Ski-Doo is getting serious about lightweight sleds. The company’s new REV XP chassis is the backbone for 11 models in 2008, including MX Zs, Summits, Renegades and GSX models. It’s a platform that is also 50 pounds lighter than the models they replace.
A Lighter, Better REV
BRP said a radical redesign of its performance machines required a radical appearance. BRP said it’s new REV-XP uses a “facetized” design, inspired by stealth aircraft and premium-performance motorcycles.
The seat is contoured well, which improves the ergonomics, but it also blends well with the design theme. In total, the styling exercise saved 8 pounds.
A new, much-needed gauge upgrade completes the appearance package. There are two different analog/digital clusters, a standard version and a premium LCD version. Either includes the basics, such as a trip meter and fuel gauge, but there is an available premium gauge with many additional features.
The light weight equation starts with the chassis. We were skeptical about the weight loss and whether or not a machine so light on the scales would withstand the abuse a sled can accrue over its lifespan. More importantly, lifespans are shortened if machines are under built.
Ski-Doo claims its REV-XP chassis is 21 percent more rigid in torsion, and 37 percent more rigid in flexion while 13 pounds lighter.
The REV-XP’s new front legs are similar in architecture to the REV, but refined for better performance and the system weighs 7 pounds lighter. The biggest difference is the ski legs are now forged aluminum as opposed to extruded on the REV, and there are new, lighter-weight spindles. The A-arms are unequal-length; the lower A-arm mounts are moved to the chassis midpoint. The upper A-arm is on a different plane than the lower, which equates to a variable caster design to deal with bump steer.
For the short-track MX Zs, the new SC-5 rear suspension is 8 pounds lighter than the SC-4 it replaces. Ski-Doo calls its new system a refined version of the SC-4 with more travel and different geometry that results in improved weight transfer and bump performance.
The Summit models have a 9-pound reduction over the previous skid. The new SC-5M has less weight transfer to keep the machine flat when climbing. Ski-Doo said it accomplished it without compromising the lift needed to keep the machine floating, and the geometry is similar to the setup used in hillclimb race sleds.
The steering system on the REV-XP is simpler with fewer parts and 5 fewer pounds. In addition to the weight savings, Ski-Doo claims a tighter turning radius and because of fewer moving parts, the overall system has near-zero play.
REV-XP machines are equipped with tracks by the same name. The trail models get a 4-pound lighter variation of the popular Camoplast track, called the RipSaw REV-XP. Summits get a Challenger Lite REV-XP shoe, which saves as much as 6 pounds on the 162-incher. Both track use a new 2.86-inch pitch and single-ply construction to tally the savings. In addition to being quieter, Ski-Doo promises improved acceleration.
BRP doesn’t have any new engines for the coming year, but there is an expansion of the Rotax 800R PowerTek engine used only in Summit models last year.
In 2008, three liquid-cooled engines are fastened into REV-XP models. The 593 two-stroke that powers the 500SS machines, the 600 H.O. SDI and the new-last-year 151-hp 800R PowerTek.
Engines are mounted 1.14 inches lower in the chassis than before to improve mass centralization and create a low center of gravity. The engine is suspended in the chassis, rather than supported from the bottom, making the engine more stable to reduce torque movement that causes drive belt flex.
The jackshaft rides high on the REV-XP chassis. The driven pulley is over the tunnel to open up the footwells for better ergonomics. Minor modifications are made to the engines for fitment, including new mount locations integrated into the lower engine case. Cast aluminum engine mounts save 1.5 pounds.
The primary pulley is called the TRA VII. A new secondary clutch is a new two-roller design on 5-axis machined cams. Ski-Doo claims a more efficient operation and better backshifting as well as a 2-pound savings. The fixed sheave is fastened permanently to the jackshaft to eliminate parts, but BRP said cams can be changed easily.
A new, lighter-weight, hydroformed drive axle uses eight-tooth internal/external drivers and houses the new Brembo brake system, with a dual-pot caliper cooled by a cut-out in the tunnel on the PTO-side. Weight is spared with a composite master cylinder.
First Impressions: MX Z “X” 800
The weights look remarkable, but the new REV-XP is more than an impressive number. Weight does matter.
Flickable is a motorcycle term, but it applies to the new MX Z “X” 800. The machine was more maneuverable, more responsive, sportier and more fun. We drove into corners deeper, tossed a big input to the bars – and because we could hang off easier – it was possible to “flick” the sled through corners with increased ease and precision.
Much of the sporty handling has to do with the new rider position with 8-inch deeper footwells that changed the angle of the driver’s legs. BRP said that the new rider position better isolates riders from bumps. Because many people didn’t like the leg placement of the REV chassis, the new setup will appeal to more people.
The lower engine positioning also helps make this chassis more stable and corner flatter than the REV. The REV-XP is a significant increase in performance that sets a new standard for sport and performance riding. Ski-Doo promises it’s pricing will be close to list pricing on its 2007 lineup, while offering a significant upgrade in performance and value.
Here is a quick list of some of the features on the new REV XP chassis. Check out the Spring issue of Snow Goer for a more thorough report on the new Ski-Doos and the other new 2008 snowmobiles.
New Brake System: The brake disc is mounted on the PTO side of the drive axle and cooled through a port in the tunnel.
New Drive Axle: The hydroformed drive axle, with its two internal/extermal drivers, weighs just 5.7 pounds, 3.6 pounds lighter than the previous drive axle used on the REV chassis.
New Gauges: All the REV-XP models get a new gauge, but several models have a premium gauge with an LCD display that displays speed, rpm, altitude, top speed recorded, top rpm recorded, average speed, altitude, air temp, two trip meters, hour meter, trip timer and a clock on electric start models. On SDI models, it expands to include actual fuel consumption or average fuel consumption. A compass is optional, as is a recording feature with a lap timer.
New Steering System: The steering rack from the REV chassis is gone; in its place a steering stem mated to a drag link with ball joints fastened to the tie rods.