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front axle and UCAs

altierior

altierior

NAXJA Forum User
Location
East Norriton, PA
i had a computer alignment done recently, and the report told me that my caster was off. since my lowers are fixed, the caster can be remedied by shortening my adjustable uppers a little (about .5"). so my plan was to shorten the UCAs while i had them out for a heim rebuild.

the problem is: when i removed the UCAs, the top of the axle axle rolled forward by a very slight amount. between that and the now-shorter UCAs, i cannot reinstall the UCAs. i bolted them up to the body end, and they won't reach the axle mounts. i tried using a ratchet strap to pull the upper axle mounts back, but to no avail.

any advice, tips, or tricks?
 
Try running a ratcher strap around the pinion, under the axle back to the front bumper. This should pull the pinion down moving the UCA mounts to the rear. JIM.
 
Ian Christiansen said:
I used a rachet strap between the UCA mount and the back of the transfer case skid to line mine back up.
Click to expand...

i tried essentially the same thing with my ratchet strap to the x-member.
 
Hey John... a few ideas...
Are your LCA's loose? If not, loosen them at both ends. Are the LCA's hitting at the back of the control arm pocket (on the axle) at full droop? If they are, then your never gonna get the UCA's on. I would think about clearancing that pocket a bit if they are hitting. If that doesn't work, take the coils out and jack up the axle a few inches. This should allow the UCA's to line up.
 
ehall said:
Pinion angle is more important than caster angle. The machine reports won't tell you if the pinion angle is right.
Click to expand...

Agreed,plus since the OP didnt say what the castor was?
 
Couldn't you just put a jack (preferely a bottle jack since area is tight) under the front end of the coil bucket? By lifting this area, it should tilt the UCA mount enough to get back to where you need it. Of course this will only work if your LCA are already attached and if the axle only rotated forward. (not actually was pushed forward)
 
ehall said:
Pinion angle is more important than caster angle.
Click to expand...

maybe. but i have sloppy steering issues and DW, the correcting of which takes precedence right now for me. bad caster can cause both.
 
I wouldn't add too much castor, what did they want it to be? You can just put a bottle jack under the track bar axle mount and it will rotate the axle so you can bolt up the upper arms. Too much castor can contribute to DW just like too little.
 
Recently had the same problem after installing the Currie JJ conversion kit.
There are numerous way to rotate the axle for which several have been addressed.
You can also use a floor jack and a 2x4 under the coil spring mount or tracbar mount or what I worked for me was a come along attached to the coil spring mount and transfer case skidplate or crossmember.
 
so before you potentially kill yourself. Just want to make sure your vehicle is on stands at the frame/unibody with the wheels removed and your suspension is fully uncompressed and at full droop before you start unbolting stuff. In this situation you should have no problem with what you are asking.

On another note. the frame/unibody side mounts for your lower control arms are adjustable. That is how your caster is adjusted in stock/fixed length arm situation. Not to say that you cant do what you did but it would be alot easier to adjust the lower mounts out a hair.
 
favaguitars said:
so before you potentially kill yourself. Just want to make sure your vehicle is on stands at the frame/unibody with the wheels removed and your suspension is fully uncompressed and at full droop before you start unbolting stuff. In this situation you should have no problem with what you are asking.

On another note. the frame/unibody side mounts for your lower control arms are adjustable. That is how your caster is adjusted in stock/fixed length arm situation. Not to say that you cant do what you did but it would be alot easier to adjust the lower mounts out a hair.
Click to expand...

dont know about that.

ive adjusted the arms on mine numerous times with the wheels on the ground.

why would you want the axle at full droop?

many ways to rotate the pinion/caster. ive done it with a rathchet strap, but in this case, i would block front wheels, release ebrake, rock xj forward, pull ebrake. the weight of the xj will rotate the top of the axle backward..
 
Just want to make sure your not pulling both upper control arms out at the same time to adjust them. I would never want to fully remove parts of the suspension with the weight of the vehicle on the suspension. Just my preference i guess. Maybe I'm misunderstanding the situation.
If you have frame on stands and the vehicle weight off the suspension you can manipulate the axle rotation freely.
 
If you take out both uppers with the weight of the vehicle on it, the axle could roll out and the coil springs could let go (under pressure mind you) and it could get ugly, like death and stuff. I usually jack it up as much as possible, loosen the LCA bolts and use the bottle jack technique to adjust the pinion angle. If the bolts won't line up after the angle is set you can usually just have someone roll one of tires one way or the other to get them in. The passenger side UCA mount is very weak and can be bent or torn very easily using ratchet straps on it making it impossible to get both bolts in without killing yourself.
 
The weight is being supported by the springs not the CA's. The more help the better. have someone apply brake, someone rotate tire,and you under dirrecting it all. I had 9 deg caster, it was too much. Better at 6-8 deg. 0 deg = DW almost every time.
 
You can easily rotate the the axle assembly by placing a large pipe wrench under the inner yoke, and using a bottle jack as required.
Since the springs on an XJ set on the axle forward of the axle's center, without both upper arms, the axle will try to rotate the axle forward. So, with springs still under compression, only remove one UCA at a time.
I think a minimum of 4* positive caster should be used, and wouldn't go more than 6* positive.
 
Highway XJ said:
I had 9 deg caster, it was too much. Better at 6-8 deg. 0 deg = DW almost every time.
Click to expand...

i can't find a good explanation as to where and how to measure caster. someone please enlighten me.
 
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