Muskoka Freerider

Modman

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I don’t know about it not being axial stress, axial is inline with the crank stub. Heat (thermal growth) along with the clutch opening and closing would be my guess at the bolt failure.
The “ lateral force” you mentioned, the clutch would have to be moving on the stub. Once slippage occurs, the bolt will be under torqued after the movement on the taper.

Doo uses a cushion to dampen the force of the clutch opening and closing, and a special washer under the clutch bolt head, along with a required retorque procedure after the engine has been run.


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Sorry, typing in a rush... I thought that's what they were discussing if the taper is not correct, the clutch would be off centered on the stub? Was thinking "laterally" (across the engine) stress if the bolt was tightening and being stretched away from the engine, but actually that should have really said torsional I guess if the theory is the bolt is tightening, and yes, it would be axial directly along the plane of the bolt.

If the engine is running and crank slips in a forward rotation, with the clutch and bolt stationary, would the bolt not then be over-torqued and stretched? Or are you referring to "movement of the taper" as in/out towards the engine, along the crank? Not critiquing, genuinely trying to understand.
 

Caper11

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Sorry, typing in a rush... I thought that's what they were discussing if the taper is not correct, the clutch would be off centered on the stub? Was thinking "laterally" (across the engine) stress if the bolt was tightening and being stretched away from the engine, but actually that should have really said torsional I guess if the theory is the bolt is tightening, and yes, it would be axial directly along the plane of the bolt.

If the engine is running and crank slips in a forward rotation, with the clutch and bolt stationary, would the bolt not then be over-torqued and stretched? Or are you referring to "movement of the taper" as in/out towards the engine, along the crank? Not critiquing, genuinely trying to understand.

If, IMO thats a big if. If the primary actually does slip on the stub, the bolt tension will actually decrease because the primary will ride slightly higher on the taper.

Now if the primary was torqued when all of the parts temperature were equal, and not rechecked when warm and heat soaked, that will also cause the clutch bolt to loose tension.
Skidoo has a final retorque procedure for this. I have always found my clutch bolt loose after.


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Lund

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Correct, the bolt is tightening and breaking.
The material used for the spider has been changed (tougher stronger)and was the cause of the bolt breaking. Polaris took it a step further and also up graded the bolt.
The bolt will tighten when the throttle is released, tinny bits at a time till it breaks, its not mystery, its called physics.
The original spider was too soft causing just enough movement to cause the bolt to tighten.

PS, there has been no taper slippage.
 
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adamg

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Correct, the bolt is tightening and breaking.
The material used for the spider has been changed (tougher stronger)and was the cause of the bolt breaking. Polaris took it a step further and also up graded the bolt.
The bolt will tighten when the throttle is released, tinny bits at a time till it breaks, its not mystery, its called physics.
The original spider was too soft causing just enough movement to cause the bolt to tighten.

PS, there has been no taper slippage.
Your theory doesn't explain why this happens to the P22 and not the P85. If the clutch was slipping in rotation on the shaft, why isn't the P85 also slipping and breaking bolts? If anything the P85 should be worse because it has less installation torque, so it should slip even more.
 

maxwell

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Correct, the bolt is tightening and breaking.
The material used for the spider has been changed (tougher stronger)and was the cause of the bolt breaking. Polaris took it a step further and also up graded the bolt.
The bolt will tighten when the throttle is released, tinny bits at a time till it breaks, its not mystery, its called physics.
The original spider was too soft causing just enough movement to cause the bolt to tighten.

PS, there has been no taper slippage.


not so sure about this. Anyone I've talked to that's had a few blow off the bolt can be retorqued almost every ride and it takes it. That shouldnt need to happen after first run up.
 

Caper11

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If the clutch slips on the taper the bolt would probably tighten.

The next time you put a primary on your sled hold tension on the side of the primary and spin it on the taper. If the taper fit is correct, you are not pulling it off back by hand, because you just spun it up on the taper.


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gedakbx

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If the taper fit is correct is the question. I know how it works I have been working on my own sleds for 35 years.
 

oler1234

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not so sure about this. Anyone I've talked to that's had a few blow off the bolt can be retorqued almost every ride and it takes it. That shouldnt need to happen after first run up.

So…. Couple dabs of red loctite and your done.

Sounds just as good as the driveshaft fix!
 

greenthumb

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So far this season in our group, all different sleds;
- One bolt un-threaded and fell out. Clutch stayed on. Flat terrain, deep snow. Sled just came from the dealer
- Broken bolt. Outer came off, inner stayed on. Happened 100' after big downhill. Tow out, extract the piece and ride the next day.
- Broken bolt going uphill. Entire clutch came off. Everything got Phu*ed.
- Re-torques often show the bolt to be below spec.

Uphill, downhill. Breaking, coming loose. Half the clutch, all of the clutch. There's no consistency.
One guy on YouTube theorizes it the hammer-action of the outer, another swears by valve-lapping compound on the taper.

I think we should just start welding the fuckers on there.
 
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