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-   -   Z4 Roadster (E85) E85 Z4 3.0si brake pedal vibration after rotors & pads replaced (http://www.bimmerfest.com/forums/showthread.php?t=649563)

goeslikeschnell 10-02-2012 10:59 PM

E85 Z4 3.0si brake pedal vibration after rotors & pads replaced
 
I just replaced my rotors and pads on my E85 Z4 3.0si roadster. I used centric cross drilled rotors all around and cool carbon pads. I'm now getting a vibration through the brake pedal while braking above 70mph. After the car slows below 70 the vibration stops. There is no vibration through the steering wheel and it makes a noticeable noise in the cabin of the car when the vibration is happening. I've bedded the brakes twice now which did not resolve the issue.

Looks like someone who installed the same equipment on an e90 (http://www.e90post.com/forums/showthread.php?t=543561) had the same issues, but I don't see any resolutions posted.

I had the front control arm bushing replaced on the car today and the issue seems better, but is definitely still there. Any thoughts??

Thanks!

brock5ga 10-03-2012 03:53 AM

If the vibration was not present before replacing the brakes one of the rotors is most likely warped. If you are not feeling it through the steering wheel, it is most likely the rear. Remove the rotors and check for rust on the hub or debris between the hub and rotor that may not let the rotor sit flush with the hub. Unless you have a dial indicator, it will be difficult to tell which rotor is out of round. To verify the fronts are ok, safely remove both hands from the steering wheel and apply brakes till you feel the vibration while watching the wheel. If the wheel moves side to side, check the front for issues. Sometimes it is hard to feel the vibration in the wheel even though you can feel it in the vehicle. Although I do not like to resurface European and slotted or cross drilled rotors, I have done so. On most Asian and Domestic cars, I resurface new rotors before installing. You would be surprised the amount of rotors that are not true out of the box. The post you linked looks like the issue was present before the brakes were replaced. If that is the case, look elsewhere. If there were no issues present prior to replacing the brakes, go there first.

Droptop85 10-03-2012 04:03 AM

Sounds like those rotors suck. Take them in and have them turned or buy a runout tool and check them yourself for fun

wifesauto 10-03-2012 06:16 AM

and use a torque wrench on the lug nuts with the correct pattern

chickdr 10-03-2012 07:57 AM

Since changing to Hawk Ceramic pads from OEM on my M, I now have vibration through the pedal as the OP stated(not like a warped rotor feels, just vibration at certain speeds). I also noticed this when I put cross drilled rotors on a 944 I had years ago. I suspect what is going on is the drilled rotors are noisy compared to the OEM rotors he had previously. It is likely normal or could be pad related.

wifesauto 10-03-2012 09:21 AM

put the car on a lift and with the tires on use a dial indicator to check for run out. as per some factory manuals ....reclock the rotor on the axel flange

goeslikeschnell 10-03-2012 10:32 AM

sounds like my next step is to have the rotors checked.

GA Z4 10-03-2012 12:14 PM

I put slotted and drilled rotors on my Z4 earlier this year. I don't have a vibration but there is a different feel and sound to them. I have driven cars with slotted and drilled rotors before so kind of knew what to expect but it is definately different than OEM. FWIW. If you can check the rotors for piece of mind, go for it, but I would guess it is probably ok.

crewdog843 10-05-2012 07:41 PM

Be very careful tightening down the lug nuts. If you have a torque wrench, use it. If you don't have, or don't want to buy one (about 80 bucks), find a friend who has one. Costco can tell you how many inch/pounds to torque to. BMW rotors are very thin and do not take a lot of pressure. Use to be a regular problem with my '91 325i, until I found out to not trust the tire company's torque sticks. Costco re-calibrates theirs every day.


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