Setting up your rear skid.
If you are looking for settings to start with, stop reading. Settings from some one else’s sled are just that, some one else’s settings and not yours. Straps stretch, arms bend, springs sag and bushing wear causing adjustments to change from sled to sled. Sleds and their riders are like snowflakes, no two are alike.
First read the rear skid article I wrote on how to tighten up your suspension and the front end alignment article. The links are below my posts.
Please keep in mind I am writing this for everyone, even those who know very little about the suspensions. Also, this is a rough draft and please ask any questions on anything I might have missed. I will add it as I go. Sorry to all you spelling bee winners and school teachers for the grammar and sentence structure.
I will describe a few terms used when talking about suspensions.
Transfer: The moving of the sleds weight toward the rear of the sled.
Pitch: This is the movement of the sled forward or back.
On plane: This is the imaginary flat reference point used to describe an untwisted sled or suspension.
Upper and lower gap: This refers to the gap above and below on the transfer rods on each side of the rear of the sled.
FRA: This is the arm that the front of the rear shock is bolted to. This adjusts the speed and distance the shock and spring travel when the suspension is compressed.
Ride height: The height the sled sits with all the weight it will be used with on the sled when measured.
Spacers: The plastic washers that adjust the gaps on the transfer rods(some sleds have adjustable rods)
Limiter straps: There are two of them, they attach to the W arm and limit it from dropping down.
W arm: The front arm of the rear suspension that is attached to the front track shock and to the rails. This arm does many things. 1. Holds the skid on plane with the frame of the sled. 2. Is the bump stop for the rail to hit against when compressed. 3. Is the bump stop for the FRA shaft to hit against when bottoming. 4. Holds the limiter straps at an exact distance. 5. Holds front shock. 6. Takes weak part, under a lot of load.
The first thing that is necessary to adjust the rear of the sled is to start at the front. The rear of the sled is adjusted to the front of the sled. You will need to guess at what you like your front shocks to be set at. Short travel sleds require preload on the springs, go with the standard setting to start with if you don’t know what you like. On most all long travel sleds you will want the front springs set to no or little preload. This gets the sled as low as it can be, making it handle better and a lot of preload usually means hard on the arms, and back on long rides. For sleds with multi-rate springs, I recommend a venture sway bar. If your sled has sway bar links that have open spots in them, I recommend you change to srx/viper links.
First thing we need to do is to take care of a bad idea, the front track spring in the xt/xtc/venture sleds. Throw it away. Install a stiffer rate spring. One from the front of an srx or sx sled works good. The inside will need to be ground out on the spring so it will fit over the washer of the shock. You will see what I mean when you do this mod. Night and day difference.
You will need to decide what your FRA will be set at. The upper position makes the valving and the spring rate seem softer as it moves slower and not as far for the same suspension travel. The lower does the opposite, making the shock and spring seem stiffer. a lot of it depends on shock valving and each sled is different. In general terms, if your heavy, go for the lower setting that will make it stiffer. If you don’t weigh much, move it to the upper setting so it will be softer.(sounds backward I know) If you use the sled for two up riding some times, set it to the soft setting, upper, then when you ride double, you can just move it to the stiffer setting, this will give you stiffer valving and stiffer spring for the extra rider. If your not sure, guess, that’s what everyone else has been doing when they tell you how to set your skid up for you.
Total transfer rod gap is another thing that is a preference. A good starting point is for short travel sleds, 8-12mm, on long travel sleds, 14-18mm. On long travel sleds this is with a thin spacer on the lower side, 2-4mm. On short travel sleds this is with a thick spacer, 10-15mm.
Now that we have the front height, total gap, and the FRA set, we can move to the part that does all the work. The rear shock and spring. Let your limiters out all the way for now. Set the front track shock preload to 0.
You set your gap with you and all your gear on the sled on a flat surface. Stand up, rock the sled around and then sit down slowly. You are setting the sled to its neutral position. Then lay over the side of it and look at your upper and lower gap on your transfer rods. For the best handling you should have 50/50 spacing.
Do not adjust you height with the FRA, this is for adjusting the speed of the shock/spring through its travel. Using this to adjust height is a band aid. Aluminum bodied shocks in the rear are easier to adjust if you remove them from the suspension. Sounds crappy I know.
*if when you set on the sled the front end of the sled lifts and the gap ends up even (50/50)then the center spring is too stiff, doubtful if it was set to 0 preload. But if it does, try setting the front ski shock preload higher. Then start over.
*if when you set on the sled the front end does not move up and the gap is too large on the top the spring in the rear is too tight. Lessen the preload on it. Then start over.
*if when you set on the sled the front end does not move up and the gap is too large on the bottom the spring is too loose. Increase the preload on the rear shock. Then start over.
The optimal setting is to be able to have the most front track pressure, sit on the sled and not have the front end lift while still having 3-4in of set in and keep the gaps even. Easy enough.
On a side note. I hear a lot of people talking about bottoming their sled and using this to judge if it is set stiff enough. If during the day of riding you have your sled set so it never does then your riding a stiff sled for no reason 99% of the time. If you bottom several or more times in a day increase FRA rate to the next stiffer setting. If it is already there, you either need to re-valve your good shock stiffer, or just have your wore out shock rebuilt.
The tighter the gaps on the top and bottom the flatter your sled will handle during acceleration and de-acceleration.
Your top gap is the amount of transfer or downward travel the rear of the skid can make without taking the front along with it.
Riding with a larger top gap gives a better ride until your driving under power. When under power your sled is closing this gap(dropping the rear of the sled). When you do hit a bump under power you are now hitting it in the lower part of your sleds travel which on a yamaha is rising rate and is a lot stiffer and you are that much closer to bottoming. Another issue with riding with a larger gap is that the front end comes up. yamahas front pro action is really a crappy design that polaris and chaperal threw away along time ago. If you lift the front of your sled, the skis will toe in , as you drop the sled and push down they will toe out, if you run your sled loose then when your on the gas your sled is now toed in, when you let of on the gas to go into a corner now the sled pitches forward and the front end toes out. (this does not apply to the four stroke sleds)
There is a myth about running larger gaps and weight transfer. “Weight transfer=acceleration.” Any time the sled comes off the ground you are wasting acceleration, a sled that has the skis 1mm off the ground has no more traction than a sled with the skis 12in off the ground and in some cases has less as the front of the track starts to lift. just watch any race and you will see that those guys that have the fast sleds almost always have the sleds that just barely lighten the skis all the way down the track. If you run adjustable rods and backed them way off then felt that your sled was hooking up better it was probably just that, felt like it. That little extra feeling of acceleration upward makes you feel like the sled has more power and or traction. It is an illusion. The object is to move the sled forward. Energy used to move the sled in any other direction is wasted. The chicks dig it though.
If your out for the great ride and do not get on the gas hard or go into corners hard then you can set the sled up with loose gaps. The ride will be a little softer. If you want it to handle great in a corner or on the brakes, the tighter the gaps you will need. A stiffer sled this will make.
If you are looking for settings to start with, stop reading. Settings from some one else’s sled are just that, some one else’s settings and not yours. Straps stretch, arms bend, springs sag and bushing wear causing adjustments to change from sled to sled. Sleds and their riders are like snowflakes, no two are alike.
First read the rear skid article I wrote on how to tighten up your suspension and the front end alignment article. The links are below my posts.
Please keep in mind I am writing this for everyone, even those who know very little about the suspensions. Also, this is a rough draft and please ask any questions on anything I might have missed. I will add it as I go. Sorry to all you spelling bee winners and school teachers for the grammar and sentence structure.
I will describe a few terms used when talking about suspensions.
Transfer: The moving of the sleds weight toward the rear of the sled.
Pitch: This is the movement of the sled forward or back.
On plane: This is the imaginary flat reference point used to describe an untwisted sled or suspension.
Upper and lower gap: This refers to the gap above and below on the transfer rods on each side of the rear of the sled.
FRA: This is the arm that the front of the rear shock is bolted to. This adjusts the speed and distance the shock and spring travel when the suspension is compressed.
Ride height: The height the sled sits with all the weight it will be used with on the sled when measured.
Spacers: The plastic washers that adjust the gaps on the transfer rods(some sleds have adjustable rods)
Limiter straps: There are two of them, they attach to the W arm and limit it from dropping down.
W arm: The front arm of the rear suspension that is attached to the front track shock and to the rails. This arm does many things. 1. Holds the skid on plane with the frame of the sled. 2. Is the bump stop for the rail to hit against when compressed. 3. Is the bump stop for the FRA shaft to hit against when bottoming. 4. Holds the limiter straps at an exact distance. 5. Holds front shock. 6. Takes weak part, under a lot of load.
The first thing that is necessary to adjust the rear of the sled is to start at the front. The rear of the sled is adjusted to the front of the sled. You will need to guess at what you like your front shocks to be set at. Short travel sleds require preload on the springs, go with the standard setting to start with if you don’t know what you like. On most all long travel sleds you will want the front springs set to no or little preload. This gets the sled as low as it can be, making it handle better and a lot of preload usually means hard on the arms, and back on long rides. For sleds with multi-rate springs, I recommend a venture sway bar. If your sled has sway bar links that have open spots in them, I recommend you change to srx/viper links.
First thing we need to do is to take care of a bad idea, the front track spring in the xt/xtc/venture sleds. Throw it away. Install a stiffer rate spring. One from the front of an srx or sx sled works good. The inside will need to be ground out on the spring so it will fit over the washer of the shock. You will see what I mean when you do this mod. Night and day difference.
You will need to decide what your FRA will be set at. The upper position makes the valving and the spring rate seem softer as it moves slower and not as far for the same suspension travel. The lower does the opposite, making the shock and spring seem stiffer. a lot of it depends on shock valving and each sled is different. In general terms, if your heavy, go for the lower setting that will make it stiffer. If you don’t weigh much, move it to the upper setting so it will be softer.(sounds backward I know) If you use the sled for two up riding some times, set it to the soft setting, upper, then when you ride double, you can just move it to the stiffer setting, this will give you stiffer valving and stiffer spring for the extra rider. If your not sure, guess, that’s what everyone else has been doing when they tell you how to set your skid up for you.
Total transfer rod gap is another thing that is a preference. A good starting point is for short travel sleds, 8-12mm, on long travel sleds, 14-18mm. On long travel sleds this is with a thin spacer on the lower side, 2-4mm. On short travel sleds this is with a thick spacer, 10-15mm.
Now that we have the front height, total gap, and the FRA set, we can move to the part that does all the work. The rear shock and spring. Let your limiters out all the way for now. Set the front track shock preload to 0.
You set your gap with you and all your gear on the sled on a flat surface. Stand up, rock the sled around and then sit down slowly. You are setting the sled to its neutral position. Then lay over the side of it and look at your upper and lower gap on your transfer rods. For the best handling you should have 50/50 spacing.
Do not adjust you height with the FRA, this is for adjusting the speed of the shock/spring through its travel. Using this to adjust height is a band aid. Aluminum bodied shocks in the rear are easier to adjust if you remove them from the suspension. Sounds crappy I know.
*if when you set on the sled the front end of the sled lifts and the gap ends up even (50/50)then the center spring is too stiff, doubtful if it was set to 0 preload. But if it does, try setting the front ski shock preload higher. Then start over.
*if when you set on the sled the front end does not move up and the gap is too large on the top the spring in the rear is too tight. Lessen the preload on it. Then start over.
*if when you set on the sled the front end does not move up and the gap is too large on the bottom the spring is too loose. Increase the preload on the rear shock. Then start over.
The optimal setting is to be able to have the most front track pressure, sit on the sled and not have the front end lift while still having 3-4in of set in and keep the gaps even. Easy enough.
On a side note. I hear a lot of people talking about bottoming their sled and using this to judge if it is set stiff enough. If during the day of riding you have your sled set so it never does then your riding a stiff sled for no reason 99% of the time. If you bottom several or more times in a day increase FRA rate to the next stiffer setting. If it is already there, you either need to re-valve your good shock stiffer, or just have your wore out shock rebuilt.
The tighter the gaps on the top and bottom the flatter your sled will handle during acceleration and de-acceleration.
Your top gap is the amount of transfer or downward travel the rear of the skid can make without taking the front along with it.
Riding with a larger top gap gives a better ride until your driving under power. When under power your sled is closing this gap(dropping the rear of the sled). When you do hit a bump under power you are now hitting it in the lower part of your sleds travel which on a yamaha is rising rate and is a lot stiffer and you are that much closer to bottoming. Another issue with riding with a larger gap is that the front end comes up. yamahas front pro action is really a crappy design that polaris and chaperal threw away along time ago. If you lift the front of your sled, the skis will toe in , as you drop the sled and push down they will toe out, if you run your sled loose then when your on the gas your sled is now toed in, when you let of on the gas to go into a corner now the sled pitches forward and the front end toes out. (this does not apply to the four stroke sleds)
There is a myth about running larger gaps and weight transfer. “Weight transfer=acceleration.” Any time the sled comes off the ground you are wasting acceleration, a sled that has the skis 1mm off the ground has no more traction than a sled with the skis 12in off the ground and in some cases has less as the front of the track starts to lift. just watch any race and you will see that those guys that have the fast sleds almost always have the sleds that just barely lighten the skis all the way down the track. If you run adjustable rods and backed them way off then felt that your sled was hooking up better it was probably just that, felt like it. That little extra feeling of acceleration upward makes you feel like the sled has more power and or traction. It is an illusion. The object is to move the sled forward. Energy used to move the sled in any other direction is wasted. The chicks dig it though.
If your out for the great ride and do not get on the gas hard or go into corners hard then you can set the sled up with loose gaps. The ride will be a little softer. If you want it to handle great in a corner or on the brakes, the tighter the gaps you will need. A stiffer sled this will make.
