Strange Shimmy @ speed - comes and goes?

[llebcire]

My wife has a 2004 Vibe AWD w/68k miles.She's noticed a shimmy in the steering wheel for quite a while, so I started with the obvious:Rotated and balanced, 4 wheel alignment - problem exactly the same.This does have new rotors (@ 60k) and the problem existed before them. I don't have any vibration when braking @ any speed.Here's the strange symptoms:At highway speeds, the steering wheel will shake like a bent wheel/balance concern. Increasing speed increases the shake, decreasing will decrease the shake (if that makes sense) but it exists from 55-80mph. When this is happening, it doesn't matter what I do - increase/decrease speed, put in neutral, go up hill , down hill, change lanes, etc.Lasts between 1-3 minutes then seems to go completely away. When it's gone, the above scenarios won't bring it back and it drives fine.The weird thing is that it repeats this cycle of coming and going every 1-3 minutes on the highway - that's what has me baffled! Bent/balance wheels, slipped belt, bad suspension/steering components or bent drive shafts should either be there all the time or not. Things happen quickly @ 70+ mph regarding rotations.I drove the vehicle last night for 130 miles miles with this repetitive behavior, and it almost feels like it's coming from the powertrain with the most obvious effect in the steering wheel.Any ideas?Thanks!BTW - I did search the forums with no similar results b4 posting.-Eric

[northvibe]

welcome!have you had the tires balanced and an alignment done recently?

[llebcire]

Thank you!I had a 4 wheel alignment and tires balanced on Tuesday (2 days ago) and had rotated 3 days earlier.-Eric

[keithvibe]

got a friend that you swap wheels with for one night?that would rule out the wheels all together.

[llebcire]

No, we don't have anyone to swap with.It's going into the Pontiac dealer tomorrow for diagnosis.Thanks!Eric

[prathman]

Quote, originally posted by llebcire »The weird thing is that it repeats this cycle of coming and going every 1-3 minutes on the highway - that's what has me baffled! Bent/balance wheels, slipped belt, bad suspension/steering components or bent drive shafts should either be there all the time or not. Things happen quickly @ 70+ mph regarding rotations.One thing that could account for the repetitive cycle would be if the effect is a result of two of the tires creating a vibration only when they act together. Say your two front tires are both just a bit out of round but not enough so that you notice it as long as the low spot on one of them doesn't happen to occur at the same time as the low spot on the other. But if they do happen to both have the low spots at the bottom of the rotation at the same time then the effect is great enough to start the vibration you feel in the steering. But since two tires won't have exactly the same circumference, they'll eventually (after a minute or so) get out of phase enough so the low spots aren't happening at the same time and the vibration goes away. Then some time later the tire that's just a touch smaller will have gone through one more complete rotation and their low spots are again perfectly aligned and you start to feel the vibration again.If this is what's happening it could be due to a problem in the tires/wheels (either roundness or balancing), or it could be a loose suspension component that makes the car particularly susceptible to any tire variation (i.e. tires will never be perfectly balanced or perfectly round). If you can't swap tires with someone else as suggested you might try rotating just the tires on one side of the car so you get a different pair of tires on each axle than before and see if that has any effect. If the problem persists despite moving or swapping tires around then I'd look for a loose suspension component.

[llebcire]

Took the Vibe to the dealer on Friday - and low and behold it was the balance!Tech took the vehicle out to confirm our complaint, and was ready to start diagnosing drivetrain or possibly a rotor that was hanging when he noticed the weights were improperly installed inside the wheels (stick on).Re-balanced all four tires and this is 99% gone.Service advisor said that in all of their years they've never had a balance issue with these symptoms.Thanks!-Eric