Gearing and clutching go hand in hand, changing the one affects the other. When you go to a lower numeric ratio you are keeping the belt lower in the clutch and add to the efficency of the clutch system if all parts go hand in hand. So by looking at a given sled lets say with 140hp like a srx, if you run the sled at 1:1 ratio in the clutching, its going to be very efficient and transfer more of the available power to the track. When getting into overdrive on the clutch's you lose approx 10-12 percent of the clutch's efficiency, and it takes more power to run the same mph in a given distance, so in short by running in overdrive you are only applying 126hp to the clutch's by running your belt all the way up in the primary and low in the secondary. The reason for this power loss is the belt goes thru thousands of cycles of stretching and contracting and by bending the belt tighter it creates more heat from friction and contact loss, this is the lesser ability to clamp the belt from reduced belt surface to sheave contact, the smaller the bend the less area of the belt your hanging on to, now also when in overdrive your speeding up the belt. This is also the reason why the belt slips easily or burns when the sled is just starting out, you have hardly any area to hang on to the belt from the tight bend it has in the primary clutch at the beginning of shift ratio, the same thing is happening here at overdrive, just the opposite of starting out!
So what does all this mean? If you run a taller gear ratio, and you have good engine power to begin with your belt will be lower in the primary and higher in the secondary clutch at wide open, the sled will go faster from less frictional loss, but what gear ratio you can run and still maintain optimum efficiency will only be found thru testing!!
Here is a formula to play with, but you still need to test, this is just a tool to use:
Shift ratio= engine speed(rpm) x drive sprocket pitch diameter = (? ), divided by,
mph x gearing x 336
So what does all this mean? If you run a taller gear ratio, and you have good engine power to begin with your belt will be lower in the primary and higher in the secondary clutch at wide open, the sled will go faster from less frictional loss, but what gear ratio you can run and still maintain optimum efficiency will only be found thru testing!!
Here is a formula to play with, but you still need to test, this is just a tool to use:
Shift ratio= engine speed(rpm) x drive sprocket pitch diameter = (? ), divided by,
mph x gearing x 336
redsnake3
New member
how high exactly is thebelt riding in the clutchs to be in 1:1 ratio?
ive been thinkin about this for a while.
great post by the way.
ive been thinkin about this for a while.
great post by the way.
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