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Rough Country long arms - can't gain caster

cfordp

NAXJA Forum User
Location
TX
5.5" front springs with rc radius arms. Just replaced the upper bushings because they were bad.

hp30 swap on my 2000. I pulled the uppers all the way in and didn't really gain any caster (2 on drivers 1.9 on passenger, swear that's what I measured from the same spot pre shortening the uppers).

My upper arm measurements are 1" shorter than RC recommends (14 3/4 with no adjustment left. RC baseline is 15 1/4) and 30 1/2 on the main (3/4 longer than RC baseline).

I know there is caster correction built in. Would I gain caster pulling my entire arms shorter?
 
Specifically what lift kit or part numbers are you working on, and where does one find the recommended settings ?

Wondering how you are measuring Caster ?


I know there is caster correction built in.

What does this mean ?

If you are out of travel on the uppers, start over with the recommended settings and confirm you are measuring correctly.



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Would I gain caster pulling my entire arms shorter?

Changing the lower's won't do anything for your caster, you would need to shorten the uppers.
 
https://www.roughcountry.com/jeep-xj-long-arm-upgrade-kit.html

It's that kit with Rubicon express 5.5 coils. I measure my caster from ball joint to ball joint with a piece of metal and an angle finder. I had my buddy at NTB measure it and got the same reading. Took it to a frame shop and got the same reading. Frame shop recommend cutting the arms shorter and rewelding to gain more adjustment on the uppers.

Frame shop said shortening the whole assembly wouldn't affect caster but I'm not 100% convinced because of the geometry of the arms.

21e5be13c0bd28a296c368479f59290d.jpg
 
When someone says shorten the whole assemble, they should then specify exactly where. If the main assembly is shortened by cutting and welding at the cross member joints, there will be no effect upon the caster. If anything needs to be cut and re-welded shorter, that would be the uppers.

If the uppers are as short as they can go, lengthen the lowers. You can always go back to where you started, or back to the recommended settings, after cutting and welding, you can't go back.
 
Sorry.

I'm wondering with the bend in the main arm if I shortened it, if it would increase my caster. My background is in programming and somehow I never learned trig and figuring out the geometry of these arms is beyond me.

The cutting and welding would be done on the short upper arm. I can weld but I don't do any structural welding, this is a job for the guys who run beads daily for a living and I don't mind farming it out. I just don't get how I would need to cut and shorten my arms to get proper caster when 1000s of people are running these arms without caster issue. Everyone I wrench and wheel with are telling me to just man up and pull the axle to rotate the C's but crap that's a lot of work for a Dana 30
 
How was the caster measured and how does it drive? Does it come back to center after making turn?
If the caster is a low as 2 degrees, and nothing seem to make it better, adjustable lower ball joints can gain up to 1-3/4 degrees. I have run a set of adjustable ball joints on my 2001 for over 100,000 miles and they are still in good shape.
 
I have the same kit with RE 4.5 coils (so a bit lower on the lift). I am at 4-5 on the caster and my Jeep handles well (sure its not spec but i noticed anything lower than 3 degrees on the XJ's then they tend to wander). My uppers still have plenty of room for shortening, so for you to have them all the way in and 5.5" of lift and still only be at 2 degrees seems odd. I would put it on a nicer alignment rack and recheck (I think i read you used some other sort of measurement).
 
Is there room to drill radias arm rear upper mount 1/2" back to shorten arm
Are you sure your setting castor on the positive side?
 
Why not just lengthen the lowers a little. Enough to get the correct caster reading. If the uppers are too short then the only other option (aside from relocating them on the RA mount) is to lengthen the lowers.
 
Why not just lengthen the lowers a little. Enough to get the correct caster reading. If the uppers are too short then the only other option (aside from relocating them on the RA mount) is to lengthen the lowers.

That will have zero effect other than pushing the axle forward, the upper are fixed to the lowers.
This is not a 4 link.
 
Was this ever resolved. Seems impossible for the upper arm to be an inch shorter than the recommended length and still be that close to zero caster. Is the back end of the XJ sticking up way higher than the front?
 
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