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Discussion Starter #1
I just had 3.31 gears put in and the car has a vibration when letting off the throttle. My mechanic thinks it's the driveshaft. He has put some clamps on it to try and balance it but can't get the vibration to fully go away. It only does it when letting off at 80 now. I'm sure it does it higher than that but he won't drive my car any faster, which I completely respect. He said I either need to take it to a speed shop to get it properly balanced or get a new driveshaft. I've read that manual's have a vibration when letting off the gas but mine's an auto. Is this normal or do I need a new driveshaft?

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You could try rotating the driveshaft 90 degrees at a time and see if it goes away. I did lose some of my deceleration vibration when I put the Aluminum shaft in though.
 

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Discussion Starter #3 (Edited)
You could try rotating the driveshaft 90 degrees at a time and see if it goes away. I did lose some of my deceleration vibration when I put the Aluminum shaft in though.
My mechanic rotated it and also put some kind of clamps on it to try and get it to balance. The more I read the more I think it’s normal. Do you think it’s safe to drive with? I have my governor set at 120. I plan on putting an aluminum one in down the road.
 

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If it didn't vibrate before he put 3.31s in and it does now then he needs to fix it.
 

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I just had 3.31 gears put in and the car has a vibration when letting off the throttle. My mechanic thinks it's the driveshaft. He has put some clamps on it to try and balance it but can't get the vibration to fully go away. It only does it when letting off at 80 now. I'm sure it does it higher than that but he won't drive my car any faster, which I completely respect. He said I either need to take it to a speed shop to get it properly balanced or get a new driveshaft. I've read that manual's have a vibration when letting off the gas but mine's an auto. Is this normal or do I need a new driveshaft?

Thanks!
I put 3.73's in my 94. It initially had quite a vibration over 60. The driveshaft had a harmonic balancer on it, which I had never seen before and we determined the it needed replacing as the rubber was crumbling apart. I just went ahead and installed an aluminum shaft and have had not vibration one since then.
 

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Discussion Starter #6

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https://m.autozone.com/drivetrain/driveshaft/dorman-driveshaft-946-812/825045_352271_6064?aqs=

Has anyone used or heard about this driveshaft? If I need another ds I really don’t want to put in another stock one but can’t afford an aluminum one right now.
I think I would just pay the Extra $305 before I put a Dorman on it. I was going to have a local shop build me one and the shop closed before I got the $600 together for the custom 2 piece. He built a lot of the local race car shafts around Knoxville and a whole lot of truck driveshafts and PTO's.
 

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If it didn't vibrate before he put 3.31s in and it does now then he needs to fix it.
If it didn't start until the new gear ratio was installed Id suspect that is the issue. I've heard unless it is done absolutely perfectly you will most likely have some sort of issue with a new gear ratio.
 
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