In Reply to: VIBRATION @ 55+ MPH ON 94' 740IL posted by BOB NADELL on December 22, 1999 at 14:26:32:
I don't want to try to over-simplify your problem, since vibration can be caused by *many* things. You didn't say where the vibration was - in the steering wheel, through the floor, etc. But from my experience, 90% of the time it is from improperly balanced tires or bent rims. I have also found that very few people know how to (or care enough) to properly balance a tire! Or, they know how, but they are still using the balancer they bought 20 years ago, which hasn't been serviced in the last 10 years!
So the first thing I would recommend is to make sure the wheels are really true and the tires are balanced. The link below will help you find a shop with the new Hunter GSP9700 balancer. It is the most sophisticated balancer on the market - and it should be almost mistake proof for the operator. It will detect any real road problems with the wheel/tire combination that cannot be corrected by balance. If you still have vibration after this machine okays and balances your wheels, then it time to start looking for other potential sources of the vibration.
I am not affiliated with Hunter - just a happy customer.
By the way, what the dealer said about a "design characteristic" (ie. flaw) which allows for a harmonic vibration" is total bull.