Hello all, I have an '06 AP2 w/ 139000 - everything stock except the front tires (long story, emergency road side decision).

I just had the rear tires replaced with the factory spec Bridgestone Potenza's. I get a vibration which starts around 53 MPH, intensifies with speed, and disappears if I disengage the clutch. Problem was not there, or not noticeable, before rear tire replacement.

I took the car back to the dealer and they said the front tires needed balancing. I paid for it. Still vibrates. They said I might need an alignment. I walked away at that point as there were no indications of an alignment problem before the new tires were installed and I was annoyed.

Had the wheels rebalanced at a different shop. Both rears were out .75 (one plus, one minus) but that did not eliminate the vibration. They inspected the motor mounts and said they look good. I should note that the right rear took (15) .25 weights to balance it (13 and 2)... which seems extreme to me.

Took it back to the dealer a couple weeks later and let the shop foremen drive the car. He said there is no problem with the tires - problem is the "drive train". Spoke with the service manager... he said they would revisit the back tire but probably there was a problem with one of the universal joints on the drive shaft. Fine, if that is true, but how do I know that is really the problem before I spend $1500? Any way to ascertain?

Do I have a bad tired and an recalcitrant dealer?
Do I have a drive shaft problem?

I plan to take the right rear off and run it up over 55 with the minispare - as that will tell me if it is the tire - but I have a broken shoulder at the moment so it is going to have to wait. All thoughts are appreciated. Scot

 

There's a dot on the tire, the dot is there to indicate the lightest part of the tire, it's this part that should line up with the valve stem, doing this will minimize the amount of weights needed. If balancing the tire properly doesn't do the trick then I'd check the axle cups. There's plenty of DIY's around here, and it's potentially free minus the cost of grease.

Did you buy this car used or are you the only owner? If not then the previous owner might have lowered the car which can cause a lot of problems, such as axle cup pitting and torn upper control arm bushings.

 

If the dealer is suggesting the drivetrain then I suspect that you are having rear CV cup vibrations that you somehow didn't notice until you changed the rear tires recently.

The options are to have $50 half shaft spacers installed or to have the CV cups swapped from side to side for the cost of a grease packet (and time).

What happens if you simply let off the gas? The vibrations are directly correlated with acceleration and high wheel speed.

 

Slow and Soviet - Thanks for the responses.

I don't find the dot for the valve alignment. Seems pretty basic - hard to believe they'd get that one wrong.
I am the original owner and the car is completely stock and is not / has not been lowered.
If I take my foot off the gas the vibration is still there but not as pronounced. Greatest in acceleration, lessons with coast and deceleration, imperceptible if i throw it into neutral - my theory is that in neutral the vibration looses a path of transfer.

Today I switched the right rear (the wheel with the excessive weights) with the mini spare.... vibration gone. So, either the tire has been balanced incorrectly by three different people or the tire is defective. I'll take it up with the dealer on Monday and post the results of their findings.

Thank you both again. S

 

Does sound like a defective tire. What brand and model tire is it? Should be changed, maybe dangerous.

Good luck!

 

P.S. For anyone else reading, keep in mind you should never drive with the spare tire on the rear, as it can damage the diff. Proper method is the spare tire goes up front, and the front wheel is moved to the back.

 

Update: Dealer agreed to replace right rear tire at their expense. Most of the vibration went away. I still get a vibration from 58 to 62 MPH. Doesn't seem to be related to RPM, only speed. Any thoughts?

 

Do you have one locking lug nut?

 

Tires out of round. Explains the need for excessive balance weights. But you only had one tire replaced, right? Sounds like the other rear tire is also out of round.

When excessive weight is required to balance a tire, its often beneficial to remount the tire to wheel, rotating it 180 degrees from how it was before. Matching heavy spot of wheel to light spot of tire.

If this sounds a bit... imprecise, there is a type of balance called road force balancing. Its a spin balance machine that applies a roller with pressure against the tire. It finds high spot of tire, and can tell technician how many degrees to move the tire on rim to match the wheels low spot. It also tells them where to put the weights.

But if its a new tire, it shouldn't be out of round. Get a new tire!

 

Spartarus, No... no locking nuts on any of the wheels. What is your thought?

Does anyone still think this is a drive train issue?

Truth is, it is bearable now as I only feel the vibration as I pass through 60 - not at highway speed or in traffic.
My new concern, not to change the topic of the thread, but the seat glide assembly cable has broken... again. 4th time! Annoying!
3 times on my previous S2K.