RE 4.5" lift = shorter wheel base?

Blaine B. · Jan 17, 2008

Well, here's an odd one....

My buddy has a 96 XJ, with a 4.5" Rubicon Express lift, along with u-bolt eliminators, shackels, and spacers in the front. Also, long arms, SYE, and custom rear drive shaft (not just a front shaft, this one is longer)

For some reason the rear seems to have came forward in terms of wheel base. The leafs are currently using the center hole of the u-bolt eliminators (not moving the axle forward nor back, but keeping it in the stock location)

We measured wheel base, and it was somewhere around 100". From my searches, I've found that an XJ wheelbase is either 100.4" or 101.4" (one of the two sources screwed up, not sure which is correct)

However the wheel base just seems so short! It's about 4" shorter than my XJ with a 3.5" lift.

Anybody have any thoughts on this? Here's a few pics as well as an album. Don't want to make this a dial-up UNfriendly thread!!

Thanks in advance.

http://s20.photobucket.com/albums/b210/bbugaski/Ryan%20Jeep/

PS: For awhile we thought that it was maybe an optical illusion since the rear quarter panels were cut. But it's not. If you look you'll see how the axle is too far forward for the bumpstops to line up perfectly....and then you can just see how close the tire is to the front of the fender wells.

Also, yes, this XJ is chopped....so some of you may be thinking that the weight which was lost caused the spring arch to be larger which moved the axle forward.

However we loaded around 400 lbs of stuff in the back and it didn't make a difference in the wheelbase.

dj's 2000 xj · Jan 17, 2008

This might sound silly, BUT, are the leaf springs on in the right direction? That would explain the 4" difference.

89xj · Jan 17, 2008

bigger question for me would be, why is yours 104"? when stock is 100.4or 101.4?

you said yours is 4" longer than his.

are his springs on backwards?

his wheel base could be shorter depending on where the front axle sits also. his front arms could be adjusted too short

silverslk · Jan 17, 2008

Yeah, to narrow this down maybe measure yours and his from crossmember bolts forward and bolts backward and see what is shorter and where. It may be a little in both directions. I do know with my RE 5.5 kit, I noticed the rear axle looked moved forward as well. I figured RE designed it that way and didnt think about it again. Give RE a call and see what they say.

jeepcomj · Jan 18, 2008

and maybe make sure you're measuring from the same point (center of axle to center of axle)

shelbyluvv · Jan 18, 2008

Looks normal to me. Every lifted 6" + XJ I have ever seen looks like that. Even mine.

tayman · Jan 18, 2008

when you go up, the front control arms have to move... Changing the angle on the arms; this pulls the axle back a bit. this is similar for the rear. it you don't get longer springs to match the height or move your foreward mounts backward (if that makes sense...), it will pull the shackle foreward. I noticed that the shackle is basically vertical. Stock angle is towards the rear a bit. I can also see that you have the shorter side of the spring toward the front... so turning the springs around won't do anything... it'll make it longer still.

WB9YZU · Jan 18, 2008

The best way to decribe the issue is arc.
Suspensions travel in an arc.

If you look at a stock suspension, everything is flat and the angle is horizontal. The suspension has equal up and down travel and is at the center of the arc.

Now, droop that suspension. The back then moves down and forward and the front wheels move down and back. The suspension is at the lower end of the arc.

Now, imagine that instead of changing the length of the "control arms", UCA/LCA in the front, and in the back, the front spring length, you simply change the spring rate.

Didn't you just do exactly what a stock suspension would do in droop?

To "cure" this, you would need to drop the spring perches instead of lifting with increased spring rate, OR change the length of the control arms.

Long arm kits are great at fixing this problem by flattening out the front control arm and changing the arc center. Same with drop bracket kits.

To fix the back however, you need to move the axle back and accept that when the suspension goes into compression that the axle will move up and back.

Ron

Blaine B. · Jan 18, 2008

Control arms are adjusted so the wheel is in the same spot as it is stock.

Coils are perfectly straight up and down, and the front wheels are centered in the fender well.

Yes, have measured the same.

I also measured the length from the front leaf bushing to the center pin for the leaf packs.

Measurements are the same for our packs.

TNT · Jan 18, 2008

Blaine B. said:
Control arms are adjusted so the wheel is in the same spot as it is stock.

Coils are perfectly straight up and down, and the front wheels are centered in the fender well.

Yes, have measured the same.

I also measured the length from the front leaf bushing to the center pin for the leaf packs.

Measurements are the same for our packs.

If you would compress the rearend down 6" the wheelbase would increase by about an inch or so.

Take a stick cut to the same length as your spring is from the front eye to the center pin. Hold it level and then the pivot it down 6" and see how much shorter it is when you measure from the pivot(eye) with a level tape measure and see how far the other end swings forward.

RE 4.5" lift = shorter wheel base?

Blaine B.

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dj's 2000 xj

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89xj

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silverslk

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jeepcomj

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shelbyluvv

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tayman

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WB9YZU

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Blaine B.

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TNT

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