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Discussion Starter #1
I've been trying to get rid of a nasty vibration / shake that my FB gets around 65-70mph. Mostly near 70.

Some history: Front end is all new, about 2 years old. Drive shaft is balanced, new U-joints and yokes. T-5 has a new tail shaft bearing and a the front shaft (?) was replaced with the newer steel version not the aluminum one.

I thought it might be wheels and tires on the front causing the vibrations I thought I was feeling in the sterring wheel.

Yesteray I swaped on a set of brand new tires and wheels a friend had. The problem is still there.

I did hear some noise from the rear now, with the new tires that were much quieter. And I tend to feel the shake in the seat also.

Could the rear be the problem? It is the one area I have not worked on yet since getting the car. I was thinking if it is shaking at speed, wouldn't that send the vibration through the axle tubes to the springs to the car and down the drive shaft to the trans, which would shake a little and then make the engine shake a bit and then transfer that through the engine mounts and make the front end feel like it was shaking a bit?

Any assistance would be appreciated.

Kory
 

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How much confidence do you have in the shop that balanced the driveshaft? Your vibration sounds just like the one I had, and a warped driveshaft turned out to be the problem. Is there another shop that could double-check the balance? Might save you some money...
 

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Check the drive shaft for a weight missing, and just because it is new or rebuilt doesn't mean it is ok. I would have it checked out by a drive line shop also. You could put the rear end on jack stands and run the car in gear and check the axles to see if they are bent. And while it is in the air check the rear end for unusual noises, maybe a broken part back there. You can also look at the drive line and see if it has a wobble to it, not likely but worth a look.
 

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I had a similar problem on a 82 GT. Turns out that the main shaft in the 4 spd was bent!!! Put the rear on jackstands and run it while watching the driveshaft. That will tell you if it is the shaft or tranny.
 

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To add to the list given by others I found that my front end vibration was being caused by the original front drums being out of balance. When I upgraded to Discs the problem went away. If all else fails see if you can have your drums checked for balance or replace them if needed.
 

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Discussion Starter #7
I have 4 wheel disc.

I think the next step is going to be to open the rear and see whats going on. It does make some noise and one side has a lot of slop in it, and with a posi it shouldn't do that.

Trans mount looks good. But I'll check it when it is in the air again.

Kory
 

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Check the U nuts that hold the U-joint the third member, if one side is loose you will have a vib that you can feel at the steering wheel.
 
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