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RC drop brackets and lca length.

Mcmadman

NAXJA Forum User
Location
michigan
Hi I have a zone 4.5 lift kit and i just ordered some ironman adjustable uppers and scored some rc drop brackets used locally. Ive read that I want stock length lca for drop brackets...i currently have the 4.5 zone fixed length lca they are 1/2" longer than stock i believe. Will these work?Also any go to bookmarked write ups on steering,suspension and pinion geometry would be much appreciated as well. Thanks!
 
The control arm chart is a suggestion for where to approximately set your control arms. I have (unknown length) Rubicon Express 3.5" lift fixed length control arms and they work fine with my drop brackets. I would recommend that at least one set of control arms be adjustable, the other set can be fixed.
 
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I just bought some iron man fab uppers... The chsrt is approximate howndo they get these numbers? Measuring caster vs pinion angle? Lets say I did want to shorten the lca what does removing shims affect?
 
I just bought some iron man fab uppers... The chsrt is approximate howndo they get these numbers? Measuring caster vs pinion angle? Lets say I did want to shorten the lca what does removing shims affect?

Any shims being used now will push your axle forward, effectively like lengthening your control arms. Removing the shim effectively shortens them.

If you have no shims, then that's it.

As a rule of thumb, adjustable lowers are for setting wheel base, and adjustable uppers are for fine tuning pinion/driveline angle.
 
I see thanks...i just have to find a good write up on caster and pinion angle , the one I keep finding is 404ed...i was going to say start with the lower shims because mine are fixed but tose shims wont really change my wheel base much tho right?
 
Once you lift more than 3-4 inches, you can't have both pinion angle and caster with nominal numbers, unless you cut, rotate, and re-weld the inner C of the axle. What you end up doing is balancing just enough pinion angle to prevent drive line vibes with just enough caster.
 
When I installed my control arm drop brackets, I used the chart suggestions to set the length of the adjustable uppers. I set the toe-in with a tape measure. The pinion angle looks OK, and has no vibrations. It drives nicely with no excessive tire wear or odd steering behaviors.

IDK what the caster is, none of my XJ's have ever been in for an alignment. I know some people have measured and recorded their caster, I suppose if you search a bit you could find some typical caster or pinion angle numbers.
 
I'd say 4-5* is the sweet spot but that depends on other things. I have a LP D30 so it's been at 3* for 16yrs now!
 
Larger tires (33+) seem to like more caster. My last two axles have been rotated to supply 6-8 degrees of caster, when the driveshaft is properly aligned to the centering ball on the double cardon joint.


David Bricker / SYR
 
Not if you do it right, but you could easily sell them "as is" and get some new ones for probably less cost.
 
Is it a bad idea to have someone cut my zone lcas and reweld them?

tube-splice.jpg


If you do go this route, there's a proper way to splice tube. Make sure that your fabricator adds an inner sleeve that spans to both original pieces of the tube along with the new section, with rosette welds (you weld in the holes in the picture to the inner tube). If you just butt-weld it together, it will crack and fail. Hopefully you won't be going too fast when it does. :eek:
 
Good call. I measured my wheel base and although i didnt get an axact measurement it was more like 99.... If my axle was too far forward wpuldnt it be like 103 stock spec 101
 
Are the ironman adjustable uppers actually any good?! I have ordered some, a couple of years ago, however I was so freaking dissapointed, I decided to throw them away. Maybe I have got a bad product, as that happens, however none of my friends have ever been pleased with these ironman adjustable uppers. I still remember, back when I ordered my uppers, I was having a problem with converting cm to inch, as I was in France at that moment, and to be honest, converting those units has been really tought for me.
 
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