[Mark e90]

I'm getting a slight shudder when braking from 70mph or over. I know it's not a warped rotor as I changed all rotors and pads a few months back.
Any ideas what could cause this ? It only happens if I'm going 70mph or more then applying brakes, slight shudder then once I go below 70mph or release the brakes it stops completely.

[Taran.J]

Control arms?

I hope that 70mph is legal

[Nati0n]

Rotors don't warp except in very few, select applications such as racing or towing extreme weight. It's misinformation, and often the reason why people don't understand it happening to a new set of brakes. What we consider "warped" is really an uneven transfer of braking material to the surface of the rotor, causing pulsation under load. Did you bed your brakes in properly when you got new rotors and pads? Have you recently sat at a stop light with the brakes depressed after a hard run with really hot discs? New or not, that could have caused it if you have uneven material build up on your rotors.

The best thing to do is probably get the rotors resurfaced if you check other components and can eliminate the control arm issue as Taran said.

Don't believe me?

http://www.stoptech.com/technical-su...nd-other-myths

[mpaone23]

Originally Posted by Markcaughey

I'm getting a slight shudder when braking from 70mph or over. I know it's not a warped rotor as I changed all rotors and pads a few months back.
Any ideas what could cause this ? It only happens if I'm going 70mph or more then applying brakes, slight shudder then once I go below 70mph or release the brakes it stops completely.

I am experiencing this as well, except mine is probably around the 45mph range. I am fairly new to the car scene as far as knowledge goes so I thought I may have warped rotors as well. I never really considered control arms. Hopefully someone can shed some light on this.

[Mark e90]

Yeah brakes where bedded in properly I'm thinking it's more likely to be the control arm as the brakes only have around 1500 miles on them

I had this problem with my old e90 (320d) changed the front rotors + pads problem solved. However the shudder was more severe and at all speeds upon braking

[Nati0n]

Do you have any strange noises associated with it? Does it happen more in the cold? Definitely possible it could be the control arms, or some suspension bushings or such.




The crux from StopTech to save you guys some reading by the way if anyone is interested:

"...in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc...

In fact every case of "warped brake disc" that I have investigated, whether on a racing car or a street car, has turned out to be friction pad material transferred unevenly to the surface of the disc. This uneven deposition results in thickness variation (TV) or run-out due to hot spotting that occurred at elevated temperatures."

[Canadian 335xi]

Check tread depth all around.

[Nati0n]

^I would think a flat spot or tire depth variation would be apparent at that speed whether braking or not, and he's describing it just under braking.

[Efthreeoh]

Sounds like control arms (thrust arms). Mine started doing that at 180,000 miles. I dropped in new M3 arms and the issue went away.

[Mark e90]

Is there any other way to check this manually ? Like shaking each wheel to check for play ?

[Efthreeoh]

Originally Posted by Markcaughey

Is there any other way to check this manually ? Like shaking each wheel to check for play ?

The bushing at the subframe is hydraulic and tends to leak once the symptom shows up.