Suspension math ??????

If I have a 21 degree driveshaft angle with 2 degree shims, is there a way to determine the angle when changing to 6 degree shims before I actually do it???

I wish I would have listened better in math class

 

Yeah, it can be done, but you'll need some measurements that might be hard to make precisely and some trig. Why do you want to change the pinion angle?

 

If I'm reading you right, I would say 17 degrees.

If the angle with 2 degree shims = 21
take out the 2 degree and add 6 degree shims
21+2-6=17

 

I wondered if it was that easy or if there were some geometric formula involved in it. I guess I need an 8 degree shim to get within the 15 degree sweet spot.

 

That's the pinion angle, not the driveshaft angle. I made the same mistake when I first read it.

 

It will reduce the angle at the lower U-joint by about 4 degrees. The angle of the driveshaft with level won't change very much. The angle of the top U-joint wont change very much.

Look at the primer on the Tom Woods site:http://www.4xshaft.com/index.html Tech Info -> Geometry 101

 

Yes. The change in the angle of the driveshaft from level won't be much, depending on the length of the driveshaft.

 

You also have to remember that on a shaft with single joints at each end, the pinion angle and the transfer case output angle must be identical or you'll introduce vibration.

 

Im gonna go read some more. This sounds complicated. I never thought a 2.5 in lift would need driveline attention. Oh well........

 

It's the short driveshaft we have to deal with. Problems pop up a lot quicker than with a larger vehicle.