70 mph vibration lt1
#1
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i have a vibration in my car i have a 1997 trans am WS6 126k all stock motor. at 70 mph the car has a vibration. I can't see out of my rear view mirror.the vibration is worse when i let off the gas and decelerate. and from 0-70 it is smooth no vibration. It shakes the entire car. I thought it was the rear-end so i got a moser 12 bolt. still vibrates so i put a new drive shaft in the car and it still vibrated. i just went through putting a new clutch in the car. still the same problem i have no clue where to look next. the transmission shifts great i have had different shops look at it and they swear its not the transmission. i have took the tires and breaks off the rear of the car and drove it on jack stands and same speed it vibrates every-time.
i need some help of where to go next??
thanks chris
i need some help of where to go next??
thanks chris
#7
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Join Date: Apr 2012
Location: Crown point, IN
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Couldn't Hurt to check those motor mounts, have a buddy brake torque it a little "not enough to break the tires" while you check to see how much motor movement you have in the engine bay
If its moving more than a quarter inch or so that could very well be your problem
If its moving more than a quarter inch or so that could very well be your problem
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#9
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I checked the motor mounts and it don't move hardly any.. Yes it is a poly tranny mount and yea I have took the spacer out of it.. Still vibrates... This is not a tremble in the wheel this is taking a jack hammer and putting it under the car and at 70 mph turn it on and see how hard it can aggregate me.. and yes it is a t56
Last edited by chris_14kingz28; 09-20-2012 at 09:13 PM.
#14
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the thang about wheel weights it dose it on jack stands with no tires in the car.. and when i run it through the gears 4th 5th and 6th are all in the 70+ mph range aould 5th and 6th make 4th gear vibrate
#16
TECH Veteran
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OP,
Drive at 70MPH in 4th and note if the vibe is there. If its vibe free, shift to 5th and note if its there, Then go to sixth and do the same thing.
If you are vibe free in 4th but detect vibes in 5th and 6th gears only, you have T56 wear and tear so go here:
https://ls1tech.com/forums/manual-tr...vibration.html
Drive at 70MPH in 4th and note if the vibe is there. If its vibe free, shift to 5th and note if its there, Then go to sixth and do the same thing.
If you are vibe free in 4th but detect vibes in 5th and 6th gears only, you have T56 wear and tear so go here:
https://ls1tech.com/forums/manual-tr...vibration.html
#17
12 Second Club
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OP,
Drive at 70MPH in 4th and note if the vibe is there. If its vibe free, shift to 5th and note if its there, Then go to sixth and do the same thing.
If you are vibe free in 4th but detect vibes in 5th and 6th gears only, you have T56 wear and tear so go here:
https://ls1tech.com/forums/manual-tr...vibration.html
Drive at 70MPH in 4th and note if the vibe is there. If its vibe free, shift to 5th and note if its there, Then go to sixth and do the same thing.
If you are vibe free in 4th but detect vibes in 5th and 6th gears only, you have T56 wear and tear so go here:
https://ls1tech.com/forums/manual-tr...vibration.html