Wheel bearing usually don't cause a shimmy. I have seen some that are very loose and did not make any noises when driving.
You want to make sure your steering and suspension is tight, no play in bearings or joints.
Do you have aftermarket rims on this vehicle? About what speed are you traveling when the shimmy occurs?
Does the shimmy have all the time or only when braking?
There are several components that can cause a vehicle to shimmy. If you have any loose steering components including the steering gear, tire tread the is abnormally worn or deformed, out of alignment (specifically with the caster angle measurement), tires out of balance, rims that are not centered on the hubs. You could try rotating the tires the front tires to the back and rear tires to the front to see if that changes anything?
Since you had the alignment done and the tires balanced I'm suspecting what is called tire "sidewall stiffness variation"
Most tires have a variation in stiffness or springiness to each tire. Manufactures attempt to reduce this variations in tire construction. Because of this variation (typically in the sidewall) the tire has a stiff spot which will cause a steering wheel shimmy at high rates of speed. In these cases it is best to have the tires balanced on a high end tire balancer. Hunter makes one of the best tire balancer machines on the market, its call a "road force". This tire balancer will load the tire as it is spinning and detects any tire stiffness variation and can calculate where to add weight to counter balance these differences in the tire. Other tire balancers just spin the wheel/tire and calculates out of balances only. So even though your tires maybe balanced the variation is still there and has not been counter balanced.
Answer my questions and I hope I answered you question
Wednesday, November 6th, 2013 AT 9:11 PM