Still Chasing a Vibration

[MikeStang 247]

Okay have some updates LOL.

Took car to an alignment shop that does a lot of old school cars around here and was told the guys there are super cool about letting you get under the car and look etc... and that they would be glad to help me find my problem.

So dropped the car off on Thursday, they did the alignment on Friday and I went to pick it up.

Guy backed the car over his lift which had a pit under it and when we climbed under the car I saw something I had not see with the car on stands.

The Transmission was actually lower than the rear end and the driveshaft was running UP HILL, not down hill..WTF... I

have had the car up on stands and level and it never looked like this.

 

So he checked the Trans angle and it was 3 degrees down, and rear was 4 degrees up... He suggested I rotate the rear Down to cure the problem.

I went home, flipped the 2 degree shim around backward and took it for a drive....Vibration is almost all but gone now,

and I think if I go ahead and put the 4 degree shim in it will likely totally eliminate the vibration.... Funny thing is I have had the 4 degree in before but never Not had the shims under the transmission and 4degree under the rear...

So word to the wise if you lower your car enough in the front and also use rever eye springs in the rear, chances are your transmission will be lower than your rear end

[bryonbush 85]

glad it worked out. i was going to suggest looking into your trans. a guy in the Dallas area did the 4R swap and was having the same issue. come to find out the input shaft was out of round. 

[RPM 1,190]

Well that's certainly good news. Hope it continues.

[barnett468 418]

i don't know how many tines i have to say this before you finally understand it but you need to do exactly what i said to make the angles correct.

 

you can run your driveshaft uphill all you want . it will make ZERO difference, and in fact, many cars have them running just like that.

 

forget about the angle of the driveshaft . if it is 3 degrees or less, it is fine as long  as it is not zero.

[MikeStang 247]

Barnett I am doing what you suggested.

The rear was up 4degrees, and when you factor in 1 degree of axle wrap it was going past that amount.

So by bringing the pinion back down some so that it was more even with the transmission down angle of -3 degrees it is coming closer to being in parallel alignment when under power Correct?

[MikeStang 247]

Basically the 2 degree shim had the rear end Way to far up after axle wrap.. I think if I get it at 0-1.5 degrees up it

Should be right hopefully.