I know Fred has....anyone else? Thoughts on moving to a steeper angle helix? Or moving to a progressive helix?
Ace
Ace
Who has changed their helix in 850? Thoughts?
- Thread starter Ace Freely
- Start date
A
C
Ive done a 927 trygstad with roosterbuilt clutching and a stock 850 with roosterbuilt clutching as well, both owners are extremely pleased with the results.
S
I have Joe's complete kit on my 17 850 3" 154. Night and day difference! The back shifting and engine braking are unreal on his set up!
I ran a rb2 (I think, maybe it’s r2b) helix from roosterbuilt. Ran it with a black secondary spring, softer start/stock finish primary and added a ton of weight to the stock weights. This was on a165x3 The dealer I bought it from geared it up one tooth on the top(crazy, I know)
I loved it. Pulled dam hard. A friend of mine had the same sled, same gearing but with stock clutching. On a 300-400’ pull up a Hill in 3’ of powder I’d pull 30-40’ in front of him.
I loved it. Pulled dam hard. A friend of mine had the same sled, same gearing but with stock clutching. On a 300-400’ pull up a Hill in 3’ of powder I’d pull 30-40’ in front of him.
J
I finally gave in and bought a roosterbuilt clutch kit. Tired of blowing belts. I liked the stock clutching honestly but not enough to pay for a belt every other ride. Helix, change springs in both clutches and add weight in primary. I cant say that I can feel any gain or loss, but I can touch my clutches and I haven't burned a belt since.
I went with a rooster built clutch kit on my 17 850 165 3" super happy with the performance. But I never blew any belts the first season when it was stock or this year with the clutch kit.
K
I have Joey's kit on my 17 and it has much better braking and lower engagement, seems like my track speed is up through the middle but lost some top end. Only one ride with it so far so we will see
about blowing belts...
The only defense one has as far as a (my) clutch kit goes is being able to adjust the pivot weight so you get 7900~8000 rpms.
The lowest temperatures will be seen at 7900~8000 rpms. Regardless of hot, warm, incinerating temperatures – the lowest temperatures (Whatever they are) will be seen when you run at 7950 rpms.
.........Overrev or underrev raises temperatures.
Lower temperatures will be seen (whether its 200 or 400 deg)
-if you can lower engine speed at part throttle running.
-if you can get the engine to maintain its rated rpms at full throttle (7950ish) best it can be.
Clutch kits can't solve dynamic misalignment, engine mount gap and other elements making a cocktail of reasons adding up to the belt blowing - but at least a clutch kit can offer control of engine speeds.
Other than that, take the belt in to your dealer and tell BRP to fix this sh|t.
The only defense one has as far as a (my) clutch kit goes is being able to adjust the pivot weight so you get 7900~8000 rpms.
The lowest temperatures will be seen at 7900~8000 rpms. Regardless of hot, warm, incinerating temperatures – the lowest temperatures (Whatever they are) will be seen when you run at 7950 rpms.
.........Overrev or underrev raises temperatures.
Lower temperatures will be seen (whether its 200 or 400 deg)
-if you can lower engine speed at part throttle running.
-if you can get the engine to maintain its rated rpms at full throttle (7950ish) best it can be.
Clutch kits can't solve dynamic misalignment, engine mount gap and other elements making a cocktail of reasons adding up to the belt blowing - but at least a clutch kit can offer control of engine speeds.
Other than that, take the belt in to your dealer and tell BRP to fix this sh|t.
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Why will the belt tempe elevate when running at the lower or higher rpm?
Could you explain please?
When the engine overrevs the engine torque goes lower. When the engine torque goes lower the upshift speed (opening) of the secondary clutch lowers. The belt does not go across the sheave face. The track speed you get is by virtue of high engine speed.
When the engine underrevs the engine torque lowers and following suit, the horsepower lowers. The belt does not shift across the clutch sheave face.
Both scenarios the belt stays in a localized area of the sheave faces and heat wont be efficiently drawn away from the belt.
When the belt can cross the pulley face, that is when the heat can be taken away the best.
Ok so you are in a 1 minute pull and have fairly stable track speed - the temperature elevates to an equilibrium point but the belt will have the lowest temperatures because of pulling at rated engine speed (whatever the temperatures are)
When the engine underrevs the engine torque lowers and following suit, the horsepower lowers. The belt does not shift across the clutch sheave face.
Both scenarios the belt stays in a localized area of the sheave faces and heat wont be efficiently drawn away from the belt.
When the belt can cross the pulley face, that is when the heat can be taken away the best.
Ok so you are in a 1 minute pull and have fairly stable track speed - the temperature elevates to an equilibrium point but the belt will have the lowest temperatures because of pulling at rated engine speed (whatever the temperatures are)
J
I'm still not following this completely, especially once you have stable track speed.
Belt slip = heat, I get that.
But over revving/under revving creating heat that somehow optimal RPM doesn't? I don't buy that.
I think what he’s saying is the secondary isn’t shifting right when it over revs and under revs. When it’s not shifting right, the “effective” gear ratio between the clutches is off. This creates more heat through slippage.
And it’s because of a lack of torque. The secondary is a torque sensing mechanism.
T
Makes me think you maybe have not worked on clutching sleds very much if you believe that heat is not created from over or under revving...in practice it absolutely runs the coolest when the clutching is holding the engine at optimum rpm...that's a fact.
I do disagree with Joeys explanation as to why though. I tend to lean more towards the heat being created through slip. The belt will tend to slip when the motor pulls off peak output either over or under rev because the shift will stall. When the shift stalls the helix does not create adequate belt bite and you will get slip.
This can be masked somewhat when using large spring pressures but when you start clutching with lighter spring force, peak horsepower rpm or sometimes maybe 50 rpm under will always provide best performance and lowest heat. Keep her pulling and shifting. That keeps the belt hooked the clutch face with the force generated through the helix
Quoted; so i can answer this later.
I have always looked at the over-rev/under-rev and the added heat associated with both conditions as a "balancing act" between the 2 clutches.
With over-rev the secondary is overpowering the primary and under-rev the primary is overpowering the secondary.
The key to the least amount of heat and most efficient calibration is a balance between the two so the RPM can respond quickly and accurately to the amount of load it feels from either the throttle or the track.
The clutches and belt do not care how this balance is achieved, whether flyweight profile, helix angle, spring pressures etc...so many ways to accomplish a similar end result.
7900-8100 is more than acceptable doo to tach error...
belt heat does show up if rpms are above or below those #s for reasons stated...
it is interesting that one guy goes shallow on helix angle with good results and another guy goes much steeper than stock with good results...
IMHO- going steeper only bandaids the fact the primary is set to light (add the wobble and you dont want to be light on weight) add the correct weight/tip weight and more helix angle is not needed...
Honestly stock or less than stock helix and more spring is needed to match what the pdrive is dooing...
-BJ
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