RockJock's 1 1/4 in.-12 left hand thread jam nut for use on RockJock Johnny Joints with treaded shanks, or in any other application that would need a 1 1/4 in. jam nut. Gold zinc plated, sold each.
| Brand | RockJock |
See It Installed
Install videos and build guides on our YouTube channel.
Watch more installs on YouTubeReviews from Google
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Ajay Paynter
Mar 4, 2026
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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.
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Ryan Colligan
Mar 4, 2026
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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.
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Marcus Torres
Jan 15, 2026
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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.
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Mike Nielsen
Nov 23, 2025
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The customer service is first class. I had an issue with a track bar I installed on my F350. I don’t have any other Core 4x4 parts yet, but with the way I was treated, I know their parts are well done, because they went above and beyond to make sure I was made whole. They wouldn’t be in business if they had to take care of a lot of people like they took care of me. Will definitely be back when it’s time to build the Jeep!
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Sal Giordano
Sep 24, 2025
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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!
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Adam
Oct 24, 2025
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I couldn't have been more excited for the initial unboxing of these new Core 4x4 UCA's!
They appear to be so well built and just a true quality product.
Installation was a breeze and the initial testing with the forklift appears to have given me some additional flex with less binding on the rest of the components now that the geometry is back properly aligned.
Time will tell how they hold up on my near future off-road adventures but I don't have any doubt that they are up to the task!
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niceguyr1
Mar 24, 2023
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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! 👍👍
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JT JT
Dec 23, 2025
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We have all shopped places where the person on the phone makes you feel like they don't have the time to talk to you the customer or answer your questions. I can tell you first hand that's not Core 4x4. They have the best customer service I have seen so far. They have taken the time to respond to all of my questions in a very prompt and professional manner, taking the time to answer each and every question I have had. Lets put it this way if Core 4x4 sells a product I am wanting for my truck I will buy it from them, I highly recommend Core 4x4.
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Logan Matejek
May 27, 2025
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The parts are a massive improvement over factory. I accidentally ordered the wrong endlinks and they helped me figure out the correct size and sent me new ones.
Definitely an awesome store
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Brad C
Mar 24, 2021
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Outstanding experience! I asked Core to build me a set of custom control arms that were larger/heavier than they normally build. They gladly accepted the challenge and turned out an expertly crafted and super strong product ahead of schedule. Fit and finish are excellent. Spence and Cameron were a pleasure to work with every step of the way. And all of this for a very reasonable price. I highly recommend these guys!