Grounded 4 RZR Trailing Arms and Radius Rods

Besides the drive belt, the easiest part to damage or break on a RZR XP 1000 is the rear radius rods. Drive extra hard into a square-edged berm or land sideways on one rear tire, and one or more radius rods can fail. When this happens, it could also take out the entire trailing arm, rear shock and axle. To prevent this failure, be gentle on those rear corners and strengthen your components. If it’s too late and you have already ruined a corner, then you should probably consider new trailing arms, as well as stronger radius rods.

Many companies offer replacement trailing arms and radius rods, and this month we are taking a look at a company called Grounded 4. This SoCal based company has had decades of ATV racing experience, spent years perfecting the Yamaha Rhino, and is now transferring that knowledge into high-performance UTV products.

So far the Grounded 4 RZR XP 1000 product line includes snap-in radiator grills ($120), trailing arms ($1575), mud flaps ($75), radius rods ($499) radius rod plates ($70) and A-arms ($1595). Similar Yamaha YXZ1000R components as well as roll cages are being developed now. You can contact them in Oceanside, California, at (760) 722-3687 or online at

The Grounded 4 RZR trailing arm is the same length and offers the same travel as a stock piece. It has a more angular look and is made from stronger 4130 steel.

To try out the Grounded 4 products, we ordered a set of rear trailing arms and radius rods for our Fox Edition RZR XP 1000. The arms are stock length and made from DOM steel tubing, with 4130 steel plates, gussets, shock and sway bar mounts. All the parts are Tig welded together, giving them a clean look. The arms are 3.2 pounds heavier than stock but appear to be way stronger. Each arm accepts Grounded 4 mud flaps, or you can build your own. We made a pair out of strong semi truck mud flap material that cost us $10. The radius rods are made from 4130 steel with 5/8-inch uni-balls on the bottom arm and adjustable heim joints up top in case you want to adjust the camber at the rear end. To replace the stock radius rods with OEM parts, you would spend over $525, and they are not adjustable. Stock trailing arms sell for just over $800 per pair.

The stock hub assembly will bolt right up to the Grounded 4 trailing arm. At the front end the pivot bearing and tip are much beefier than stock. The setup weighs just over 3 pounds more than stock.

We have raced this machine several times and want to keep adding strength to it. The arms and rods showed up raw, so we powder coated them to match the RZR. The stock hub assembly bolts right onto the Grounded 4 arms with the stock hardware. Installation took only an hour. The only deviation away from the stock setup as far as mounting goes is that the brake lines have to be routed around the shock instead of under it. Driving the car, you couldn’t feel any difference in weight over stock, and we didn’t even have to make any shock adjustments. What we did do is adjust our driving style. Instead of babying the rear end like we do with the stock setup, we hammered it. We slammed berms, went over jumps sideways and even landed sideways. Heck, in one race (www.race, we even encountered curbs, tree stumps and trash cans that line the course. The arms and radius rods came through with flying colors. The mud flaps we made held up well too. The flaps are actually there to keep rocks from flying off your front tire and ending up between your rear wheel and brake caliper. That can cause a catastrophic wheel failure.

Stock radius rods are vulnerable and can bend if you land wrong off a jump or slide into a square edge at high speed. These stronger radius rods from Grounded 4 actually cost less than replacing the stock ones. To upgrade yours, contact (760) 722-3687 or visit them online at

Overall, the Grounded 4 arms and radius rods were a solid addition to the RZR platform. The parts are strong enough to take abusive driving or even big mistakes. Until Polaris changes the design of the rear end of this RZR, products like the Grounded 4 radius rods and trailing arms should be considered. Give them a call at (760) 722-3687 or visit them online at

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