Building the Perfect UTV

(NARRATOR)>> THEY'RE FAST, FUN, AND BELIEVE IT OR NOT THEY CAN BE AFFORDABLE TOO. TODAY ON XTREME OFF ROAD WE TAKE A MODESTLY EQUIPPED SIDE BY SIDE AND GIVE IT SOME NEEDED UPGRADES TO SUSPENSION, TIRES, AND EXHAUST, CREATING A RIG THAT'S READY FOR HIGH SPEED ACTION, TIGHT TRAILS, AND TALL ROCKS.

(IAN)>> NOW I KNOW WHAT YOU GUYS ARE THINKING. THE XTREME SHOP RIGHT NOW IS LITERALLY BURSTING AT THE SEAMS WITH PROJECTS. I HAVE A LOT GOING ON BUT JUST THE OTHER NIGHT I WAS CRUISING AROUND A COUPLE OF ONLINE CLASSIFIEDS AND I STUMBLED ACROSS THIS BEAUTY RIGHT HERE, POLARIS RAZOR 900, AND THE PRICE WAS INCREDIBLY LOW. SO I HAD TO SNATCH IT UP. NOW THE REASON THAT IT WAS SO LOW IS BECAUSE THIS IS A 900 TRAIL MODEL. ONE OF THE LESS THAN POPULAR VERSIONS OF THE POLARIS RAZOR. THE TRAIL MODELS ARE A LOT NARROWER THAN THEIR SISTER, THE XP. THOSE ONES HAVE THE WIDE LONG TRAVEL SUSPENSION. TRAIL MODELS ARE GREAT IF YOU LIVE IN AN AREA WHERE YOU'VE GOT TO GET THROUGH SOME TIGHT TREES OR TIGHT TRAILS. IT'LL BASICALLY GO PRETTY MUCH ANYWHERE A FOUR WHEELER WILL GO, BUT JUST LIKE EVERYTHING ELSE THAT NARROW TRACK WIDTH LIMITS YOUR SUSPENSION TRAVEL. SO MY PLAN IS SIMPLE. I PICKED UP THIS CHEAP SO I CAN THROW A WHOLE BUNCH OF PARTS AT IT AND MAKE IT JUST AS GOOD AS AN XP. EQUIPPED WITH A LIQUID COOLED 875cc ENGINE PUTTING OUT 75 HORSEPOWER, THE POLARIS 900 TRAIL EDITION MEASURES 105 INCHES LONG WITH AN OVERALL WIDTH OF 50 INCHES AND WHEEL BASE JUST UNDER 80. IT LEAVES THE FACTORY WEIGHING IN JUST OVER 1,000 POUNDS WITH 11 INCHES OF GROUND CLEARANCE AND A PAYLOAD CAPACITY OF 740 POUNDS. FOUR WHEEL DISC BRAKES AND FRONT AND REAR AARM SUSPENSION SYSTEM WITH COIL OVERS ON ALL FOUR CORNERS WITH 10 INCHES OF SUSPENSION TRAVEL ALL THE WAY AROUND. IT IS A GREAT ENTRY LEVEL SIDE BY SIDE WITH A LOW PRICE POINT AND ENOUGH FEATURES TO GET YOU INTO THE DIRT AND HAVING FUN, BUT WE CAN MAKE IT EVEN BETTER.

FIRST STEP IN UPGRADING THIS SIDE BY SIDE IS TO DITCH ALL THE FACTORY SUSPENSION PIECES, KNUCKLES, UPPER AND LOWER ARMS, COIL OVERS, AND THE AXLES WILL NEED TO BE REMOVED FROM THIS 900 ON ALL FOUR CORNERS, GETTING READY TO UPGRADE THEM WITH A PILE OF PARTS.

NOW WHEN I SAID A PILE A PARTS I ACTUALLY MEAN A PALLET FULL OF PARTS. EVERYTHING FOR THIS RAZOR CAME FROM THE THIS COMPANY RIGHT HERE, RT PRO, AND THERE'S A LOT OF PARTS THAT NEED TO COME OUT OF THESE BOXES.

THE RT PRO SUSPENSION SYSTEM WILL INCREASE THE OVERALL TRACK WIDTH OF OUR TRAIL RAZOR TO THE SAME TRACK WIDTH AS A RAZOR XP, THE LONG TRAVEL VERSION OF OUR SIDE BY SIDE. NOW THEY DO THAT BY REPLACING THE UPPER AND LOWER CONTROL ARMS AT ALL FOUR CORNERS. THEY ALSO UPGRADE THE CONTROL ARMS WITH UNIBALLS INSTEAD OF THE WEAK LINK FACTORY POLARIS RAZOR BALL JOINT THAT OFTEN FAILS OFF ROAD. NOW THE KIT COMES WITH FOUR NEW FOX SHOCKS THAT ARE VALVED SPECIFIC AND SPRUNG FOR THIS RAZOR. NOW THAT PACKAGE WOULD BE AN UPGRADE EVEN FOR A FACTORY RAZOR XP. SO IN ESSENCE WE'RE UPGRADING PAST THE VEHICLE THAT WE'RE TRYING TO EMULATE, AND WHILE WE'RE AT IT WE'LL GO AHEAD AND THROW ON SOME OF THESE RT PRO BODY PROTECTION ITEMS, A FRONT AND REAR BUMPER, AS WELL AS A SET OF ROCK RAILS, OR SIDE STEPS, JUST TO PROTECT THIS RAZOR WHEN IT'S IN THE DIRT. LET'S START AT THE BACK.

(NARRATOR)>> COMING UP, A PRECUT CAGE PROVIDES PROTECTION WHILE STICKY RUBBER AND DOUBLE BEAD LOCKS GIVE US PERFORMANCE. PLUS SUSPENSION SEATS, A ROCKING SOUND SYSTEM, AND A FULL THROTTLE SHAKEDOWN RUN.

(IAN)>> NO MATTER WHAT TYPE OF SIDE BY SIDE YOU HAVE, PROBABLY ONE OF THE FIRST UPGRADES YOU SHOULD THINK ABOUT IS A NEW SET OF AXLE SHAFTS. THEY ARE ARGUABLY THE NUMBER ONE WEAK LINK IN THE DRIVETRAIN OF ONE OF THESE MACHINES. NOW WE HAVE TO CHANGE OURS OUT BECAUSE WE'VE INCREASED THE TRACK WIDTH OF OUR SUSPENSION. SO WE NEED A LONGER AXLE SHAFT TO WORK WITH IT. SO WHY NOT UPGRADE IT AT THE SAME TIME? NOW AN AXLE COMPANY THAT KNOWS A THING OR TWO ABOUT SERIOUS ABUSE IS RCV PERFORMANCE. THEY BUILD HIGH PERFORMANCE SHAFTS AND CV ASSEMBLIES THAT SEE SOME SERIOUS ABUSE IN THE WORLD OF OFF ROAD, AND THEY'VE TAKEN EVERYTHING THEY'VE LEARNED FROM PLACES LIKE ROCK BOUNCERS AND ROCK CRAWLERS, AND ADAPTED IT TO THE SIDE BY SIDE MARKET. NOW THEY HAVE AN UPGRADED SHAFT WITH A BIGGER SPLINE COUNT THAN FACTORY. IT'S A LOT LARGER, LOT STRONGER, AND THEY USE ONE OF THEIR CV STUB SHAFT ASSEMBLIES AT THE END. NOW THIS IS A LOT STRONGER, IT'S CHROMOLY CONSTRUCTION, AND THEY PROVIDE A GREASE FITTING AT THE END OF THE SHAFT SO YOU CAN SERVICE THE SHAFT BY GREASING IT FROM THE END WITHOUT HAVING TO DISASSEMBLE IT IN BETWEEN TRAIL RIDES. THIS WILL JUST GIVE YOU A LITTLE BIT OF ROCK BOUNCER STRENGTH IN YOUR SIDE BY SIDE. THE NEW RCV AXLES ARE INSTALLED INTO THE RAZOR, AND THE REST OF THE RT PRO LONG TRAVEL SUSPENSION CAN BE INSTALLED.

KNUCKLES, BRAKES, AND UP FRONT SPINDLES, TIE ROD ENDS, AND FINALLY THE COIL OVER SHOCKS ARE BOLTED UP.

NEXT STEP, A CAGE UPGRADE IS ORDER FOR THIS LITTLE RIG. THE RT PRO CAGE KIT IS A DO IT YOURSELF CAGE THAT IS PREBENT, NOTCHED, AND HAS ALIGNMENT SLOTS AND KEYS LASER CUT INTO THE TUBING TO HELP WITH TUBE ALIGNMENT. CROSS BRACES ARE TACKED INTO PLACE TO TRIANGULATE THE ENTIRE CAGE STRUCTURE. [ welder crackling ]

(IAN)>> THE ROLL CAGE IS NOT THE ONLY CHANGE WE'RE GONNA MAKE TO OUR RAZOR TO IMPROVE ITS SAFETY. WE'RE ALSO GONNA UPGRADE THE SEATS WITH A SET OF THESE PRP XC SERIES RAZOR FACTORY REPLACEMENT SEATS. NOW THESE ARE A LOT BETTER THAN A STOCK RAZOR SEAT BECAUSE THEY ARE A TRUE SUSPENSION SEAT AND THEY'RE FULL TUBULAR CONSTRUCTION. THEY ARE STRONGER AND THEY WORK BETTER TO CONTAIN THE DRIVER IN THE DRIVER COMPARTMENT. ALSO IT ALLOWS US TO RUN A SET OF THE PRP FIVE POINT HARNESSES, WHICH ARE A LOT SAFER THAN THE TYPICAL LAP BELT THAT YOU'LL FIND IN THESE RAZORS. THE BEST PART IS, IS THEY WILL BOLT USING THE FACTORY BRACKETS.

(NARRATOR)>> COMING UP, WITH A FEW FINISHING TOUCHES OUR RAZOR IS READY TO ROCK!

(IAN)>> TODAY ON XOR WE HAVE A POLARIS 900 TRAIL SIDE BY SIDE IN THE SHOP FOR A PILE OF UPGRADES. ONE THING THAT'S BECOME A STAPLE IN THE SIDE BY SIDE MARKET IS HIGH END AUDIO, AND TO DELIVER THAT JASON PLANK FROM MTX AUDIO IS HERE WITH A PILE OF RAZOR SPECIFIC AUDIO GEAR.

(JASON)>> SO WHAT WE TRIED TO DO WAS BASICALLY CREATE A SURROUND TYPE OF EFFECT. WE HAVE SPEAKERS IN FRONT OF YOU, SPEAKERS BEHIND YOU, WE HAVE SUBWOOFERS HIDDEN AWAY IN THE VEHICLE, AND A SIMPLE SOURCE UNIT LIKE YOU MAY HAVE IN A VEHICLE TO CONTROL IT ALL.

(IAN)>> THE COMPLETE MTX AUDIO RAZOR PACKAGE CONSISTS OF FOUR SPEAKERS, A SUBWOOFER THAT MOUNTS BEHIND THE DASH, AN AMPLIFIER, AND A MULTIMEDIA HEAD UNIT, ALONG WITH A COMPLETE WIRING HARNESS THAT MAKES INSTALLATION QUICK AND EASY, AND THE GEAR IS DESIGNED FOR SOME SERIOUS OFF ROAD ABUSE.

(JASON)>> THE DURABILITY OF THE PRODUCT IS OUTSTANDING. IT'S ALL WATERPROOF, DUSTPROOF. YOU CAN DO SOME RIDING, GET IT ALL MUDDY, UP TO YOUR NECK, WHATEVER YOU WANT, YOUR FAVORITE MUD HOLE, TAKE IT HOME AND POWER WASH IT, AND DO IT AGAIN THE NEXT DAY.

(IAN)>> OUR 900 HAS ALREADY CHANGED A LOT. WE'VE GOT A CUSTOM CAGE, SUSPENSION SEATS, LONG TRAVEL SUSPENSION, AND NOW A ROCKIN' SOUND SYSTEM. NEXT STEP WE'RE GONNA PULL A LITTLE BIT OF EXTRA POWER OUT OF THAT LITTLE 900 MOTOR. NOW I'M GONNA DO IT WITH A STAGE TWO KIT FROM BIKEMAN PERFORMANCE. NOW THIS IS MORE THAN JUST A MUFFLER UPGRADE. THIS IS A COMPLETE NEW EXHAUST WITH A FREE FLOWING HEAD PIPE WITH AN XPIPE BUILT INTO IT TO HELP THAT LITTLE ENGINE BREATHE. IT COMES WITH A TUNER SPECIFICALLY SETUP FOR OUR RAZOR THAT'LL PULL ABOUT 22 TO 23 EXTRA HORSEPOWER OUT OF THE ENGINE, AND A CLUTCH KIT THAT'S TUNABLE DEPENDING ON WHAT ELEVATION YOU RIDE IN. NOW THIS ENTIRE KIT DOES THINGS LIKE REMOVE FACTORY TORQUE LIMITERS, AND ALLOWS 100 PERCENT THROTTLE OPENING TO GET US ALL THAT EXTRA POWER, AND THE NICE THING IS, IS THAT IN THE FUTURE IF WE EVER TEAR INTO THAT MOTOR AND UPGRADE IT WITH HARD PARTS LIKE CAM SHAFTS OR BIG BORE KIT, ALL OF THIS STUFF WILL WORK WITH THOSE UPGRADES.

WITH THE RAZOR FIREWALL REMOVED, THE FACTORY PIPE IS UNBOLTED FROM THE 900 ENGINE, AND THE RETAINING SPRINGS ARE UNHOOKED TO RELEASE THE PIPE AND THE MUFFLER. THE NEW HIGH FLOW PIPE IS BOLTED ONTO THE CYLINDER HEAD AND MUFFLER IS MOUNTED TO THE REAR OF THE RAZOR.

INSTALLED! NOW THE REST OF THE RAZOR BODY WORK CAN BE INSTALLED FOR GOOD, ALONG WITH THE RT PRO REAR BUMPER ASSEMBLY TO PROTECT US ON THE TRAIL.

THE TIRE AND WHEEL PACKAGE I'VE CHOSEN FOR OUR RAZOR IS ACTUALLY PRETTY COOL. NOW IT'S GONNA START WITH A SET OF THESE MAXXIS LIBERTY MLTHREE TIRES. NOW THIS IS AN EIGHT PLY RADIAL, KIND OF LIKE AN ALL TERRAIN TIRE, BUT THE COMPOUND IS SPECIFICALLY DESIGNED FOR MANY DIFFERENT TYPES OF TERRAIN ON YOUR SIDE BY SIDE. AS A MATTER OF FACT THIS PARTICULAR MODEL OF TIRE ACTUALLY HAS A PODIUM FINISH UNDER ITS BELT AT THE BAJA 500. SO WE KNOW THAT WILL BE PERFECT ON OUR RIG. I'VE WRAPPED THEM AROUND A SET OF THE NEW RACELINE RIPPER DOUBLE BEAD LOCK WHEEL. NOW WHAT MAKES THIS WHEEL VERY UNIQUE IS THE FACT THAT THE CENTER BOLTS TO THE OUTER RIM SHELL, AND YOU CAN ACTUALLY UNBOLT IT, SPIN THE WHEEL AND TIRE AROUND, AND BOLT IT IN FROM THE OTHER SIDE. THAT ESSENTIALLY CHANGES THE BACK SPACING OF THE WHEEL. I CAN MOVE THE WHEEL FURTHER OUT FOR CERTAIN TYPES OF TRAIL CONDITIONS OR I CAN MOVE THE WHEEL FURTHER CLOSER TO THE BODY IF I'M IN TIGHT TRAILS, ALL WITHOUT UNMOUNTING THE TIRE FROM THE WHEEL. IT IS ALSO A DOUBLE BEAD LOCK WHEEL. THAT MEANS THAT BOTH BEADS OF THE TIRE ARE CLAMPED IN PLACE. IF THE TIRE EVER GOES FLAT IT WON'T JUST GO COMPLETELY SOFT AND FALL UP UNDERNEATH THE RIG. IF YOU CAN GET IT MOVING AND START DRIVING, THE TIRE CAN SELF INFLATE AND GET YOU OFF THE TRAIL IF YOU NEED IT. ALL THAT IN A WHEEL THAT WEIGHS RIGHT AROUND 20 POUNDS.

[ drill spinning ]

(IAN)>> THE SEATS ARE BACK OUT OF THE RAZOR. NOW I ORIGINALLY PULLED THEM OUT SO I COULD PULL THAT REAR PANEL TO PUT THE NEW PIPE ON. NOW I'VE LEFT THEM OUT BECAUSE WE HAVE ONE LAST JOB TO DO. OUR ROLL CAGE IS JUST TACKED TOGETHER. NOW WE LEFT IT THAT WAY BECAUSE WE WANTED TO MAKE SURE THERE WAS GONNA BE NO INTERFERENCE WITH ALL OF OUR AUDIO GEAR. NOW THAT WE KNOW THERE ISN'T THE LAST STEP BEFORE WE GET DIRT ON THESE TIRES IS TO GO AHEAD AND FINISH WELD THIS ENTIRE CAGE. [ welder crackling ]

(NARRATOR)>> UP NEXT...

(IAN)>> DUSTY TODAY! WE'RE OUT HERE AT WOOLY'S OFF ROAD PARK. NOW THIS IS A GREAT PARK TO RIDE YOUR RAZOR AT. WE'VE MADE SOME HUGE CHANGES TO THIS LITTLE 900 TRAIL. WE'VE GOT LONG TRAVEL SUSPENSION NOW. SO WE SHOULD BE ABLE TO BLAST SOME OF THESE TRAILS WITH A LITTLE BIT OF SPEED. I MEAN WE DID ALL THIS WORK TO THIS RIG. WE MIGHT AS WELL HAVE SOME FUN WITH IT. SO WHY NOT SPEND THE REST OF THE DAY GOING FOUR WHEELING, IN A RAZOR! WHAAAA!

OUR FIRST TEST IS SOME SIMPLE TRAIL RIDING ROCK CRAWLING WITH OUR RIG. LARGER WHEELS AND TIRES GIVE US MORE GROUND CLEARANCE, BUT THE LONG TRAVEL SUSPENSION IS WHAT REALLY ALLOWS THIS RAZOR TO CRAWL OVER SOME SERIOUS OBSTACLES. PLUS A LITTLE EXTRA POWER CAN COME IN HANDY AS WELL.

WHENEVER YOU'VE DONE AS MUCH WORK TO YOUR SIDE BY SIDE AS WE HAVE HERE YOU WANT TO GO AHEAD AND JUST EASE YOURSELF INTO THE TRAIL RIDE. MAYBE JUST DO A LITTLE BIT OF ROCK CRAWLING FIRST LIKE WE DID. THEN GET OUT OF THE RIG, GIVE IT A QUICK ONCE OVER. CHECK FOR ANY FASTENERS THAT MAY HAVE BECOME LOOSE. YOU WANT TO SPOT THAT BEFORE YOU START HITTING STUFF AT SPEED. SHOCK'S GOOD! TRAILING ARM'S GOOD! WITH THE RAZOR NUT AND BOLTED, IT'S TIME TO TURN THIS LITTLE MONSTER LOOSE ON SOME OF THESE TRAILS. THIS IS WHERE THE LONG TRAVEL SUSPENSION, FOX SHOCKS, AND PRP SUSPENSION SEATS SHINE. THIS LITTLE MACHINE CAN NOW HAUL THE MAIL THROUGH THE TIGHT, TWISTY TRAILS, AND REALLY RIP WHEN THE TREES OPEN UP.

ONE BENEFIT TO THE SMALLER SIZE OF THE SIDE BY SIDE IS THEIR ABILITY TO FIT THROUGH SOME TIGHT PLACES YOU COULD NEVER GET A TUBE BUGGY OR A JEEP. TREES CAN MAKE A TRAIL TIGHT, BUT WITH A SHORT WHEEL BASE AND NARROW TRACK YOU CAN EVENTUALLY FIND YOUR WAY THROUGH. STEEP HILL CLIMBS CAN BE LOOKED AT ONE OF TWO WAYS, SCARY OR A PILE OF FUN, BUT IF YOU CAN CRAWL THEM, KEEP YOUR ARMS AND HANDS INSIDE THE VEHICLE AT ALL TIMES, THEY ARE A BLAST.

NOW THERE IS NO QUESTION WE HAVE IMPROVED THIS LITTLE 900 TRAIL. NOW I'M GONNA BE HONEST WITH YOU GUYS. I'VE ALWAYS KIND OF BEEN RIGHT ON THE EDGE WHEN IT COMES TO THESE RAZORS. THERE'S NO QUESTION THAT THEY ARE COOL MACHINES, BUT THE PRICE POINT TO GET INTO ONE HAS ALWAYS BEEN RELATIVELY HIGH. THAT'S WHY THIS 900 TRAIL IS THE PERFECT MACHINE. YOU CAN PICK UP ONE OF THESE RELATIVELY CHEAP, THROW A BUNCH OF UPGRADES AT IT THAT YOU'D THROW AT A MORE EXPENSIVE MACHINE ANYWAY, AND YOU HAVE A MACHINE THAT WILL FIT YOUR BUDGET, AND YOU CAN GET OUT AND HAVE TONS OF FUN ON THE WEEKEND. NOW I KNOW YOU GUYS HAVE TO GO, BUT MYSELF, I HAVE SUN STILL IN THE SKY, OFF ROAD PARK TO MYSELF, I'M HAVING SOME FUN.

THEY APPEAR TO BE INCREDIBLY COMPLICATED PIECES OF EQUIPMENT, AND IN ESSENCE THEY ARE. WE'RE TALKING ABOUT COIL OVER SHOCKS, BUT WHEN YOU BREAK THEM DOWN INTO EACH INDIVIDUAL COMPONENT AND UNDERSTAND WHAT IT DOES, WELL THE MYSTERY IS REMOVED. THEY HAVE BECOME A STAPLE IN THE OFF ROAD INDUSTRY, FROM ROCK CRAWLERS, DAILY DRIVEN DUAL PURPOSE JEEPS, TO SERIOUS OFF ROAD RACE RIGS. COIL OVER SHOCKS HAVE A VERY IMPORTANT JOB TO DO. NOT ONLY DOES THE COIL OVER SUPPORT THE VEHICLE WEIGHT BY ACTING AS THE SUSPENSION SPRING RETAINING DEVICE. IT IS ALSO THE DAMPENER IN THE SYSTEM CONTROLLING BOTH THE JOUNCE AND REBOUND, BUT MORE THAN THAT THEY ARE COMPLETELY TUNABLE PIECE OF EQUIPMENT DESIGNED TO IMPROVE THE VEHICLE'S ABILITY OFF ROAD. BUT DOES EACH PART OF A COIL OVER SHOCK DO? WELL EACH ONE HAS A VERY SPECIFIC JOB, AND IT STARTS WITH THE UNIBALL. AT EACH END OF A COIL OVER SHOCK THERE UNIBALLS THAT ACT AS THE SHOCK MOUNT. THEY ARE THE SAME BASIC DESIGN AS A SUSPENSION ROD END. THEY ALLOW THE SHOCK MOUNT TO PIVOT AND TWIST DURING THE SUSPENSION CYCLE. THE BOTTOM SPRING MOUNT SITS ON THE ALUMINUM HOUSING THAT HOLDS THE UNIBALL. THIS ITEM IS REMOVABLE TO GET THE COIL OVER SPRING OFF OF THE SHOCK. SOME SHOCKS HAVE A JOUNCE BUMPER ON THE SHAFT. NOW THIS IS NOT A BUMP STOP BUT MORE OF A SAFETY DEVICE TO KEEP THE VALVE STACK FROM BOTTOMING OUT INSIDE THE SHOCK. THE SHOCK SHAFT IS HARDENED STEEL AND SOMETIMES COATED TO REDUCE FRICTION. THIS MACHINED SURFACE NEEDS TO BE PROTECTED DURING ANY FAB WORK ON YOUR RIG. A SMALL NICK OR BURN FROM WELD SPATTER CAN CAUSE THE SHOCK TO FAIL PREMATURELY. LONG DISTANCE OFF ROAD CARS, LIKE ULTRA FOURS OR SCORE DESERT RACERS, OFTEN RUN SHOCK BAGS TO PROTECT THE SHAFT FROM BECOMING SAND BLASTED DURING A RACE. THE BODY OF THE SHOCK IS WHERE THE BUSINESS HAPPENS. INSIDE IS THE SHOCK OIL AND THE VALVES THAT ARE ATTACHED TO THE SHOCK SHAFT. THAT IS WHAT DAMPENS THE SUSPENSION MOVEMENT. THE BODY IS ALSO THREADED AND HAS ADJUSTOR NUTS ON IT. NOW THE ADJUSTOR NUTS HAVE TWO JOBS. THEY'RE NOT ONLY THERE TO SET THE RIDE HEIGHT ON THE RIG, THEY CAN ALSO ADD WHAT'S CALLED PRELOAD TO YOUR SUSPENSION SYSTEM, OR EXTRA PRESSURE ONTO THE COIL SPRING WHEN IT'S AT REST. THAT JUST HELPS THE SUSPENSION DROOP OUT A LITTLE BIT FASTER.