High speed vibration....driveshaft?

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Oct 11, 2005 | 01:00 AM

vetteresearcher

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High speed vibration....driveshaft?

After having 3.73 dana gears installed in the 94 LT1 with the D44 rear, I have a high speed vibration. Its only present at speeds of 60mph and above. Could the driveshaft have been installed 180 degrees out of phase? Is there a factory mark that should be observed when the drive shaft is re-bolted back to the diff? I did not do the work myself.
How hard would it be to get the original balance back?

Oct 11, 2005 | 06:46 AM

_twisted_

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From: The Pines South Jersey

How long ago was the install done? Take it back

If not covered, easiest thing to try is what you stated, reposition the drive shaft and see if it improves or goes away altogether.
If that doesnt do it, check tires/balance, wheel bearings, send the d shaft out to get balanced etc... process of elimination.

Oct 11, 2005 | 08:08 AM

Mr Mojo

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There is a mark on the driveshaft and most mechanics will make a mark anyway to be sure. So that can be a possibility.

Oct 11, 2005 | 08:25 AM

Tom Piper

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From: Mexico Beach FL

For balancing the driveshaft, there is a procedure in the shop manual that tells you to use a large stainless steel hose clamp around the driveshaft and keep repositioning the clamp using the "screw" on the clamp as a weight to find the optimal position.

If you need to determine if the driveshaft or half-shafts/wheels are the problem, you can disconnect the half-shafts at the rear-end yokes and just spin the driveshaft and rear-gears without the wheels, axles, brakes, and half-shafts. If the problem goes away, it isn't in the driveshaft.
Be careful using this procedure and allow plenty of extra time for the driveshaft to spin down because the rear brakes aren't connected to stop the driveline from spinning and you can damage something trying to put the transmission in gear/park before it comes to a stop.

Tom Piper

Oct 11, 2005 | 08:51 AM

FD2BLK

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From: Charleston SC

Tom is exactly correct but the first step is to turn the drive shaft 180 and see if it corrects the problem and then they have the ballancing procedure if that does not work

Oct 11, 2005 | 08:58 AM

aboatguy

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From: Slidell Louisiana

Quote:

Originally Posted by Mr Mojo

There is a mark on the driveshaft and most mechanics will make a mark anyway to be sure. So that can be a possibility.

The factory marks the driveshaft and the pinion yoke. These marks should be 180* apart to be in phase.
It sounds counter intuitive at first but the subassembles are marked on the heavy side during manufacture and when assembled together the heavy sides are installed opposite each other to help with balance.

Mike

Oct 11, 2005 | 10:49 AM

65Z01

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From: SE NY

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Are you sure the vibration is in the drive shaft or rear wheels?

If not, down shift one gear and see if the vibration changes.

Oct 11, 2005 | 12:09 PM

JonLT4CE

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Joined: Mar 2005

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From: Tempe AZ

I'm having the exact same problem in my 96 LT4. I just replaced my half shaft ujoints and the problenm is still there. I also re-mounted the drive shaft 180 out. Problem still there. My next stop is a Hunter road force wheel balance, then rear rotors.

If you find it please post!