Just today my car (2001 330 ci sport) started wobbling in the front end
while braking from 40 mph+. The tires and wheels are fine. Any probable
cause? A place for me to start? TIA

sgfan3 wrote:

Hmmm... hadn't considered that. Any other possibilities? Worn parts like
tie-rods, control arm bushings, steering box?



"JimV" <jv9999 (AT) yahoo (DOT) com> wrote

"sgfan3" <sfgan (AT) bigfoot (DOT) com> wrote


plus

loose bottom link

failed shock absorbers

cracked spring

detached strut

warped bodywork

loose wheel nuts,

worn wheel bearings

damaged brake pads

flat spot on tyres

balance weights knocked off

etc.

However if the sensation is strong, you haven't kerbed it or hit anything
and only happens under braking then the most likely cause is

warped braking disk(s).

Warped brake rotors can cause this.




"sgfan3" <sfgan (AT) bigfoot (DOT) com> wrote

Worn parts would manifest themselves under other conditions. If the shaking
is limited to braking, the most likely cause is the rotors.

The brake pads get thin and do not disipate the heat as well as they should,
and the rotors can warp. If you did a hard stop that got the rotors hot,
then went into a puddle, the heat shock could cause warping. In any case,
you can get new rotors for about $50 each and they are easy to install at
home.





"sgfan3" <sfgan (AT) bigfoot (DOT) com> wrote

My bet: a front brake caliper is seizing.

This is pretty common. The front calipers slide back and forth on metal
rods; any dirt or corrosion on the rods and the caliper seizes, then
when it gets hot it gets VERY grabby.

Next time this happens, stop the car, get out, and sniff near each
wheel. If you get a strong odor of brake dust that's a big clue. (You
might also notice that one wheel is getting MUCH dirtier than the
others). You can also CAREFULLY touch each wheel - one might be
significantly hotter than the rest.

If it's under warranty, then BMW replaces that caliper, the pads, and
the rotor, and then fills and bleeds the fluid.

That sounds like a possibility. I'll check the calipers tomorrow and let you
know what I find.


<sunderland56 (AT) yahoo (DOT) com> wrote

I don'tthink there is anything wrong with the calipers, the rotors are the
suspect to be looking at.




"sgfan3" <sfgan (AT) bigfoot (DOT) com> wrote

Just "re-discovered" this thread and have an update. The wobble in the front was caused by loose lug nuts (RF). I was so focused on finding another, more complicated solution, that I hadn't considered the most obvious and simplest fix. Fortunately, no harm was done while the nuts were loose, but this incident has made me more aware (again) of the importance of the driving experience. Proper maintenance, quick inspections (and corrections while still relatively inexpensive) of the simple things as well as the hi-tech, high-dollar stuff we worry about. In exchange, your BMW will reward you with a great deal of driving pleasure, instead of trip after trip to the garage. Then there is the withdrawal and inconvenience of it all. This is all part of my quality of life. M3 forever!!! Lug nuts! Who knew!

sgfan

....feelin' kind of silly right about now...




"Jeff Strickland" <crwlr (AT) yahoo (DOT) com> wrote