Hardcore Sledder banner
81 - 100 of 131 Posts

·
Registered
Joined
·
3,302 Posts
On the p85 the bolt torques down on the stationary sleeve shaft the moveable sheave, and cover slides back and forth on. The spider unit provides the contact points for the weights to push on. The bolt collar washer washer stops the moveable sheave movement. Honestly, I never have seen a clutch slam closed that hard. Actually it closes relatively soft. Maybe it would slam close by stabbing the breaks? Looks like it broke at the threaded portion of the bolt. Do they all fail at the same point? Does the bolt just need to be more robust at the thread region of the bolt? Maybe the crank PTO stub needs changed on how it holds the stationary sheave and the clutch bolt?
 

·
Registered
Joined
·
52 Posts
On the P85 you have a threaded spider and jam nut bolted to the stationary sheave. When the clutch slams open you have the momentum of the movable sheave, weights and cover. On the P22 the spider is not mechanically retained so when the P22 slams open you have the momentum of the movable sheave, weights, cover and now the spider. The higher the spring rate the harder the momentum.

The Ski-Doo TRA clutch is similar but does have a slight press fit on the external spider to the splines of the stationary sheave. You normally cannot remove the spider from the stationary sheave on a TRA without removing the clutch and some persuasion.
 

·
Premium Member
Joined
·
19,720 Posts
On the p85 the bolt torques down on the stationary sleeve shaft the moveable sheave, and cover slides back and forth on. The spider unit provides the contact points for the weights to push on. The bolt collar washer washer stops the moveable sheave movement. Honestly, I never have seen a clutch slam closed that hard. Actually it closes relatively soft. Maybe it would slam close by stabbing the breaks? Looks like it broke at the threaded portion of the bolt. Do they all fail at the same point? Does the bolt just need to be more robust at the thread region of the bolt? Maybe the crank PTO stub needs changed on how it holds the stationary sheave and the clutch bolt?
The clutch does not slam open as the weights are still applying a certain level of resistance until well below engagement rpm. This appears to be a weak bolt issue.
 

·
Registered
Joined
·
2,819 Posts
My take is the splines are not long enough to provide the stability needed to keep movable sheave square under hard pulls and bolt is being flexed and fails. I really don’t believe the clutch slams open hard enough for bolt to fail unless bolts are defective. Hopefully that is all it is. I have a p85 on my 2000 xcr with 11,000+ miles and one on my 2004 pro x2 800 with 20,000+ miles well maintained and cleaned. They have been very good to me.
 

·
Premium Member
23 650 Adventure, 22 850 Assault, 21 XC 650 137
Joined
·
4,304 Posts
The bolt could be to hard and not ductile enough to take the repeated stresses. Or the bolt has a sharp corner near the threads that is causing a stress riser. I haven't seen one up close yet.

All the P85 needed is a larger / wider bearing surface for the weight pivot so they don't eat into the spider IMO. Other than that they are pretty solid.
 

·
Registered
Joined
·
52 Posts
My take is the splines are not long enough to provide the stability needed to keep movable sheave square under hard pulls and bolt is being flexed and fails. I really don’t believe the clutch slams open hard enough for bolt to fail unless bolts are defective. Hopefully that is all it is. I have a p85 on my 2000 xcr with 11,000+ miles and one on my 2004 pro x2 800 with 20,000+ miles well maintained and cleaned. They have been very good to me.
Good point. On the Ski-Doo TRA you only have .120 to .187 engagement on the spline but they also have an end plate on the exterior spider that does have a clamp load on the cover to the end of the spline.

If the bolt is breaking always at the same point on the end of the threads there could be too sharp of a termination point at the end of the threads.

All theories but I don't think the sky is falling.
 

·
Registered
Joined
·
6,960 Posts
You guys are right now that I slowed down and thought about it they don’t slam out that hard at all. At least the p85 doesn’t. Either way I’m not into the self adjusting deflection at all. So I still think the new set up is bullshit but I agree it’s not pounding hard on bolt head. Don’t doo clutches mount same way ? I can’t remember but I know I’ve pulled one off befor and the fixed sheeve and shaft was still on crank.
 

·
Premium Member
MY21 650 SBA 146, ES, ICE Storm 1.5
Joined
·
7,324 Posts
On the P85 you have a threaded spider and jam nut bolted to the stationary sheave. When the clutch slams open you have the momentum of the movable sheave, weights and cover. On the P22 the spider is not mechanically retained so when the P22 slams open you have the momentum of the movable sheave, weights, cover and now the spider. The higher the spring rate the harder the momentum.

The Ski-Doo TRA clutch is similar but does have a slight press fit on the external spider to the splines of the stationary sheave. You normally cannot remove the spider from the stationary sheave on a TRA without removing the clutch and some persuasion.
The spider is always pressed up against the bearing, by the primary spring. It does not move unless the primary spring is removed during disassembly.
 

·
Registered
Joined
·
1,244 Posts
I have been running thunder products clutch cover on my sleds for several yrs now. It’s a great set up for reliability and keeping a perfect belt side clearance on the belt in the primary clutch as it’s adjustable as the belt wears. The cover plate had 200% more bearing surface.
 

·
Registered
Joined
·
2,819 Posts
Going from a tapered crank to a splined design probably wasn't the greatest idea either. I'm losing faith in the quality of engineering in these sleds nowadays lol
It is still same tapered crank, splines are on the clutch center shaft. I hope we are all over analyzing this and it’s just a mounting bolt problem.
 

·
Premium Member
Joined
·
19,720 Posts
In studying the way the P22 clutch works, it appears to me that the bolt will be stressed every time the weights swing out and engage the belt This is because it appears that the bolt clamps the spider in place unlike most other designs where the spider is held in place by a separate method such as a spanner nut, etc. It's hard to see exactly what's retaining the spider for sure in the video.
So, the bolt either is not designed strong enough and/or the spider must be retained by a better method.
 

·
Vendor
Joined
·
11,456 Posts
Discussion Starter · #99 ·
right from the factory. the p-22 has .080-.100 of belt the sheave clearance. this can not be adjusted. the clutch slams in. this puts torque side load on that bolt. if hard on the brakes the clutch slams open. this put tensile/ shock load on the bolt. the bolt is holding the movable sheave with weights and springs with the spider on. the spider just slips onto the shaft with is splined. not tapered like ski-doo. i have had many of these apart. i do not believe a bolt change is going to fix this? the other thing is look at the drive clutch on these at idle. it's not running true. looks like it's running in a oval. the moveable sheave can flex as a unit because of the roller center bearing the tolerance is loose from the get go. very bad engineering period. we are taking the p-22 off and throwing it away. and installing a p-85. as cv-tech doesn't have a 850 pb80 yet? i can see these wearing out in short mileage. and these bearings go to hell on atv's constantly. the reason these are used on atv/utv's is because you can not adjust your belt deflection easily.
 

·
Vendor
Joined
·
11,456 Posts
Discussion Starter · #100 ·
That’s great if your brother owns a boost, I know guys that own them as well.
I’m sure you’re doing lots of service work on a new sled with 400 miles on it… Obviously you didn’t have the P22 clutch off because its easy to see why the bolt is failing from what the video shows. Clearly because you drove one and your brother owns it didn’t make you an expert on the Boost.
i've had this sled clutch off twice. Polaris doesn't even have the soft wear to put these on the d-wrench. can't do a fucking thing to it. nice $23,000 only just recently have these been able to be flashed etc, basically the thing was a turd out of the box. so i looked at stuff like ex. valve issue etc. pretty hard to see a issue when you can not put it on the computer. $23,000 shit pail.
 
81 - 100 of 131 Posts
Top