Most snowmobile suspensions will be set up correctly out of the box (for the typical riding style expected of each model type) only requiring a simple adjustment to the rear spring(s) for the correct amount of rear sag.
If the factory settings need to be adjusted, it is important to remember that when you make a change to the front it will affect the rear of the sled, and vice versa. Only small incremental changes are to be made, always keeping the balance of the sled in mind. Remember, it is also possible to create a new problem when trying to fix another problem.
The initial set-up procedure should be to adjust the rear sag of the sled, specific to the rider’s weight with gear. A good rule of thumb is to add 15-20 pounds for gear. This is the single most important initial adjustment you can make, matching the sled to the rider weight.
Once you have established the proper ride sag (refer to sled’s owner’s manual for proper sag for each sled) take note of the snow/trail conditions, as snow conditions greatly affect handling and ride behavior. As an example, a sled will push through the corners more in loose snow, and adjustments made to compensate for this can easily make the sled steer hard when you encounter firm snow.
When riding the sled, pay attention to three areas of evaluation & concern;
1. Front skis, as felt through the handlebars & hands.
2. Center shock/front arm, as felt through the feet and running boards.
3. Rear shock/rear arm, as felt through the seat and your back.
Noticing how the sled is acting in these three areas will guide you to the proper adjustments for each.
Adjusting coupler blocks is also an option on many sleds, and one must understand how coupler blocks affect the suspension action. Blocks behind the rear arm (or those that limit rearward movement of the pivot) affect weight transfer, also referred to as rear-to-front coupling. Blocks in front of the rear arm (or those that limit frontward movement) reduce pitching, known as front-to-rear coupling. Both affect ride quality, in different ways. When the rear arm hits a block, its movement is stopped and the resulting action is to then also compress the front arm. When this happens, you are combining the spring and shock action of both front and rear suspension arms. This causes the suspension to become firmer, and it also causes the sled to compress both arms simultaneously, sort of squatting the sled level instead of allowing it to pitch, or rock.
For example, you want to limit how far the sled lifts the skis off the ground when you crack the throttle. You adjust the coupler blocks so the rear arm does not move as far back to hit the block. This indeed will reduce the ski lift, but also combines the spring and shock action of both arms earlier, resulting in a firmer suspension – once coupled.
Another example would be to improve the ride quality in choppy stutter bumps. An uncoupled rear arm is desirable in this condition, so you open up the gap between the rear arm and the coupler block so the rear arm has to move further back to hit the block. This will improve the ride comfort, but will also increase the amount of ski lift.
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