Pinion angle?

[TubeTruck]

I bet you thought this was going to be a post asking how to set pinion angle. Well it is! Out of the truck..

I don't have the luxury of putting the rear in, setting pinion angle, burning the perches in and going on my merry way. I need to do this out of the truck while I'm still driving it and swapping it in later. Anyone know how to calculate pinion angle for a 4" lift? Or should I give it my best guesstimate off the factory angle? I'm thinking of setting the pinion about 2 degrees higher than stock. Currently the truck is stock height but somewhere in the near future (about a year) I plan on lifting it. Should I just set the pinion angle to stock and use shims later to adjust?

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[Keith Seymore]

Should I just set the pinion angle to stock and use shims later to adjust?

Probably your best bet.

You really can't know until it is installed, with all the weight on the suspension.

Otherwise you are just shooting in the dark.

K

 

[C10MixMaster]

If using a regular drive shaft with 1 u joint on each end then you retain the factory angle to match the output shaft angle. If you have a cv joint drive shaft then you have to change the angle.

 

[RoryH19]

Since you have to weld on new perches I would try to determine the angle instead of shims.
Some also use spacers on the cross member to lower the T-case.
Would it be possible to install the lift kit and then set the angle at the same time?
The truck will be apart anyway and this will be the best time.

 

[TubeTruck]

Since you have to weld on new perches I would try to determine the angle instead of shims.
Some also use spacers on the cross member to lower the T-case.
Would it be possible to install the lift kit and then set the angle at the same time?
The truck will be apart anyway and this will be the best time.

I agree. I want to stay away from shims if I can but I'm going to be installing the axles in the next month or 2. The lift will come later in the year or beginning of next year. I would love to be able to install it all at once but this is my DD and I don't have a garage. All the work is being done at my job after hours and some hours on the weekends so I can't have the truck down for more than a few hours. Maybe if someone has a long bed on here with a 4" lift they could measure their pinion angle, preferably with a TH350 and NP203. That would get me close.

 

[bucket]

How are you going to lift the rear? Blocks, springs or shackle flip will set the pinion differently.

 

[TubeTruck]

How are you going to lift the rear? Blocks, springs or shackle flip will set the pinion differently.

Shackle flip, which will raise the pinion more. Good catch. I'm just going to set it to stock and worry about it later

 

[eskimomann209]

Shackle flip, which will raise the pinion more. Good catch. I'm just going to set it to stock and worry about it later

I’d set it as you need it today. When you do the lift kit later, Grind of the perches you install this time and put new ones on (again).There are, of course, shims. But If you have the skills and resources to do it right, Why not?

 

[Travlr]

Okay, I have a question. When putting shims in to change the angle of the rear pinion, do you put the shim in under the springs between the diff and the springs... or can you put it above the springs? Does it really matter?

My concern is this. The spring pin is just the bolt head coming out the bottom of the spring and into the centering dimple on the top of the diff. Putting a shim in would likely make very little of the bolt head in that centering hole.

The top of the spring has a lot more material than the bottom to place the shim over and to go into the centering hole.

If I turn the pin over to get the longer part on the bottom, there will be so much that is will bottom out in the differential centering dimple and not tighten down

 

[SquareRoot]

It goes between the bottom of the spring and top of the perch. The pin goes thru the shim and spring pack. If it's not long enough you need longer pins.