Never ending brake judder: solved!!

[jonbarrett]

I've had brake judder since I've owned the car. I decided to replace components, one at a time, till I found it. Here is my story, I hope it helps others.

1) New discs. No change
2) Discs reground to ensure they were parallel. No change
3) New Mintex pads. No change
4) New Red Stuff pads. No change
5) New upper ball joints. No change
6) New wheel bearings. No change
7) New drag bar compliance bush. Fixed!!!

a) First conclusiuon, I'm a muppet
b) Second conclusion, start with the smallest cheapest part first
c) It's amazing how a seemingly OK bush could casue so much trouble
d) I'm now going to change all the suspension bushes to Poly

[optimax sniffer]

Glad you got to the root of the problem, now go and reward yourself with a drive

[HarryW]

sounds a bit like the ususal BMW 5-series trait.

[HRG]

HarryW said:

sounds a bit like the ususal BMW 5-series trait.

What's that then just in case mine ever start doing it?

[HarryW]

HRG said:

HarryW said:

sounds a bit like the ususal BMW 5-series trait.

What's that then just in case mine ever start doing it?

Vibration under braking from 50+mph normally but can also be a bit of a shimmy through the steeerng wheel at ~55mph feels almost like an wheel imbalance. Caused by the bushes on the front stabiliser bars.

[HRG]

HarryW said:

HRG said:

HarryW said:

sounds a bit like the ususal BMW 5-series trait.

What's that then just in case mine ever start doing it?

Vibration under braking from 50+mph normally but can also be a bit of a shimmy through the steeerng wheel at ~55mph feels almost like an wheel imbalance. Caused by the bushes on the front stabiliser bars.

Thanks, I'll check them first on mine if it ever happens.

[HarryW]

HRG said:

HarryW said:

HRG said:

HarryW said:

sounds a bit like the ususal BMW 5-series trait.

What's that then just in case mine ever start doing it?

Vibration under braking from 50+mph normally but can also be a bit of a shimmy through the steeerng wheel at ~55mph feels almost like an wheel imbalance. Caused by the bushes on the front stabiliser bars.

Thanks, I'll check them first on mine if it ever happens.

Bush part No5 attached to the stab bar part No4 is the first thing to check this drawing http://www.realoem.com/bmw/showparts.do?model=DP62... if you've never seen the realoem site before then it is a god send to BMW owners, worth bookmarking.

[HRG]

That's fantastic, thanks

[trackcar]

did you go with a poly bush in the end Jon or with the solid spacer arrangement we also chatted about?

[jonbarrett]

Managed to get two Poly Bushes off the shelf. I would class them as a soft polymer rather than a stiff elastomer so, in theory, machining two nylon spacer discs would have had exactly the same effect.

It has transformed the braking and steering. Because ther problem has existed since I owned the car I've never really appreciated what it should feel like.

Before replacing the bush I placed a crowbar between the chassis mounting plate and the front of the original bush. With a little force I could get the entire wishbone assembly to rock back and forth. It must have been playing havoc with the geometry.

This movement will undoubtedly have worn the other wishbone bushes unevenly so they are next.

None of this was ever picked up by the garages and MOT test centres I asked to check the brakes.

If changing one bush has made this much difference I'm really looking forward to a full bush set plus new shock, springs and alignment. Fingers crossed some time next year.