warped rotors

bigwave2255 · #1 03-17-2011, 01:43 AM

hi

i have replaced my front rotors due to warping with Zimmerman after market rotors, and they to have warped slightly in a very short time, so i had them skimmed, and they are now showing very slight signs of warping again.

(yes i know BMW doesn't recommend skimming however these still had more than the minimum thickness after skimming)

i have driven very conservatively since i had them skimmed.

this is starting to get frustrating, i know all the negatives for cross drilled and/or slotted rotors but i wonder if cross drilled would be an advantage in my case, i,m assuming the rotors are getting to hot driving constantly in stop start traffic

what do you think,

oh and i saw in a pic posted here of what looked like a break cooling duct but with a blanking plate over it!!!

what experiences have you had???

Ewen

JCL · #2 03-17-2011, 02:10 AM

It is very unlikely that the rotors are actually warped. It is likely that they have uneven pad deposits that cause that sensation.

Recomend that you read through this, it is one of the better summaries out there:

StopTech : Balanced Brake Upgrades

Essentially, it is caused by a combination of your pad material, the initial surface finish of the rotor, and the break-in procedure by which the pads were bedded in, or not.

Cross drilled rotors have less ability to handle heat, so if the rotors were overheating, that would be the wrong way to go.

bigwave2255 · #3 03-17-2011, 06:11 PM

thanks, that was worth while reading, so it seems that this whole warped rotor thing might be a miss diagnosis, however skimming them probably does nothing more that cleaning them up but is not really the correct way to address the issues

thanks for the post

JCL · #4 03-17-2011, 06:32 PM

Quote:

Originally Posted by bigwave2255

thanks, that was worth while reading, so it seems that this whole warped rotor thing might be a miss diagnosis, however skimming them probably does nothing more that cleaning them up but is not really the correct way to address the issues

thanks for the post

Yes, it will clean them up, but if you bed them in the same way, and use the same pads, there is nothing to prevent it from happening again (as happened to your vehicle). You can try some different pads, and/or try bedding them in according to the instructions on the link.

Roadkill · #5 03-17-2011, 06:16 PM

ewen, when was the last time that the lower control arm bushings were replaced. as these wear, they mimic the feel of warped rotors. if you don't know, check the bushings for cracks or wear. i'm doing mine tonight because of the very same symptoms you are having.

phil47 · #6 03-17-2011, 06:58 PM

Quote:

Originally Posted by dinan e39

ewen, when was the last time that the lower control arm bushings were replaced. as these wear, they mimic the feel of warped rotors. if you don't know, check the bushings for cracks or wear. i'm doing mine tonight because of the very same symptoms you are having.

I am having the same problem. Seems to only occur when lightly braking from higher speeds and it goes away as speed is scrubbed off...and it is very intermittent. Does this describe your symptoms?

Reason I am asking is I only have around 40,000 miles on the brakes and rotors. I am also going to try rebedding them tonight.

Roadkill · #7 03-18-2011, 12:16 AM

phil, sounds like control arm bushings. i've had warped rotors on other cars and it seems that the harder you brake the worse the shaking. my symptoms are like yours in that the front only shakes under certain conditions and it doesn't do it all the time.

RichiRich · #8 03-18-2011, 10:29 AM

I've blown through two sets of stop techs.....warped and confirmed both times...first set resurfaced and good for a couple of months then..the warping started again...front end thoroughly checked and replaced what needed to be done... this time around my rear stoptechs are fine and just bought some r1concepts slotted front rotors to match the ST's. went with akenebo euro this time for pads instead of axxixs deluxe......after a great bedding in....we will see.....

Rich

phil47 · #9 04-17-2011, 05:54 PM

Quote:

Originally Posted by dinan e39

phil, sounds like control arm bushings. i've had warped rotors on other cars and it seems that the harder you brake the worse the shaking. my symptoms are like yours in that the front only shakes under certain conditions and it doesn't do it all the time.

Yup...diagnosed as worn control arm bushings. Lower control arms changed (under extended warranty) and problem is gone.

CT_X5_Joe · #10 03-18-2011, 02:55 PM

I had Zimmerman's on my E36 M3. Hated them, started shaking after only 5k.

I switched to brembo cross drilled. No issues after. For pads I think EBC green are hands down the best.

I put the above combo on my last ride, Mercedes ML 55 (know for eating up brakes) and I got over 40k out of pads/rotors.