<VV> vibration/shimmy?

[Bill & Chris Strickland]

On a car with modern suspension, meaning not a straight axle,  worn 
suspension parts or brake issues rarely are "The Cause" of a shimmy or 
vibration -- worn parts will certainly not help control a shimmy / 
vibration, but they likely are not the cause.

You said the tires were balanced -- did you watch them do it?  If they 
were spun balanced of any sort, did you watch the tread as the tire 
turned?  there should be no bumps or wiggles in the tread as it spins.  
Often a tire separation can be felt at very low speed, like 3-5 mph, as 
a somewhat "boaty" feeling to the ride, like ripples from a small wake 
in a small boat. Did you tell the tech what your problem was, or did you 
just have the tires balanced?

Could have a bent axle, bad rear wheel bearing or something weird with a 
u-joint I suppose, but tires and wheels and brake drums are the usual 
culprits.  Balancing is only as good as the technician that does it 
(like alignments). With no steering wheel wiggle, one could expect the 
problem to be with the rear tires / wheels -- so try rotating them, 
fronts to the rear and vice versa, then test drive.

Have you recently done anything with the brake drums, like replacing 
them, machining them, rotating them, getting them really hot and then 
applying the parking brake and leaving the car?

I don't suppose you have tested it at 68-70 to see if the shimmy goes 
away at that speed?  If it does, don't try for 75!

Godspeed!

Bill Strickland