Car has the shakes once in a while
 

I have a strange problem with my car. It is a 2005 base model coup. So no antilock brakes, or anything else special.

A while ago I had the tires rotated. 2 days later I was driving down the interstate, and the car started vibrating slightly. At first I thought I lost a weight off one the wheels or something. When I applied slight brake, it vibrated more. Then I took an off ramp, and it dissappeared. So I figured maybe it was the road.

A week or so later it happened again. Except it went from the interstate, down an off ramp, and onto another road. Maybe 2 or 3 miles. I came to a stop light, and applying brakes hard enough to make the car stop made it really come to life! It was shaking so bad I had a water bottle on the floor bouncing into the air. When the light turned green, I started off again and there was no more vibration.

I checked all 4 wheels, and they are all bolted on securely, and straight. The tires are not wearing funny at all. At all other times, the car drives smooth. No hint of a tire being out of balance.

I'm hoping someone here can help me. It has only happened those 2 times, and GM can't fix something they can't reproduce. But I don't feel safe at 65mph anymore. Could it possibly be a brake issue? What do you guys think?

Thanks.

RE: Car has the shakes once in a while
 

From what you say I would guess you need to get new rotor, (or turn them) and a new set of pads. When they start to get groves in them they can do this. Is it only when you brake? If it is under warrenty I would take it to them anyway. They can at least take the tires off and look at them. I would request to see the rotors after the tires are off, if they say it is an insurance issue tell them to take it in the parking lot and use a jack and jack stands, (what you would do if you were changing a tire) and feel and look if the rotor feel like they have groves in them, they should at least turn them and tell them to change the pads too.

RE: Car has the shakes once in a while
 

Thanks for the reply.

It doesn't start when I apply the brakes. Though it gets much, much worse if I do apply the brakes. But only when it is shaking to begin with. Like I said, when I brought the car to a stop, the shaking stopped. The car drives smoothly, and brakes smoothly at the moment.

I have been reading though, and it seems the Cobalt has some issues with rotors. So I'll have the dealer take a look at it. I lifted it up and checked out the wheels to make sure they were on correctly, and as an after thought I peaked at the rotors. Looking through the wheel they didn't look too bad. I didn't feel them though.

It seems like if it was caused by the wheels or the rotors, I would have the problem all the time. But I don't, and I don't know what else could possibly be wrong. Unless I'm wrong about it happening all the time. It is definately a rotational type vibration. As it vibrates faster at higher speeds.

I wonder if a brake pad is not secured properly. Possibly making contact with the rotor, but when I applied brakes to stop the vehicle, it forced the pad back into it's correct position.

RE: Car has the shakes once in a while
 

i own a 2007 cobalt haven't looked to see what kind of rotors it has yet, but i had the same problem with my wifes toyota matrix after i bought it, if it sits for a period of time the new kind of rotors it has warps, per toyota service guy. you will have to replace them if thats the case. hope this helped