Stirring wheel vibration while braking over 40 Mph

if the wheel alignment is faulty ( castor wobble ) at 70 mph there is no way that you can describe it as a vibration as it virtually rip the steering wheel out of your hands. If it is a torque converter problem then at around 3850-4025 rpm stationary there will be a vibration of the vehicle and engine The sort of vibration that you are experiencing at 70 mph will come from a drive line problem. If rear wheel drive then it could be faulty "U" joints, worn slip joint or failed rear engine mount
If front wheel drive it may be cv joints or bent drive shafts,wheel bearings or brake callipers not moving freely on the mounting bolts.

Turn off the a/c & see if it still does it
Try dragging the brake while still on the gas to turn off
torque converter lock-up & see if changes
Check front drive axle CV Joints.
Check motor & trans axle mounts

Vibration from about 40-60 mph is usually attributed to wheel balancing, but the onset when you hit a bump seems to indicate play in the steering linkages (tie rods etc) or suspension members and stabiliser bar rubbers but you had that all checked out, that brings us back to the wheel balancing.

If this is happening at around 40 to 50 mph and it goes away when you go faster or slower then those speeds you probably need a wheel balanced. (please rate if this helps any Thank you)

Bring in the car to a PROFESSIONAL shop. Mention your problem & ask about a wheel balance, alignment & make your problem clear before any work is done. Mention bearings etc. Ive dealt w millions of csrs at my own private shop & that would be your best approach. NO JIFFY LUBE TYPE SHOP

Hi:
Since your BMW 540 series is a rear wheel drive car, a common cause of that sort of vibration is often the U joints on your drive shaft. The vibration often only shows up and certain speeds.

It isn't a particularly expensive repair, but is something to have checked out!

maybe the rotors are bigenuff and heat up too quick and warp but thats what they put on the car so youre out of luck,,,,you could put aftermarket rotors on it that are slotted and or crossdrilled which would greatly reduce the heat and your warping isue,,,,or maybe youre just too hard on the brakes,,try avoid sudden stops and braking at the last minute

if it were the rotors it only happens when braking take in have them turn rotors see what happens good luck

This is your one of your axels.. they are damaged inside.. Get them removed asap it can cause major damage if it brakes loose..each axle costs about $90-100

Front shocks are week