Positraction Problem or Other?
Thread Starter
Racer
Joined: Oct 2006
Posts: 445
Likes: 0
From: State of Perplexity California
Positraction Problem or Other?
Hi All,
I've noticed that when I drive the the car slowly when it's not warmed up, like maneuveriing thru a parking lot after it has been sitting several hours, on sharp turns I notice what feels almost like one of the tires has a flat spot or something. Kind of a "thump" sensation about every wheel revolution I think. Feels sort of like somone completely forgot to tighten the lugnuts, but it disappears when warmed up. Seems worse in reverse, but is there going forward too. Only does it on fairly sharp turns, only when car is cold. Once I've driven it a few minutes this ceases to happen.
My guess is that maybe I need new diff. fluid and friction modifier, but that's only a guess at best. I'm really new to positraction, and fairly new to 'vettes. '99 A4 hatch 125K miles, 2.73's, diff fluid probably never changed but I don't know for sure. Have had the car about 2 months. Thanks much.
I've noticed that when I drive the the car slowly when it's not warmed up, like maneuveriing thru a parking lot after it has been sitting several hours, on sharp turns I notice what feels almost like one of the tires has a flat spot or something. Kind of a "thump" sensation about every wheel revolution I think. Feels sort of like somone completely forgot to tighten the lugnuts, but it disappears when warmed up. Seems worse in reverse, but is there going forward too. Only does it on fairly sharp turns, only when car is cold. Once I've driven it a few minutes this ceases to happen.
My guess is that maybe I need new diff. fluid and friction modifier, but that's only a guess at best. I'm really new to positraction, and fairly new to 'vettes. '99 A4 hatch 125K miles, 2.73's, diff fluid probably never changed but I don't know for sure. Have had the car about 2 months. Thanks much.
Drifting
Joined: Jan 2006
Posts: 1,726
Likes: 97
From: Castro Valley State of Insanity
My 99 GMC 1 ton did that when it was brand new, added a tube of posi additive, end of problem. I would consider changing both the tranny and rearend fluids in light of the miles accrued, and your uncertainity of previous maintenance. Good luck and happy trails with your new ride.
Thread Starter
Racer
Joined: Oct 2006
Posts: 445
Likes: 0
From: State of Perplexity California
Originally Posted by Bubbletop409
My 99 GMC 1 ton did that when it was brand new, added a tube of posi additive, end of problem. I would consider changing both the tranny and rearend fluids in light of the miles accrued, and your uncertainity of previous maintenance. Good luck and happy trails with your new ride.
Le Mans Master
Joined: Dec 2000
Posts: 9,918
Likes: 1,880
From: Hot Springs AR
As mentioned above, changing the fluids out is a good idea. However, I have the same problem and no diff or tranny issues at all. I believe it's the tires (especially runflats) being so stiff that they do develop a small flat spot that goes away after a few revolutions. If at the beginning you make a sharp turn the tire is a bit out of round and that causes the slip to occur.
HTH, and have a good one,
Mike
HTH, and have a good one,
Mike
