Re: Stearing wheel shake.

["Jerry A. Cohen" <cohen@xxxxxxxxxxxxxxxxxxxx>]

Wheel shake can occur for a number of  reasons, including:
1. Warped rotors - occurs only on breaking
2. Unbalanced tire - usually gets better at certain speeds
3. Various suspension problems
4. Bad motor mounts
5. Resonance in a failing rack and pinion - this is one of the most 
elusive causes and my personal favorite, having put my Town and 
Country into dry dock on and off (mostly on) for two months, while 
the local techies slowly ruled out the first 4 problems.  While doing 
this they insited that the rack & pinion could not be the cause of 
the front end vibration.  In my case it got worse on turning, but it 
could improve in any given vehicle.  The basic problem, as I 
understand it, is that the hydraulic pressure oscillates, causing the 
wheel to oscillate with it.  This is a lateral motion, but it feels 
very much like a thrown weight.  It may occur more at one speed than 
another because the hyraulic pressure in the rack & pinion can vary 
with changing engine rpm, at least in a faulty rack & pinion.  They 
replaced the rack & pinion and the problem went away.  This is fairly 
expensive, so I hope you have a more mundane problem, like a thrown 
weight.

Jerry Cohen
BMW CCA 157750
98 328 is
94 Town & Country (soon to be replaced)

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