you don't understand why a person involved in an investigation doesnt have to personally have ownership of the product, then you are as dumb as fuck, period. Think about that carefully before you reply.



It's big, fast and It's heavy. These rotors are not up to the task for this car. Pretty simple.

If it is so simple, then can you explain root cause to everyone here? We are all dying to hear. Please, go ahead and educate us.

[s8prtotype]

If you don't understand why a person involved in an investigation doesnt have to personally have ownership of the product, then you are as dumb as fuck, period. Think about that carefully before you reply.

You see the thing is, no one asked for your help. No one here needs your help, NO ONE is taking you serious, you have no experience, you have no RS6, you quite frankly have no reason to be here.




If it is so simple, then can you explain root cause to everyone here? We are all dying to hear. Please, go ahead and educate us.

I can't do that you see, because I have no real world experience with the rotors on my RS6..... but here is what I'm NOT going to do... I'm NOT going to go over to.. lets say... the porshe or lambo forum and start posting random brake links in a thread about a car I don't own, like I know it all. Get it? You're making yourself look like a noob. and I'm trying to save you. I'm done here. Hopefully you get my point by now.

[v8a6]

You see the thing is, no one asked for your help. No one here needs your help, NO ONE is taking you serious, you have no experience, you have no RS6, you quite frankly have no reason to be here.

The second someone opens a thread for discussion on a public forum then it is open for discussion by the public. Are you the guy who says who can and can't post around here?



I can't do that you see, because I have no real world experience with the rotors on my RS6..... but here is what I'm NOT going to do... I'm NOT going to go over to.. lets say... the porshe or lambo forum and start posting random brake links in a thread about a car I don't own, like I know it all. Get it? You're making yourself look like a noob. and I'm trying to save you. I'm done here. Hopefully you get my point by now.

Thank you so much for trying to save me. Thank you also for admitting you have no idea what the root cause is of the pulsation issues. And thank you for leaving, so that people who are actually interested in figuring out the root cause, can continue their discussion.

[na1mt]

I am not specifically going after anyone. I will reimburse the shipping charges to anyone with the problem willing to donate their rotors to investigate root cause. That is if Essex agrees to examine them.

You are mistaking an investigation for a fight. And I dont have to own an RS6 in order to investigate the reported issues with JHM rotors.

If you have no interest in ever purchasing a set of JHM rotors, and you dont own any at the moment, then just fuck off out of here. You arent ever going to buy them anyway, so what do you care what other people talk about? Seriously, what the fuck do you care what other people are discussing if you have no interest in the product?

I must add here that in all the time I've been here, I've never seen a bigger jerkoff join this forum. Why don't you take your abusive shit somewhere else.

[v8a6]

It is clear that we are not going to be able to determine the root cause of the rotor issues without examining a problem set in person (and ideally it would be with the complete car). So, Ill repeat my invitation...If anyone is having issues of pulsation with JHM rotors, they are not using them, and they are outside warranty period or cannot get the issue resolved with JHM for any reason, then I will pay for the shipping for an expert in braking systems to examine them (Essex or someone else), and hopefully determine if there is any issue with them or not.

The odds are that the vast majority of these issues being reported are due to pad transference of material to the disc. But, that may not account for all of them, so if there is another issue it would be good to know.

Personally, I had one set of JHM rotors on my old car, and Ill be purchasing another set for my 390mm C6 RS6 brakes, if they will produce them.

I had a similar experience in the past with a JHM tune. I had a project car at the time that was having problems, and when I got the JHM tune, a few people on the forums and in person convinced me that it must be the tune that was root cause of the issues. I contacted JHM and they put me in touch directly with their Tuner, when basic troubleshooting couldnt resolve the issue.

Their Tuner spent countless hours with me on the phone, troubleshooting the issues on my car. And guess what? In the end, it had nothing to do with the tune, as JHM knew from the very beginning. Yet still, they worked with me for tens of hours to resolve my issues. That is customer service!

So, when I see someone having problems with a JHM product, and it seems as if people are jumping to a conclusion without logically troubleshooting the issue, then I feel it is in part my duty to try and help. So hopefully Corbett or someone else will donate their rotors to the cause, so future people with pulsation issues will have an idea of the possible causes.

Good Luck OP! Hope you get your problem solved.

[v8a6]

I must add here that in all the time I've been here, I've never seen a bigger jerkoff join this forum. Why don't you take your abusive shit somewhere else.

And you didnt see me join either. I was here on the forums three and a half years before you. So unless you are the forum owner, then beat it.

[na1mt]

I stand strongly by my evaluation.....and something tells me I'm not alone with that.

[koolade9]

While uneven pad deposits are the cause of vibration in braking systems "90%" of the time, the root cause in this instance is due to the rotor rings not being properly balanced after manufacturing. There are shops out there that can do this for you for a minimal charge. Now quit quibbling, get your rotors balanced, bed your pads properly, and start enjoying the stop-fast bits you spent your hard-earned money on.

[DHall1]

I ran out of popcorn last week or I might have had a dog in this fight.

But really what hahnmgh63 says about JHM opening the air gap is the very first thing that caught my eye years ago. Someone was posting up a group buy on these and one look at metal thickness and my mind said pass.

SHWs all the way for me. No brainer

It would be nice to compare the rotors side by side with an IR temp gun to check the heat differential in different areas. On this one I would have to lean with Steve again. JHM's look like they have opened up the air gap channels ("to get better airflow") but they are cutting the weight a lot. Less heat sink and less metal support. SHW rotors of the same design as our OEM were used on all of the later Porsche GT3's up until they switched to Carbon Ceramic rotors and I would say Porsche knows Brakes.
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[lswing]

While uneven pad deposits are the cause of vibration in braking systems "90%" of the time, the root cause in this instance is due to the rotor rings not being properly balanced after manufacturing. There are shops out there that can do this for you for a minimal charge. Now quit quibbling, get your rotors balanced, bed your pads properly, and start enjoying the stop-fast bits you spent your hard-earned money on.

Really? Nice first post with this enlightening info. How about the manufacturer making them right in the first place. And I think we all know how to bed in pads/new rotors. Many other things at play here.

Edit; these are go slow parts:)

[Erik]

Can I ask everyone to please behave.

I'm sure the subject is interesting, but please refrain from getting personal.

[JayB]

How is this thread still going?

[lswing]

How is this thread still going?

Well...you did just continue it. Pretty sure it's over, popcorn is burned...

[alrightroad]

I'll be doing dial/run-out measurements on both new OEM and the JHM's on two different cars over the next few weeks as I get to it. Will also resurface the JHM's after dial measurements and then test with new OEM pads with proper bed-in (per Stoptech article, as a well know go-to for procedure). I have very clean and even pad wear rotor markings. no blotches or hot spots. Will post up pics as I pull things apart and start physical analysis.

[essexmetal]

Alrightroad is going collect solid data and not subjective estimates. Can't argue with those findings no matter how much you think you understand about brakes. To earlier discussion on rotor vane count and friction surface stability, it definitely matters but usually only when some big heat and load is put on the rotor. If the rotor as produced has some residual stress those inputs can be less to get the same effect. As noted if the friction surface sinks or get wavy it has the same pedal feel as the proverbial warped rotor. I just want to say again, there are so many things that can be out of whack, or go out whack on an assembled rotor. Beside the disc settling, the mounting hat to disc interface could have run out, the hat can go out during use as well. Some companies use 6061 aluminum for the hat material. That bar is extruded and you would be surprised by how much it moves when you cut a large portion of it away. If I am using 6061 for a hat or any thin wall shape I rough out the parts, remove them from the machine and then we rechuck them the next morning to machine to finish dimensions. There is a far bit of wobble once it settled.

The attached picture shows rotors used in the same application. The vent count is the difference between an endurance rotor and a sprint rotor. As you can see the extra vents offer a lot more support for the friction surface.

[koolade9]

Once again.


While uneven pad deposits are the cause of vibration in braking systems "90%" of the time, the root cause in this instance is due to the rotor rings not being properly balanced after manufacturing. There are shops out there that can do this for you for a minimal charge. Now quit quibbling, get your rotors balanced, bed your pads properly, and start enjoying the stop-fast bits you spent your hard-earned money on.


You can check runout all you like, but have a peek at the outer edge and look for balancing marks, or a lack thereof. They typically look like this:
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I've already been through all this:
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[s8prtotype]

If that's the case then JHM should replace or rebalance all the rotors they've sold that's had issues...

[v8a6]

Essex, there you go again making too much sense :)

alrightroad, sounds like you have a good plan to investigate the issue. Looking forward to results.

koolade, OP is experiencing brake pedal pulsation, not consistent vibration, from what I understand. If the rotor itself were unbalanced (yet true), then I would think that the vibration would be persistent on or off the brakes (which it is not). Also, OP states that "Within about 15 miles after bed-in, I noticed I've got major pulsation". This implies that they showed no sign of pulsation when new, and the pulsation started only after bed-in. If the rotors were out of balance from the factory (as you state), then the issue would have been there from new. According to OP, it was not. alrightroad, please correct me if anything I am stating about your symptoms or experience is inaccurate.

Finally koolade, while I do not doubt that there is such a thing as an imbalanced rotor, what we need to get to root cause of this issue is proof. You stated the following While uneven pad deposits are the cause of vibration in braking systems "90%" of the time, the root cause in this instance is due to the rotor rings not being properly balanced after manufacturing. With the evidence we currently have available, there is no way that you can make that statement with 100% certainty. And actually, I would say that there is evidence that the rotors were fine when they left the factory (the car showed no pulsation when first installed)

This thread has been filled with speculations, and that is good, because it gives us a list of possible root causes. Now, OP is going to run some tests to try and determine the actual root cause.

[essexmetal]

I balance all my assemblies on a knife edge balancer that is accurate it to less than .5 of a gram at 150mm radius. Far more accurate than a rotor could ever utilize. Balance is important on anything that rotates, but it won't cause the kind of pulsations that previously mentioned issues will cause. It will impart more vibrations /pulsations into the steering. If there is a rotor thought to have a noticeable imbalance it will also decrease as the car slows. Before focusing on imbalance as your main issue, also note that in a dynamic state it is part of the entire rotating mass of the wheel. This brings in variables of accurate tire / wheel balance as well. The radius of rotor is much less than a tire, so the tires mass and speed will register much worse. On the other side the same radius and mass of a tire is also capable of dampening a rotor imbalance.

This is just information not an indictment of balancing. I support properly balanced, surfaced and true running rotors. Conversely, on a car that weighs 4000lbs, has a high unsprung weight, high rotating mass and overall pretty low average top speeds, one does not need to get as precise as a race spec car.

[v8a6]

Great info, Essex

[koolade9]

I balance all my assemblies on a knife edge balancer that is accurate it to less than .5 of a gram at 150mm radius. Far more accurate than a rotor could ever utilize. Balance is important on anything that rotates, but it won't cause the kind of pulsations that previously mentioned issues will cause. It will impart more vibrations /pulsations into the steering. If there is a rotor thought to have a noticeable imbalance it will also decrease as the car slows. Before focusing on imbalance as your main issue, also note that in a dynamic state it is part of the entire rotating mass of the wheel. This brings in variables of accurate tire / wheel balance as well. The radius of rotor is much less than a tire, so the tires mass and speed will register much worse. On the other side the same radius and mass of a tire is also capable of dampening a rotor imbalance.

This is just information not an indictment of balancing. I support properly balanced, surfaced and true running rotors. Conversely, on a car that weighs 4000lbs, has a high unsprung weight, high rotating mass and overall pretty low average top speeds, one does not need to get as precise as a race spec car.

le sigh...

Rotors were out of balance by 70g...significant. I have tried multiple sets of these trying to chase down the problem, experienced the same issue(s), and after a proper balance/resurface, I now have smooth rotors with zero issues. As I'm apparently the only one in this thread to have this issue and actually solve the problem...why discredit someone who's actually been through all of this and is providing a valid solution? When the folks on here tire of fiddling with the options on the last 7 pages, please come back and revisit my post.

[v8a6]

Hey kool, you didnt state in any of your posts that you had the JHM rotors and that you fixed the issue by balancing them. The two pics you posted don't seem to be of JHM rotors (unless they are an old design that look different)

So can you clearly state the details of your case and findings? Confirm you are talking about JHM RS6 rotors, and confirm that you had pulsation issues, etc. You say you had the same problem with multiple sets? You are skipping over key facts, and it looks like you may have information that could help here.

Thanks!

[koolade9]

I'm sure you're a good guy who means well, please pardon my snarkiness...


Hey kool, you didnt state in any of your posts that you had the JHM rotors and that you fixed the issue by balancing them.


While uneven pad deposits are the cause of vibration in braking systems "90%" of the time, the root cause in this instance is due to the rotor rings not being properly balanced after manufacturing. There are shops out there that can do this for you for a minimal charge. Now quit quibbling, get your rotors balanced, bed your pads properly, and start enjoying the stop-fast bits you spent your hard-earned money on.

In proper forum etiquette, it should go without saying that I'm posting about JHM rotors for an RS6, as I posted in a thread titled: 'JHM Rotors - who has? Anyone have pulsation issues when new.' that is in the 'RS6 / S6 / RS7 / S7 / S8' section.


The two pics you posted don't seem to be of JHM rotors (unless they are an old design that look different)

2nd was pic of said rotors after all was said and done. Balancing pic was generic to show what balancing marks look like to those who are unaware. Those who are skeptical, or have already tried resurfacing/re-bedding and are still experiencing these issues, please check your rotors for the existence of said marks.


So can you clearly state the details of your case and findings? Confirm you are talking about JHM RS6 rotors, and confirm that you had pulsation issues, etc. You say you had the same problem with multiple sets? You are skipping over key facts, and it looks like you may have information that could help here.

Thanks!

Rather than tell a long, drawn out story about my journey with multiple sets of JHM RS6 rotors, and the pulsation issues I was seeing, I've tried to keep it concise:


le sigh...

Rotors were out of balance by 70g...significant. I have tried multiple sets of these trying to chase down the problem, experienced the same issue(s), and after a proper balance/resurface, I now have smooth rotors with zero issues. As I'm apparently the only one in this thread to have this issue and actually solve the problem...why discredit someone who's actually been through all of this and is providing a valid solution? When the folks on here tire of fiddling with the options on the last 7 pages, please come back and revisit my post.

As this is my 4th post on RS6, I have no desire to go back and forth over hat torque specs, run-out, metallurgical observations, etc., challenging opinions in an effort to establish some perceived level of credibility amongst members. I'm not even an RS6 owner, I'm a B7 RS4 owner, and am using RS6 rotors in that application. It was brought to my attention that the folks over here were still having issues with them...So I joined, and have posted facts; feel free to believe them...or don't.

[v8a6]

Thanks for your input.

Just one question, on the 2nd pic that you say are JHM rotors, are you using both JHM rotor rings and JHM rotor hats, or are you mixing and matching JHM rings with different hats? I have never seen JHM rotors with that floating design that yours show in the 2nd pic.

http://www.rs6.com/attachment.php?attachmentid=15891&d=1421806118

They look more like something on these K-sport hats
http://www.carid.com/images/ksport/brakes/supercomp-brake-kit-8-piston-5.jpg

[koolade9]

Thanks for your input.

Just one question, on the 2nd pic that you say are JHM rotors, are you using both JHM rotor rings and JHM rotor hats, or are you mixing and matching JHM rings with different hats? I have never seen JHM rotors with that floating design that yours show in the 2nd pic.

Valid question. They're RS4 OE hats with RS6 rings. The issue(s) I had were related to the rings. I have no experience with the JHM hats and it looks like they were covered on previous pages in this thread.