Most BMW's have a factory installed rubber guibo between the tranny & drive shaft; as well as a balancer. I have seem them dry rot and tear but never just tear as the amount of torque need to do this would be something to truly behold.
The vibes in the front could come from any of the above mentioned items, except the rear axle cv-joints.
An improperly pre-loaded center bearing can cause harsh shifts, intermittent vibrations that tend to wander, constant vibrations and hi pitched squealing when bearing finally dies. Also, flat spots in the u-joints can cause wadnering vibes if coupled with the afore mentioned center bearing issues. Pre-load on the center bearing keeps shifts crisp/ solid and not stiff or clunky. As the rubber in the center bearing wears this pre-load goes away.
Start simple/ cheap on your checks. One, if you have warped front rotors a simple check, jack the car and spin the wheel, if brake pad makes intermittent contact that is a safe bet, not so on the rear if your car has internal rear e-brake shoes this test can be mis-leading. On the rear you will have to isolate the rub. It is usually easier to pull the rear wheel and spin by hand to confirm beacuase you have a better feel and easier isolate the source.
I do a wiggle test on wheel bearings. If there is any doubt I pull the wheel and pop the dust covers to check.
Same with front ball joints, steering linkages and rod ends. A simple wiggle/ lash / play check. A key indicator will be if the dust boot is missing.
Any of the above steering and suspension items can give an itermittent vibration. The cars speed effects a certain harmonic thus vibration. This vibration coupled with the tracking of the wheels (which is affected by the stiffness/ looseness of the bearings, steering & suspension links & rods) is what causes pro-nounced/ discernable vibrations in the front & rear of the vehicle.
The trick is to start with the easiest, isolate, negate and move on. Sometimes you get lucky and get it on the first shot; other times you get the joy of learning tips & tricks to share with others.
is est, quis is est ...
Last edited by dyn2liv; 10-18-2011 at 06:32 AM.