Thread: shaking at 50-60 mph HELP!!!

Ok I'm completely stumped and so are the guys I bought my wheels from. I have a 2005 grand prix base model, i put after market 18's on it when i first bought it in 2005 but decided to upgrade to 20's in December of this year. I had zero issues with the 18's but after i put the 20's on there was some vibration but I just thought it was from upgrading to bigger wheels. It has gotten worse though, it got so bad at one point I couldn't go over 60 mph without thinking my car would shake apart. So of course I just thought it was the balancing and so did every one else. I had them balanced 4 times, road force and sonar to no avail. then they thought it just needed hub rings which made it better at speeds over 60 mph but worse at 45-50 mph. So I left my car for a whole day with the wheel place and they decided it was the wheels and tires (this was last week). They replaced them with brand new wheels and tires (completely different ones) and still is shaking at 50 mph. They re-torqued them after 50 miles and it actually got worse. It seems to shake more when I accelerate also. I've read a few things online about CV joints, alignments, rubber bushings, steering bushings, or rotors. Anyone have any ideas?

I'm not having any issues when i brake.. it does it more when I accelerate quickly and mostly at 50 mph, not as noticable around 60-70. I have a free alignment check coupon for Firestone so I'm gonna see what they say, I hate taking it there but I don't want to have to pay for something that may or may not fix it.

I'm not sure, I told the guy at firestone what was going on and so they're gonna check it all out while it's up in the air, I've asked a few of the guys I work with and they seem to think it may be a tie rod or bushing.. who knows?? there's just too many variables i guess

do you have any other wheels to try on the vehicle?

i don't have any other wheels.. firestone said everything looks good, don't need an alignment, bearings are good, rotors are good, they couldn't find anything wrong with the suspension. the only thing they could think of that the wheels are too heavy for the suspension to handle. i went back to the guys i bought the wheels from again yesterday and they're gonna look at it again on wednesday. i'm at a loss and so is everyone else that has looked at it..

Not to steel the thread... but I have a similar problem.. mine is more of a shimmy in the steering wheel when I am accelerating or braking slightly.. I have all original wheel, new brakes. And rotors 2 new hubs..

Mine is bad between 60 and 70

had the same problem at 50-60 my car was shaking pretty bad. I just did the front bearings 2 months ago. Checked the passenger front tire and the wheel had a wobble again with the car jacked up. Thought it was weird the wheel bearing went bad again so contacted amazon where I bought my Timkin bearing and sent me a new one. Just replaced it today but today I noticed the outer tie rod was in bad shape and thats what was moving when I shook my tire. Replaced the bearing anyway but also did both front outer tie rods. Fixed my problem, took it on the freeway and no more shaking. So possibly that could be the case with your car.

Originally Posted by Explicit_Spade

If it's shaking at high speeds, your wheel weights could be off.

I just put new rims and tires on my car and the shimmy is gone. Must of been that my old rims were out of balance

I work for the Tire Rack. I would say that the wheels very well could have been out of balance. Anytime I hear of a car shaking at those speeds that is the first thing I would think of. there could be a bad belt in the tires. Personally I think 20's are too big for that car. But everybody is different. Also if the hubs are bad it will vibrate some also.