[panos]

Hello to all...
I have a '03 4200CC coupe, and i face a trembling at over 100mph on the steering wheel.
It is getting more intense as speed grows, and at around 130mph i cannot hold the steering wheel.
I did wheel alignment, balancing, and checked the alloys for bends or cracks and they seem OK.
is it possible that the tyres ('04 FULDA EXTREMO) are not suitable for the car and cause all this trouble???
Any thoughts are wellcome
PaNoS

 

[RickBullotta]

Based on your information, I'd certainly suspect the tires. Could be a flatspot, belt separation, or other defect. I had a similar situation with my 2003 Coupe (with the original stock tires). I had replaced my rear tires at 10K miles, but the front tires were still the original ones, at 16K miles. I had a very similar (but not violent) vibration above 100 MPH. I replaced the front tires (with the OEM Pilot Sports) and it went away. I assume you also checked the lug nut torque specs to make sure they weren't overtightened.

Another thing that went away when I replaced the front tires was an occasional activation of the MSP system on certain turns. I suspect that the difference in wear (therefore difference in diameter of the tires) was enough to fool the MSP into thinking there was slippage.

 

[Crapjokes]

wobble

also check that the mating surfaces are all pefectly flat. There could be a small piece of something between the wheel and hub that's throwing it ever so slightly off line. Wouldn't show up on a wheel balance etc.

CJ

 

[kbrookings]

Find a shop (probably dealer or large tire shop) that has a Hunter 9700 Road Force Vibration System balancer and someone trained to use it. Have your wheels rebalanced. Good shot that this will solve the problem.

 

[panos]

Find a shop (probably dealer or large tire shop) that has a Hunter 9700 Road Force Vibration System balancer and someone trained to use it. Have your wheels rebalanced. Good shot that this will solve the problem.

Thanks a lot for your advices
although i do not believe that i can find such a balancer here in Greece, i did the job on several different equipments and all showed the same thing.
Alloys almost perfectly circular, and the front tires slightly ellipsoid.
i believe i will fit the Pirelli's PZeros and see if any good might happen.
My worries are if any defect on the steering system causes this trembling, not very possible though, but slightly possible eh?