I know every car different probably but what do most run pinion angle at. I have a 70 swinger with a 833 4 speed and 83/4. It was vibrating at 60-70 mph and the pinion angle was not set right. I ended up putting 4 degree shims making angle now about 2 and 2 between rearmed and driveshaft. Still has a vibration. Maybe not as bad?
Pinion angle
- Thread starter Mick65
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Use the Crank shaft and Trans shaft for ground level and make it 5-10 degrees nose down. There is a chart below. So if the transmission main shaft is level with the ground that would be ground level
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I haven’t had driveshaft balanced. That was going to be my next move I think. I replaced rear ujoints and they are lined up. Someone suggested turning shaft 180 and reinstalling. Is there any merit to this?
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Balancing the driveshaft should have been your First move.
The goal of setting the Pinion angle, is to have it equal and opposite to the front angle when under full power. Obviously then, cruising speed only requires about 35/40 hp, so the pinion angle will have to lowered. Furthermore, the spring "stiffness" is gonna play into this.
The net result of this is that I had to set my P-angle to 7* down relative to the driveshaft, even after adding one full-length extra mainspring on each side..
Your combo, I'm sure, will be different.
Anytime the the angle is not Zero, the U-joints are continuously speeding up and slowing down on every revolution at engine speed. At slower speeds you will feel this not as a vibration, but as a cyclical whu-whu that permeates the entire body and cabin. The faster you go, the more the whu-whu becomes a vibration. You cannot eliminate this. All you can do is mitigate it with isolation in the spring's bushings, and the transmission mount. Poly is very good at transmitting this type of vibration. The factory rubber bushings are pretty good at damping it. Bad shock-absorber bushings will also send it.
BTW;
a blown cord in a tire will also excite the body.
The goal of setting the Pinion angle, is to have it equal and opposite to the front angle when under full power. Obviously then, cruising speed only requires about 35/40 hp, so the pinion angle will have to lowered. Furthermore, the spring "stiffness" is gonna play into this.
The net result of this is that I had to set my P-angle to 7* down relative to the driveshaft, even after adding one full-length extra mainspring on each side..
Your combo, I'm sure, will be different.
Anytime the the angle is not Zero, the U-joints are continuously speeding up and slowing down on every revolution at engine speed. At slower speeds you will feel this not as a vibration, but as a cyclical whu-whu that permeates the entire body and cabin. The faster you go, the more the whu-whu becomes a vibration. You cannot eliminate this. All you can do is mitigate it with isolation in the spring's bushings, and the transmission mount. Poly is very good at transmitting this type of vibration. The factory rubber bushings are pretty good at damping it. Bad shock-absorber bushings will also send it.
BTW;
a blown cord in a tire will also excite the body.
Thank you.
67Dart273
Well-Known Member
Usually though, you should be able to tell if it's a driveshaft related or tire related, just by the speed of the vibration.
If you have a smartphone Tremec has an app that measures driveline angles. Super easy to use. It also has calculators for engine RPM based on gearing and tire size, tire size calculator, etc. Pretty handy, probably not quite as accurate as if you have magnetic angle finders but it would definitely tell you if you're in the ballpark to the point that you shouldn't have any vibrations.
https://www.tremec.com/menu/tremec-toolbox-app/
Like everyone else said, there are a lot things that can cause a vibration and pinion angle is only one of them.
https://www.tremec.com/menu/tremec-toolbox-app/
Like everyone else said, there are a lot things that can cause a vibration and pinion angle is only one of them.
There it is ^^^^^ in black and white! I've preached it for years. The MP chassis and suspension book has it dead right!
Exactly that! I prefer an old school inclinometer, because I sound smart when I say it and my "smart" phone's a piece of ****.
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