Feel a rattle when I brake.

[Shadow01]

As stated, I feel a slight rattle up front when I brake. It happens for a sec or two, then stops. It can be a little scary when going fast and need to make a quick stop. What should I check?

Sway links, tie-rods, shocks, springs, sway-links, dogbones, hubrings are all in excellent condition. Thanks for your input.

[E39esp]

I'm going to start tearing my hair out soon.

Please use the search function.
In the past 2 weeks there have been about 5 threads on this. Over the past year maybe 100, over the past 2 years around 1,000,000

[Shadow01]

I searched. Read 5 threads but found nothing useful.

[K Fox]

Search for 'thrust arms' or 'warped brakes' and see if you match the symptoms described. Fixes will accompany various descriptions.

Fox

[M Quick]

Is this rattle/shimmy usually around 45-55mph?
It belongs to the well known 55mph shimmy problem (bad thrust arms). Any thread you find that says something about a rattle, shimmy, vobble or vibrations, that's it. There are as said thousands of answers to that.. Very known problem.

[Shadow01]

Thanks, my thrust arms are good. It turns out my front rotors have a little lip forming (what u call warped I guess) and that can cause the shake. I got some cross-drilled for the back 6 months ago when my caliper froze and killed one of the rotors. Ill save up and get the same for the front with some braided steel lines. That should do the trick.

[sse34]

Yea i was gonna say its your rotors... ah well u foudn out

[upallnight]

ABS kicking in.

[Shadow01]

ABS kicking in.

ABS kicking in big time! I almost redecorated a ford windstar's ass on the highway the other day..

[Elekta]

I feel a little clunk under my seat if I press and then completely release on the brakes. I was approaching a stop sign this afternoon and purposely make the clunk. It's not in the wheel at all, car brakes straight and fine. Why do I feel it under my seat?

[K Fox]

Thanks, my thrust arms are good. It turns out my front rotors have a little lip forming (what u call warped I guess) and that can cause the shake. I got some cross-drilled for the back 6 months ago when my caliper froze and killed one of the rotors. Ill save up and get the same for the front with some braided steel lines. That should do the trick.

Actually, that lip is normal. As the rotors wear with normal use they get a lip on the outside edge where there is no contact with the pads. It can make it really fun to change brakes if you don't have a piston compressor and an old worn rotor. ;) But that lip does not in itself mean that the rotors are warped, only that they slightly worn. If you think they may be warped then just heck them for runout, or if you can't do it go get a quote from somewhere that gives free quotes. They will measure it if they are even halfway worth there business license - only takes them about 5 mins.


I feel a little clunk under my seat if I press and then completely release on the brakes. I was approaching a stop sign this afternoon and purposely make the clunk. It's not in the wheel at all, car brakes straight and fine. Why do I feel it under my seat?

I've felt the same thing, but I'm awfully sure it's the thrust arm bushings in the 94 540. It clunks bad in that one, to the point that I can feel it in both the wheel and the seat. Since you say only seat, it may be a worn bushing in the back end? How are your dogbones?

Fox

[M Quick]

I feel a little clunk under my seat if I press and then completely release on the brakes. I was approaching a stop sign this afternoon and purposely make the clunk. It's not in the wheel at all, car brakes straight and fine. Why do I feel it under my seat?


I'm guessing it has to do with the rear subframe bushings(those big ones). How does the car handle? Does it feel like the rear end is steering along with the car sometimes?

[Elekta]

It's a feeling reminiscent of the CSB, but I rebuilt the shaft, new guibo, CSB and tranny mounts right when I bought the car.

If it's subframes I am going to be pissed because I had purchased them when I did my initial overhaul and my indy said they were fine. We had this out and didn't put in fresh ones? It's not really a clunk, but more a thud under my seat..

http://img.photobucket.com/albums/v11/ggil-tx/bmw/elekta/DSCN0481.jpg