Vibration

Vibrations or shimmys are sometimes due to a failed steering rack bushing, a lower ball joint going out, as well as a balence problem. Those gigantic wjeels,tires & brake rotors put a hige load on all the suspension parts. What area of the country do youlive? There are a few wide-body suspension specialists around

Jack:
Thanks for your help. As I mentioned in my post the car rides very smooth, steering tight(slight left pull) up to about 43 mph. Vibration begins strongly there and lessens as speed increases above 50 mph. The car smooths out above 50-55 mph but still vibrates moree than it should. I am located in Naples, FL the southwest area of the state.

The steering rack seems tight but I am not an expert. The slight play in the left rear wheel would not be causitive? Half shafts?

Percy Hill

Please advise any suspension experts that might be around.

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Originally posted by jack DeRyke:
Vibrations or shimmys are sometimes due to a failed steering rack bushing, a lower ball joint going out, as well as a balence problem. Those gigantic wjeels,tires & brake rotors put a hige load on all the suspension parts. What area of the country do youlive? There are a few wide-body suspension specialists around

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Marino Perna is just up the road in north FL and also owns a GT5-S. He runs Pantera East & is a parts vendor as well as an all-round good-guy. (www.mapenterprises.net/pe/1024x768/main.htm, or 813-381-1151). This does sound like a balence problem, given the road speeds you quote and the reactions of the car, though. Long-distance diagnosis is difficult; don't neglect to check the rear suspension. Noises & shakes travel under the car, making locating them difficult even when you're riding in it! One 'expert' on the wide-body cars is Pat MIcel in Ma. (www.detomasopantera.net). Not quite in your backyatrd, but....

Phill1
If everything checks out OK, and your still stumped, then go find a wheel shop with a Hunter 9700 tire/wheel balancer. These are pretty new to the scene and are very expensive. Usually only the better dealerships have them. In my case I had my old tires rebalanced and actually saw the guy doing it and the read outs look fine. But when I got on the road, I had a vibration from 40 to 60 and then it almost went away. An old buddy has a shop with this new Hunter machine in it. He mounts the front left wheel/tire on the machine, it does a "Road Force Balance" test, and the tire/wheel is out by 21 pounds. The machine actually tells him to rotate the tire on the rim a certain amount of degrees, we rebalance the wheel/tire and now it is PERFECT........... The first tire shop did not know how to fix it and had never heard of road force balance. I have been told that the car factories do it this way. I think that Hunter actually some info on it's web site that explains what this Road force balance is.............good luck and let us know how you fix it. Doug.H