Jeep XJ Overhaul Part 3: Rear Suspension

With fresh Bilstein 5100’s installed all the way around I needed to next look into upgrading the front and rear suspension.  In my mind there were two main reasons for doing this: For one, the new Bilsteins would most likely bottom out with my current 3 inch lift set up (yes, I ordered the correct shocks, Bilstein doesn’t make a perfect size for my current lift height of 3.5 inches).  Secondly, I want to move up in tire size to at least 33’s for now.  At the same time I want to leave 35’s as an option in the future.  So I decided to lift the rear to 5.5 inches and the front to 5 inches even.  My thought process with the extra half inch in the rear is based on the amount of gear that usually comes along when wheeling, thus leveling out the Jeep when fully loaded and trail ready.

Getting Started

Let’s just put this out there right from the get go… This job was an absolute bitch.  There’s no other way to describe it.  After some careful inspection of the current set-up, it looks like it was an add-a-leaf job meaning that these bolts have not been wrenched on for 20 years.  That’s 20 years worth of dirt, salt, trail dust, mud, and road grime caked on them.  They might as well have been welded in there.  This how-to post is going to mostly focus on removing the front leaf spring bolt, modifying that area to make it more accessible in the future, and the replacement parts/tools needed to get the job done.  The actual install of the leaf springs is easy and there are already a ton of articles and videos out there on how to do that part.  Here we go…

Rear Leaf Spring Bolt

On my Jeep this bolt ended up not being too hard to remove.  This is the bolt that attaches to the frame and the upper portion of the shackle.  I caught a break here as others have mentioned that this bolt can be brutal to remove.  A week’s worth of PB Blaster and a 2 foot breaker bar busted it loose for me.  Others who have had trouble with the bolt have removed their rear bumper to gain access to the welt nut that is inside the frame.  From there, they are able to break that loose and replace the hardware.  One quick note about the rear axle: remember that once you take the U-bolts off, the axle is still only going to sag as low as the shocks.  Make sure to remove the lower shock bolt to give the axle more droop.  This will make removing the existing leaf springs much easier.  Also, be sure to have jack stands and an additional jack on hand to support the rear axle.

Front Leaf Spring Bolt

This bolt was a son of a bitch.  Most likely never removed, the bolt was absolutely frozen in place.  Even with about a week’s worth of PB Blaster, this front assembly was not going anywhere.  Eventually I resorted to heating the head of the bolt with a torch and then hitting it again with the longest breaker bar I had on hand.  Finally!  It started to turn!  It was not easy going but at least I was getting somewhere.  All was well until POP!!  The bolt broke free.  Or so I thought.  Unfortunately, what actually happened was the weld nut located inside the frame rail busted loose.  Now I was stuck.  After about a week or so of brainstorming, I decided to try to cut into the floor in the rear of the vehicle to access the frame rail and in turn, the broken weld nut.  At least I could retrieve it and then move on from there.  As you can see from the pictures, this didn’t give me the direct access to the nut as I hoped.  The weld nut, as I learned, is NOT located inside the frame rail, but rather inside an enclosed bracket that is welded to the frame rail.  Although cutting into the floor ended up not being the answer I was also relieved that I wouldn’t have to cut into the frame itself.  I would though, need to cut into the bracket that houses the weld nut.  I made a triangular outline for my cut and decided to employ both my angle grinder and my Dremel tool equipped with a cutting attachment.  The angle grinder cut through the thick metal nicely while the Dremel struggled a bit.  But, the Dremel ended up being a must for certain spots since the angle grinder didn’t fit very well next to some of the bracketry that is underneath the vehicle.  I finished the cut with a grinder attachment to smooth out any burrs and finally had access to the nut.  With a window now cut into the frame rail, I could run a new grade 8 bolt and nut through the opening.  Even though this ended up being an absolute pain in the ass, it’s kind of nice knowing that I can access this assembly easily if need be in the future.  The removal of the bolt on the passenger side proved to be no easier.  This time, I tried to get ahead of the game and just cut the bolt off directly next to the leaf spring spacer and the bracket.  Although getting the leaf spring out this way proved easier, breaking the weld nut loose was tough.  Now, I was dealing with a fully intact weld nut.  Not ideal.  So, out came the air hammer and after about an hour of pounding away at the weld nut it finally broke loose from the frame.  The rest of the disassembly went the same as the driver’s side except that I DID NOT cut into the floor on the passenger’s side, now that I knew about the exact location of the weld nut.  Below are some pictures of the disassembly portion of the job along with captions.

Clamp the leaf pack so they stay together when removed.

Old add-a-leaf pack.

View of what the bolt looked like when it broke the weld nut loose. Head of the bolt snapped off right before this.

Measure twice. Cut once.

Cutting into the floor got me into the frame rail. No weld nut inside though.

20 years worth of dirt packed inside the frame rail bracket. No wonder this bolt didn’t want to come out.

Cutting into the frame rail bracket to access the weld nut inside.

A good view of the finished product. Don’t forget to hit this with black paint.

The offending weld nut. Only took about a week to get it out.

New Hardware

For the new springs I went with the Rubicon Express Extreme Duty Leaf Springs, part number RE1462.  I chose the 4.5 inch lift height knowing that my shackles would add an additional inch of lift.  Speaking of those shackles I decided on the Rubicon Express solid, greasable shackle, part number RE2700.  Other necessary hardware included new U-bolts/nuts, new upper and lower shackle bolts, grade 8 nuts and bolts for the front shackle mount, and shims (see my adjustment notes below for more on shims).  As I mentioned before, installing the new parts was easy.  I added a ton of anti-seize to every bolt that I installed and also carefully torqued everything down according to specs.  Lastly, it’s important to mention that all leaf spring/shackle bolts should not be torqued until the vehicle is back on the ground.  Failure to do so may cause unnecessary wear on the new suspension parts and may also effect performance.

Pretty happy with the 4.5 inch leaf spring packs from Rubicon Express

New leaf springs fit pretty well. I was able to install them myself.

Job mostly complete. Be sure to check U-bolts for tightness after 500 miles.

Initial Thoughts

After taking the Jeep for a quick spin around the block when all of the work was done, I can already tell a difference in ride quality.  The combo of these new leaf springs with the Bilstein 5100 shocks is definitely a winner.  In the future I’ve got my eye on a shackle relocation kit that would help with the shackle angle and give even more flex.  But that’s way down the road.  Up next are new front shock springs, bump stops, and upper/lower control arms.  Until next time!

Install Notes

Below are a few things to keep in mind heading into this job:

  • Have quality grease and a grease gun on hand so you can grease the shackle fittings and the grease nipple on the backside of the shackle (if yours has this option).
  • I did not disconnect the rear drive shaft for this job.  Mainly because I had an additional jackstand that I put under the pumpkin to make sure that there was no stress on the shaft.
  • Speaking of the driveshaft, your new lift height is going to throw off the driveshaft angle and will cause quite a bit of vibration while driving.  Shims are nessasary to correct this problem and come in various heights based on your need.  Installation is easy: simpley place the new shims under the new leaf springs prior to installing the U-Bolts.
  • Check all bolts after about 500 miles of on-road driving or a couple of wheeling sessions.  They will come loose during this time and will need to be re-tightened.
  • A lot of people who install after market shackles mention the need to grind the exhaust pipe down a bit. I can happily report that with the shackles I bought I did not need to do this.
  • There is a bolt near the rear bumper that needs to be cut or ground down in order to allow the new shackles to fit. See the pictures below.
View of the rear bolt that needs to be cut and ground down.

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