SHOCK THERAPY RZR XP 4 1100

Shock Therapy is one of the many aftermarket companies in Arizona specializing in modifying UTVs for dunes, desert and short-course racing. The Shock Therapy crew has more than 25 years of off-road racing experience with Trophy Trucks and Class 1 buggies, and when more and more race teams started using UTVs for pre-running, they started re-valving and -springing Rhinos, Teryxs, RZRs, Mavericks and Wildcats for a plush ride at speed. Now, ST is a premier suspension-tuning company that holds several patents, and their Polaris RZR XP 4 1100 and XP Turbo are rolling test beds for developing new products like the XP frame supports, silent cross-over rings and the brand-new triple bypass system. The XP 4 build also has support from Weller Racing, DragonFire Racing, TMW Off-Road, BS Sand Seats, LoneStar Racing, RCV Performance, Wolf Designs, Sin-Fab, Trinity Racing, Sand Tires Unlimited, DWT, Baja Designs, Rugged Radios, 5150 and ATVonics; many are based in Arizona.

Shock Therapy’s RZR XP 4 1100 is a rolling test bed for suspension and other high-performance products for duning, desert racing and playing. Check them out at Glamis’ vendor row on any big weekend.
Shock Therapy’s RZR XP 4 1100 is a rolling test bed for suspension and other high-performance products for duning, desert racing and playing. Check them out at Glamis’ vendor row on any big weekend.

 

WELLER RACING POWER

Weller Racing provides the power with its WR Stage 5 big-bore kit ($3,299.99), which includes two 96mm forged piston kits, bored and plated cylinders, CNC porting and polishing, +1mm valves, head studs, valve-bucket kit, dual valve springs with Ti retainers, adjustable shim kit, WR-profiled cams, automatic timing-chain tensioner, new OEM oil filter, spark plugs and gasket kit including valve seals. This kit bumps rear-wheel horsepower from 84 to 95-plus horsepower. The CVT is upgraded with Weller’s Kyle Tuned clutch kit ($389.99) with modified helix, springs and adjustable weights, and the transmission is armed with WR heavy-duty bearings. RCV Performance Pro II Series axles ($725 each) beef up the drivetrain for the extra power and stress of turning 31-inch Sand Tires Unlimited Tribute front and Blackbird rear paddle tires. RCVs have a 33-spline 300M shaft and 4340 chromoly CV bodies, with the inner CV plunging 2.25 inches. Sinister Fabrications arms the rear end with 5/8-inch radius rods ($489.99).

Shock Therapy is developing an IBP shock kit for RZR XPs in partnership with Walker Evans Racing to bring Trophy Truck ride quality to UTVs. Frame-support plates stiffen the area and prevent the torsion-bar mount from breaking.
Shock Therapy is developing an IBP shock kit for RZR XPs in partnership with Walker Evans Racing to bring Trophy Truck ride quality to UTVs. Frame-support plates stiffen the area and prevent the torsion-bar mount from breaking.

 

TMW & DFR OFF-ROAD STYLE

TMW’s XP 4 Venom cage starts at $1899, with MIG welding, 0.95-inch DOM tubing and extra support tubes, and powdercoating and an aluminum roof add $780. XP 4 full doors by TMW are $1350, plus graphics, but ST went with a full Extreme Plus Wrap by Wolf Designs ($480). BS Sand supplied four Extreme full-suspension seats, and they were fitted with DFR 3-inch, 5-point harnesses ($139.99 each). DFR also supplied the Sport V steering wheel with a quick-disconnect kit ($281.99), and TMW also fitted its Venom cage with a glass windshield and rear-view mirror.

Weller Racing’s Stage 5 big-bore kit includes two 95mm forged piston kits with three compression choices (9.5:1 Turbo, 11:1 91 octane pump and 12:1 race gas), CNC-ported heads, +1mm valves, Weller Racing profiled cams, bored and plated cylinders, head studs, valve-bucket kit with shims, dual valve springs with Ti retainers, oil filter, spark plugs and top-end gasket/seal kit.
Weller Racing’s Stage 5 big-bore kit includes two 95mm forged piston kits with three compression choices (9.5:1 Turbo, 11:1 91 octane pump and 12:1 race gas), CNC-ported heads, +1mm valves, Weller Racing profiled cams, bored and plated cylinders, head studs, valve-bucket kit with shims, dual valve springs with Ti retainers, oil filter, spark plugs and top-end gasket/seal kit.

 

LED lighting is a must for night riding, and the stock RZR headlights were replaced with Baja Designs’ Sportsmen XP1K headlight kit ($584.95), which includes four Squadron Sports LED cubes (two spot and two combo at 1800 lumens each), mounting brackets and plug-and-play adapters. Sinister Fabrication’s XP1K front grill with a 10-inch, 30-watt LED is $199.99, and Sin-Fab’s Totron 40-inch combo LED light bar is $299.99 and puts out 9600 lumens. The 5150 LED whips have built-in three-button controllers, in-line fuses and quick-release mounts; their 6-foot color-changing LED whips are $325 for two.

Rugged Radios’ Dune Rider 25-watt car-to-car radio and four-person intercom system (RRP660) is $1,259.90; the RM-25R radio has 200 programmable channels and 40 pre-programmed off-road channels, and the RRP660 intercom has Vox control for loud environments, music in with auto muting and an iPhone connect port. ST also added Dunertunes’ five-speaker audio system with JL Audio speakers; this Phoenix-based company is no longer in business.

A TMW cage with roof and windshield upgrades safety and comfort, while Rugged Radio’s Duner radio/intercom and Dunertunes audio system provide communications and entertainment.
A TMW cage with roof and windshield upgrades safety and comfort, while Rugged Radio’s Duner radio/intercom and Dunertunes audio system provide communications and entertainment.

 

RIDE BY SHOCK THERAPY

This XP 4 has LoneStar Racing’s factory-length front A-arm kit ($1550), and the Walker Evans Racing (WER) 2.5-inch front and 3.0 rear shocks are Stage 4, including Ride Improvement System valving ($749.95), dual-rate spring kit with silent cross-overs ($895.95), and a front torsion bar kit ($649.95) and ST rear torsion bar ($549.95). The XP 4 also gets frame supports ($199.99), billet rear torsion-bar links ($149.95) and steel shock bodies ($125 each). If you move the aluminum preload ring on the OEM aluminum shock body, it galls and seizes, so ST machines steel bodies to eliminate that chance. Between the RIS, DRS and ST torsion bars, your XP or XP 4 will float like a hovercraft over the nastiest chop yet track like it’s on rails, but ST has more tricks in the works.

Baja Designs Squadron LED headlights and Sinister Fabrication’s grill LED and 40-inch LED bar extend testing to well after dark. Shock Therapy’s adjustable front torsion bar and stiffer rear bar make the LoneStar Racing XP 4 track like it’s on rails, while ST RIS/DRS shock magic makes the RZR float over obstacles.
Baja Designs Squadron LED headlights and Sinister Fabrication’s grill LED and 40-inch LED bar extend testing to well after dark. Shock Therapy’s adjustable front torsion bar and stiffer rear bar make the LoneStar Racing XP 4 track like it’s on rails, while ST RIS/DRS shock magic makes the RZR float over obstacles.

 

TRIPLE BYPASS SURGERY

Shock Therapy is working with Walker Evans Racing (WER) on Internal ByPass (IBP) shocks for RZR XPs. Shock Therapy’s IBP shocks work in conjunction with the OEM WER needle shocks that are modified with lighter valving and spring rates, and they mount behind the rear shocks with bolt-on bottom and clamp-on top mounts. The IBP shocks have three external tubes—two for compression and one for rebound—to provide a plush ride in the small stuff and eliminate bottoming on big dune jumps. The triple-tube design provides four stages of travel, and finger and wrench adjusters on the external tubes control when each stage engages.

Basically, small chop is handled by the coil-over shocks only, as the lowest tube on the IBPs displaces fluid for no damping. Get into whoops and the coil-overs control the first half and the IBPs control the second half of damping. When the IBP pistons pass the top of the first and second tubes, those sections increase damping forces, and the last stage firms up more to prevent bottoming. On big jumps and dune G-outs, which fool speed-sensitive damping, the IBPs do all of the damping work. Once dialed in, the Shock Therapy IBPs provide a plush ride with no bottoming, whether there’s only the driver in the RZR or three passengers and the driver in an XP 4. MSRP will be $2,695.95 for WER-shocked RZR XPs only. Fox Editions require reservoir mounts, and Turbos will need CVT duct reroutes.

With the IBP kit, lifting for big whoops and tabletops on Sand Highway will be a thing of the past.

STXP4_6_DSC_7315

CONTACT:

BS
Sand
Seats

2609 N. 35th Ave.

Phoenix, AZ 85009

(877) 9BS-SAND

DragonFire
Racing

3191 N. Washington St, Suite 2

Chandler, AZ 85225

(800) 708-9803

Shock
Therapy

P.O. Box 116

Wittman, AZ 85361

(623) 217-4959

www.shocktherapyst.com

Sinister
Fabrication

2010 W. Parkside Lane #122

Phoenix, AZ 85027

(623) 242-8572

TMW
Off-Road

1148 S. Lewis

Mesa, AZ 85210

(480) 969-9261

5150
Whips

P.O. Box 402512

Hesperia,, CA 92345

www.5150whips.com

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