Dealing with high speed brake vibration

[noremaC]

Originally Posted by nrubenstein

So, brake vibration can come from:
1) Pad deposits on the rotors.
2) Bad wheel bearings (a big concern if you are also getting an intermittent long pedal, as this suggests pad knockback).
3) Balljoint or bushing failure. The thrust arm bushing, and the front lower link seem to be the weakest components in the E9x front suspension.
4) It is possible that the rotor is warped. I've had issues in the past with the BMW "floating" rotors. I wouldn't rule it out.

1 - attempting to correct with ESB Yellow pads - haven't gotten a chance to heat up the rotors, yet
2 - don't believe I'm experiencing "long pedal", however not entirely sure what that is
3- what is the replacement part(s) here? Is this FCAB (i.e replace with monoballs)?
4- will likely put on new rotors all else fails (maybe a used front BBK)

[nrubenstein]

Originally Posted by noremaC

1 - attempting to correct with ESB Yellow pads - haven't gotten a chance to heat up the rotors, yet
2 - don't believe I'm experiencing "long pedal", however not entirely sure what that is
3- what is the replacement part(s) here? Is this FCAB (i.e replace with monoballs)?
4- will likely put on new rotors all else fails (maybe a used front BBK)

1- I'm going to second others and say that I'm not convinced that the EBCs will solve your problem. Hawk Blues are famous as rotor cleaners (and paint destroyers) for a reason. One of the difficult parts about this is that you want to keep the brakes COLD when you do this.
2 - You said the pedal has gone to the floor. That's "long pedal." Or when the pedal just goes down further than expected. Although if it's from just the one time, probably not the bearings. (Note, if you haven't bled your brakes, you should do that after boiling them.)
3 - The thrust arm is commonly "upgraded" to monoball, although there's an NVH penalty. The lower control arm link (the little arm) just has to be replaced if it's bad.
4 - Buying an expensive set of brake pads to maybe or maybe not fix a bad set of not *that* expensive rotors probably doesn't make much sense. If you've been unable to make this go away after a few hundred miles, it's probably not going to.

[noremaC]

Originally Posted by nrubenstein

1- I'm going to second others and say that I'm not convinced that the EBCs will solve your problem. Hawk Blues are famous as rotor cleaners (and paint destroyers) for a reason. One of the difficult parts about this is that you want to keep the brakes COLD when you do this.
2 - You said the pedal has gone to the floor. That's "long pedal." Or when the pedal just goes down further than expected. Although if it's from just the one time, probably not the bearings. (Note, if you haven't bled your brakes, you should do that after boiling them.)
3 - The thrust arm is commonly "upgraded" to monoball, although there's an NVH penalty. The lower control arm link (the little arm) just has to be replaced if it's bad.
4 - Buying an expensive set of brake pads to maybe or maybe not fix a bad set of not *that* expensive rotors probably doesn't make much sense. If you've been unable to make this go away after a few hundred miles, it's probably not going to.

It's a catch 22. Buy a new part and hope it fixes the issue. Or chase the problem with different approaches (i.e. aggressive pads to clean up the rotors). I don't think it's a suspension issue - I really believe it's something to do with the rotors. Can I get there with a $100 fix (brake pads)? Or bite the bullet and spend $700 on new rotors and pads.

[Redd]

https://itstillruns.com/clean-glaze-...s-4421355.html

[noremaC]

Originally Posted by Redd

https://itstillruns.com/clean-glaze-...s-4421355.html

Can you visibly see glaze? Rotors don't look abnormal.

[SAMM3Y]

If you were going to go to all that trouble I'd just pull the rotors and have them turned... do we not turn m3 rotors for some reason?

[noremaC]

Originally Posted by SAMM3Y

If you were going to go to all that trouble I'd just pull the rotors and have them turned... do we not turn m3 rotors for some reason?

I read a comment from Malek@MRF from 2012 that he has resurfaced tons of cross drilled M3 rotors without issue: see here / full thread.

Judging from the craters in my OEM pads (right before I put on the EBC's) I'm willing to bet there are deposits in the cross drills which are causing the vibrations. I just need to figure how to BLAST them out.

[nrubenstein]

Originally Posted by noremaC

I read a comment from Malek@MRF from 2012 that he has resurfaced tons of cross drilled M3 rotors without issue: see here / full thread.

Judging from the craters in my OEM pads (right before I put on the EBC's) I'm willing to bet there are deposits in the cross drills which are causing the vibrations. I just need to figure how to BLAST them out.

How much have you gently driven the car since this issue?

Gentle is the key to cleaning off rotors with aggressive pads as you're actively trying to avoid pad material transfer.

[noremaC]

Originally Posted by nrubenstein

How much have you gently driven the car since this issue?

Gentle is the key to cleaning off rotors with aggressive pads as you're actively trying to avoid pad material transfer.

Normal street driving mixed with some hard stops when I first swapped in the EBC Yellow's. Been about 2 weeks and definitely a judder/vibrations still there. It's a shame since the rotors have only 15k miles on them. On my e92, they went about 75k miles. Neither car had seen the track on those sets of rotors.

[Ashley_rj]

Originally Posted by nrubenstein

So, brake vibration can come from:
1) Pad deposits on the rotors.
2) Bad wheel bearings (a big concern if you are also getting an intermittent long pedal, as this suggests pad knockback).
3) Balljoint or bushing failure. The thrust arm bushing, and the front lower link seem to be the weakest components in the E9x front suspension.
4) It is possible that the rotor is warped. I've had issues in the past with the BMW "floating" rotors. I wouldn't rule it out.

I warped my stock front rotors on a track day with padgid rsl 1's. I was a bit naieve and cooked the breaks, they became extremely juddery when hot and ok when not but there was a bit of vibration in the steering wheel when driving. I have since up graded to a BBK. Yet to take that to the track though... damn COVID!!