Jeep XJ

My Jeep
2" XJ Lift
4.5" XJ Lift

Rubicon Express 4.5" RE6130 Super-Flex Lift Installation

Rear  |  Front  |  Final Impressions

Post-install next to a stock XJ - I like this new look

Wow, I'm not even sure where to start on this; it feels so good to be DONE finally and yet I've already noticed a case of 'Inch-itis' coming back. If you read my 2" lift saga, you may notice it took more than three months to finish the lift. I had that in mind when I bought the RE6130 4.5" Super-Flex lift, so it actually sat in my living room taunting me for a good month until I could set aside enough time for the installation and post-install corrections. My biggest beef (and it really isn't a worthy beef) with this kit is that there was no instruction sheet or guide saying "replace this first to make life easier" - that's not a big deal though.

I took the Jeep and all the parts over to my friend Tiffster's garage about 1pm; it was later than I wanted to start, but what can I say? Following my philosophy of 'keep it drivable if needed' we tackled the rear lift first.


The rear involves a 3.5" spring pack and a 1.75" extended shackle to give the 4.5 advertised inches from this lift, so we were going to have to remove the old pack and shackle. People will tell you repeatedly to spray everything down with PB Blaster a few times in the days prior to removal, and I'm one of them. If only I would have listened to myself better this job might have been done sooner; I never got around to that and only had a few hours of Blaster on the bolts.

Parts included for the rear:

  • 3.5" Extreme Duty XJ Rear Spring
  • Shackle, XJ Rear 1.25" Lift
  • U-Bolt Kit 2.75" x 9.0" - This size became a problem...see below
  • T-Case Lowering Kit XJ/ZJ

    Not installed:

  • Brake Line, Stainless Steel XJ/ZJ 18" - I already installed one during the 2" Budget Boost

I learned on my first lift (a 1987 Toyota 4x4 X-Cab) that removing both spring packs at the same time means the axle isn't supported, so we did one side at a time. Blocking the front wheels is a good safety precaution since the rear wheels and e-brake are going to be off the ground. Remove the wheels for easier access; if you have enough sturdy jackstands or a lift you may consider putting the entire Jeep up in the air. My u-bolts were semi-loose on one side which I'm sure wasn't a good thing, so it's a good thing they were getting removed. Keep the original mounting bolts for the spring pack and shackles, as you will need them to mount the new pieces. This task is a LOT easier if you remove the shackle while the old spring is still mounted to the Jeep.

Installation Prep
By the way - when you put the Jeep up on jackstands, make sure they are TALL. As if there wasn't enough poor planning involved, we had to re-lift the back end halfway through because of poor planning. Get it right the first time and avoid all that, the Jeep has to sit HIGH in the air so the springs will fit correctly.

With that said, there really wasn't much involved with the rear. Remove spring pack and shackle, add new one, repeat on the other side. If you want to separate the pieces for re-sale later, it's easier to unbolt the lower shackle bolt first, then remove the front spring bolt before removing the upper shackle bolt.

I received some feedback awhile ago about this page; it seems that I got lucky with the springs on mine. The writer had a similar Cherokee but because he lives near the Great Lakes, the underside of the Jeep is a nice, even rust color. The Jeep engineers use a sleeved rubber bushing in the front end of the spring, and the bolt through the hanger often rusts to that metal sleeve. When this happens, the bolt cannot be removed without cutting it off and prying the spring out. If you have to do this, be careful not to cut into the spring mounts themselves. There are numerous recurring threads on NAXJA that describe this procedure, and I'll see if I can grab a writeup for future use here.

One of the additions from the 2" Budget Boost was 18" long RE1515 Stainless extended rear brakeline that I wrote up separately, so there was no need to mess with that. The bolts on my JKS Bar-Pin Eliminators were seized, so I left the earlier Doetsch Tech shocks in place until I can remove them. This is one reason I highly recommend soaking everything with PB Blaster, from multiple points in the days before installing, and even then sometimes you will need to use a SawZall to cut the bolt out.

If you are doing this lift from stock, remove the rear swaybar and discard (or eBay) it at this time. Keep the mounts though, as they can be used to relocate the shocks if desired. The swaybar will need to be threaded out toward the drivers side, so having the wheels off and the spring pack out of the way will definitely help. The rear end definitely feels different without the swaybar and body roll will more pronounced, but remember that Up-Country XJs came from the factory without a rear swaybar because they used a stiffer springrate in the rear. Use good sense when driving without the swaybar, as the Cherokee is a top-heavy vehicle.

You'll notice I commented on the 2.75" u-bolts that were included with the lift. This is because I neglected to specify my axle type during my order, so the default Dana35 u-bolts were shipped. The D35 actually uses a 2.62" axletube, while the Dana44 uses a 2.75" tube. At that time, I had a Chrysler 8.25" rear axle, which required a larger u-bolt to fit over the 3.00" axletubes. We had to make the first parts run of the day to locate correctly-sized u-bolts, and if I recall correctly that meant more than one parts store. Make sure you positively identify your rear axle before ordering a lift to make sure you don't have to stop midway through to get parts.

Leaf-Spring Issues
One thing I noted during the original install was that the centering pins on the rear springs were too large to fit the axle mount, and even included a spacer that made them about 0.5" taller - long enough that they would have hit the axle tube if I didn't remove them first. I had no plans at that time to run any degree shims, and completely overlooked the real reason for those spacers; they extend the head of the pin far enough to go through any shims that are installed. I talked to Rustin Smith of Rubicon Express last year, and he confirmed that the center pins they use are larger and stronger than stock, at 7/16" instead of 3/8" diameter.

As I said, we didn't know any better at that time, so I decided to remove the center pins and discard the spacer. Clamp the leafsprings with c-clamps on either side of the center pin, and unbolt the center pin to remove it. The threaded portion of the pin was chucked into a drill, and while Tiff spun that I hit the head of the pin with a grinder. This did short work of reducing the diameter and we were able to reconnect the pin and mount the springs. Had I really been thinking about it we would have drilled out the axle pad to fit the pin...that's what RE really intends anyway.

This whole The rusted centerpin after only one year's use.  This is actually the better-looking of the two.debacle with the spring pins should have been a simple thing. It wasn't until I installed a Dana44 rear axle that I really knew there was a problem, since the D44 already had a larger hole in the axle-side spring pad. Although they were a snug fit in the Chrysler 8.25" axle, my custom-ground spring pins were now too small. Unable to locate any nearby, I ended up buying another set through RE.

After only one year installed in the Jeep my center pins were rusty hunks o'junk thanks to the Colorado Department of Transportation and the decision to spray our roads with Magnesium Chloride (MgCl). I guess that's a hint to waste more water in the middle of our drought by rinsing the underside more often during the winter.

One more thing I was missing from my installation was a driveshaft and Slip-Yoke Eliminator (SYE), which were ordered these from Rubicon Express after the lift was in place. The stock driveshaft fit with the lift in, but there isn't much engagement left between the driveshaft and t-case output shaft. More importantly, the 1996+ design for the NP231 t-case makes it very prone to vibrations, and that's the case with mine as well. The t-case drop helped reduce the vibes, but was not a long-term solution.
Update: August 24, 2003 (one week after installation). After a week of PB Blasting I was able to remove the old shocks.
Note: Use Anti-Sieze on the bolts before reinstalling

I noticed the shocks from the 2" kit only had about 2 inches of downtravel remaining before bottoming out. Don't try running your old shocks on a new lift, especially if you are moving up from a stock Jeep...


  • Track Bar XJ/MJ/ZJ/TJ 3"+ (I substituted the RE1660 Extra H.D. Track Bar and RE1665 Bracket)
  • Coil Springs, XJ 4.5"
  • Bump Stop, 2" Front XJ/ZJ/TJ
  • Brake Lines, Stainless Front XJ/MJ/ZJ/CJ 22" long
  • Control Arm, SF2 Lower Fixed (I substituted RE3715 Adjustable Lower Control Arm/LCA)
  • Control Arm, SR2 Upper Fixed (UCA)




    Not Installed:

  • Sway Bar Disconnect Set, 6" Centers
  • Sway Bar Disconnect Adapter Bracket ZJ-XJ

Since it has 2/3 of the parts, we knew the front end was going to take longer simply because of the complexity. We removed the shocks early, knowing that they will be in the way. Replacing the brake lines would have been a good idea for early on as well just to allow more room for movement later on when replacing the coil springs. When installing other lifts including that 2" Budget Boost, a set of coil spring compressors can be invaluable, but in this case we didn't need them since the Upper and Lower Control Arms were going to be replaced and the axle is able to drop far enough to insert the coils.

The first step is simply to remove enough of the old parts that the lift installation can proceed. this meant removing the Trackbar, swaybar, and old springs to allow the new control arms and springs to fit. Once they were in place, reassembly of the Trackbar, brakes and swaybar can take place.

ALWAYS keep at least one control arm pair or a trackbar connected at any time, as the axle will try to roll out and can cause serious bodily damage!

RE1665 Extreme-Duty Trackbar Brace

The RE1665 Extra Heavy-Duty Trackbar Mount
The old, stamped-steel trackbar mount and trackbar

I opted to upgrade the adjustable RE1600 trackbar to the adjustable RE1660 Heavy-Duty trackbar. This new, larger trackbar also requires a new mount instead of relying on the stamped steel of the stock piece. Rubicon Express also includes a brace to go across the frame to better keep the new RE1665 Trackbar mount in place, but that's another story.

The stock trackbar needs to be removed, and since I was replacing the bracket I pulled the whole unit as one piece. There are four bolts holding the stock trackbar mount in place; two underneath and two on the side. We reinstalled the mount but left the trackbar itself off until the rest of the installation was complete.

The swaybar can be disconnected and the bar pushed up out of the way. For this installation, that's all we did. On some taller lifts, the swaybar needs to be dropped forward and down at the frame, but that's not needed right now.

Although they appear to have a Torx head, the lower swaybar pins on the axle are pressed in place, and would not come out with a socket/c-clamp press. I installed JKS Quicker Disconnects later on, and wrote that installation up separately.

Control Arms
Since I know of a number of people who have lifted their Cherokees and TJ Wranglers only to experience bad vibes or 'Death Wobble', I wanted to be able to fine-tune the axle placement if needed so upgraded to RE3715 Super-Flex Adjustable Lower Control Arms. At the time we did the install, there wasn't much info available regarding the proper lengths needed for the arms. Tiff had done a little research earlier and came up with a figure of 16.25" eye-to-eye on the arm. Stock is 15.75". That longer measurement worked for me on the first attempt but the Adjustable LCA came in handy later on when I installed the RE Drop Brackets. I also have control arm measurements available on that page now.
Once the shocks, trackbar and swaybar are out of the way, it's time to tackle the Control Arms. In theory there's not much to say with these, unbolt the old ones and replace the new ones. In reality, it's a little more complicated since the upper arms (UCAs) are held in place by a "flagged bolt" The bolt has a long tab on the head that will spin until it hits the inside of the frame, allowing you to loosen the nut. For the UCA, you will need a 15mm box wrench or something similarly flat since the starter 'lobe' on the bellhousing did a fine job of being in the way. While loosening and installing the UCAs, take care not to drop the bolt or your wrench into the hollow part of the frame as there are no easily accessible ways to remove it.

Springs and Bumpstops
Since I didn't have the Jeep on a lift and the jackstands weren't high enough to drop the axle down to allow me to install the coils alone, I had to prep the bumpstops and springs together. If your Jeep is on a lift that's tall enough to allow the axle to droop away, you can skip this step and install the bumpstops and springs separately. Tape the bumpstops midway down the length of the coil spring. You'll see why in a minute. Drill a 5/16" hole in the 'dimple' of the axle pad coil mount, the bumpstop will be bolted down here shortly.

Replacing the springs is done in conjunction with the Control Arm replacement. Once you have the Arms in place, the springs may need to be compressed in order to fit between the coil tower and axle. Instead of that, you can either insert the coil while one of the control arms is off, since the axle will move very freely at that point. As another option, you can force the axle down either by hanging body weight on it or by using a small jack to push it down. I opted for the first method (control arm off) since the Jeep was already up on tall jackstands and I didn't want to bring it down on me. Be sure that the coil is turned sufficiently to seat it in the pocket in the mount, and if you still have them, tighten the coil spring retainers.

Once the spring is in place, cut the tape holding the bumpstop in place and position the bumpstop with the recessed portion facing up. Insert the self-tapping bolt and tighten it down. The new bumpstop itself looks like little more than an overly-thick hockey puck, but it helps keep the front axle from compressing so far into the wheelwell that larger tires get stuck. Since it's held in place by a self-tapping screw but completely enclosed by the coil it can be hard to get at.

Brakelines and Final Touches
Once there was no concern about the axle falling forward/off the jackstands, it was time to swap the brakelines. I'll get some pictures up here one of these days, but there's not much to the swap since there really aren't too many pieces. One thing to keep in mind is that the longer brakelines can look appetizing to your tires, and it is very possible to tear the brakeline when the tire is compressed and turned to the side. To prevent this, be aware of the routing of your lines. I have found that by twisting the line before attaching it to the caliper, it will get a natural 'lean' away from the tire. You can also twist up a carb spring to hold the line away from the tire; when the axle extends the spring will stretch but it's supposed to keep the line safe.

Trackbar, Part II
I've heard some confusion recently about adjusting the trackbar; people seem to get overly technical trying to put an adjustable trackbar in, but there's really nothing to it:

  • Set the Jeep on all four wheels once the rest of the lift is in place
  • Leave the trackbar either completely rmoved or just bolted in at the axle end
  • Turn the steering wheel back and forth to center the axle
  • Have a friend bounce on the front bumper to help even out the tension in the bushings
  • Center the axle, use the fenders for reference if you still have them
  • Adjust the length of the trackbar to fit the mounts.
  • Torque it down

Actually, at this point you can torque everything down. Unless otherwise specified, use the factory torque specs but don't torque ANYTHING while the Jeep is in the air!.

Final Impressions

The whole process took the two of us almost 15 hours including a few trips to AutoZone and McDonald's. About 3am I actually fell asleep under the Jeep while torquing the trackbar mount. I wouldn't recommend that... One thing I did notice originally and griped about in the original writeup was that many of the components had a brief install sheet that listed torque values, but there was no Master Install sheet. RE has changed that recently, as the instructions are available online.

On my first 70-mile drive home I had no problems with "Death Wobble", although the steering wheel was about 90 degrees off-center. It turns out I was actually pretty lucky during the first trip home, since the trackbar mount had been overlooked in our zombified torquing session. I had a few shakes when hitting uneven road surfaces, but nothing major. Oddly, when I headed back to Tiff's a few days later I had horrible Death Wobble at about 55mph, forcing me to slow to 45mph or less and take the backroads down to her house. I had just had the 30" BFGs rotated and balanced and wonder if that may have aggravated existing problems. Swapping the 32" BFG All-Terrains onto the Jeep helped, but I still needed an alignment to correct toe-in problems.

So how much lift did it give?
  Front Rear
Typical stock XJ measurements, wheel hub-to-fender 17.5 17.0
Measurements, following lift install 22.0 21.5
Estimated lift 4.5 4.5

It looks like this lift netted the advertised height; it seems common for many of the RE lifts to provide a bit more than advertised amount. I keep a large box of gear in the back, which may account for some of the settling already. The good news is that even now, 18 months later it's still sitting just about that tall. I think the rear lost about 1/4" to 1/2" in that time.

Almost finished (for now).  This picture shows the black AR767 Rock Crawlers and 32-inch Dunlop Mud Rovers
Almost finished (for now).
This picture shows the black AR767 Rock Crawlers and 32-inch Dunlop Mud Rovers as well as the BPI Front bumper.
Both were added after the lift.
e-mail Jim
created: August 13, 2003
Modified April 30, 2005