Need help with brake wobble on 540i

[H-K]

Need help diagnosing brake wobble on 540i

Need to pick your brains. My '94 BMW 540i is getting a wobble when braking with medium+ brake pressure between 55MPH and 40MPH. It's not the kind of surging you get with warped rotors, it feels more like a lateral shimmy/wobble kinda like the early stage of death wobble (a rapid/tight wobble). It only occurs when braking and only in that speed range. The car has ABS.

Before I took it in, I'd see if anybody could help me diagnose it so that I can possibly fix it myself.
Any ideas?

Thanks

 

[crapmanche4l]

Aftermarket rims or stock? Vibrating in your steering wheel or your butt or pulsating in the pedal?

 

[Tacoma]

Vibrating in your butt or pulsating?

Man, keep that talk off this board. Sheesh. Have some decency, will ya?

 

[H-K]

Aftermarket rims or stock? Vibrating in your steering wheel or your butt or pulsating in the pedal?

Stock wheels.
Mostly in the steering wheel, a little in the pedal and buttox.

thanks

 

[H-K]

Man, keep that talk off this board. Sheesh. Have some decency, will ya?

LOL

 

[81Ramchargerman]

Hey H-K, your tires could be out of round...or rotors, in my gf's 93 eclipse the rotors were bad, but it was only at certain speeds and brake pressure(with slight brake pressure, no wobble) but if you're sure it's not rotors, tires is my next thought.

edit. I would lean more towards the rotors though... Go to the place where you got your tires and have them throw em on the balancer and see if it is just your tires...

 

[H-K]

Hey H-K, your tires could be out of round...or rotors, in my gf's 93 eclipse the rotors were bad, but it was only at certain speeds and brake pressure(with slight brake pressure, no wobble) but if you're sure it's not rotors, tires is my next thought.

edit. I would lean more towards the rotors though... Go to the place where you got your tires and have them throw em on the balancer and see if it is just your tires...

I'm not sure it's not the rotors, it's just that my limited experience with rotor probs is that it just creates a surging when you near a stop. I'll check the rotors out. I do have some cheap snow tires on it now, that are due to switch, so I'll do that too and see how it goes.

thanks for the help

 

[81Ramchargerman]

Np, I hope it helps

 

[crapmanche4l]

Does it do it only whaen braking or all the time. A pulsating in the pedal will be a thickness variation in the front or the rear drums or rotors are warped if the steering wheel shakes side to side it is either in the tires, a aftermarket wheel that isnt hubcentric with no hub rings or the rotors are warped if you want bring it by the les schwab on highland dr and 4011s and we'll take a look at it and try to get to the bottom of it

 

[BBowski82]

in the front or the rear drums or rotors are warped

FRONT DRUMS!!! LOL You know how long it's been since we had front drums on anything??? Not to mention this is a BMW!!

Have you taken a look at your steering rack mounts? (Assuming that it uses a rack--I'm not to familiar with the early beemers)

 

[BBowski82]

BTW----An out of round wheel or missing hubcentric ring would be evident at all times.....not only with brake application.

 

[H-K]

Does it do it only whaen braking or all the time. A pulsating in the pedal will be a thickness variation in the front or the rear drums or rotors are warped if the steering wheel shakes side to side it is either in the tires, a aftermarket wheel that isnt hubcentric with no hub rings or the rotors are warped if you want bring it by the les schwab on highland dr and 4011s and we'll take a look at it and try to get to the bottom of it

yeah, only when braking and only between maybe 60mph and 45mph.

Thanks, I might be able to drop by and have you take a look at it.

 

[H-K]

FRONT DRUMS!!! LOL You know how long it's been since we had front drums on anything??? Not to mention this is a BMW!!

Have you taken a look at your steering rack mounts? (Assuming that it uses a rack--I'm not to familiar with the early beemers)

Front and rear large disk brakes to stop the V8

I haven't looked at the rack mounts. Something's been making a light clunking sound when I run over bumps/potholes/cats in the front end and I think it might be related.

I'm building a house and moved into a relative's house to save up money and all my tools/equipment are in a storage unit so that makes it difficult to work on it myself. Other than using a bottle jack in the driveway under the pouring rain, I don't have many options. I was hoping the problem could wait until my house is done in June, but I guess I'll just bite the bullet and have it looked at.

Thanks for everybody's help with this.

 

[BBowski82]

I haven't looked at the rack mounts. Something's been making a light clunking sound when I run over bumps/potholes/cats in the front end and I think it might be related.

Again, I don't know much about beemers, but if your car runs struts up front you could have a bad strut mount...this could also cause a vibration/shudder at highway speeds