Return of the brake judder

W

Wildfire

Senior member
 Epsom
I have recently developed very severe brake judder from anything 70mph+ until about 50mph when it does not occur. I have recently (<4000) miles put in new Pagid Discs and Pads on the front, along with Meyle HD bushes. When I took the callipers off recently all looked fine with decent wear all round and no un-evenness. I gave the callipers a clean anyway and everything spun well. There was no excess heat being radiated from either wheel.

Any ideas?

Could I have a buckled wheel?

My next steps will be to check the seating of the front discs along with the rear discs and callipers.

But this problem only manifested itself over the last 500 miles?

I can feel it through the car and not the steering. The steering is rock solid under braking and the wheel doesn't shake at all?
 
About 18 months ago I had similar on my DD ( not BMW ).
Anything over 50mph on motorway, it was warped discs, new discs and pads solved the problem for me.
 
If you're feeling it through the car rather than the steering then I doubt it's a buckled wheel, but it can't hurt to check the alignment. One of my wheels has a tin buckle in it and having the tyres changed / wheels balanced sorted it. But I could feel it through the steering wheel.

Does it happen under braking or is it constant ? Again, on my last car I had juddering, under braking. Turned out to be a fecked control arm bush, and the resulting vibration had buggered the front discs and pads.

Check all the trim on the underside of the car - the undertray on my wife's car was half hanging off and at motorway speeds the vibration through the car body was horrible, a constant background judder.
 
Currently it's just under braking from 70ish to about 55mph. Under that you can't feel anything. The handling feels fine so I'm ruling out the control arm bush as when they were worn, the car weaved all over the place.

I can really only think that it could be the rear with a seized caliper that is more pronounced when braking from higher speeds due to the brake biase being mostly front.

If I hold the steering lightly and do it, the wheel is rock solid and doesn't shake at all. I'm going to have to get up under the car again.
 
Before you get into anything more re-bed the pads as most vibrations are caused by pad deposits on the discs.

Simple version of the process is find a long quiet road, 60 mph braking firmly to near stop, back to 60. Repeat 2 or 3 times never stopping completely. Then drive without using brakes to cool them.

If that doesn't work then you can get into all the possibilities of discs, bushes, alignments, seized calipers, etc.
 
Yep, I've tried re-bedding the pads too.

But on quick inspection of the rear discs I may have found the culprit. Big lip on the outer edge and pronounced bright, score mark on the rear inner edge. It looks as if on hard braking the pad is making contact with the rusted part of the disc.

I will change out the rear discs this week and see.

Anyone know if the caliper pistons are screw in on the rear?

The rear pads have done about 9000 miles, can I get away with these or should I change them out too?
 
Wildfire said:
Yep, I've tried re-bedding the pads too.

But on quick inspection of the rear discs I may have found the culprit. Big lip on the outer edge and pronounced bright, score mark on the rear inner edge. It looks as if on hard braking the pad is making contact with the rusted part of the disc.

I will change out the rear discs this week and see.

Anyone know if the caliper pistons are screw in on the rear?

The rear pads have done about 9000 miles, can I get away with these or should I change them out too?
Click to expand...


If you've rebedded and no benefit and the vibration is from the body not the steering then I'd agree the rear is a good place to start.
Rears are straight push in pistons, but of course you have to back off the handbrake shoes to get the disks off (and readjust once new disks fitted)

Personally I'd never use old pads on new disks as the deformed pad shape matching your damaged disks causes uneven wear on the new disk. If you were being tight you could flat them using paper on a flat board or glass, but all that work to not change :thumbsdown:
 
Cheers. good to know about the handbrake shoes. New pads it is for the price, I don't want to skimp.

Are there any guides on doing this? I couldn't find a Z4 Haynes manual that was 2005+.
 
Wildfire said:
Cheers. good to know about the handbrake shoes. New pads it is for the price, I don't want to skimp.

Are there any guides on doing this? I couldn't find a Z4 Haynes manual that was 2005+.
Click to expand...

Try this online version of the TIS Manual:

http://workshop-manuals.com/bmw/
 
Wildfire, oops - sorry, early morning and didn't read your post properly. Sorry about that :oops:
 
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