I just bought a 2002 sc430 40k miles with 20" rims. The car is overall great, except when it comes to bumps at speed over 20mph. It rides extremely rough and I can hear and feel the wheels/steering wheel shake. Is this because of the rims or is it a problem with the coilcovers. I own a Porsche Cayenne with 20" rims, it does not feel like this on bumps, in fact I can freely ride over them with high speed. Major difference, which leads me to believe it might be something else.

Wanted advice from someone who knows more about the sc430.

Thank you.

 

Are you in the right section ?? (this is sc300/400)

 

Chances are you aren't use to the smaller tires.

 

I would lead to believe that you have maybe 235/30/20 or something close? Those have absolutely no forgiveness when hitting a bump. Its like having a rim on a rubber band. Let us know what you found out.

 

maybe you have a bent rim(or maybe poorly repaired rim?) and don't know it? with 20's and little or no protection from the tire, I wouldn't be surprised, cause 20mph is slow to say have a wheel balance issue. Maybe rotate tires, get them rebalanced and checked for bent rims at the same time??

That's where I'd start, and then check for broken/lose suspension components
GL

 

No bents, had the car checked today. The car seems to be perfect, surprisingly. Must be the stock suspension everyone is complaining about in the 2002 sc430.