I was hoping someone could explain or give me their theory on why the frequently discussed 50-60 MPH shimmy occurs only between 50-60 MPH.
I have read many archives and have not been able to dig up any info that would clarify the effects of the cause. I, too, have recently replaced my thrust arms, got the tires rebalance, and a four-wheel alignment only to still be plagued with the infamous shimmy. Although, I must admit the medicine I gave my bimmer has definitely helped. And, you should know that as a result of being cheap, I elected to pass on the alignment when I purchased my last set of tires, I have worn the tires unevenly. Therefor, I realize my hopes of eliminating the shimmy are not going to be resolved until I buck up for some new tires or the tires manage to wear evenly from daily trips to work – not sure if that’s possible. Now, if I only had one of those Quaife Differentials, then I could help the wear along with a few burnouts. :) Again, I am being cheap (more like stupid) because letting go of a new set of tire with less than 10K miles ails me to death. Truth be told, (don’t want you to think I am stupid) I would have new rims and tires on her tomorrow (and the differential) if the wife was more financially secure. But, that's another story....
I am not looking for suggestions on how to fix my shimmy problem cause there is plenty of threads archived that have covered those possibilities. I am turning to you for understanding of cause and effect. I know about the many things that can cause the shimmy, but why does the effect only surface between 50 and 60 miles per hour?