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PLEASE HELP ASAP: STOCK XJ REAR ALIGNMENT ISSUE

89xjgrey

89xjgrey

NAXJA Forum User
Location
Columbus, Ohio
Well guys, I need some help...I've been on this one all day and am still stumped. The vehicle is a 2001 4WD XJ, stock suspension, brand new track bar. The alignment in the rear is off. Here is the situation. The thrust angle currently is +0.6 degrees. Specification is -0.2 to +0.2 degrees. Left rear toe is +.75 degrees and the right rear toe is -.45 degrees. Basically looking like /----------/ . Now we all know that it is a solid rear axle and solid rear axle shafts, with no toe adjustment. With that in mind...what could cause this? Bent axle housing? All leaf spring bushings look good and intact. With the suspension loaded on the drive on rack, when I look up at the differential from underneath, i can physically see that it is off...Any suggestions? The pinion on the differential is pointing slightly to the passanger side. This thing has been pissing me off all day...
 
Hmmm...I will check the center pins again in the morning...but let's say that they are straight and intact...any other ideas?
 
89xjgrey said:
Hmmm...I will check the center pins again in the morning...but let's say that they are straight and intact...any other ideas?
Click to expand...
Has it ever been in an accident, wrecked? Bent unibody damage?
 
The unibody is straight, for certain. As far as an accident/collision, I'm not sure. Bottom line is my boss seems to think that the axle itself is bent, but I'm having a hard time believing that being a street only driven jeep with only 80K miles on it. And I don't want to waste my time replacing the axle if it is not the problem. All leafs in the pack are intact. I was looking on napa's website and came across a 'thrust alignment kit' which looks like it installs between the perch and spring, and slides back/forth then gets locked down in place. But i'd really like to fix it right...not just band-aid it.
 
Like you said that kit is just a band-aid. You need to find the root problem & fix it right. If not you are going to eat tires like crazy & those are not cheap. Plus you will look pretty silly dog tracking down the rode.
 
I agree with you 100 percent. Like you said, I don't want to band-aid it. I might if it was mine, but since we are a repair shop and since it is a customer vehicle. I need it done right. I'm just having a hard time convincing my boss that it is not a bent axle hosing.
 
89xjgrey said:
I agree with you 100 percent. Like you said, I don't want to band-aid it. I might if it was mine, but since we are a repair shop and since it is a customer vehicle. I need it done right. I'm just having a hard time convincing my boss that it is not a bent axle hosing.
Click to expand...
I would say, If the center bolts look good w/ no shifting, the shackles & hangers look good & you don't see any unibody frame damage. Your boss may be right. Even tho this is street driven rig does not mean some idiot tried to pull it by rapping a chain around the axle. Just a thought.
 
89xjgrey said:
I might if it was mine, but since we are a repair shop and since it is a customer vehicle. I need it done right. I'm just having a hard time convincing my boss that it is not a bent axle hosing.
Click to expand...
Wow,thats scary!!
 
UPDATE: Well when I came in this morning, running short on ideas...I decided to swap the left spring to the right, and right spring to the left. My thrust angle came in .3 degrees. So now the thrust angle is only +0.3 degrees, rear toe is now at +0.45 and -0.20 degrees left/right. Not quite where I want it, but if it was yours, would that be acceptable? Or should I dig further into it? Thanks everyone...
 
That's weird, because if it was in the springs you swapped, shouldn't it be pointing the opposite way than it was at first. And it seems like it's still the same direction, just less. It's also weird that they aren't both parallel. At first, you were .3 out of parallel between the two sides, and now you're .25 out. So the axle was either made that way (OMG what a shocking thought), or bent that way. I'd drive it and have somebody follow to see if it's dog tracking. It's probably OK. It couldn't be in a bent wheel could it? I assume that you spin the wheel and take the average reading.

Have you checked the rear alignment on many other RWD solid axle vehicles? Do they usually check good?
 
To be honest, I do a lot of solid axle alignments, and 95% check out good. Even my XJ with 6.5" of lift has a better thrust angle than this stocker. I thought a bent wheel might be the cause, but I spun balanced all 4 and they are all true. I'm just wondering if one spring is flatter than the other one under load.
 
here is the sheet last time I got mine aligned. There is some measurements for the back
I don't think there is any way to get zero.
align.jpg
 
So Spark's axle is only 0.15 deg out of parallel from side to side, about half of what you're looking at. My trig memory in the shop tells me that it is 0.015/inch/degree. So 0.10 degrees would be 0.0015/inch. Across a 16" wheel that would be 0.020" or 1/50th of an inch. So its less than 1/32" but more than 1/64". So if the vehicle you're checking is 0.3 out of parallel side to side, that would be 1/16th of an inch. So between the front of the wheel should measure 1/16" less than at the back of the wheel.

Don't really know how significant that is, but toe in on the front says it can be 0.25 and it's OK, so 0.3 is probably not that bad.

Hey, what's the deal with Sparky's front toe-in spec? It says that the spec is +/- 0.25 deg. I thought they always had to have zero to toe-in. FSM says 0 to 0.45 degrees with 0.25 preferred.
 
winterbeater said:
Hey, what's the deal with Sparky's front toe-in spec? It says that the spec is +/- 0.25 deg. I thought they always had to have zero to toe-in. FSM says 0 to 0.45 degrees with 0.25 preferred.
Click to expand...


While his toe specs could be adjusted a little tighter.... take a look at the caster....
Looks as though his Jeep is lifted without adjustable control arms or drop brackets.
Caster that low will make the steering light and drifty when on the highway....

Years ago... I installed adjustable LCA and UCAs to provide proper caster and pinion angles.... The caster on my 98 is run at 7.1* with no driveline vibrations.... and tracks very well on the highway even at 80+ mph.....

Back to the problem at hand.... If the leaf springs are factory and have not been replaced, the end bushings are in good condition, the center pins are not sheared and the U bolts are tight, the leaf pack degree shims are installed properly and not broken, the shackle bushings are in good condition, the rims are true and the axle flanges are not bent... there really isnt much more to check other than the axles tubes being bent....
Which rear differential does the Jeep have.... D44 or D35???
D35s would be more prone to this problem than the D44.
 
CharlesS said:
While his toe specs could be adjusted a little tighter.... take a look at the caster....
Looks as though his Jeep is lifted without adjustable control arms or drop brackets.
Caster that low will make the steering light and drifty when on the highway....
Click to expand...

Yea I put a long arm kit on the front and just guessed on the caster, it was very darty on the road, I have fixed it now.

And I am pretty sure there has to be a fractional toe in to help in return to center steering.
 
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