What should the rear pinion angle be for my Cherokee be if lifted 6-7 inches and an SYE installed? I've read if you have a slip yoke, the rear axle pinion should be pointed at or near the transfer case yoke. And if you have an SYE, the rear axle pinion should be pretty straight. Any thoughts?
I'm about to start mocking up the perches on a Ford 9 inch and any help would be great.
Thanks!

 

this is the angle i would aim for

 

Is it better(stronger, less vibration) to go with a double cardigan style drive shaft in the rear after installing an SYE?

 

it greatly decreases the angles and make for less vibration probs also if you did not no a front shaft out of a xj is the same shaft you can use in the rear after installing sye

 

You'd think by now that after all the lifts that have been done to the XJ someone would have charted the optimum pinion angle for the the amount of lift.
I mean it would be easy enough.
Stock height has X pinion angle
1" lift has X pinion angle
2" lift has X pinion angle
and so on till you get ridiculous.

I went to a local 4X4 shop and asked them to weld on new spring perches onto the axle I want to swap into my rig with a 4" lift.
They said just tell us what you want.
I said "Don't you know?"
They said it was up to me, that way if it %^#ks up it's my problem.
I left with out getting any work done.

 

I do have a spare front drive shaft and was looking in to using it for the rear. I'm hoping there wont be to much of a difference in length between rear pinion yoke and t-case yoke after the new axle is installed. Would save some money.

 

im running 10.5 lift and had to extend mine 3 inchs there are a couple of xjs here using stock length one in the 7.5 to 8.5 inch lift zone

 

all vechicles are different dont think there is a set way best way to me would be to mount the rear lossle and set the angle accordingly then tack eld then remove and final weld just my 2c worth

 

Is that the Mr. Rogers style driveshaft? I don't really think a double cardan is stronger, but it does eliminate the vibes that the Cherokee is so prone to. I'm giving some angle shims a try this weekend and if that doesn't do it I'm gong to put in an SYE and double cardan front shaft.

 

im running 6" and my measurement after an advanced adapters sye was 32 1/2 from yoke face on t case to yoke face of axle (chry 8.25). the rear yoke should be in line with the drive shaft (as you see in the pics) and the double cardan will absorb the angle... i think 4* up is what you wanna aim for...maybe 6* if higher than six inxhes of lift for the rear yoke

 

i ran 7.5 lift with tc drop and stock ds for 5 years no nothing all xjs react different for some reason ive noticed one thing complete spring pack get wobbles a lot easier than ones with packs and angled blocks

 

Actually if you don't mess with the cross member the output shaft angle will not change. That we will assume is a given start point for the optimum drive shaft to pinion angle.
the ujoints work best at certain design angles.
If we had those than it should be simple to draft a formula to arrive at the best pinion angle.
Just plug into the formula the height difference over stock and out comes the angle at which the pinion should be to allow the ujoints to work without undue strain.
I keep reading posts where someone uses a 2.5° shim to change the angle. How did they come to decide this was the proper angle?
And how did the engineers that designed the XJ decide the best pinion angle for the stock height?
I can't believe they just eyeballed it and said "Looks good. Make the next 3 million Cherokees with that angle.".

 

What you mean by angeled blocks ?

 

What you mean by angeled blocks

 

lift blocks with angles on one side to pitch pinion up