Made in USA
Orem, Utah
Lifetime Guarantee
Unconditional
10 Colors
In-house powder coat
Fully Adjustable
0-6" of lift
3 X-Series Options
Only Core 4x4
RockJock's front coil spring shim for JL Wrangler and JT Gladiator is 1/4 in. thick and mounts between the welded on coil spring axle pad and the coil spring isolator. The indexing pin in the coil spring isolator fits thru the hole in this shim to properly clock it. These shims are used to fine tune vehicle height per model, engine combination and added weight load. Shims may be stacked a maximum of 2 high. Semi-gloss black powder coat finish.
| Make | Model | Submodel | Years |
|---|---|---|---|
| Jeep | Gladiator | 2020 - Present | |
| Jeep | Wrangler | 2018 - Present |
| Vehicle | Jeep Gladiator JT (20–Present) or Jeep Wrangler JL / JLU (18–Present) |
| Brand | RockJock |
Reviews of Core 4x4
5.0
★
★
★
★
★
132 reviews
JS
Jeffrey Shafer
Jan 22, 2026
★
★
★
★
★
Exceptional customer service. All my questions were asked in a timely manner and parts were replaced when an error occured. I encourage people to make purchases due to their exceptional quality products, but also because of their customer service. Will make additional purchases in the future.
PM
Paul Melancon
Aug 25, 2025
★
★
★
★
★
Ordered a control arm and track bar kit for my WJ from Core 4x4 on Monday 7/28 and received it today, Friday 8/1. Im not a state or two away, im in CT aka the other side of the country. Communication is phenominal, emails were responded too in an hour or less. Parts arrived well packed, not damaged, and are great quality for my needs. There arent many companies left that service customers as well as Core 4x4 and i wont hesitate to check them out again if i need something else. Well done!
P
Paul
Mar 24, 2023
★
★
★
★
★
I've been having trouble with the track bar (on my 2nd gen Dodge) since I installed the 3rd gen Synergy adapter bracket and a 3rd gen stock bar.. oddly, they call it a '3rd gen bracket' and the stock 3rd gen bar doesn't quite fit, making contact with the bracket. I had attempted to clearance the bracket but it was still making contact and I could feel it over large bumps.
I reached out to a lot of companies, but Core 4x4 offered to make a custom bar for the application with adjustability and dual Johnny joints. The first pass on it didn't work but they sent me out another passenger side end that made it fit incredibly well.
This was all done solely over email/descriptions/pictures/measurements.
Bar is super high quality and heavy duty, made in the US by a family owned company and carries a lifetime warranty. The customer service was responsive and superb, and the price was a lot less than I expected.
DW
Derek Whitfield
Nov 20, 2025
★
★
★
★
★
Solid product, the lifetime warranty sealed the deal for me. Installed on my TJ and the ride quality improved noticeably. Shipping took a bit longer than expected but the parts were worth the wait.
RH
Rex Hodges
Jun 26, 2025
★
★
★
★
★
After ordering an upper and lower adjustable control arm kit manufactured by CORE 4X4 from a jeep parts distributor who's intials are E.T., they came with 3 of the threaded ends missing. After over 2 months of phone calls and emails to this E.T. company nothing was resolved. I finally decided to call CORE 4X4 myself and tell them my dilemma. I spoke with a very personable and professional gentleman named Korby, who is one of CORE 4X4's representatives, after a brief discussion of what I went thru he simply asked me for a picture and some measurements and the items I was missing and asked if I could cover ONLY the cost of shipping and I had my missing parts in exactly 1 weeks time. This company not only builds all it's parts in the U.S.A., they stand behind their products with great customer service and life time warranty. My experience with this company and their Rep Korby was fantastic. I would definitely recommend CORE 4X4 to anyone who needs parts for any 4x4 projects. You just can't beat their quality and service.
Rex Hodges
Valparaiso, Indiana
AL
Andrew LaFave
May 27, 2025
★
★
★
★
★
I am really please with this company. Great product, i had an issue with a couple of the jonnhy joint bushings, they explained what had caused it and how to fix it. Within hrs of receiving my inquiry, i had heard back with the required info I needed. A couple hrs later problem was fixed and ready for the trail again. They care about heir product and their customers. Thanks crew, you rock
ZA
Zen Asher
Mar 23, 2025
★
★
★
★
★
The quality and durability of the arms are the best. They are super heavy duty. And lifetime warranty is crazy
RP
Robin Poole
Jul 26, 2025
★
★
★
★
★
I had several questions before my purchase and Korby helped me with the correct parts to order and recommendations. Outstanding customer service and product knowledge! Can't wait to install them!
EA
Eric Ahonen
Mar 24, 2021
★
★
★
★
★
Awesome control arms! My mechanic said “ your Jeep is pretty much bulletproof now.” And I just got the tier 1 arms! The people at the core 4x4 shop were really nice too. They were running behind on shipping, (which is understandable) so I decided to go pick it up because it was only an hour drive. They gave me a free $60 hardware kit for the inconvenience. Thanks core 4x4! You guys are awesome!!
DN
Devan Nelson
Mar 25, 2019
★
★
★
★
★
Had a great experience with Core 4x4, I desperately needed a custom track bar and found out just a couple days before Easter Jeep Safari. Spence was a huge help and made it happen with plenty of time to spare. Their parts are top notch!
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Specifications
| Vehicle | Jeep Gladiator JT (20–Present), Jeep Wrangler JL / JLU (18–Present) |
| Brand | RockJock |