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Have you ever come home from the dealership with your brand new sled and been totally confused by the salesman on how best to adjust your suspension?
It's a more common occurrence these days because riders can make more adjustments to their stock suspensions than ever before. Compression, rebound, transfer, bottoming and more can be adjusted quickly on the trail.
AmSnow recently talked with the main suspension engineers at each of the Big 4 about what they see as the biggest areas of concern for customers when it comes to dialing in stock suspensions. Here are some quick hints from the engineers and our staff.
Yamaha Dual Shock Pro1. You'll probably need two people to do this, but first you should check and set the rear suspension ride height by measuring the gap at the coupler block. The distance should be 16-22mm with a rider on the sled.
2. Once you've measured, you can use the 3-position preload adjuster to adjust the gap. The tri-cam torsion spring preload adjuster just below the upper idler wheels can be adjusted using the tools found in your Yamaha tool bag. The bag comes with each machine. High, medium and low stiffness on the preload will increase or decrease the gap. Correct ride height for each rider is critical to get the best suspension performance.
3. With ride height correct, ride the sled for a tank or two. This allows the springs to take a set, and allows the rider to get familiar with what the stock settings feel like. This will give you a baseline so you can feel the effects of further adjustments.
4. On the front and rear shock you can adjust compression damping to control bottoming. If you turn the compression damping so that it is maxed out and you are still bottoming, you may need a stiffer spring. However, you can adjust the center shock spring preload as well. This is done by turning the collar up or down through the threaded adjustment range. If your ride is stiff and almost never bottoms, then you should probably reduce compression damping because the suspension should bottom occasionally.
5. Next, you should adjust the rebound damping to control pitching and also ride comfort over multiple bumps. Rebound controls the speed that the suspension spring returns to its full length after being compressed. Too little rebound allows the suspension to bounce back too quickly to full-extension. You want to avoid the sled's rear kicking up over bumps, which gives you a harsh "bucking-bronco" type ride. Too much rebound damping slows the rebound and the rear suspension will "pack down" and get stiffer as you hit multiple moguls.
6. Finally, the Dual Shock Pro suspension has a 5-hole adjustable limiter strap up front. If you shorten the strap, you'll increase ski pressure and decrease transfer resulting in more aggressive steering response on hard snow, but you may also see a bigger tendency for the sled to dart. If you shorten the strap significantly, spring preload on the center shock should most likely be decreased. Lengthening the limiter strap will decrease ski pressure and increase transfer. This is good for deep snow riding or track-grip on an icy surface, but you give up steering responsiveness. Note that the limiter strap isn't really a "trailside" fix, but something that can be done relatively easily in your garage.
Ski-Doo SC-51. Possibly the easiest adjustment you can make on your SC-5 is with the ACM (Acceleration and Control Modulator). Coupling adjustments with the ACM help control weight transfer on quick starts and hard corner exits. Starting with ACM position No. 1, you'll get more transfer, more ski lift and better traction. As you move through to ACM position No. 4, you'll get less transfer, more aggressive ski-bite, less track-grip, better cornering and possibly more darting.
2. The second adjustment you can make to the SC-5 suspension is changing the front arm spring rate and preload. Like other sleds, preload equates to big differences in comfort. Changes can be felt through the feet and seat of the pants in rider-centered sled designs such as the REV-XP. With the SC-5, the more rate or preload on the front arm spring means less ski pressure, better bottoming resistance, increased harshness, increased tail fishing and less suspension sag. Less rate or preload will tighten up the steering, making it more aggressive. You will most likely bottom out more, but stay straighter down the trail.
3. The third big adjustment is the rear arm spring rate and preload. Your rear torsion spring controls suspension sag, and this spring rate determines most of the comfort felt through the seat of the pants. Again, the more rate or preload, the better bottoming resistance you'll experience, but there will be an increase in harshness and less suspension sag.
4. On the MXZ "X" models, there is a C-36 racing clicker shock on the rear arm. This shock has both high- and low-speed adjustments. The high-speed adjuster - the red 17mm knob - can be turned several times by hand for a good range of adjustment. This knob adjuster controls the anti-bottoming damping force during severe bump hits. The low-speed adjuster can be changed using a flat-head screwdriver and has more than 20 positions. Weight transfer and tail or "G-bump" hits are controlled by the low-speed damper. All the tools you'll need come in Ski-Doo's standard tool bag.
5. The last bit of adjustment comes with the limiter strap. As stated earlier, the shorter the limiter strap is, the more ski pressure and aggressive ski bite you'll have. There'll be less transfer, and possibly a harsher ride on the front arm. Also, if spring preload is not readjusted, there will be more bottoming. The longer the limiter strap is, the less ski pressure there will be, and there'll be more weight transfer and better traction.
Arctic Cat F-series
Slide-Action Rear Suspension1. Like the Yamaha and Ski-Doo, the recommended first step with the Slide-Action Rear Suspension is to adjust the coupling blocks, which will add or remove transfer.
2. Next, the Cat has adjustable torsion spring blocks. You have your choice of soft to hard settings. Simply add/subtract more/less preload to the torsion springs for heavier/lighter riders or conditions. The stiffer you set the torsion spring, the less transfer you'll have, and you'll experience more aggressive ski-bite and less bottoming.
3. On Cat's Slide-Action suspension, front arm spring preload adjustments are key. Since this is a sliding front arm, the suspension's ability to soak up bumps without that "kick" is incredible. It's almost like terrain-following radar! You can add or remove spring preload. As we said before, more preload on the front arm spring means less ski pressure, better bottoming resistance and increased harshness. You will get a plusher ride in the stutter bumps too. Less preload will give more ski pressure, making steering more aggressive.
4. The last step is again working with the adjustable limiter strap on the Cat suspension. Ski lift will be greatest at full limiter strap length and can be nullified by cinching up the strap.
5. Shock adjustments should be left to qualified shock professionals, as they are not trail-adjustable. Performance can only be modified by disassembling the shocks and revalving/shimming/etc.
Polaris IQ Dragon
Rear Suspension1. Like many suspensions today, torsion spring adjustments on the IQ are the easiest performance changing adjustments you can make. Low, medium and high designations are options on the torsion spring block. The sparkplug wrench in the Polaris tool bag is the same hex-size to turn the block. Sometimes this block will ice up, and if you have difficulties turning it, you can pull the front of the spring off the roller and then rotate the block easily. You should measure suspension sag from the ground to the bumper with the rider sitting on the sled. Look for 2-3 inches of sag. A common mistake is setting the spring too stiff. Polaris suspension reps suggest going as soft as you can without bottoming. You're trying to use the whole suspension stroke.
2. Another easy change is rear clicker compression. Riders have a wide range of adjustments and we suggest you change compression here small bits at a time. Try going just 2 clicks at a time either way. These shocks come from the factory set for a 200 lb. (fully dressed) rider, which is the 4th position (there are 16 in all) from all the way soft. You shouldn't try compression adjustments until your springs take a set. Rear shock adjustments give you bottoming resistance and big G-bump compliance.
3. The next step is adjusting the coupling blocks on the skid's rear. The block is a rectangle, but there's only three positions as two are the same width. The tighter the block is coupled, the more transfer and ski lift is reduced. It's not ideal for riding in chattery stutter bumps, but it keeps more pressure on the skis for more precise turning. There's actually a second hole in the rail that you can move this block to if you want, but Polaris doesn't recommend it.
4. While this is a rear suspension story, Polaris reps are adamant that you move to the IFS system up front next and work on spring preload. You should turn up the preload on the IFS if you're bottoming consistently. If you take the pressure off the skis (turn the sled on its side) you can turn the collar by hand. Turning up the preload means less transfer and more responsive steering, but an increase in steering effort. Reduce it, and the sled will roll around the track more, and be less planted. The IQ's A-arm front suspension geometry makes this more pronounced. On all springs you should start by marking the installed length and go from there. With the clicker shock, you should keep track of where you started by writing it down, counting, making a hash mark, etc.
5. One of the last adjustments is front track spring preload. Again, it's threaded and you shouldn't need a tool to turn it as long as you get the bumper off the ground and ice and snow is cleared out.
6. A final adjustment can be made with the limiter straps, but again, this often is used only by deep-snow guys for big transfer and flotation atop the snow. There is a combination of 4 different positions with 2-holes on each side.