front end shake 1997 328i

[jcain]

My 1997 328i has developed an annoying shake in the front end that is quite prenounced when applying the brakes, the steering wheel oscilates approximately a 3/4 inch left to right and the entire car vibrates strongly.

I replaced the front control arms (new bushings and ball joints) as well as the tie rods and ends) and had an alignment

problem still persisted.

Replaced both the front struts and had new tires installed and had an on car high speed balance performed.

Problem still persisted.

Replaced both the front rotors and pads.

Problem still persists.

The car has the original 16 inch rims that came from the factory.

Frankly, I am stumped. The only thing that I haven't replaced is the front wheel bearings, This doesn't seem likely as there was no bearing noise present when the high speed balance was being done and there is not any observable play eitherl.

I am left to consider perhaps the ABS could be causing the condition but am loathe to swap out the abs controller on a hunch.

Any ideas?

Thanks.

[Rick V]

check the caliper slides and the rubber they hang on. here is a kit to remove the rubber and replace it with all steel for no caliper deflection. Also check the condition of the brake hoses If one is restricted it will cause uneven braking.
Good luck

[Jeron]

Does it only happen when braking? I highly doubt ABS is the cause.

[blkongry]

I highly doubt your front end bearings are going out... you would hear/feel a rumble before you'd ever feel a shaking in the front end.

I'm guessing if you replaced nearly your whole front end, then you took the time to check the tires/wheels for balance and straightness, right? Have you tried swapping the rear wheels/tires to the front and vice versa?

[jcain]

Thanks for the suggestions. They spurred me to think more along the lines of the calipers being the problem.

I now believe that the problem lies with excessive deflection of the passenger side caliper resulting in uneven pressure being applied to the disc surfaces. I looked at the last set of pads (glad that I hadn't disposed of them) and the inside pad shows noticeably more wear that the outside. additionally the inside pad is also worn unevenly from side to side.

It's surprising that the symptom shows up more in the steering than in the brakes. I would have suspected that a pulsating pedal would have been the result of this particular condition rather than showing up so strongly in the steering. But then again I am used to working on cars with significantly less responsive steering than BMW's.

Since it is rather simple and inexpensive to install new caliper bushings, i will start there and see how it goes.

I will give an update tomorrow if this solves the problem.