The Switchback XCR is advertised by Polaris for extreme performance riders that need to dominate tough terrain at high speeds. Last winter we had the 800 version in our fleet so we could pound 1500 miles out of this sled to see if it lived up to Polaris’s advertising claim.
PRO-XC Rear Suspension
2018 marks the 4th year on the snow of the AXYS chassis. The 2018 Switchback XCR featured the (progressive rate) outside of the tunnel PRO-XC suspension, known for providing an excellent ride and weight transfer capability. What has evolved with the evolution of this unorthodox snowmobile is the longer front torque arm on the AXYS chassis. The PRO-XC suspension locates the front arm rail pivot location right in the neutral point of the chassis. Your butt literally is positioned directly over this pivot location.
Shift your body forward and the weight transfer under braking allows for more aggressive (and faster) cornering. Slide you butt behind the pivot point and the front-end unloads and the sled lifts the skis and accelerates hard in deep snow or hard pack. This is the advantage of an uncoupled track suspension and the PRO-XC system plain works as advertised. The SB XCR benefits from a 2” diameter Walker Evans Piggyback shock with trick hi-speed and lo -speed adjustable compression damping mounted on the front arm. I found that running the low speed setting right in the middle (5) and the high speed firmer (7) that the front arm gave me excellent damping for most conditions. After riding the PRO-XC suspension since its introduction my experience is that the front arm is now being used as the main suspension member that sucks up the bumps. This load bearing arm acts much like the swing arm on a motorcycle. This explains why Polaris went with the oversize 2” diameter shock up front. More oil volume results in a cooler running shock and less fade.
The XCR models use a 95-300lb/in spring rate with 1” of preload from the factory. The PRO-S versions use a softer 95-280lb/in spring rate. My take on the shock package however is that it is overkill for most riders. The difference between 1 click to the next is very minimal in the seat of your pants. Sometime more adjustability just complicates things. That said the XCR is built with the best from the PRT (Polaris Race Tech) parts bin and you’re paying the big bucks for features like these shocks.
Out back the rear arm on this suspension is where all the controversy has been with this design. Polaris calls it the rear crank and pivot. The rear arm ratio is a true progressive design which the shock outside of the tunnel allows (or at least makes it easier to do so). Over the years Polaris has refined the shock damping and spring rate to provide better movement over stutters yet still take big hits with minimal risk of fully bottoming out on those sucker bumps. Can you bottom it out? Yes. The reason? Simple because you can’t help but seek out the roughest trail to test your riding skill and athleticism. The XCR uses the same spring rate (130lb/in) as the PRO-S versions. If you’re a heavier rider you can opt for the PRO-X spring which is rated at 150lb/in.
One last note about the XCR PRO-XC suspension. Polaris fabricates both the rear and front arm from 4130 chromoly. Why chromoly? Higher tensile strength. That means for continuous pounding, chromoly tubing is less prone to fatigue cracking. This is not new to the snowmobile industry as plenty of aftermarket shops offer chromoly suspension components, but these days production sleds seldom use this material. The PRO-XC also features the same rear axle from the Sno-X sled with solid wheels to take those hard tail landings and with four wheels there’s less chance of de-railing the track. On the snow with the rear torque arm and shock assembly relocated above the tunnel there is less snow/ice accumulation resulting in less unsprung weight. That means better suspension response and less added weight to carry around.
Camso Cobra Track –
With a Twist
This past winter I soon discovered quickly that the Switchback version of the XCR offers better bump capability advantage over the 121“XCR with the longer 137” track. All XCR’s come with the 1.352” Cobra with a 2.52” pitch using a 9-tooth drive shaft. The shorter pitch compared to the 2.86” pitch Cobra (8 tooth driver) found on the Switchback PRO-S puts more lugs in contact with the snow for better acceleration. After spending a year on both versions of the XCR, the Switchback I discovered is less prone to dancing side to side when riding hard in the rough. The SB XCR is much more planted and confidence inspiring allowing you to cover ground faster with more confidence – which is exactly what this sled was designed to do.
What about the added Weight?
The SB is just 7” longer and 12 pounds heavier than its 121” brother. That added size is only felt when you must dig yourself out or when riding a tight and twisty trail in the north woods. Honestly I never felt that the longer track and extra weight compromised or fatigued me on a 200-mile day of riding. Riders everywhere are migrating to longer track x-over sleds for a better ride and in some cases, more top speed for the reasons mentioned.
Liberty 800 HO is Awesome Power
Introduced back in 2015, the 800 HO Cleanfire was designed specifically for the AXYS chassis. Polaris engineers optimized the air flow intake and exhaust for increased power output. This motor (at 150+ HP) has excellent throttle response from idle to WOT. I ran Polaris VES oil the past two years with these motors and never experienced excessive smoking at idle or hesitation due to exhaust valve sticking. The move to the electronic oil pump was a huge change allowing engineering the ability to program the amount of oil delivered at any given engine rpm. They days of having to carry a quart of oil on a 200-mile ride just in case are long gone. The 2018 800 HO did receive some updates from 2017. The thermostat is now set to open at 110F vs 125F and was increased in size to increase coolant flow 12 percent. The crankcase received upgrades for improved lubrication and durability. Polaris Engineering is now focusing on minor durability improvements for future applications. This engine today is now well established as a reliable power plant. The evolution of the Liberty Engine continues to evolve.
Handlebars to Skis: Telepathic Connection
As good as the PRO-XC suspension is, the heart of the AXYS chassis is the bonded aluminum front bulkhead that houses the 800 HO and locates the unequal length A-Arms. The secret to telepathic handling from the bars to the snow is the rigid front end with zero flex and the correct suspension geometry.
When I threw my leg over this sled for the first time, I was expecting the longer track to push the machine through the corners (under steer). Yes, there is more inside ski lift with the longer track depending on how tight the corner is. The turning radius is longer, so depending on the corner I found the sled not as nimble as the short track XCR. On long sweeping corners, the sled felt the same as the 121” XCR transferring the weight to the skis when you slide up onto the tank and lean into a corner. Unlike the Switchback with the IGX144 rear suspension and its tipped rails, the full contact patch is on the snow with the SB XCR. This requires a little more body English to get this sled to carve. Unlike other less rigid chassis sleds, the inside ski does not lift unexpectedly. You can feel and see it happening in a controlled fashion and you can adjust with more throttle or a tap of the brake. The handlebar post angle and flat bars do not interfere with your knees or bodywork turning in either direction.
One fact you may not realize is that the XCR models are equipped with a smaller diameter sway bar than the PRO-S version. This does keep the front end more lively in the bumps but does compromise the flat cornering capability. Did I miss it? Not a chance. This sled, in off camber bumps or through a washed-out rail line trail, just eats the bumps with little motion transferred to the skis. I don’t know how Polaris can make the front end any better other than maybe adding taller spindles for increased ground clearance.
Summing it all Up
Since the first RUSH hit the snow back in 2010, I have ridden every iteration (both Pro-Ride and AXYS platforms) of the RUSH, Switchback and now the XCR. This 2018 Switchback XCR is hands down the best version of this chassis. Ideas to improve the sled would be to add taller spindles for more front clearance and simplify the shock damping. I am not convinced a hard-core ditch banging rider needs a 10-position hi/lo speed compression damping shocks, but please let me know if you think I am mistaken. The positives of this sled FAR outweigh the negatives. Engine, clutching, suspension, reliability is all top notch. The storage limitations, right foot restrictions from the chain case location and cold weather protection are all areas still in need of improvement, or compromise.
Better, Faster, Stronger, Bigger? You Bet! Would I buy one? Hell, Yes!
By Hal Armstrong – SnowTech Canada
Photos by Phil Moto