looking for pinion/yoke angles...

[Eturnit3]

Im trying to find any info on proper way to set pinion angle. Im swapping in a 14bff into a half ton 72 long box on about 4" lift running 350-sm326-205 if its relevent. I need to know:

What surface should my angle finder should be measuring from (the face of the yoke?)?

What should the angle be relative to? the ground? the yoke at the transfer case? the driveline?

Is the slope my truck is resting on, a problem in determining proper pinion angle? What do I need to take into consideration if so?

Is the a General ideal angle?

Thats about all... oh, one more. Its my understanding this measurement is to be taken at ride height? does it matter? (Im getting ready to weld on my perches and I dont want to put too much pressure on whilst unwelded and mocked up, Im not sure if it would hurt anything, but I hate finding out the hard way) Thanks in advance.

[Burt4x4]

When I did mine I put the angle finder on the yoke. The idea is to get the angle finder flat with the yoke.
Now what type of driveline do you have? CV or Non-CV?
CV = point the yoke straight at the Xfercase yoke
Non-CV = Measure the Xfercase yoke angle and set pinion yoke angle within 3deg.
Yes you want the weight of the truck on the axel so your springs are pressured by the weight.

I run a CV type rear and I set my yoke 2-3deg down from straight at it, so when my 454 sends all that power to the rear and the yoke starts to stand up...well it was a theroy of mine to equalize axel wrap

[LONGHAIR]

"Lifted" 4x4s kind of throw a wrench into things with this....

"In theory" your pinion angle (at ride height) should be exactly opposite of the out-put yoke from the transfer case. The "Sticky" part comes in because of the lift. Most lift blocks are angled to tilt the pinion upward, lessening the "overall" angle of the driveshaft, but this "lessens" the angle of the rear joint more than it does the front. This is not "ideal" in the first place, just because the joints are no-longer "equally opposing", but it brings in other issues. First, it tilts the outer pinion bearing up and away from the gearlube.
Second, on axles with the fill plug in the cover, it lowers the "fill level" by rotating the back of the housing downward, which makes the "pinion up" situation worse....

Most of all, never tilt the pinion upward to the point that the driveshaft is straight in line. The there needs to be some angularity between the pinion and the driveshaft, or the u-joint will not last long.

[Keith Seymore]

Originally Posted by Eturnit3

Im trying to find any info on proper way to set pinion angle. Im swapping in a 14bff into a half ton 72 long box on about 4" lift running 350-sm326-205 if its relevent. I need to know:

What surface should my angle finder should be measuring from (the face of the yoke?)?

Along the pinion centerline. You can approximate this by putting something in the u joint cup and setting your angle gage on that - or - by going perpendicular off the face of the pinion (where the u joint straps mount) - or - sometimes that casting flange on the case is a good approximation.

Originally Posted by Eturnit3

What should the angle be relative to? the ground? the yoke at the transfer case? the driveline?

Not the ground. You are interested in the working angle formed by the two components.

Originally Posted by Eturnit3

Is the slope my truck is resting on, a problem in determining proper pinion angle? What do I need to take into consideration if so?

Nope - the working angles would be the same if the truck was upside down or on it's side ( it would just be harder to measure) because you are going to subtract the angle of one thing (like the driveshaft) from the angle of the other (like the pinion).

Originally Posted by Eturnit3

Is the a General ideal angle?

For leaf springs I think it's like 3 - 7 degrees, so that as the pinion winds up during acceleration the angle tends to straighten out.

Originally Posted by Eturnit3

Thats about all... oh, one more. Its my understanding this measurement is to be taken at ride height? does it matter?

Yep. Do it at ride height.




See if any of this helps:

Originally Posted by Keith Seymore

What you are really interested in is the "U joint working angle". You want to know the angle the U joint sees.

Therefore, it's the difference between the raw angle of the drive shaft and the raw angle rear axle pinion nose.

I've never said this publicly before but - ideally you would want that to be straight (ie, zero) EXCEPT then the u joint would brinnell the rollers into the cap and either make noise or cause a failure.

Fortunately, it's never going to end up straight anyway, because of the static angles required to make the connections and because of the dynamic changes in angle due to load under accel/decel.

Having said all that: for a "four link" car (ie, not leaf spring) I'd want the rear u joint working angle to be between one and three degrees, and ideally would want it to cancel out with the front (trans/prop) u joint working angle.

To answer your question specifically: assuming the drive shaft is angled 5 degrees down (as you follow it towards the axle), then the pinion nose of the rear axle should be 3 degrees up, giving a difference of 2 degrees.

My $.03.

K

[Keith Seymore]

By the way - if any of you guys ever have the opportunity to drive your truck around without the pickup box on it - you should do so.

It is really amazing to look out the back window and see how much that pinion nose moves up and down during acceleration and deceleration.

FWIW -

K

[Eturnit3]

Thanks a ton for the info guys.. I was feelin pretty lost. If you're ever in nor cal hit me up for a beer.

[gmc 2500 4x4]

its nice to find info like this..

[Keith Seymore]

It's nice to re-find info like this.

I've been looking for those.

[Richard]

Not sure why so many have problems with this. If you get the pinion about 1-2 degrees less or more than the trans all should be good. Because of axle wrap, torque and suspension movement the angles constantly change. A good article on modified suspension drive shaft angles. https://4xshaft.com/blogs/general-te...veshaft-angles Note that terms like close are used. Exact is not mentioned. There are several other articles on the site on vibrations, etc. A working angle above 3 degrees will not kill the ujoint, just affects longevity. This is addressed in the article and the answer provided may surprise some.

[Keith Seymore]

Originally Posted by Richard

Not sure why so many have problems with this.

Like most things: it's easy once you understand it, and mysterious when you don't.

K

[gmc 2500 4x4]

i have some work to do, and i will get this. right now rear axle is down 6degrees then 10 on the shaft to the carrier bearing then 5 on next shaft and 5 on t case. slip joint was off 1 or 2 teeth,

[Richard]

Originally Posted by gmc 2500 4x4

i have some work to do, and i will get this. right now rear axle is down 6degrees then 10 on the shaft to the carrier bearing then 5 on next shaft and 5 on t case. slip joint was off 1 or 2 teeth,

Your current setup should be pretty close and be okay with some problems. If doable, drop carrier bearing to put 6 degrees on front shaft, making 1 degree working angle at trans which is within spec. Will lessen rear shaft angle to maybe 9 degrees, making working angle at pinion and carrier the same. Adjusting pinion down 1-2 degrees (4-5 degrees) will probably be necessary due to load (wrap)