pinion angle help!

[hansonharley02]

hey i got drop shackles in the rear and wanted to set pinion angle i drag race the truck alot and dont really drive it around town that much. what should the angle be? i hear all kinds of different answers and then where can i buy the shims? thanks fellas!

[Madferraristi]

Got traction Bars? If so, set it 2-3* down. If not, get a set! Acid test is vibration. If it is too far off, it will vibrate either all the time or when you go WOT, not good for the U-joints.

Does it vibrate now? Under what condition?

['02 H-D #677]

If all you have done is lower the trailing ends of the leafs with shackles, then rule of thumb = 2* pinion delta per 1" lower of back-end of leafs. That is, if the 1" shackle hole is used, then remove the stock 2* shim. If the 2" shackle hole is used, then reverse the stock 2* shim from stock position. The pinion angle should always be as close to "zero" as possible for all applications ... drag, DD, twisties, etc.

Search the suspension forum. There is a whole lot of info.

[ilaybrk]

for Drag racing you do like Mike said -2 static so on launch it will go to zero

[hansonharley02]

so thats positive 2 degrees, which means the rear should point up that way when the tires spin forward it points the rear down a little to get zero degree, correct?

[Madferraristi]

When you are accelerating, the pinion is trying to rotate the opposite direction to the tires. In other words, it will rotate from 2* down to 1-2* up which is just about perfect since the engine is about 2* down in the rear. Under max acceleration, the angles want to be equal but opposite.

[hansonharley02]

thanks mike i understand i was being a dumass, 2-3 degrees it is thanks to all!