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Discussion Starter #1
I am trying to tone down the vibration in my driveline. Its not super bad under normal acceleration but when I get on it hard it feels like its gonna tear my car apart. I am looking to do some pinion angle measuring and adjusting. Its my understanding that the axel rotates when under acceleration and this is really accented while under hard acceleration. I understand how to measure the angle. What I can figure out or seem to find online is the exact way to go about adjusting it. So how do you actually adjust the pinion angle? I have seen something about shims. As always thanks ahead of time for the great info I am sure you guys will chime in with.
 

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Summit seems to have a good supply of different angles. I will look at my current set up. So I just install those between the axle and springs? Depending on my current angle I get the corresponding shim to change the angle to what I need right?
 

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Summit seems to have a good supply of different angles. I will look at my current set up. So I just install those between the axle and springs? Depending on my current angle I get the corresponding shim to change the angle to what I need right?
Since your car vibrates under hard acceleration you need to have the pinion lowered from where it currently is. So you need the thicker end of the shim behind the axle. If I were you I'd look for a package of 6 shims, 1* angle. You can put 1 shim on each side and test drive. If it still vibrates add another shim to each side. Hopefully by the time you have added 3 shims to each side the vibration under acceleration will be gone.
 

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Discussion Starter #6
Since your car vibrates under hard acceleration you need to have the pinion lowered from where it currently is. So you need the thicker end of the shim behind the axle. If I were you I'd look for a package of 6 shims, 1* angle. You can put 1 shim on each side and test drive. If it still vibrates add another shim to each side. Hopefully by the time you have added 3 shims to each side the vibration under acceleration will be gone.
Traction bars help with this as well right? They prevent some the axle wrap and therefor keep the pinion from moving.
 

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Had a similar vibration under hard acceleration and intermittently on deceleration on my 65 Mustang, the vibrations were what I consider violent, It felt like a mechanical part failure.
This was after a fresh restomod build, 302. T5 transmission ,Ford king cobra clutch, custom made and balanced drive shaft, 4 link suspension 8.8 diff.
The initial pinion angle was set based on the information I gathered on the topic, because the car has a 4 link adjusting the pinion angle up or down is relatively simple.
At first I tried subtle pinion angle adjustments, slightly downward...test drive no change, slightly upward...test drive no change, I then tried what I considered drastic pinion angle changes both up and down angles, these drastic changes actually produced another vibration but never corrected the violent vibration during acceleration.

I found a vibration post on VMF, similar to the OP and the solution to the problem was to ensure at least a 1/4" of clearance from any driveline or exhaust components to the chassis or stationary parts, sure enough a careful inspection showed the drivers side muffler was contacting a parking brake cable bracket and the oil pan was contacting the front suspension k member when under load( k member part of aftermarket strut suspension )

After providing more clearance the vibration was gone
 
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