It’s no secret that the Polaris RZR XP 900 is the hottest off-road vehicle on the planet. Ride areas, dune spots and even the woods are full of them every weekend. Another arena that has seen plenty of XP activity is on the track. In fact, organizers like GNCC and WORCS are having record turnouts in all UTV classes. Furthermore, brand-new series’ are popping up all over the country that cater to UTVs.
While we still enjoy the thrill of sawing handlebars and leaning off of the side of a quad, driving a RZR or any sport UTV is a lot of fun—so much fun that we decided to build our own racing RZR XP 900. The machine will help facilitate some product testing and get us some kicks on the track.
Our focus is primarily on the WORCS races, since it is local to the Dirt Wheels headquarters, and the build will follow WORCS rules. Most other organizations have a similar rule book that racers have to adhere to.
You definitely want to check with the particular race organization prior to showing up at the event for full rule details. Some sanctioning bodies may require more safety features than what we have put into our WORCS build. An aftermarket fuel cell is something some desert promoters require. Others also require the use of horns, rear tail lights, two-way radios and tracking systems that you would not want to show up without. We have included a list of the major promoters of UTV races across the country for reference.
Driver safety and cockpit construction take up a big portion of rules and modifications a racing UTV must go by. While the stock ROPS (roll-over protection system) meets OSHA requirements and will prevent injury in a low-speed crash, most race organizers what something stronger.
The WORCS rule book reads for all UTVs as follows: “Aftermarket well-built roll cages made for racing are recommended. No factory stock roll cages will be allowed. Factory cages will only be allowed if modified/reinforced and tied into rear bumper/frame at two points. Gusseting of the factory cage is highly encouraged.” You also need to have a metal roof covering the driver’s compartment. Furthermore, a safety net must be attached to the driver’s side, and a 3-inch-wide, five-point harness-type seatbelt must be used.
For these items, we sourced equipment from Pro Armor ( 343-9270). Their new Asylum roll cage is one of the strongest you can buy. It adds a little weight, but the peace of mind of being well protected when dicing against the competition gives you a big advantage. It is made of 1.75-inch DOM steel tubing and mounts to the four stock locations while also tying into the rear section of the Polaris frame. The look of the cage structure adds racy styling as well. The Asylum cage passes ANSI/ROHVA 1-2011 certification and sells for $1700. For comparison, a stock Polaris roll cage at the dealership sells for about $700. Attached to that beefy roll cage we installed a set of Pro Armor racing seat belts. This is a $134, five-point set with sewn-in shoulder pads. They bolt right into the stock belt locations and loop around a roll cage crossbar behind the seat. Some additional features include convenient flashlight and cell-phone pockets.
So far we have left the pedal assembly, seat and steering wheel stock. Pro Armor and a ton of other companies do make upgraded versions of these items. Per the WORCS rules, we did install a fire extinguisher inside the cabin. It’s secured with a $125, billet-aluminum, quick-release mount from Off-Road Solutions (www.quickreleasemount.com). Holz Racing (www.holzracingproducts .com) also sells a compact, steel, quick-release mount for $80.
A Pro Armor aluminum roof ($375) and a pair of aluminum doors ($649) seal up the cabin. Per WORCS rules, the door must have a secondary latching system so they don’t randomly come open during a race. We use steel hose clamps, and we keep the tool in the car to operate them. In the event of a tipover, we could exit the car through the passenger front or rear window areas. Our driver’s-side window net is hose-clamped on as well.
Our single-seat cockpit features one other item that we haven’t seen any other racer install. In the spot where the passenger would sit on a normal trail ride, we installed a Polaris Lock & Ride cargo box at $249. It’s the same box that comes in the back of the Jagged X RZR. Inside that box we filled it with foam and cut out specific spots for tools and spare parts. We have included a small electric impact gun, clutch tool and a spare belt. The belt is the most common failure in a racing situation, and we have it set up so we could change one quick enough (two minutes) as to not lose a lap. For longer races, we also include an upper and lower ball joint and the needed tools to change them.
Although the RZR XP 900 is an awesome machine, we have found some other weak points. Holz Racing, one of the top Polaris race teams, has developed a few fixes for the machine. The most important are front and rear chassis braces. According to Holz, in racing conditions, if the vehicle experiences a sudden hard hit during a drift or slide, or if the machine ends up on its side, the stock rear chassis brace is not strong enough to keep the radius rod bolts from bending. We have never suffered this problem, but the 2-pound part for $99.95 is good insurance to keep it from ever happening. Up front we installed another steel brace at $35 that Holz claims reduces unwanted flex near the front-suspension pivot points. What we do know is, if you reduce flexing, you can tune your shocks more precisely for sure.
As for shocks, we equipped the four corners of our racing XP 900 with the latest Race Tech 46mm G3 shocks. The stock shocks are good for casual trail riding but really can’t hold up to pounding race conditions. The Race Tech product has similar dimensions of the stock shocks with added benefits. Race Tech Gold valves, super-slick fluid and high-temp seals are some of them. Two speed-compression and rebound adjustments are the others.
The Race Tech shocks are custom-built to the rider’s preferences. Plus, if you don’t like the initial setup of the shocks, Race Tech will make needed spring and valving adjustments for free. The set we are using sells for $1499 per pair. Race Tech can also upgrade all four stock Polaris shocks with new springs and their Gold valve kit for around $1200.
Choosing the right tire is important for any race ATV or UTV. For this RZR, we wanted a strong carcass with a consistant tread pattern that wasn’t overly aggressive. The key to going fast in one of these machines is to keep corner speeds up, so you want to be able to slide or drive through turns without having to lift on the throttle too much. You also don’t need too much side bite for our mostly hardpacked tracks. So, we installed ITP’s eight-ply Baja Cross tires. We used the same-size 26x9-12s on all four corners. Again, we wanted the rear end to be able to slide and not two-wheel. If you look at a Baja car or truck race machines (two- and four-wheel drive), the top teams run the same-size front and rear tires. It works on UTVs too.
We mounted the ITPs on a set of Hiper Technology’s 12-inch Sidewinder wheels. They are part carbon fiber, part aluminum. They are a single beadlock design and ultra light. One advantage the carbon fiber construction has over cast aluminum is that it will bend (then bend back) and not crack during a hard impact. We expect this combo to be a solid choice and not leave us stranded.
You can tell that the one thing that we are trying to accomplish with this build is to avoid failures. This sort of racing has a high attrition rate. Even the top drivers suffer multiple DNFs during the season. Our goal is to finish every lap, go as fast as we can and see how the results stack up.
We plan on racing this RZR in the remaining WORCS events and possibly a short desert race or rally event. You can follow us at www.face book/dirtwheelsmag to see how we do. Or, check out a video of the racing RZR XP 900 in action on www.dirt wheelsmag.com.
WARNING: Much of the action depicted in this magazine is potentially dangerous. Virtually all of the riders seen in our photos are experienced experts or professionals. Do not attempt to duplicate any stunts that are beyond your own capabilities. Always wear the appropriate safety gear. Copyright 2008 Hi-Torque Publications, Inc. All rights reserved. Console Login