1963 T-Bird Vibration

[Phil]

I have replaced the rear leaf springs and new rubber spring insulators in my 63 bird, ever since the replacement, my car vibrates, it starts to vibrate at about 35 miles per hr, I have had my car to a few shops, and nobody is able to get the vibration out, I have had a new drive shaft built and balanced, rear wheel bearings and pinion angle changed a few times, I also bought new rims and tires for my car and it still vibrates, can somebody please help me.
Thanks
Phil.

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[Pleyden]

I know this is a old post but I have the same problen. Mine is a 65. Did you find anything? I changed drive shaft u joints rear diff and still no luck. Oyherwise runs great just did 300 miles today. Figured it would let go if something was real bad.

 

[sam donahue]

rear transmission mount

 

[Pleyden]

rear transmission mount

I'll check. Did you experience this problem. Was the mount broken or just miss aligned.

 

[Phil]

I also have replaced the rear transmission mount with a new one, it still vibrates.

Phil.

 

[zeroroadkill]

Harmonic balancer? I've done all the above, new motor mounts, trans mount, spring bushings, shocks, motor torque rods, new U-joints, balanced drive shaft, new tires, new fan, anything that goes round-n-round etc... I suspect the harmonic balancer. One I think I have done, but forget, is to test in neutral/park, but will test again. I know the vibration stops when I'm rolling and shift into neutral, but engine rpm also drops, so I need to retest a static test.

 

[zeroroadkill]

I have replaced the rear leaf springs and new rubber spring insulators in my 63 bird, ever since the replacement, my car vibrates, it starts to vibrate at about 35 miles per hr, I have had my car to a few shops, and nobody is able to get the vibration out, I have had a new drive shaft built and balanced, rear wheel bearings and pinion angle changed a few times, I also bought new rims and tires for my car and it still vibrates, can somebody please help me.
Thanks
Phil.

You mentioned you replaced the rear leaf springs? Maybe the pinion shaft angle has changed as the rear of the car was lifted??? Does the vibration change as more passengers are in the car?
Check out this article: https://www.killfab.com/blogs/news/pinion-angle-setting-up-proper-pinion-angle