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

[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/23...ibration-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-su...nd-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)

[v8a6]

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

[Corbett]

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

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


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.