My daily driver duties is split between the S and my 2000 Toyota Celica (depending on the weather and how much space I need). The Celica has recently developed a weird problem where I get mild to moderate vibration through the steering wheel at highway speeds (70-75). Sounds like a balancing issue, right? Well the strange part is that it doesn't happen all the time. There are times when it drives as smooth as silk and other times I get vibration. I'd probably say it's 50/50 at highway speeds. I've paid careful attention at the surface of the road doesn't seem to matter. Sometimes I get vibration over very smooth roads and sometimes it rides smoothly over rougher roads.

At my last dealership checkup I asked them to balance the tires. They said that the tires had lost their roundness (?) and that the issue couldn't be fixed with balancing. Ok, I'll buy that. However if that were the case, wouldn't the vibration be persistent? Why the car drive smoothly sometimes and vibrate other times?

My suspension is completely original and no parts have been replaced. I pushed on the corners of my car yesterday and the shocks seem to be in good shape (no bouncing). There is a chance some bushings are getting worn out, but at this point I'm just blindly guessing.

Any ideas what's going on here?

 

Bumping this thread.

Possible that worn out shocks are causing small vibrations at speed? Or is it more likely the tires are out of round? Oddly the vibrations come more from smooth pavement than from rough payment.