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Vibration at 55 mph

Hello. I have a 2007 PT Cruiser with 44,000 miles. The first 27,000 miles were put on while it was a rental car. Several months ago, I began to notice a vibration in the front at 55 to 60 MPH. I had the rack n pinion replaced, had all the struts replaced, had an ew alignment, and have had the wheels re-balanaced. I am good about having the tires rotated in a timely fashion, but they had to be rebalanced and re-rotated after the rack n pinion work. The car stopped vibating for about two weeks, and now is doign it again. It stops vibratng after 60 MPH, and it stops when I take my foot off the gas. The motor mounts look worn, but not broken or loose. What is wrong?

I think you may have lost one of the wheel weights that balanced the wheels. See if a re-balance fixes the problem. They were probably out of balance before, and I would bet they are out of balance again.

Thank you, but I just had the wheels rebalanced last week. I will check into this again, though. Anybody have any more ideas? Is there any way this is related to the transmission? Especially since it smooths out when take my foot off the gas at 55 MPH

How old are the tires, are they the OE’s? Could have a shifted belt. It may be time for new ones. If they are new-ish, as Whitey says, rebalanced them.

Could also be drive line related? Have the shop recheck their work

As racer said, it could well be a tyre problem. Uneven wear or a shifted belt can cause a problem.

If you want to spend a few minutes to check if it is a wheel (balance or belt type problem) you can rotate the wheels. If it changes or even goes away, it means it is a wheel or tyre or balance. Switching tyres around can pinpoint the offender.

Thank you all! The tires were rebalanced today. Still the same problem. There are two new tires, and two older tires, but not OE. One of the rims has been roughed up, as if it hit a curb.

If your rim was damaged enough to cause a vibration problem it would not have “balanced” on the spin balance machine, at least not without adding a ton of weights. Assuming all that balancing was done correctly, I’d start by looking for something loose like a front wheel bearing, tie rod or rack and pinion rod end loose, etc. Jack up the front and just shake and try to move everything. Could be in your trans, but hard to say. The fact that when you let up the gas it goes away, just means it only does it when there is power to the wheels, which could be a lot of things.

Thanks once again. The rim is rough nearly all the way 'round , but no big gouges. The rack n pinion and all the struts have been replaced, the wheels have been rebalanced . I guess we’ll look in the transmission, though that may open a can of worms.

Im curious if the vibration is isolated to one area, for instance you feel it mostly in the steering wheel or more in a general area like the whole front or whole rear of the vehicle. If it is more isolated to the steering wheel there could be a tie rod failing, if its less isolated it could be some suspension part or perhaps a failing half shaft if, like you said, it goes away when you take your foot off the accelerator. Also, is there any sound involved with the vibration?

The key here is that the vibration stopped for a while and that it stops when the gas pedal is released. Wheel end related vibrations would be there all the time. They may be speed related (has to do with the wheel hop frequency), but the wheel end vibrations would be there under accelration, constant speed, coasting etc.

No, something other than tires and wheels is causing the vibration. My guess is CV joints.

One more suggestion is that you could have them checked on a machine that does a “road force balance”. It spins the wheels while applying similated road forces via a spinning drum pressed against the tread. It can detect internal tire defects that regular balancing machines cannot.

Not all shops have these, so you’ll have to ask.

If the wheels pass that test, it has to be something mechanical.

Hi!

The vibration appears to be coming from the right front wheel area, no matter what tire is in that position. Will check CV joints and tie rods. I’ll keep you posted. Thanks again and again.