Need help with pinion angles

[USAFEXPLORER]

I'm in the process of swapping a '99 Explorer 8.8 rear axle (4.10 gears, disc brakes) into my '94 Sport. I'm almost ready to paint the axle and install but I would really like to weld the spring perches first, then paint it all at once. Since I'm doing a SOA conversion my question is this, does anybody know how I can get the perches lined up right so my pinion angle is correct and avoid any vibrations later on? (I hope all this makes sense) I'm not in a position yet to install the transfer case and driveshafts but I would love to get the axle installed. Thanks for the help.

Derek

 

[CoryL]

I am assuming you have a stock rear driveshaft which has a single u-joint at each end. This is called a single cardan driveshaft.

The front driveshaft on an Explorer (91-94) is called a double cardan driveshaft.

When you are setting the pinion angle for a single cardan setup, the angle of the pinion needs to be parallel with the angle of the output at the transfer case.

Can you visualize that? If not I can find a drawing or something.

So what you need to do is keep eh same angle that the axle was when it was SUA. What you will want to do is weld the new perch exactly on top of the old one and exactly parallel with it (i.e. same angle when axle position is fixed).

Good Luck!

 

[Speedfreak]

The simplest way is to but an angle meter on the rear flange on the transfercase. If it reads 4 degrees down then you want the diff at a 4 degree up angle. However, make sure that the drive shaft is not parallel with the angles of either the transfer case or diff, the u-joints are designed to work at an angle and will brinell (the roller bearings will not move and pit the surface of crossshaft and bearing cap) and self destruct.

 

[Sandy]

My only problem with setting up the angles, before test install, is that what are you going to use as a reference point, how to mantain the flat from the pinion to the spring perch?

Why not do a pre install to set up the angle and tack weld the perch in place. Take the rear out and bang weld it up.

I think you have the idea of the angle being equal at the transfer case and the rear end on a single u-joint type shaft. The CV joint one always threw me off.

Let us know what you do,

 

[USAFEXPLORER]

What if I get the angle close, then tack weld it. After it all goes together I could shim the leaf pack to get it perfect. How much shimming is possible?

 

[Speedfreak]

With my diff, I bolted the assembly up snug but not tight and lined up everything. I then tacked the mounts into place, loosened it and finished welding the mounts up. That worked perfect in my Explorer.

 

[Sandy]

To me what Speedfreak say is the way to go!
You not only need to align the pinion angle but also the side-to-side centering of the differential. Check out the differential alignment with the transmission output shaft too; you don't need the drive shaft running at an angle.

Do it the way that it works for you.
I always try to keep things simple as possible.

Good Luck,