Yes. That’s my guess too. It’s the bottom one with the with the bushing that needs torqued after the car is lowered. It often gets torn.

This one. (Not advocating for a specific parts supplier)

https://www.ecstuning.com/b-lemforde...126760275~lem/

Gonna wait it out in that case, is seeing /feeling any sort of play in those lower control arms up front something the alignment garage should have picked up on and warned me about as it would have an impact on the alignment? they did so when they identified an issue with rear bushings when i last went for an alignment and so got em replaced.

so to recap braking and steering wobble = rotors? and if no wobble yet but starts to wobble with gentle low 40-50 speed braking = the front lower control arms?
PLUS possibility U joint in steering column is loose

Yes. The rotors have effect only when applying the brake. You’ll usually feel a pulse through the brake pedal.

The thrust arm/wishbone/control arm will cause the wheel to bounce on the road at a ~65 to ~75 mph but smooth out above 80. It also cases shake at light breaking ~45 because it changes the caster angle of the wheel. Like a broken shopping cart wheel.

The shop may have missed the loose bushing because of the way the preload works. The car has to be lifted some to unload the tension on the arm, but not all the way. Then it can be felt by shaking it.

U joint play can be felt by turning the steering wheel back and forth while the engine is off. Inspect the joint as a helper moves the wheel.

Steering shake at over 65mph
 

Perfect explanation about the shopping cart analogy.


Definitely look into the loose bushing. The fronts loose virtually all spring pressure when off the ground so you can push stuff around. Also: some chance if any bushing was tightened in the air could cause an upset.

I saw a thread not long ago the front shimmy was due to a thrust arm bushing that was loose

Did anyone mention a bent wheel? A slightly bent wheel will cause a shimy as well, though whoever balanced OP’s tires may have missed seeing that as the balancing process is primarily machine controlled. It would take someone spinning a wheel and looking from the back side.

One of the cars I maintain has a bent rim and has a shake at 52 as and 64 mph due to harmonics.

Have somebody turn the wheels when off the ground when you are under the car hold something like a stiff wire you can hold tight against suspension yet bend right next to the rim. Any pothole dent will become very obvious.

Just replaced the second front axle rearward control arm.

https://www.icloud.com/sharedalbum/#B0SG1CvrSGW29Ur

It was horribly sloppy. Now I have to tune the alignment since naturally the new arms aren't the same length as the old.

Cool vid andrew. I don't work nearly as fast as you do. ;)

I loathe diagnosing problems like this (I am not skilled enough to learn how to do it in a timely manner, and greatly admire those who can) so I replace the entire front suspension. Yep, I'm a cheater. But it's amazing how tight a BMW with 100,000 miles+ on it gets after doing so. It's like night and day. Did the entire front end on the wife's X35d @ 155,000 miles for ~$700 in parts. She can't stop commenting about how much she loves it now. Happy wife, happy life, am I right? :D

Congrats! Most owners never suspect that everything is wearing out microns at a time. The whole suspension is flexing in those applications, so replacing one part only magnifies the slack on all the other components. CONGRATS on doing it RIGHT!
:thumbup::thumbup::thumbup::thumbup::thumbup:

I had the same issue, it was the aftermarket spacers, wheels, and tires the PO installed. I got stock wheels and tires and had them balanced. Problem solved.