Pinion Angles

[unccpathfinder]

growing up i always heard this huge hype on pinion angles and if you lift your vehicle you need to adjust for this so you dont destroy u joints and what not...

 

for all you lifted guys/gals have u experienced problems with this...i know theres a limit on our height but if you could go higher would it eventually put the U joints in a bind and cause some major carnage?

[89_trailboss]

yes. you can bind a Ujoint. changing pinion angle on a rear axle is pretty damn easy. with leafs you can get shims. on a linked setup you just screw with your arm lenght. the front is more of a PITA. you can use the same idea as with the rear. but there is also a limit. once you go too many degrees your caster gets way screwy. causing wondering and steering bind. at that point you do a "cut and turn". you cut the welds off the C's. pound the C's off and turn them. you DONT want to point your pinion at your tcase. you will get vibs. that is, unless you have a dual cardian or CV joint on your Dshaft. thats the basic run down. thats quite abit more too it tho.

Edited February 9, 2007 by 89_trailboss

[offroad95pathy]

When you shim a leafed rear axle, that's what you're doing, pointing the pinion toward the trans output shaft, to help reduce the acute angle at the u-joints. Average OEM DS's will do 25-30 degrees either end, Cardan equiped shafts will do 40-42 degrees, these are always under full travel conditions. A well built shaft would be dynamically balanced, the orientation of the pinion to the output shaft will not induce vibration as long as the angles are not exceeded in full travel relative to the limits (angles and rpm) of the DS.

Edited February 11, 2007 by offroad95pathy

[unccpathfinder]

so my next ?...with 3 " of suspension lift how much will that increase the angel and should i have to adjust it?

[offroad95pathy]

I doubt that 3" of SL is is going to put you out of spec, or cause you to start having issues with you DS. But if your conscience needs to be soothed, once you get the lift finished, raise your truck so the rear axle hangs free without touching the ground and measure the angle you end up with (shop lift is the best way, where they can lift by the frame). You'll need one of those angle finders that can zero either horiz./vert., place it on top of the shaft and see what you get. You could actually calculate approxiamately what the angle change would be, but that's kind of a PIA.

[unccpathfinder]

i'll snag one from T&D 1 weekend and measure it its all fancy with the magnet and what not...good info thanks

[88pathoffroad]

Ditto, it's not really a problem until you get more lift and more suspension travel in the rear. I've never heard of anyone having DS/pinion angle problems with a WD21.

[mws]

The rear driveshaft is pretty long, I doubt you will have any binding issues unless you exceed 6" or so of SUSPENSION lift.

 

It is a much bigger problem on vehicles with very short shafts - like CJ's.

[Mookie]

You won't have any problems. There are a lot of Sas'd Pathys out there with no pinion correction for the rear. Before you get pinion angle problems, you'll hit the rear cross member first.

[unccpathfinder]

yea i was looking at that under the truck at the yard...stock axle completely maxed out there was like .5-.75 ins of clearance on the x member with the safety loop...that would suck...

 

i was just curious b/c i never heard about it on the boards here and was suspecting we didnt approach the limits...most i heard it on were like chevy blazers and the shortbed reg cap pickups

[88pathoffroad]

You won't have any problems. There are a lot of Sas'd Pathys out there with no pinion correction for the rear. Before you get pinion angle problems, you'll hit the rear cross member first.

Funny you should say that. My rear DS has rub marks right where the x-member is...is that bad?

[Mookie]

Funny you should say that. My rear DS has rub marks right where the x-member is...is that bad?

Nah, not at all :cool2:

 

I've only seen once where it caused the pinion seal on the 3rd go all leaky-leaky.

[mws]

Funny you should say that. My rear DS has rub marks right where the x-member is...is that bad?

And if it wears more than 1/8" deep, you ought to consider replacing it!

[88pathoffroad]

Yeah, it's just paint scrapes, not real hard rubs.