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Discussion Starter #1
I've been reading through different posts about making suspension adjustments and I have a basic understanding, but would like to learn more. I know/understand that a guy can play with the limiter straps, rear scissor blocks, and front track shock to get more or less weight transfer. What I would like to know is in what order should I start making adjustments? Are there symptoms that's would indicate I need to do one or the other? Let's say I have no ski pressure, do I loosen front track shock? Tighten straps? Turn the block? Or a little of all? Any help would be great, would love to learn more about it. Thnx

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I'll copy and paste a series of suspension tuning tips I've collected from various places over the years. It's mostly Polaris-specific when referring to Front-Rear Scissor Stops and Rear-Rear Scissor Stops.
I'll break it up so each article is its own post. Italicized sentences are key points.

This should be more than enough info to tune your suspension to your liking. I had my old XC500 dialed in for my weight and riding style, and man did it rip!

Front Suspension Setup and Adjustments
Spring preload is one of the adjustment options which affects ride. Preload is the amount of pressure at which the spring is held. The longer the installed length of the spring, the less the amount of pre-load. The shorter the installed length of the spring, the more the amount of pre-load. An increase in IFS shock spring pre-load will result in an increase in ski pressure.

Increasing the spring preload too much may adversely affect the handling of the snowmobile and the performance of the rear suspension.

To determine if your machine is using full travel, push the shock Jounce bumper down as far as it will go on the shock rod and test ride the machine.

The preferred method for changing ski pressure under steady throttle conditions is to increase or decrease IFS spring preload.

To determine if your machine is using full travel, push the shock
jouncebumper down as far as it will go on the shock rod and test
ride the machine.(See Illistration 3)
The correct spring rate will allow full travel of the shock with occasional
LIGHT bottoming.

If full travel is not being used you can:
- Decrease clicker position (if applicable)
- Install a lighter spring rate
- Revalve shock (if applicable)
If hard bottoming occurs:
- Increase clicker position (if applicable)
- Install a heavier spring rate
- Revalve shock (if applicable)

Weight Transfer
Energy used to lift the front of the machine is not available to push the vehicle forward.

Lengthening the limiter strap allows the front of the suspension to extend further; increasing the angle of the torque arm and decreasing ski pressure during acceleration. Limiter strap adjustment has a great affect on weight transfer. Limiter straps only affect ski pressure during acceleration.

Front track shock spring preload also affects weight transfer. A stiffer spring and/or more preload on the spring transfers more weight to the track. A softer spring and/or less preload keeps more weight on the skis. Keep your riding application in mind when choosing springs and setting spring preload. Soft springs/preload will increase ski pressure, but may bottom out. Stiff springs/preload will provide more track pressure (reduced ski pressure), but may result in a less comfortable ride.

During acceleration, the rear of the suspension will compress and the IFS will extend, pivoting the machine about the front torque arm. Because of this pivoting effect, rear spring and spring preload also have some effect on weight transfer. Softer rear springs, or less preload, allow more weight transfer to the track and reduce ski pressure.

Stiffer rear springs, or increased preload, allow less weight transfer to the track and increase ski pressure.

Moving the RRSS to a higher position or forward hole will have the following effects on the suspension:
-Reduced weight transfer
-Improved chatter bump ride
-Improved cornering performance

The FRSS only controls ski pressure under steady throttle positions or deceleration. The RRSS controls ski pressure under acceleration.

Moving the FRSS to a lower position or the forward hole increases ski pressure.

To increase the stiffness of the rear suspension, the RRSS should be set in high position, but weight transfer will be reduced under acceleration.
Moving the rear torque arm mount rearward will stiffen the suspension and decrease weight transfer.

2,726 Posts
Most suspension adjustments are geared toward setting ride height. Shock clicker adjustments are geared toward changes in trail conditions or personal feel. Setting a sled’s ride height will establish a baseline and allow you to effectively make further adjustments — shock calibrations, weight transfer — if necessary.

Correct Adjustments Bring About Balance
A rigid chassis links a snowmobile’s front and rear suspensions. Adjustments made to the front suspension will transfer energy to affect the rear suspension. Lowering the front suspension will unload the rear suspension causing it to top out. Raising the front suspension will cause a low rear ride height, simulating the need for more torsion spring preload.

Test this by pushing down on the front bumper. Notice the rear suspension tops out. Now lift up on the front bumper, notice the rear suspension sag and the weight of the front becomes increasingly heavier at the point where the rear suspension becomes coupled. This exercise displays that spring rates and preload have an effective relationship between the front and rear ride height.

Snowmobiles set up with a good ride height baseline will tend to have fewer ill-handling characteristics. Taking the time to set the ride height will give you a good starting point and eliminate the majority of those symptoms before you ever get your sled on the trail.
The following technique is a basic principle to properly set ride height on most snowmobiles built since the mid 1990s. Suspensions vary by manufacturer so you might need to refer to your owner’s manual for specific information, but the components in skidframes are generally the same, so the principles apply across the board.
Problems with handling can be caused by worn, bent or loose parts. Maintenance is important, too. Before you get started, take some time to give the front and rear suspension a good inspection, and grease it.

Step 1: Set Spring Preload
Preload is the difference from the spring’s free length compared to its installed length. With the sled raised off the ground, check the ski and center shock coil spring. Set the preload with 5 to 10mm of compression. This will be slightly enough pressure to keep the spring retainers on the shocks when they are fully extended.

Step 2: Check Limiter Strap
Set the snowmobile on a smooth, hard and level surface without dolly wheels or other devices under the skis or track, and make sure the front torque arm limiter strap is free of tension, otherwise it will cause uneven weight distribution between the front and rear suspension. Set the coupling system adjuster device in an uncoupled position. These systems vary, so check your owner’s manual to find your sled’s neutral setting.
Step 3: Verify Even Weight Distribution
Step back and look at the skidframe rails to make sure they are resting flat on the floor. This ensures that weight is distributed evenly from front to back within the suspension. If the front of the rail is off the ground, the limiter strap probably needs to be let out. If the rear axle is off the ground, the ski shocks’ preload might be too soft, allowing the front end to sag. Check the torsion springs’ preload setting to make sure there is adjustability if required in Step 6.

Step 4: Check Front Free Sag
Free sag is the amount the suspension is compressed by the weight of the free-standing snowmobile without a rider on board. This should be about 20 percent of the sled’s total travel. For example, if the front suspension has 10 inches of suspension travel, free sag should be 2 inches. My shop doesn’t use a specific measurement for free sag other than some additional compression is good. The reason for this is because a measurement setting will vary based on the chassis design, such as rider-forward versus a chassis that has more load distributed against the rear suspension. To check your sled, lift the front bumper until the skis come off the ground. Then set it down and give it a good bounce. Measure off of the front bumper, and adjust the spring preload as needed.
Step 5: Set Rear Free Sag
Lift the rear end off the ground and gently set it down; make sure the rear suspension will compress, or “settle in” a little bit under its own weight. As with the front suspension, my shop doesn’t have a specific measurement for this due to the fact that friction in the rear suspension between the slide rails and track will prevent an accurate and consistent measurement. Friction plays a major role when setting the ride height and it’s why your suspension doesn’t feel responsive when pushing on the bumper. We’ve found that gauging through the coupling system provides more consistency when trying to set ride height. Also, make sure the sled doesn’t rapidly slam to full extension when you lift the bumper. This is called “top out.”

Step 6: Set Rear Loaded Sag
Also known as race sag, loaded sag is the amount of suspension displaced by the load applied to the vehicle; for example, the weight of the rider plus gear, luggage, etc. Apply the rider in riding position with gear and any additional load being carried. What you are looking for here is to make sure that the coupler device is centered within its forward and rear stops; adjust the torsion springs to achieve this position. This is the position between full top out and the transition point where the suspension becomes stiff when you’re pushing on the bumper. Setting the couplers in this position provides the ideal location for the rear suspension to feel balanced with the front. Loaded sag for the front suspension is virtually negligible.


Suspension Troubleshooting Tips
A sled’s unbalanced ride height setting can be the source of many problems. Note that the similarities of the problems described below are in many ways all linked to the ride height setting.

Problem: Body rolls or dives in corners
Possible solution: Try adding preload to the front springs. If your snowmobile comes with a progressive wound coil spring, there might not be enough initial rate available without affecting ride quality at the mid and bottom of the stroke. Installing a single-rate spring or a more-effective dual-rate setup with adjustable ride height and rate is an effective solution.

Problem: Sled tips up in corners, lifting the inside ski
Possible solution: Lower the front ride height to reduce the vehicle’s roll center. A sled with a lower center of gravity will typically outperform a vehicle that sits up high. Most roll or ski tip situations are generally related to excessive spring preload that was added to increase bottoming resistance.

Problem: Heavy steering
Possible solution: Heavy steering can be tricky to solve, and we often see adjustments in the rear suspension affecting the cause. If you are experiencing this on a sled with stock skis and carbides, check the rear torsion spring setting, center shock spring preload, and possibly reduce the amount of coupling action. Make sure center shock spring preload is 5 to 10 mm. Typically, more preload to the center spring causes track spin, rear kick-up and a harsh ride. Remember, when you create load in the rear, the load is transferred to the front. In some cases more torsion spring preload will reduce load to the skis by holding the rider higher in the travel and away from the coupler stops.

Problem: Inside ski lifts when trying to accelerate out of a corner
Possible solution: Make sure that your ride height is set correctly and you have good front to rear balance. In many cases we have found that increasing the rate of coupling, which reduces weight transfer, will transmit more load to the skis.

Problem: Rear end raises up easily and then drops with little effort
Possible solution: One of the most common causes of excessive rear sag is a geometry-related issue such as the front torque arm limit strap is pulled in or the vehicle isn’t resting on a flat surface. One of the most common misunderstandings is the shock has failed, causing excessive sag. The reality is that a shock with a fresh charge may help a little bit, but it’s insignificant. Instead, check ride-height settings.
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