[squixs]

Hey guys,

For some time now, I'm experiencing brake vibrations at highway speeds (55 mph++). Since the car is still under warranty, I already went to the dealer with it. They were able to reproduce the error, said to me the rotors were warped and that this isn't covered under warranty.

I found this really strange since, to be honest, I don't drive the car that hard and I've never tracked it. When inspecting the rotors, I do see some imprints from my brake pads, so I think it's likely that this has something to do with it.

I also don't feel the vibration in my steering wheel. To me, it's even less likely that I've warped the rears.

Is there anything I can do to resolve this? I already tried some hard braking (130mph -> 50mph) but this really didn't change much.

I've attached two pictures of a rear rotor, others look similar.


2018 M2 LCI (N55)
Stock rotors + pads
Never tracked

[3t3p]

There is no spoon aka warped rotors

https://www.google.com/url?sa=t&sour...geQ47I6fsJZy3W

I've had periodic judder from drivers side front disc but right now it's gone. No tracking.

[squixs]

Originally Posted by 3t3p

There is no spoon aka warped rotors

https://www.google.com/url?sa=t&sour...geQ47I6fsJZy3W

I've had periodic judder from drivers side front disc but right now it's gone. No tracking.

That's indeed what I was thinking. I've seen some post that in Ida yes running a track pad for a week can work

[Daytona_550]

From the quoted article:

The obvious question now is "is there a "cure" for discs with uneven friction material deposits?" The answer is a conditional yes. If the vibration has just started, the chances are that the temperature has never reached the point where cementite begins to form. In this case, simply fitting a set of good "semi-metallic" pads and using them hard (after bedding) may well remove the deposits and restore the system to normal operation but with upgraded pads. If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse. Do not bead blast or sand blast the discs for the same reason.

[squixs]

Originally Posted by Daytona_550

From the quoted article:

The obvious question now is "is there a "cure" for discs with uneven friction material deposits?" The answer is a conditional yes. If the vibration has just started, the chances are that the temperature has never reached the point where cementite begins to form. In this case, simply fitting a set of good "semi-metallic" pads and using them hard (after bedding) may well remove the deposits and restore the system to normal operation but with upgraded pads. If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse. Do not bead blast or sand blast the discs for the same reason.

Thanks!!

[Drop the hammer]

I had a similar issue on my disks after I baked them at the track on stock pads. The brakes juttered so bad I thought I had warped them.
Going off what some guys were saying here, I bought some track pads from Ferodo ds1.1 I think. And ran them for a bit and they scraped it all off. Sounded terrible though as the track pads squeal terribly. Sounds like a dump truck!
Once the jittering was gone I switched back to more street friendly ferodo ds2500 pads. All was good after that!
Can try it to see if it works. Way cheaper than new disks.

[squixs]

Thanks!! Good to know

[jritt@essex]

Here is a video we produced quite some time ago that shows how to scrub discs using race pads. This shows what Drop The Hammer mentions above. You may find it helpful!

[Doublej]

Also a tip, if your brakes/discs are hot after a spirited drive, don't engage the parking brake if you stop until the brakes cool. I think that is a top reason why pad material bakes onto the rotor and given your photo, may have been why you can see the outline of the pad on your rotor.

[Maynard]

Dealership is not being straightforward on this. Discs really won't 'warp' and if they do, then it would be because the expansion pins were defective or some other issue (unless you'd been abusing them, which you say you are not). This should be covered under warranty as it isn't simply wear.

But since they aren't likely to reverse themselves, try this before you spend on special pads and double swapping them. Try washing it to get 'em all 'rusty', then next day go out someplace you can truly bed them properly: warm them, then do multiple 70-5 or 80-5 hard stops right in a row; probably at least 8-10 cycles of stopping. Just a few hard stops won't have the same effect.

[tux2005]

Originally Posted by Doublej

Also a tip, if your brakes/discs are hot after a spirited drive, don't engage the parking brake if you stop until the brakes cool. I think that is a top reason why pad material bakes onto the rotor and given your photo, may have been why you can see the outline of the pad on your rotor.

You're right in that you shouldn't engage the parking brake if the rotors are hot but it shouldn't really make a difference with pad deposits. The parking brakes on our cars are drum-style using the rotor hat as the drum. The issue with applying the parking brake while the rotors are hot is that the parking brake shoes can seize to the rotor/drum and not release when the handbrake tension is released.

[Doublej]

Originally Posted by tux2005

You're right in that you shouldn't engage the parking brake if the rotors are hot but it shouldn't really make a difference with pad deposits. The parking brakes on our cars are drum-style using the rotor hat as the drum. The issue with applying the parking brake while the rotors are hot is that the parking brake shoes can seize to the rotor/drum and not release when the handbrake tension is released.

I actually didn't realize that. I guess I learned my 1 thing for today.

[squixs]

I never apply the parking brake on the car actually. Since the imprints are also at the front, I sort of ruled that out already. DoubleJ, I’ll try your suggestion as wel as giving the dealer an additional call.