Tom84

Hi all,

It's been almost a year now that I've been struggling with a persistent brake judder problem. The problem occurs as soon as I apply the brakes, it gets worse as I apply more brake force, and it stops with maximum force. The judder seems to get worse when the brakes heat up, up to a point where the judder gets dangerously violent and the car doesn't seem to decelerate the way it should. (Only) At this point all 4 brakes get a blueish hue, I suspect it's because with the judder I have to push the brakes a lot harder to get the needed deceleration.

By now I've been through 3 new sets of ATE brake discs, one time I had one of those 3 resurfaced, 2 sets of TRW brake pads (the exact same parts as came with the car, though without the BMW logo). Every time the brake judder was completely gone for about 2500km, and then returned slowly to the same level by 3000km.

This weekend I installed my 4th set of new brake discs and 3rd set of pads and after 400km (250 miles) the same marks are appearing on my discs so I'm pretty confident that I still haven't removed the cause of my problem.

Up to this weekend I've been convinced that my brakes must have all gotten warped. However while installing the new brakes I noticed that when I turned them, the same minimal (far less than a mm) wiggle could be noticed when using the installed new pads as a reference point.

What did I try:

- Cleaned hub and contact surfaces on my wheels and apply copper grease for better heat conduction
- reconditioned and greased the slider pins
- checked free movement of the caliper pistons
- checked for slack on the bearrings
- Changed the control arms
- Changed the hydraulic bushings
- had my rotors resurfaced to erase warping by released material tension.
- opened the brake cooling channels (were originally closed on my 520d)

Use of the car and driving style:

- I use the car 90% on highways, mostly at a pretty much constant 90mph without much brake abuse. It is an automatic, so even though I try to avoid it as much as possible there are points where I have to keep the brakes applied.

- The last time the brake judder started, I was on a 3500km trip and didn't encounter any puddles or rain along the way, and yet at 2500km I started to notice the judder had returned. So I'm sure that the rotors didn't get a thermic shock.

- I consider myself a fast driver, but I don't use the road as a racetrack. If I can't keep a continuous speed because of the traffic, I just drive slower. So I haven't been cooking the brakes.


Car:

'08 E61 LCI 520dA, remapped at 155KW
230000km (143000mls), problem has been there since 195k-ish, bought the car with 110k km
324x30mm rotors front
17" oem BMW wheels


Below you'll see a few pictures with the markings that have been returning in 4 generations of rotors. Please meet the family


This is my new set of Bosch rotors with Bosch pads, 100mls after bedding in. You can see that on the inner ring a discoloration is starting to form. You'll see the same pattern return on all the discs I replaced.

https://www.dropbox.com/s/tqop1dwsc02ffho/IMAG0215.jpg

https://dl.dropboxusercontent.com/u/...n/IMAG0232.jpg

https://www.dropbox.com/s/69ezy0xw03sjdai/IMAG0227.jpg

https://dl.dropboxusercontent.com/u/...n/IMAG0228.jpg


Has anyone got any idea what might cause this judder to keep returning so I can tackle the cause before it ruins another expensive set of rotors? I'm out of inspiration and pretty desperate to find a solution.

Thanks for your help

turboawd

either you have a bent hub or warped rotors. do you have a dial indicator? maybe attach it and see if the hub face and rotor face run true.

turboawd

a sticking caliper can cause the rotor to heat up and warp also.

Tom84

Thanks for your reply. I'm pretty sure that the calipers don't stick, my brakes aren't hot when I check after parking the car.

A bent/untrue running hub might be something to look into. I hadn't yet because since there was no slack on them, and it seemed unlikely to me that both sides would have the exact same problem.

Has anyone here had a similar problem with their hubs?

e6t.lab.rat

Compare the thickness of the pads, both the inner and outer pads. Is one thicker than the other? I'm willing to bet they are not wearing down evenly based on the pics. Also if you have a thickness caliper, compare the thickness of the pads towards the inner and outer portions of the pad. A sticking caliper may not necessarily cause an excessively hot rotor. One piston may move freely but the other may be stuck and not move at all, thus the clamping pressure will be on one pad only causing uneven wear (both pad and rotor). Any sign of uneveness indicates a sticking caliper. Good luck

biz77

I suspect calipers that need to be replaced or rebuilt.


BTW, BMW says do not apply grease to the guide pins.

Hyper_545i

Correct.

Did you bed in the pads/rotors? If so, did you follow the proper procedure per the manufacturer? Did you take it easy for a few hundred miles on the setup before really heating them up? Thermal shock is a bad thing. Try bedding the pads and rotors and see if that helps. You could have an issue with the transfer of the friction material from the pads/rotors. You need to get an even transfer.

I had a similar issue a few months ago. Bedding helped for a little while but not completely. I had to replace my front rotors. No issues since. Just weird you have repeatedly had this issue now. It could be the rotors or pad you are using.

dgjk

I had a similar problem on my Excursion. It was the slide pins. Take them out and polish them. Then clean the hole where they go. No grease. It can attract dirt and make them stick. Also clean the path of the pads on the caliper. And bleed the brakes for good measure.

twh

Slide pins are one of the usual causes of a stuck caliper. If the caliper can't release it's tension when you release the hydraulic pressure, then the pad keeps rubbing against the rotor.

BimmerFan52

Maybe something in this writeup can help.