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LIFETIME WARRANTY
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MADE IN UTAH, USA
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https://jerdev.core4x4.com/web/image/product.template/24121/image_1920?unique=2d5d26f

RockJock Front Coil Spring Isolator, JL Front, Urethane

SKU: CE-9818FSI
Fits: 2018 - Present Jeep Wrangler JL / JLU Add vehicle

16.00 16.0 USD 16.00

16.00

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Lifetime warranty Made in USA

Made in USA Orem, Utah
Lifetime Guarantee Unconditional
10 Colors In-house powder coat
Ships in 3 Days From our UT facility
Fully Adjustable 0-6" of lift
3 X-Series Options Only Core 4x4

Why Builders Choose Core 4x4

The only aftermarket suspension brand with an X-Series product system

vs. MetalCloak

One price point, no tier options. Core 4x4 Crawl matches their performance at a better price with a better warranty.

Their “lifetime” language refers to their service model. Actual parts warranty: 1 year. Ours: lifetime.

vs. Teraflex

Skip a grease interval? Warranty voided. Core 4x4 Cruise requires zero maintenance — and our warranty covers everything.

Skip a maintenance interval? Their warranty voids. Ours doesn’t.

vs. Clayton / Budget

Cheaper arms exist. But adjustable, American-made, 10 colors, lifetime guarantee, and an upgrade path? Only Core 4x4.

Clayton warrants their Johnny Joints for 90 days. We cover ours for life.

RockJock's black urethane front coil spring isolators for JL Wranglers and Unlimiteds are designed to fit on the front coil spring buckets of the stock JL front differential housings.

Make Model Submodel Years
Jeep Wrangler 2018 - Present

Vehicle Jeep Wrangler JL / JLU (18–Present)
Brand RockJock

Select your lift size in Step 1 — the kit ships with the correct geometry for that height. If you’re running a non-standard setup, call us before ordering and we’ll confirm compatibility.

Death wobble is a geometry problem, not just worn parts. Cruise Series corrects caster angle and eliminates the flex points that let shimmy start. Replacing one part at a time delays the fix — this replaces the geometry.

Yes, if you’ve done a lift kit before. Full-day project. Watch the complete JT install walkthrough on our YouTube channel — most owners wrap it in a day. Any off-road shop can run it if you’d rather have it done.

Any non-wear component fails — we replace it. No mileage cap. No maintenance intervals to track. No fine print about voiding if you miss a service. Lifetime means lifetime.

Teraflex’s lifetime warranty voids if you miss a maintenance interval. MetalCloak’s actual parts warranty is 12 months — their “lifetime” language refers to their service program. No conditions here.

See It Installed

Install videos and build guides on our YouTube channel.

Watch more installs on YouTube
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Reviews from Google

See all on Google
5.0
132 reviews
5
97%
4
2%
3
0%
2
1%
1
0%
AP
Ajay Paynter Mar 4, 2026
Google
Great company, who worked with me on shipping parts to arrive in time for a show. When I explained my concern they went above and beyond to make it happen. Quality of the parts is top notch.
RC
Ryan Colligan Mar 4, 2026
Google
I have nothing but good things to say about Core 4x4. I have the crawler series on my JKU and we take it all over the place. These parts handle everything we throw at them.
MT
Marcus Torres Jan 15, 2026
Google
Best control arms I have installed on any of my builds. After running every major manufacturer, Core 4x4 is on par or better than all the high-end companies at a fraction of the cost. Lifetime warranty is the cherry on top.
BS
Bailey Smith Mar 23, 2025
Google
Core 4x4 excels with precision and service and keeps nothing else higher in mind. Everyone I've met at the company is very honest and down to earth, 10/10 would recommend.
FS
Fernando Salazar Aug 25, 2025
Google
Great quality control arms and great customer service. Korby has been a great help at answering my questions on some issues I’ve been having with installation!
LS
Leonard Smith Jan 22, 2026
Google
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.
AL
Andrew LaFave May 27, 2025
Google
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
MS
Mr. Smith Nov 23, 2025
Google
Have yet to get to try them but I bought some upper, and then later , lower control arms for my 03 rubicon. The pricing is very fair, so fair I was hesitant to even purchase. When the product came in I was happily mistaken. These are some beefy units with an incredible warranty! I’m very excited! I went with the “Camp”series as I mostly daily it. I have trouble with the shipping at times when I ordered but Corby is quick to notice things and help communicate the solution. Looking forward to buying more parts!
GN
Glenn Nowosad Jan 22, 2026
Google
I just finished installing the Peak 2.0 Front Suspension system with the Core 4x4 Blue Tacoma Rear Suspension system on my 2024 TRD Offroad Premium Tacoma. The two upgraded suspension systems really made a difference in how the ride feels, whether we’re off-road or on the road. A big thank you to Korby and the team at Core 4x4 for their support and for getting the shipping sorted out so quickly!
DW
Derek Whitfield Nov 20, 2025
Google
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.
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