im working my heart out on lowering temperatures. Up to a little over 450 miles now -
Im leaving all the factory installed fiber parts on, not modifying any of the clutch guard area. Leaving all felt linings in.
Not running a prefilter grill kit either - I want as much natural under hood heat & moisture to give "from factory" a good go.
Trying to break the system down into its component parts based on track speed.
Start of shift
I been doing slow wrong foot forward, sidehilling across hills, just fast enough to walk and after about 120 feet...."peeeuewwee....stinky belt smell" The engagement speed is too high at 3600 for the 967 ramp and im running enough pivot weight with tungsten down here to allow the use of that ramp.
I been trying the 967, 951, 968 ramp with 170 and 185 start forces (getting to try out custom springs) Next will be 150, 140 and 120 start forces.
Midrange track speeds (correspondence from a customer)
Some people have to travel long distances from the trailer to the deep
Mike) we are out of ID and where were riding have blown belts in 100 miles, this is going to be an expensive winter
Joe)Q1] Was there at any time ever on the hardpack to get up to where you both ride the sled, was there any time ever the sled reached a vehicle speed of about 72 to 75mph. Like say some switch back that has a long enough stretch on it to boogie up to over 72mph (yes or no?)
Q2]Do you two have to run a long distance on roads to get to where you ride to snow, like having to ride a distance at steady part throttle up or back from the snow?
Mike) the majority of what we did was breaking our trails into the back country so we maybe had 2 miles of hard pack riding to get to the snow. We did have one ride with search and rescue, 14 miles of trail to get into the stranded sledders. For most of those 14 miles we would have been in and out of half throttle probably keeping a consistent speed of 50 mph and hitting a top speed of 65 it's very very rare that we would hit a vehicle speed of 75 mph
Joe) but you could have hit 75mph even just once, yes? This is all it takes to start to damage a belt with gears that are in the latest summits.
all it takes is one to two times to get there and this happens
https://www.ibackshift.com/article/gearing-150.asp#summit_overrev
1] The belt "compression cogs" hits the roller pivot stud and
2] the angle of the secondary clutch where the sheave angles to straight up and down (overdrive portion) – this "ridge" where the angle transitions to perpendicular wants to separate the belt in two - Separating the tension section from the compression section.
Belts will cumulative raise heat to overheat by...
High engine speed at part throttle, heating up the belt from steady running down trails.
OR
Steady part throttle at long trails will raise temperatures of the belt because you are putting the belt on one small area, pulling from the primary clutch. When the belt stays in one area (Within a ½ inch of sheave travel) the temperatures will soar to 180~190 degrees. Eventually so much heat a chord will pop and sentence the belt to death.
Death sentence belt temperatures
https://www.ibackshift.com/article/belt-143.asp#belt_temp
Watch your belt sidewall color turn from green to brown to black(185 degrees and no rest)...*
badoing*...there goes a chord.
Run the sled hard as you normally do, but stop every once in a while to check the color of the belt. Monitor the clutch temps and when you start to see the belt glaze from that point on it will start to turn brown. You'll end up knowing how long you can run the sled for whatever you do and that "timer" will be going off in your mind giving you a conscience "im at the point of ...or...im almost at the point of - giving the belt a rest. Pop the side panel off, clutch guard off and take a drink of water or whatnot to give the belt and clutches an "open air" break.
When running down hardpack, then vary the engine speed while driving, speed up, slow down, speed up, slow down – imagine you are able to watch your belt move across the sheave face – changing speed will move the belt across the sheave face and draw away more heat from the belt. Staying fairly one vehicle speed traveling will have heat localized on one area of the sheave faces and heat can’t be drawn away from the belt.
Trail sleds can get away with long distances of steady part throttle because of their higher gearing, lower track loads and
much lower engine speed at part throttle. Example an 800 trail sled can poke along at 60mph at 5500~6000 rpms to where I see on my own 850 x 154 x 3" running at 6900~7200 rpms at 50mph depending on load.
For long distances like that you can run in clicker #2 to lower engine speed and make the engine lug more when traveling…..that 14 mile you mention. Like riders going from Cooke city to top of the world is 18 miles and they’ll clicker down to get good mileage and low clutch temperatures.
Track speed sentence belt to death
orange box maximum safe track speed
red box....starts damage and engine will take off into overspeed.
