Primary clutch blew up...

R

ryanwillden

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Joined
Sep 14, 2003
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My clutch blew up today on a return "trail" ride back to the trailer. All of a sudden I heard a loud Pop and my sled stopped... It blew clutch pieces through the belt shroud, and my brand new fiberglass hood, and blew out a chunk of the belly pan... I read on Snowest that other people have had similar problems... What gives? Anyone know what causes this? I hear that the Polaris P-85 from Hartman Inc is a better clutch... Any feedback on that?

Thanks
 
mine blew on new years day. i think it was the cover that holds spring tension that let go, but im not sure. yeah i had parts eject through my hood blew the belt shroud right out the side of the sled. your lucky you didnt get hit.
 
how many miles on sled? i have also heard of this problem with the primary . you should all check your fixed and movable sheaves for stress fractures . this also happened to a friends 01 sx-r 600 with 10000 km. his clutch gernaded into about 100 pieces taking out his hood,bellypan, and belt gaurd. (and almost his big toe) !! scary.
 
the clutch was probably getting hot, the yammie clutch and the tra are the most durable pieces out there. I have like new yammie clutches as well as brand new Polaris if ya need one
 
Mine wasnt hot. I was pulling it out of the garage to put it on the trailer. I took off down my backyard and the first time I pinned it it, it blew the hood open.
 
I'd like to learn more about this whole issue.

I think it's safe to say that as certain components wear over time, they can cause the clutch to begin to run hot.

If you're running hot and don't know it, the aluminum can get stressed. It may let go the next time it gets hot, or it may let go the next time you load it up while its still cold.

My questions:

How hot is too hot?

I would expect it to run fairly cool while on the trail, but what about a long blast through deep powder. Should it feel hotter right after that?

Or should it always feel just barely warm, regardless of the type of riding you're doing?

If you're running hot, is there a list of things to check to find the cause?

Thx.
 
baker -- hot clutches are caused by belt slippage-- which is caused by a number of things.. secondary tension not tight enough, wrong helix angles,(i think) dirty clutches, clutch alignment, etc.-- somebody else might chime in on some others. i think too hot would be so hot you couldn't keep your hand on it
 
This is common on these clutches IF you don't take the time to get them set up efficiently. They get hot from belt slip from the extremely conservative factory clutching and it causes stress cracks, which grow and eventually weaken the clutch enough to cause it to grenade. This happened to me with my 97 sx 700 at about 9,200 rpm. Tore apart everything on the pto side of the sled, and it is a miracle i didn't get hit with any of the pieces, because there were holes all through the footwell and cowling. Set your clutching up to run efficiently (cool) and you will be much better off in ALL areas.
 
If you go to the Hartman site and read his stuff on clutching he says one of the biggest factors contributing to this problem is the 8DN belt that everyone uses. Hard belts slip more generating more heat but they last forever (which everyone likes). He recommends using softer belts which don't last as long but give better performance and run cooler.
 
I called and talked to TJ's Alpine Sports in Wyoming and he told me that this was a common problem on the Mountain Max, and that it was contributed a great deal to the hard compound used on the Yamaha Belts. He also suggested running a softer belt. This clutch was fine tuned and babied to Yamaha Specifications and was not abused. It was not even being run hard at the time that it happened. I was going across a trail at about 25 mph. I've also decided that once fixed, I am going to get a 1/8th piece of aluminum the same size as the top of my belt guard and rivet it over the top of the belt guard. I don't want this happening again, and throwing the clutch through the hood. I can understand a clutch failure, but a catastrophic failure that destroys the hood, belly pan, etc is a little rediculous.
 
could have been worse. could you imagine getting hit with a chunk at 9,000 rpm? I found pieces of mine a good 20 yards from where it grenaded
 
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