Pinion angle

[383Scampman]

Setting up pinion angle on my '72 Scamp . 383, 727, 9" The pinion angle is 1.5 degrees nose down . The driveshaft is 4.5 degrees nose down . Car is at ride height . combined angle is 6 degrees nose down . Is this correct or am I messed up ? Should I adjust , and, if , by how much ? Thanks in advance , Tom

 

[RustyRatRod]

You should measure the front u-joint angle at the transmission. It should be opposite the same amount as the pinion. In other words, one should be negative X amount and the other positive X amount for a total of 0 degrees working angle.

 

[bbrroowwnn]

front of rear end yoke angle and rear tail shaft of transmission are the angles you need to measure....they should be parallel....Like Rusty said....they should offset one another....one positive one negative

 

[383Scampman]

thanks guys . So if my pinion is 1.5 Degrees nose down the angle at the trans should be 1.5 degrees nose up ? This will cancel each other out for a 0 degree angle ? What happens under load when the pinion wants to rotate upward ? Will it bind ?

 

[bbrroowwnn]

technically yes.....Usually the trans is fixed so you can only adjust the pinion angle from rotating the rear.......So I would use whatever angle you have off the back of the trans......And make the rear pinion angle opposite that one.....And yes, depending on what rear suspension you are using you can go more......Ex. if your rear tail shaft is at 1-1/2 degrees up you need to be at least 1-1/2 degrees down at the pinion yoke...I would add a degree or two down for leaf springs as they allow the most wrap up.....This is where a pinion snubber comes into place though, if you are running one and have it adjusted pretty close to the floor you won't get much wrap-up

 

[DDodger]

thanks guys . So if my pinion is 1.5 Degrees nose down the angle at the trans should be 1.5 degrees nose up ? This will cancel each other out for a 0 degree angle ? What happens under load when the pinion wants to rotate upward ? Will it bind ?

You are going to want to estimate how much it will rise under power and try to get the angle at zeo then

 

[383Scampman]

Thanks Rusty,Brown , Dodger . this clears up a lot of wrong ideas I had about pinion angles . Great advise , you guys are he greatest . thanks again , Tom

 

[AJ/FormS]

I use no snubber and have street springs back there with a second mainleaf on each side. It took 7 degrees to compensate. It's been abused since the early 2000s that way. No more u-joint failures. Very little cruise vibration with 3.55s. With 4.30/4.88s there was quite a bit.