1998 GMC Suburban Shimmy at 50 MPH

1998 CHEVROLET SUBURBAN
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NOOM
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my transmission went out 2 years ago and had it fixed. since then, it was running fine until just recently. at 50mph i get a light shimmy underneath the front of the car.when i let the gas pedal up during the shimmy, it stops, then when i press it down again to regain speed, it shimmy's again for a few seconds at 50mph. i also just put all terrains on my suburban. so i took it to discount tire to see if it was an alignment problem, but with no success. what could be the problem?
Feb 25, 2007 at 9:13 AM
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CHEVY22
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did the shimmy start before or after the tires and if so was it right away and is it 4x4
Feb 25, 2007 at 11:21 AM
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NOOM
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how are ya,

the shimmy definitely started after the tires were put on, the only reason why i feel like its the trans is bc right before my trans died, i felt a similary shimmy but much more violently, but this was for literaly a day or two before i my trans died. i could be completely wrong, but to answer your question... right after the tires were put on, it started pretty consistently and no its not a 4x4. 98 gmc sub SLT.

thx for the quick response... this is great,
noom
Feb 26, 2007 at 2:53 AM
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CHEVY22
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i would suspect the tires being out of balance then, the shop that put them on should have no problem taking them off and atleast checking the balance before just balancing them again , this shoul all be done free of charge

let us know
oh and leave some feedback if you were happy with your help , we all donate our time here helping others free of charge
Feb 26, 2007 at 5:20 AM
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NOOM
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thank so much, that makes sense. i will most definitely leave feedback. thanks again for the quick response...

-noom
Feb 26, 2007 at 5:22 AM
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CHEVY22
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no problem buddy let me know what happens

jim
Feb 26, 2007 at 5:30 AM

Suggested Repair

Have the shop that installed the all-terrain tires remove them and recheck the balance, then rebalance if needed, at no charge. The shimmy began right after the tires were installed and occurs around 50 mph under throttle.

Conversation Summary

The owner of a 1998 GMC Suburban reports a light front shimmy at about 50 mph that started right after all-terrain tires were installed. It stops when the throttle is lifted and returns briefly when accelerating back to speed. An alignment check did not fix it. The owner wondered about the transmission because a stronger shimmy preceded a transmission failure two years earlier. The expert suspects the tires are out of balance and recommends a free balance recheck by the installing shop.

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