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Discussion Starter · #1 ·
Im in the middle of installing a RK 2.5 max travel in a 2010 2 door Rubicon. Started on the back and got to the LCAs and ran into a snag. They will not adjust down to the recommended 19 5/8" bolt hole to bolt hole, tightest I can get them is 19 7/8". I mad two snug fitting steel pins for the bolt holes and machined a point on them to take my measurement from, not just eye balling it. Any ideas? I sent RK a pm waiting for a return. I know the measurements are crucial, dont know what will happen if i install them at this setting. Will my pinion angle be off too much, wheel not centered in wheel well? Im a newbie and just want to do it right
 

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I honestly don't know the answer for you, but those guys have great customer service. Have you tried to call them direct?
 

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i had the same issue when i installed the front RK LCA's with a TF 2.5" coil lift.
I just mounted them as short as possible and it was still within factory caster specs.
Later on i lengthened the LCA's a tad to get about 5.5* caster to get rid of that flighty feel.
 

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Discussion Starter · #5 ·
Im gonna try tomorrow, I cant call them during the day.....my work has phones locked so you cant dial long distance and I live in a small town with very limited cell service. Dont wanna call from the cell and they not be able to hear me lol
 

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Discussion Starter · #6 ·
No biggie RK, cant imagine the amount of messages and mail you guys get in a day lol. How late are you open?
 

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Discussion Starter · #8 ·
Dont be sorry, i know you guys are busy! Thanks for the info, just wanted to check so I didnt screw anything up:) Thanks again guys, your stuff is awesome, very heavy duty. I wleded on the rear track bar bracket last night, the stocker is a joke compared to yours.
 

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Discussion Starter · #11 ·
No issues as long as i can use them at that length. Thanks for the help guys.
 

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i had the same issue when i installed the front RK LCA's with a TF 2.5" coil lift.
I just mounted them as short as possible and it was still within factory caster specs.
Later on i lengthened the LCA's a tad to get about 5.5* caster to get rid of that flighty feel.
I'm also out of shortening adjustment on the RK LCAs. Running the 2.5 max travel. My caster is at 4.9 (shop alingened) and would like to get it within recommended spec of 4.2 - 4.7. Bought the UCAs to help, just need to install. Jeep seems to be running fine at 4.9 though.

When I do install the uppers, thought I'd measure the factory UCAs and the add one turn of length to the RKs. Really don't want to pay for another alignment. Will this one turn in additional length work? I'll probably call you guys tomorrow and ask.
 

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I'm also out of shortening adjustment on the RK LCAs. Running the 2.5 max travel. My caster is at 4.9 (shop alingened) and would like to get it within recommended spec of 4.2 - 4.7. Bought the UCAs to help, just need to install. Jeep seems to be running fine at 4.9 though.

When I do install the uppers, thought I'd measure the factory UCAs and the add one turn of length to the RKs. Really don't want to pay for another alignment. Will this one turn in additional length work? I'll probably call you guys tomorrow and ask.
I thought the uppers were for pinion angle specifically, lowers for caster....A shop will probably just F it up anyways. As RK said previously, I lot of places don't tighten the jam nuts down enough and they end up coming loose over time. But then again you may have a shop that knows what they are doing, but i would just go off the info you get here for caster specs and the correlating control arm lengths and go from there. I set my front lower arms to the lengths recommended by RK and have had no issues as of yet. I think the length is 23 1/8th. She rides like a dream now that I have the added caster thats for sure but I have no idea what caster numbers are exactly but as long as your not getting driveline vibs and your pinion angle looks ok you should be good to go.
 

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I thought the uppers were for pinion angle specifically, lowers for caster....A shop will probably just F it up anyways. As RK said previously, I lot of places don't tighten the jam nuts down enough and they end up coming loose over time. But then again you may have a shop that knows what they are doing, but i would just go off the info you get here for caster specs and the correlating control arm lengths and go from there. I set my front lower arms to the lengths recommended by RK and have had no issues as of yet. I think the length is 23 1/8th. She rides like a dream now that I have the added caster thats for sure but I have no idea what caster numbers are exactly but as long as your not getting driveline vibs and your pinion angle looks ok you should be good to go.
Yep, that is what I understood, but forgot until you mentioned it, about the uppers being for pinion angle, hate this CRS as I get older. But my lowers are fully adjusted in, hell there is only about 1/4 turn left on the threads and the jam nuts are tight. I had three alignments done over several months as I fought DW at three different shops. The first two shops couldn't get it under 5.5, the last got it to 4.9. Long story about why I went to three different shops, I'll spare you.

Maybe Im over thinking this and should be happy everything is running smooth. It just annoys me that I'm beyond what RK recommends.
 

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Discussion Starter · #16 ·
how are you guys using a angle finder to measure your caster and your pinion angles? can you post a pic of where you are placing the angle finder? how accurate compared to the alignment shop is this method? I have a couple of the angle finders (magnetic ones) that I use for welding, would like to learn how to check this stuff myself.......
 

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Discussion Starter · #17 ·
I put the lower arms on tonight after work, they went on without much work, The drive shaft looks pretty steep now but I assume that is normal after lifting? Im gonna have to run both stock drive shafts until next year.....pockets got nothing but lint left in them after buying lift, tires, wheels, and some other parts. Next year will be gears and drive shafts and hopefully RK upper arms......
 

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Yep, that is what I understood, but forgot until you mentioned it, about the uppers being for pinion angle, hate this CRS as I get older. But my lowers are fully adjusted in, hell there is only about 1/4 turn left on the threads and the jam nuts are tight. I had three alignments done over several months as I fought DW at three different shops. The first two shops couldn't get it under 5.5, the last got it to 4.9. Long story about why I went to three different shops, I'll spare you.

Maybe Im over thinking this and should be happy everything is running smooth. It just annoys me that I'm beyond what RK recommends.
Actually 5.5 degrees caster seems about right for your lift. You want a little more caster than the stock setting (4.2) to take out the flighty feeling in the steering.
 

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Just to clarify, upper arms don't set pinion angle and lower arms don't set castor, the entire rotation of the axle sets both. You can't change one without changing the other unless you start cutting and rotating the axle Cs or differential itself. The recommendation to use lower arms to set your castor is that it will lengthen your wheelbase (since you are making the arms longer) instead of having to shorten the upper arms (making your wheelbase shorter).

RK, I know you guys are busy, but why is it so imperative to set the lower length on the 2012s specifically?
 

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The 2012's have different drive line angles than the 2007-2011's.

The front measurements are all based on caster settings and axle positioning, so they have not changed, but pinion angle adjustment in the rear, especially with aftermarket shafts requires a few variations in arm length!

RK
 
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