ktmriderxjdriver

i have a 3" RC add a leaf and want to go higher in the future.
i plan on buying 4.5 coils, leafs and new shocks.
i want to know if i have to replace the lca's because i have the rc tubular ones for the 3" lift. if i kept the 3" kit lcas, would it screw with the angle of the front axle? or would it be too slight to notice? if so could i just buy longer upper arms?
i plan on an sye and brakelines.
any more suggestions for parts needed for the upgrade would be appreciated

cdn_xj

First off, understand that your caster and pinion angles are affected by the lift. also keep in mind that pinion angle is the more important of the two. Of course, the ideal solution will retain stock specs on both caster and pinion angles but sometimes that's not achievable.

My recommendation would actually be to invest in adjustable control arms. that would allow you greater flexibility in terms of setting both your caster and pinion angles, and allow you to upgrade to drop brackets in the future if you so desire. And in all honesty, at 4.5" of lift and short control arms you should be considering drop brackets anyways.

Added bonus: you can also relocate your front axle further forward (to an extent) to compensate for the fact that it will move back relative to the body when you lift it.

just_jeepin

Everyone's jeep is different when lifted so you could try the ones from RC but if they arent adjustable you may end up having to get a drop bracket at the very least. I would recommend redoing your steering. Atleast a stabilizer, zj v8 tie rod, maybe a drop pitman arm, and a trac bar.

b. lee

Two things, an incorrect pinion angle won't do much more than cause some vibration and wear out u-joints in extreme cases. Incorrect caster angle will cause many drivability issues, including but not limited to death wobble and wandering.

Second, they are tied together, you can't seperate them without rotating the C's. There's no reason that with the proper parts you can't retain factory specs by locating the axle in the stock orientation after lifting the vehicle. You may not want the stock specs, but it's do-able.

b. lee

Call RC and see if the LCAs they use are the same for both kits. If not, what's the difference? Probably slightly longer for the 4/5" and likely have some clearance built into them, as hitting the shock/spring mount on the axle end will be your biggest problem.

cdn_xj

ehhh..yes and no. your first point is correct. and your second point is 1/2 correct.

at a certain point, you can have proper caster with a lifted stock diff and lose your pinion angle. @ 4.5" it's unlikely to be a problem, but hey, we're talking about Jeeps here

clocking the diff housing (or rotating the Cs as you put it) is not really worth the effort for a 4.5" lift. in the case of a more extreme lift, yes. or if you're custom building the axle anyways, also yes.

For what the OP is trying to do he should be ok but occasionally people run into situations where resolving both pinion and caster angle become mutually exclusive. depending on how great the variance is, you are better off sacrificing a little caster angle for pinion angle.

Yes, caster angle affects the steering but the degree of variance we're talking about here will probably manifest itself in the steering not returning full to centre on its own and/or change in camber angle the closer you get to lock. This can be compensated for by slight changes to one's driving habits providing it's not too severe. ie. not relying on the steering to self-centre. Contributing to death wobble? Absolutely. But if you're experiencing DW then there are probably other things you need to fix as well.

Besides, if a couple of degrees of reduced caster are enough to cause you to lose control of the vehicle, you were probably driving it in an unsafe manner to begin with.

The reason I say sacrificing a little caster for pinion is ok is because our front drivelines only disconnect at the TC (and @ the passenger inner shaft for the disco D30s) That is, unless manual hubs were installed. With the front driveshaft ALWAYS rotating you will almost ALWAYS get vibes if the pinion angle is out. 1) it's annoying as hell on the freeway (BTDT) and 2) yeah, you wear out the u-joints faster. And believe me, you don't want one of those babies letting go @ 65 on the freeway (don't ask me how I know )

Bottom line: if you go for the adjustable control arms, set the LCAs to position the axle relative to the chassis. The set the UCAs the achieve your caster angle. THEN check your pinion angle. if it's close, take the jeep for a drive to see if you can live with the vibes. if not, adjust the pinion angle until the vibes diminish.

b. lee

Yes sir I agree on all points, I overlooked the increasing pinion angle aspect by considering only the 1.5" difference. Well stated.

ktmriderxjdriver

Thanks for all the info guys huge help!