StewartsDragon
Active member
OK so for over a million years, everyone has argued whether or not "looser" tracks gain or rob horsepower from a sled. Yes we all understand there's a line of to loose and to tight, however; I was reading Avid-Products site and wanted to see what all you experienced riders think upon these subjects. I have a Pro and am looking to swap out the 155 for a 163 2.5, I don't want to do a 3" because I have heard of issues of running them without not enough snow and overheating them, like in Edmonton.
SO here's Avid's write up, all I want is your opinions upon these statements.
[h=4]Stay loose[/h] Tightening the track stops the ratcheting, but a tight track doesn’t roll as easily as a loose track. You can check this out on your own sled at home. Put it on a stand and take off the belt so that you can rotate the track. Use a fisherman’s scale to pull the track and see how much force it takes to make it move. Now loosen the track so that you can get your finger between the inside drive lugs of the track and the hyfax. Measure this force. You should notice quite a reduction. Our tests indicate that a sled with , an eight-inch kit, and a set of anti-ratchet drivers () pulls at ten to twelve pounds. Any drag over and above ten to twelve pounds is like having your brake on all the time. You are likely using three to five horsepower just to overcome that extra drag at forty to fifty miles per hour. It’s only logical that lower resistance in the drive system translates into greater available horsepower and speed. Anti-ratchet drivers and help to lower that resistance, delivering increased performance without affecting the reliability of your engine.
[h=4]Lighten up[/h] If you are replacing your track, you will increase your performance by buying a track with a 3” pitch. A track with a 3” pitch will weigh less than a 2.52” pitch track of equal length. An old rule of thumb is that every pound of rotating mass you remove is equal to reducing your sled’s gross weight by 7 pounds. Putting a 5-6 pound lighter track on your sled will increase track speed.
When you are selecting what size of , you should consider several things. An eight-tooth 3” driver is approximately a half-inch bigger than the nine-tooth 2.52” driver you probably have in your sled stock. A seven-tooth 3” driver is a half-inch smaller. A bigger driver might seem the logical choice, but not necessarily. Tracks act like conveyor belts, carrying snow and air to the front of the tunnel. If there isn’t anywhere for this air and snow to go, it piles up in the front and slows the track down. Unless you have a lot of room up front, it will be better for you to use the smaller driver.
[h=4]Find your groove[/h] A third item you should consider is chain case gearing. Mountain sleds as they come from the factory are geared too high for mountain riding. Perhaps yours is too. There is a simple test to see how efficient your gearing is. Mark the inside sheave of your primary clutch with a Marks-a-lot and go riding. After you have gone on a couple of trips, look at the mark. If the mark hasn’t been wiped off, you can gear down and not affect the top speed of your sled as you ride it. We have talked with people who were afraid to gear down, because they felt it might affect their top speed. This is a valid concern, but if you aren’t wiping all the marks off the clutch, then either you don’t have the horsepower to go as fast as you are geared or the top speed of your sled doesn’t fit your riding style. Lower gears increase drive belt life because the normal operating range is moved out further from the center on the primary clutch. More of the belt is in contact with the clutch and is less prone to slip and reduces belt temperature. You will also gain more throttle control at the lower speeds. Your engagement will be smoother and you will be able to get started in really soft snow without digging a hole.
SO here's Avid's write up, all I want is your opinions upon these statements.
[h=4]Stay loose[/h] Tightening the track stops the ratcheting, but a tight track doesn’t roll as easily as a loose track. You can check this out on your own sled at home. Put it on a stand and take off the belt so that you can rotate the track. Use a fisherman’s scale to pull the track and see how much force it takes to make it move. Now loosen the track so that you can get your finger between the inside drive lugs of the track and the hyfax. Measure this force. You should notice quite a reduction. Our tests indicate that a sled with , an eight-inch kit, and a set of anti-ratchet drivers () pulls at ten to twelve pounds. Any drag over and above ten to twelve pounds is like having your brake on all the time. You are likely using three to five horsepower just to overcome that extra drag at forty to fifty miles per hour. It’s only logical that lower resistance in the drive system translates into greater available horsepower and speed. Anti-ratchet drivers and help to lower that resistance, delivering increased performance without affecting the reliability of your engine.
[h=4]Lighten up[/h] If you are replacing your track, you will increase your performance by buying a track with a 3” pitch. A track with a 3” pitch will weigh less than a 2.52” pitch track of equal length. An old rule of thumb is that every pound of rotating mass you remove is equal to reducing your sled’s gross weight by 7 pounds. Putting a 5-6 pound lighter track on your sled will increase track speed.
When you are selecting what size of , you should consider several things. An eight-tooth 3” driver is approximately a half-inch bigger than the nine-tooth 2.52” driver you probably have in your sled stock. A seven-tooth 3” driver is a half-inch smaller. A bigger driver might seem the logical choice, but not necessarily. Tracks act like conveyor belts, carrying snow and air to the front of the tunnel. If there isn’t anywhere for this air and snow to go, it piles up in the front and slows the track down. Unless you have a lot of room up front, it will be better for you to use the smaller driver.
[h=4]Find your groove[/h] A third item you should consider is chain case gearing. Mountain sleds as they come from the factory are geared too high for mountain riding. Perhaps yours is too. There is a simple test to see how efficient your gearing is. Mark the inside sheave of your primary clutch with a Marks-a-lot and go riding. After you have gone on a couple of trips, look at the mark. If the mark hasn’t been wiped off, you can gear down and not affect the top speed of your sled as you ride it. We have talked with people who were afraid to gear down, because they felt it might affect their top speed. This is a valid concern, but if you aren’t wiping all the marks off the clutch, then either you don’t have the horsepower to go as fast as you are geared or the top speed of your sled doesn’t fit your riding style. Lower gears increase drive belt life because the normal operating range is moved out further from the center on the primary clutch. More of the belt is in contact with the clutch and is less prone to slip and reduces belt temperature. You will also gain more throttle control at the lower speeds. Your engagement will be smoother and you will be able to get started in really soft snow without digging a hole.
