Vibration

Q: Vibration

I finally got my car out this summer and at about 50mph the car began to “resonate”. I could feel a vibration through the steering wheel and the pedals. Once I hit about 65mph, it went away and the car cruised great again. The vibration is there regardless of what gear I’m in and it doesn’t matter if I’m accelerating or braking. I drove the car around for hours reproducing the vibration and trying to figure out what it is and to see if whatever it is would let go on me. It did not get any worse or any better.

Based on my “testing” I don’t think it’s engine or transmission related. I think it’s probably something in the rear (driveshaft and back). I’m going to pull the driveshaft this weekend and have it balanced and get new u-joints installed as well. If that doesn’t work I’ll try getting the tires balanced and rotated. If that doesn’t work………..? Does anyone have Currie’s web address? 🙁

Any ideas or experiences would be greatly appreciated.

A: check u joints first. i had a similar problem……..turnd out to be a loose u joint.

A: Check the tire balance. If you feel it more through the wheel it’s in the front. If it’s the whole car in general it’s the rear. Maybe a tire went out of round from sitting. At any rate check the easy stuff first!

A: As I was reading your description of your problem I was thinking U-joints. So, glad to see we are on the same page. The other obvious questions are:

• The rotors. Is there any “pulsation” when you break at a slow speed?

• Have you looked at the wheel bearing, front and back?

• This may sound strange but check your shocks. If one has collapsed it could set up a resonance.

• Could b flat spots on the tires.

A: And now the answer for people who, like me foolishly let someone else put on their wheels. About oh say 20 years ago, I took my car out of winter storage. For the winter, I removed the wheels and tires and put it up on blocks. In spring, a friend helped me mount the wheels. I took it out for a spin and had the exact same problem as you. Turned out my friend didn’t torque the lug nuts on one tire tight enough. I was darn embarassed when the local garage found them all to be loose. But hey… life goes on. I married my friend anyway.

A: I think its has to do with the tires but here is some extra stuff to look at. Two hard to track down vibrations problems I have had are the following

Bad motor and trans mounts (all 3 bad at the same time) and Bad rubber rear leaf spring cushion. This caused the rear end to move slightly out of line and float. It felt like the whole car was going to self destruct. (it was very inconstant) It was by dumb luck that I discovered the problem. Also if you body mounts are bad the car is less tolerant of bad tires.

A: It appears to be a simple wheel/tire balance problem. If in doubt about whether the tires will balance properly, look for a tire dealer with the newest balance technology, the load force variance type machines. They apply a road load to the surface of the tire while spinning the wheel/tire assembly, and can determine if there’s a problem in the tire (such as a belt shift or other imperfections), and even tells the tech if the tire needs to be indexed differently on the rim.

I worked at a Buick GMC dealer that had this machine, it was a Hunter 9000 I think, and we could condemn defective tires all day long on this thing. The down side is it’s labor intensive, and requires a tire technician who can actually think. If you need to index all 4 tires, that means attempting the balance, determining the index position, moving the assembly to the tire changing machine and breaking it down, moving the tire to the new index and re-inflating it. Figure about 2 hours shop labor for all four.

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