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

**alrightroad** · January 3rd, 2015, 01:26

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** · January 3rd, 2015, 02:09

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** · January 3rd, 2015, 02:24

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** · January 3rd, 2015, 02:24

Did the rotor hat bolts come loose?

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

**DHall1** · January 3rd, 2015, 04:43

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** · January 3rd, 2015, 05:58

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

**Corbett** · January 3rd, 2015, 06:33

Originally Posted by 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.

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** · January 3rd, 2015, 07:25

The JHM rotors are junk. Nuff said...

**alrightroad** · January 3rd, 2015, 15:51

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** · January 3rd, 2015, 16:40

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** · January 3rd, 2015, 18:33

http://www.rs6.com/showthread.php/23...ibration-issue

**lswing** · January 3rd, 2015, 20:21

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** · January 4th, 2015, 01:56

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** · January 4th, 2015, 03:37

Always liked Hawk pads...

**DHall1** · January 4th, 2015, 03:43

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** · January 4th, 2015, 05:07

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

Here they are after resurfacing.

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

**s8prtotype** · January 4th, 2015, 07:40

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

**nistah** · January 4th, 2015, 15:48

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

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