Alright, I've hijacked the thread about ARB Seth's KJ enough. Anybody wanting backround information about what I'm rambling about, check here:

http://www.lostjeeps.com/forum/phpBB3/vie ... php?t=8221

Now, here is what I'm thinking. Due to the four link points on the rear axle, when you lift a KJ you are moving the rear wheel foward and in turn causing the pinion to rotate up. This is where my thought process is getting cloudy. If I measure the pinion angle pre-lift with an angle finder, install the lift and RE adjustable lower control arms; I can then in turn adjust the lower control arms out until the pinion angle is back to factory stock with an angle finder and have the wheel more realigned in the well?

I'm looking into fabricating an adjustable boomerang, but right now I'm not thinking it isn't neccessary.

Any mechanical engineers, craftsmen, or mathematical geniuses feel free to chime in.

My thoughts exactly on moving the tire back to recenter it with the adjustable control arms. However, all I've ever seen posted, was they only adjusted to stock the lenght.... WHY NOT BACK FARTHER???

_________________
Slightly modified Lt. Khaki 3.7 2004 LTD 4X4. Purchased new 8/6/03.
What I don't have....A Mag light mounted to my seat.
Original Old L.O.S.T. #000354

Nick's Pics & Mods click here: http://www.cardomain.com/ride/531173
http://www.survivaltopics.com/forums/

Exactly, if my examination and summation of the suspension is correct, then the lower control arms locate the axle position from foward/rear and the boomerang controls the side to side attitude.

Ever wonder why long arm kits came out? Well they did because with the shorter arms the rear (and front on TJ's) would move downward and forward hiting the front of the back fender and the back of the front fender with anything over a 4 inch lift. The stock arms and their position create a short arc and the rear wheel (back to the KJ) will contact the door flare at anything over 2.5 inches. The longer arms give a nice long arc for the wheel to travel therefore the motion the wheel appears not to leave the center of the wheel well.

When I lifted mine over 4 inches the rear wheels almost came into contact at ride hit with the door flare. So I adjusted my Rusty's arms out to the point where there is 18.5 inches between the bolt holes. About 2 inches longer than stock if I rememeber. I would recomment that you get adjustale arms for a lifted Liberty. As you move the rear wheels back with the arms, you also off center the spring. In addition, as the lower arms get longer the pinion drops down, rotating the diff forward. This will cause a vibration. So you are correct in saying that a adjustable top arm or boomer rang is needed. To solve my problem at 3.5 inches (almost 4 in the back) you can see in the post under "Lift Experimntation".

http://www.lostjeeps.com/forum/phpBB3/vie ... imentation

Here I took the ball joint out and welded a "johnny joint" to the boomer rang futher back causing the pinion to rotate up.

At 5.5 -6 inches I will be building a new tri-link this weekend to really adjust the pinion. At this height you have no option but to go for a new driveshaft, the stock one vibrates too much. I had one made with a slip yoke from a GM tranny, and a double u-joint (cardone (sp?)) joint. This type of set up you need the pinion at the same angle of the driveshaft. Its still a little off so I get vibration from 0 to 35 MPH, than it stops, or you can't feel it. I need to adjust the upper point of connection, meaning a new tri-link.

With the extreme rotation of the rear axel to adjust the pinion on my KJ I needed to cut the spring pads off the diff. and rotate them to so they are parallel with the upper perches. And there is now about an inch difference in the center line of the upper and lower spring perches which makes the spring look weird. 9th degree (great TJ lift) has solved this problem with upper spring perch relocators. They move the upper perch back and tilt it at the same angle the lower spring perch wines up at when that kit rotates the rear axel (pinion) upward.

Did this help or just confuse things more?

Al

_________________
One Ruby, One Grand Cherokee, One YJ, One disassembled CJ, one Chevy Mason dump, one hotrod IH Pick-up, couple of antique tractors.
Former owner of a 5.5 inch lifted KJ

Al,

I'm tracking with you. When you lift the KJ (with stock rear lowers and uppers) you're moving the spring pad off axis towards the rear, so if you adjust the LCA out, wouldn't it bring the spring pad back to level? Also, wouldn't the lift cause the pinion to rotate up? Now of course, we've raised the transmission/transfercase, so the only way to accurately set the pinion angle would be with a angle finder.

I'm remembering some old drag race chassis stuff here. I looked up this article for reference:

http://www.carcraft.com/howto/91758/

Looks like I'm going to purchase some adjustable LCAs and then fab an adjustable boomerang and go from there. All this just to get 31x10.50"s to work, I couldn't imagine your hair pulling sessions getting the 33"s to work.

I just want it to work, not just be a pretty rig with no function.

Thanks for your input. I'm studying.

Hey Mutt.. Give Andy a call at Carolina Rock Shop.. They fab all kinds of crazy stuff.. I know he can weld about anything and his work is on a few of the KJs here (Mine included - Rock Rails).. If you need anything fabbed, maybe he can help you..

Just a thought,

Ben

_________________
06 KJ with stuff..
07 JKU Rubi with even more stuff
95 YJ - Waiting on some surgery..