I see alot of posts about rear axle pinion flange being offset right or left from t-case output and this being a problem. I understand the pinion needs to be at the correct angle from the ground but since the shaft travels in a circle pattern my idiot brain says offset right or left is the same as offset up or down when it comes to radial angle. I guess in other words when you look at the joint from the back of the vehicle the u-joint doesn't feel a difference between a 10* angle at the 6,5,4 or 3 o'clock position.
Tell me I'm right or wrong but please explain it to me.
you got it right. the only issue with having a compound angle (up/down combined with left or right offset) is making sure the pinion flange on the diff is at the same angle as the output flange on the t-case. i have a 14 bolt in my 80 and the driveshaft angle is no problem at all with the flange angles matched.
In a 40 the length of d-shaft is an issue when trying this. The driveshaft will have 2 contact point changes instead of 1 which will be fine unless there is any slop/play it will get exagerated. Meaning that during standard set up each u-joint cap while under load has a specific contact point/area that rotates a little as the two opposing caps come thru the horizontal plane. With a compound angle you will have both the horozontal opposing caps and vertical opposing caps rotating a little as the pass thru the vertical and horizontal plane. will wear the caps/needle bearings faster and IMO be sure to use Toyota u-joints or pop for some bling ones made from harder material.
I see alot of posts about rear axle pinion flange being offset right or left from t-case output and this being a problem. I understand the pinion needs to be at the correct angle from the ground but since the shaft travels in a circle pattern my idiot brain says offset right or left is the same as offset up or down when it comes to radial angle. I guess in other words when you look at the joint from the back of the vehicle the u-joint doesn't feel a difference between a 10* angle at the 6,5,4 or 3 o'clock position.
Tell me I'm right or wrong but please explain it to me.
The drive shaft does not like being "angled" in 2 planes.
I thought about this once and figured the drive shaft doesn't care what plane it is angled in....but its not true.
When the drive shaft moves in 2 planes the amount of angle in the first plane will decrease the amount of angle you can get in the second plane. If you put a drive shaft on a bench and keep the flanges parallel you will get x* of angle up and down. Then move one of the output flanges to simulate an offset axle on a axle/centered t-case output, see how much angle you get now. It will be less than x*. The u-joint/cv will bind earlier.
I have seen 40's go through drive shafts on command because they were binding a rear offset shaft very early in the travel.
True...its not a problem until you get a certain point of suspension travel, and hit that "bind point"
In factory applications its actually a good thing when the drive shaft would otherwise be strait and fixed (IFS/IRS), cause it causes the u-joint to move a bit and keeps it from seizing up.
Right. The bearings don't turn without a little bit of angle.
I have both angles on the pig but it doesn't go very fast down the road and the drive shaft doesn't have a great deal of up and down angle due to the limit strap and limited up travel. I'm running an 80 rear with a lesser off set than a 55 rear. It's not a lot.
I also use Toyota U-joints which seem to be the strongest known to man.
