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

[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




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.