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 rear bump stop kit for TJ Wrangler and LJ Unlimited vehicles is the only bump stop on the market that incorporates coil spring retainers to positively attach the top and bottom of the coil springs to the vehicle. This kit extends the top and bottom bump stop impact points the necessary amount for a 4 in. lift. Constructed of quality polyurethane components and billet aluminum spacers, these bump stops mount inside the coil springs. This is a kit for the rearend of the vehicle only.
| Make | Model | Submodel | Years |
|---|---|---|---|
| Jeep | Wrangler | 1997 - 2006 | |
| Jeep | Wrangler | 2004 - 2006 |
| Brand | RockJock |
Reviews of Core 4x4
5.0
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132 reviews
RH
Roger Hooks
Jun 26, 2025
★
★
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2018 Ram 2500 Rear Control Arms and Rear track Bar been running for about a year, Great Solid Products and great one on one customer service, same day response with issue resolved!
Thanks Korby!
N
niceguyr1
Mar 24, 2023
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★
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I purchased upper and lower adjustable arms for my WJ and lowers were missing the spacers. I didn't know until 3 months later when I was installing them. With absolutely zero hassles they quickly sent me the missing spacers. Fantastic product and service! Huge thank you guys for the awesome service and parts!!! Customer service is quickly becoming a lost commodity and you guys gave me hope that it's still alive and well, you just have to buy from the right people... Thanks again for going above and beyond! 👍👍
DR
David Rogers
Aug 25, 2025
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★
★
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Ive had the front adjustable control arm kit in bright green for my 1996 ZJ.
Ive had the kit for about a year now and i have to say, im extremely impressed, over 1000 miles off-road and roughly 20,000 miles on the highway. These control arm kits for any vehicle built by core 4x4 are well worth the money, just be aware thereight be some minor scatches or chips from shipping ( but who should care about that if you're beating the crap out of em' they way they were built and designed for)
AH
Abbey Hiett
Mar 25, 2019
★
★
★
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Company finally made things right
LS
Leonard Smith
Jan 22, 2026
★
★
★
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★
I don’t write reviews often, but Core 4x4 absolutely earned this one.
I recently ordered leaf spring mounts and realized after the fact that I messed up my order. Totally my mistake. Instead of giving me the runaround or pointing at a return policy, Core 4x4 emailed me back and forth, worked through exactly what I was doing with my build, and made sure I ended up with the correct parts.
That kind of customer service is rare these days — especially in the off-road world where a lot of companies stop caring once the order is placed.
The parts themselves are exactly what you hope for: solid, well-made, confidence-inspiring hardware that looks like it belongs under a vehicle that actually gets used. You can tell these are designed by people who understand suspension geometry and real-world abuse, not just CAD screenshots.
Mistakes happen — especially on custom or modified builds — and Core 4x4 handled mine like pros. Fast responses, clear communication, and a genuine effort to help me get it right.
If you’re on the fence: don’t be. Core 4x4 is the kind of company you want backing your build — the kind that treats customers like fellow enthusiasts, not order numbers.
SG
Sal Giordano
Sep 24, 2025
★
★
★
★
★
I want to take the time to share my experience with Core 4x4.
I have a 2004 Jeep Wrangler and was looking to upgrade some suspension parts. I went with Core 4x4 upper & lower adjustable control arms and a front adjustable track bar. Everything arrived quickly, and right out of the box I was impressed with the quality and craftsmanship.
I had a few questions during installation (measurements and torque specs), and I spoke with Korby on a couple of occasions. Not only did he send me detailed instructions, but he also shared an installation video specific to the part and vehicle I was working on, something you don’t get from many companies.
The control arms fit perfectly, look great, and perform exactly as I hoped. I did run into an issue with the front track bar touching the front diff. When I reached out, Korby had me send pictures and then immediately offered two solutions: his bar guy could make a different bend and send it out to me, or I could get a full refund. His response honestly blew me away. As much as I wanted to run the Core 4x4 track bar, I chose the refund. Korby sent me a prepaid shipping label right away, no hassle.
My experience with Core 4x4 has been excellent. Korby was extremely understanding, communicative, and helpful every step of the way. The parts I received were high quality, and the customer service was second to none.
I would absolutely recommend Core 4x4 10 out of 10 times and will be using them again. Just a great American company with awesome people who truly care about their customers.
Thank you Korby, and thank you Core 4x4!
JI
Jerome Segura III
Jun 26, 2025
★
★
★
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I bought the 16pc Cruise Series Adjustable Control Arm, Track Bar, Steering, End Link Kit to replace a worn budget 4" lift on my used JKU. These are top quality parts; very solid. Customer service is unsurpassed. They even matched prices on my order placed before the tax day sale. I made an error in ordering a drag link flip kit; they were quick to help me fix this too. There's peace of mind knowing these components are made in the USA. Thank you. 👍👍
DS
Dana Smith
Jul 26, 2025
★
★
★
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★
Excellent, strong, and durable products—perfect for both on-road and off-road applications. The customer service is outstanding—friendly, knowledgeable, and extremely helpful with understanding installation and ensuring I got exactly what I needed. I would definitely order again. Top-notch company with high-quality products made right here in the U.S.A.
MH
Matthew Handy
Sep 24, 2025
★
★
★
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Ran into an issue with a part that I ordered. Got ahold of them explained to them the issue I was having and they jumped in and got the issue fixed. Hands down the best customer service I have ever dealt with. The parts are hands down amazing. Highly recommend.
ST
Sal Torres
May 27, 2025
★
★
★
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upper control arms look great and went on easy.. only reason I gave 4 stars and not 5 is because of a shipping issue which put my build a week behind. The issue was resolved quickly and painlessly, great customer service. Only time will tell how control arms perform but they look great and like they will go above and beyond control arm demand.
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Specifications
| Brand | RockJock |