I have a question about the rear axle leaf spring mounts. The axle that came out of the car was indeed an 8.2 with a multi leaf set-up and what's going in the car is an 8.5 multi leaf set-up.

The leaf spring mount on the 8.2 is 1 inch deep and the leaf spring mount on the 8.5 is 1.5 inches deep. I assumed at first that the 1 inch leaf mount was for a mono leaf, and the 1.5 inch leaf mount was for the multi leaf set-up, but the 8.2 axle that was originally in the car has the 1 inch mount and had a multi leaf set-up, I'm confused. Then again it could have been some shade tree mechanic. INFO............????

The perches on your rear are for monoleaf springs. It sounds like someone swapped in multi leaf springs sometime during the cars long life. You can purchase multileaf perches from any of the aftermarket suppliers. Moser makes a quality replacement. If you intend to replace them yourself, make sure you have an angle gauge with a magnetic base. Check the angle of the perches in contrat to the centerline of the center section. The perches should be 28 - 31 degrees negative angle to the pinion. You can check this turning the rear over, place the gauge on the cast webbing below the pinion and take a reading. Now, check the angle of the perch. There should be a 28 - 31 degree difference. Now you can cut of the old ones. and using the same references, weld the new ones on. The perches should be 3 inches from the axle flange, measured from inside of flange to the inside edge of the perch. Try to keep that measurement to within an 1/8 of an inch. It will effect the placement of rear under the car and you could wind up off center. If you don't want to do this take it to an axle shop.

Lotsa guys successfully use multi springs on mono perches. When I did that, I just made up some metal spacers to fill the gap. Some have simply torqued the u-bolts down and let the gap be.

28-31 degrees difference between the pinion c/l and the perch surface? Sounds like it should be closer to zero to me.

it is, but you can't check it that way. The bottom of the axle housing runs at an angle, that's the 30 degrees.

Trust me. When the rear is installed it actually pitches forward and the result is a pinion angle of negative 1 to 3 degrees which is right where you want to be. You do not want to have zero degree pinion angle at either end of your driveshaft. The harmonics will shake your equipment to pieces.

JimM is correct, you can use the monoleaf perches and either install spacers or just torque the plate down. If you choose that method, use the multi leaf lower plate. The mono leaf plate will bend too easily. Good luck which ever way you go.

Thanks once again!!

I'm making myself a nice litte package with all the information that I recieve from you guys. All this knowledge comes in super handy.

Originally posted by 69X11SS:
Trust me. You do not want to have zero degree pinion angle at either end of your driveshaft. The harmonics will shake your equipment to pieces.

How does a zero degree joint angle create harmonics?

http://www.iedls.com/guide.html

Ideally, both ends of the driveshaft should be of the same angle.

Having one end of the d/shaft at 2*, and the other end at 0*, this will definately send out harmonics.