How to Replace Long Arm Control Arms on a Jeep Cherokee XJ | Core 4x4 Custom Arm Guide

If your XJ Cherokee is running an older long arm kit with worn-out bushings — and you can't even identify the brand anymore — you're not stuck buying a whole new kit. Core 4x4 builds custom replacement arms to fit your existing brackets, in any of 10 powder coat colors, with a typical turnaround of 3–5 days.

In this video, Spence from Core 4x4 walks through the entire process on a shop XJ: measuring for custom arms, swapping polyurethane bushings for Johnny Joints, installing double-threaded adjustable arms, and dealing with the kind of surprises that older Jeeps always seem to throw at you — including an impromptu Dana 30 axle bushing upgrade.

Fitment: Jeep Cherokee XJ 1984–2001 | Also applicable to MJ Comanche

The Problem: Old Long Arms with No Replacement Parts

This XJ came in with a long arm kit that had no markings, no part numbers, and no branding. The arms had polyurethane bushings at both ends — not ideal for a long arm setup where you need maximum articulation. The joints were worn, and there was no way to source OEM replacements from whoever made the original kit.

This is a common situation with older XJs. Instead of scrapping the entire kit and starting over with new brackets and crossmembers, Core 4x4 can manufacture custom arms sized to drop right into your existing mounts.

Three Measurements You Need for Custom Arms

Ordering custom replacement arms is straightforward. Core 4x4 needs three measurements plus photos of your setup:

1. Bolt-to-Center (Eye-to-Eye) Length

Measure from the center of the bolt hole on one end to the center of the bolt hole on the other. This is your fully collapsed length — Core 4x4 builds adjustment range around this number.

Pro tip: Measure both sides. On this XJ, one side was 34.25" and the other was 34.5". Subtract about 1/2" to 1" from your measurement to give yourself adjustment room. You want most of your thread engagement available for extending the arm, not shortening it.

Common mistake: Don't give end-to-end measurements. Every arm end is different — bushing housings, Johnny Joints, weld-on tabs — so end-to-end doesn't translate. Always measure center of bolt to center of bolt.

2. Mount Width

This is the inside width of your mounting bracket — basically, how wide your bushing or Johnny Joint needs to be. On most Jeep XJs with factory axle brackets, this is 2-5/8". Check both sides.

3. Bolt Size

On XJ Cherokees:

• Lower control arms: 9/16" or 14mm
• Upper control arms: 10mm (many owners drill out to 1/2" or 9/16" for strength)

This is also your chance to upgrade bolt size if your brackets allow it.

Photos to Include

When you email sales@core4x4.com, send pictures of:

• Bracket ends — especially if they are narrower than standard, which could interfere with Johnny Joint fitment
• Any bends in the arms — inward bends for tire clearance, downward bends for frame clearance
• Shock mount proximity — if your arms are close to shock mounts at full droop, a clearance bend might be needed

Custom Arms: What You Get

For this XJ, Core 4x4 built:

• Two lower long arms — double-threaded (adjustable from both ends without removal), Crawl Series, with Johnny Joints at both ends
• Two upper control arms — Crawl Series at 17" eye-to-eye, replacing older Tier 2 uppers that were adjusted way out

All four arms were powder coated red to match the existing setup. That is one of the advantages of going custom — you can change your color or match what you have.

Turnaround: 3–5 days for standard colors, add a couple days for special-order colors. Everything is manufactured in-house at Core 4x4 in Orem, Utah.

Camp vs. Crawl Series

• Camp Series: Bushing (welded) on one end, Johnny Joint on the adjustable end
• Crawl Series: Johnny Joints on both ends — maximum articulation and adjustability

For a long arm kit where you need every bit of flex, Crawl is the way to go.

Setting Your Arms to Length

On a double-threaded arm, both ends thread in and out. Here is how to get your measurement right:

1. Thread the arm to approximately your target length
2. Measure outside edge of one Johnny Joint ball center to inside edge of the other — this equals center-to-center and is more accurate than trying to find the exact bolt center
3. Adjust until you hit your target (34.5" on this build)
4. You want most of your adjustment range available for extending, not shortening — this maximizes thread engagement for strength

Upper arm note: Spence recommends keeping upper and lower arms as close to the same length as possible. Short uppers with long lowers causes axle wrap and puts extra stress on the system.

Pre-Torquing Jam Nuts

If your jam nut will end up right against the Johnny Joint once installed (making it hard to wrench on the Jeep), torque the jam nuts on the bench first:

1. Clamp the Johnny Joint in a vise
2. Use a crow's foot wrench — 1" jam nut: 200 ft-lbs / 1-5/8" jam nut: 250 ft-lbs
3. Make sure the bolt holes on both Johnny Joints are aligned before you lock everything down

Core 4x4 recommends Tekin crow's foot wrenches in 1-1/2" (uppers) and 1-5/8" (lowers).

Installing the Arms

One-at-a-Time Method

Since the arm lengths are not changing drastically, Spence uses the one-arm-at-a-time method: remove one old arm, install the new one, then move to the next. This keeps the axle from shifting on you.

If you are changing lengths significantly or pulling multiple arms at once, support the axle with jack stands to prevent it from moving.

Clearance Issues to Watch For

On this build, the Johnny Joints were slightly wider than the old poly bushings. The crossmember bolt head was interfering with the joint. The fix: move the bolt to an adjacent hole. Problem solved without any cutting or welding on the frame side.

The driver's side had a stud (not a bolt) in the way — that had to be cut out and relocated. Every XJ is a little different, and older rigs always have surprises. Budget extra time.

Getting the Bolt Through

With the axle hanging at full droop, the track bar pulls everything to the driver's side, making bolt holes not quite line up. The solution is leverage — use a pry bar to rotate the axle forward slightly until the holes align.

Critical Torque Specs and the Bushing Rule

This is the most important section if you are doing any suspension work on your XJ.

Johnny Joints: Torque in the Air

Everything Core 4x4 makes has an independent crush sleeve inside the Johnny Joint. This means you can safely torque these components with the Jeep on a lift at full droop.

Rubber/Poly Bushings: NEVER Torque in the Air

If you have rubber or polyurethane bushings anywhere in your suspension, do not torque them until the Jeep is at ride height with full weight on the axle.

The sleeve inside a rubber bushing is fused to the rubber. If you torque it at full droop, the sleeve locks in that position. When you set the Jeep down and the suspension cycles up, the bushing cannot rotate — it creates a preload that will destroy the bushing prematurely.

How to Torque Jam Nuts on Double-Threaded Arms

This trips up a lot of people. Here is the technique:

1. Alternate sides. Tighten the right-side jam nut a bit, then switch to the left side
2. Gradually increase torque on both sides, going back and forth
3. The Johnny Joints will get cockeyed as you tighten — this is normal. You will straighten them after
4. Stop tightening a side when you feel the bar is about to spin in your hand, then switch to the other
5. Once both are locked at 250 ft-lbs, the arm should move as one solid unit when you pry on a joint
6. Straighten the joints by hand — they will rotate freely in the housing once the jam nuts are set

The goal: lock the jam nuts against each other without spinning the bar or changing your arm length.

Bonus: Dana 30 Johnny Joint Axle Bushing Upgrade

This was not planned, but it is one of the most useful parts of the video.

During the upper arm install, Spence discovered the passenger-side axle bushing housing was worn out — the bushing was literally falling out. Instead of forcing a new bushing into a worn housing, he upgraded it to a Johnny Joint right there on the lift.

The Process

1. Cut the old bushing housing off the axle bracket
2. Weld a new Johnny Joint cup to the tower — this is a permanent, stronger mount
3. Let it cool, wire brush the weld, hit it with rattle can to prevent rust
4. Assemble the Johnny Joint with grease and press it into the housing

The driver's side bushing housing was in better shape, so that got a standard Johnny Joint replacement (no welding needed) — hammer out the old bushing, press in the new sleeve and joint.

Real talk: This is the kind of thing that turns a 2-hour job into a 5-hour job. But driving on a bushing that is falling out of its housing is not an option. The Johnny Joint upgrade means this XJ will have better articulation than it ever did with the original poly bushings.

Johnny Joint Axle Bushing Replacement Kit

Core 4x4 sells this as a standalone product. If your XJ, TJ, LJ, ZJ, or MJ has worn factory rubber axle bushings, you can upgrade to Johnny Joints at home. The kit includes the joint, sleeve, snap ring, and hardware.

Shop Johnny Joint Axle Bushing Kits

Tools Required

• Floor jack and jack stands (or a lift)
• Tape measure
• Socket set (9/16", 10mm, 1/2")
• Torque wrench (up to 250 ft-lbs)
• Crow's foot wrenches — 1-1/2" and 1-5/8" (Tekin recommended)
• Cutting wheel / angle grinder
• Penetrating fluid (PB Blaster or similar)
• Pry bar and hammer
• Anti-seize compound
• Rattle can paint (for touch-ups)
• Welder (only if axle bushing housing needs repair)
• Vise (for pre-torquing jam nuts)

Why Upgrade Your XJ Long Arms to Johnny Joints?

If your Cherokee XJ is still running polyurethane bushings in a long arm setup, you are leaving performance on the table:

• More articulation: Johnny Joints are a spherical rod end — they rotate freely in all directions, unlike poly bushings that resist rotation and bind
• No maintenance schedule: Johnny Joints do not need to be greased on a strict interval (though occasional grease does not hurt)
• Independent crush sleeve: You can torque them at any suspension position without creating preload — huge advantage during install
• Rebuildable: When they eventually wear, you rebuild them instead of replacing the whole arm. Core 4x4 has a video on 3 methods to rebuild Johnny Joints
• Custom color options: 10 powder coat colors, all done in-house

How to Order Custom Replacement Arms

1. Measure: Eye-to-eye length, mount width, bolt size (both sides)
2. Photograph: Bracket ends, any bends, clearance concerns
3. Email: sales@core4x4.com with measurements, photos, and your color choice
4. Turnaround: 3–5 business days for standard colors, under 2 weeks for special orders
5. Phone: (385) 375-2104

Fitment: Jeep Cherokee XJ 1984–2001 | Jeep Comanche MJ

Frequently Asked Questions

Related Content

• How to Install Adjustable XJ Leaf Spring Shackles — another XJ suspension upgrade from Core 4x4
• 3 Methods to Rebuild or Repair Your Johnny Joints — maintenance guide for when your joints eventually wear
• Why You Need Control Arms — educational overview of what control arms do and why upgrades matter

Shop XJ Cherokee Parts

Fitment: Jeep Cherokee XJ 1984–2001 | Jeep Comanche MJ. Custom arm orders: sales@core4x4.com | (385) 375-2104