93 Grand Caravan 3.3 Shimmy part II

Ron;

With your bent rim, did the problem go away at higher speeds ? I would think if the rim is bent, the shimmy would be there no matter what speed you were driving at. Maybe the shimmy is just more pronounced at the slower speeds.

thanks, Nick

One other thing, the wheels are those aluminum alloy wheels and not the steel rims. thanks

Vehicles respond to imbalances differently at different speeds - it's called "resonance". At a resonant frequency, parts of an object (vehicle) can shake with more displacement than what the excitation (the displacement of the actual bent part) is. At other frequencies (vehicle speeds), the same vibration gets damped out and may not be noticeable. This is often seen in vehicles with slightly out-of-balance or out-of-round tires where the shake is felt at, say, 47 to 49 mph, but hardly noticeable, or not noticeable, at other speeds.

Also sometimes a vibration can come and go. This can be caused by more than one tire/wheel being bent or out of balance. As the vehicle travels, the very slight difference in tire diameters (or going around turns) can at times put the two imbalances in-phase with each other, reinforcing (adding to) each other and being noticeable, and at other times being out of phase with each other and mostly canceling each other out so that the shake is not felt. This is often the case when a shake comes and goes under otherwise identical conditions with no other explanation.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Larry,

Thanks, I plan on having someone check the cv joints. The passenger side is a couple of years old, had to replace it when the ABS tone ring cracked. I had the tires rotated and balanced the other day. No change. The problem is somewhat intermittent. By that I mean there are times when it doesn't shake/shimmy, but more times than not it does it. Also, it seems to occur only between 20 and 35/40 mph. At speeds higher than that it is gone. A real puzzle. I would rather it be a bad tie rod or ball joint, but those are good.

Thanks, Nick