Primary Clutch Failure

[mdkuni]

My primary blew apart today. Clutch was serviced by dealer before the season started, about 2,000 miles ago. Everything was replaced but the spider and spring. I have never had a clutch break on me before. Anyone have any ideas on if this was an installation or a part failure?

I am glad I installed Schmidt Bro's clutch guard this year! Could have saved me from getting hurt. I still felt a clutch part slam into my boot. Might have went into my boot without the extra plate.

 

[nitris223]

I would think there were some stress cracks in the clutch from heat. The Yamaha belt is good and will last a long time but I also find them so hard that they tend to groove out the clutch faces. I think the harder belt slips a little more then a stick belt therefore heating up the clutch and over time something gives. Make sure your clutch is not running to hot, it not only kills belts but like you found out it will take out a clutch. Friend of mine blew on his nytro last year but was not a new sled to him so past treatment is unknown.

 

[Supa Dexta]

Something to keep an eye on as these clutches age I guess. No other damage to the sled ?

 

[canoehead]

IMO looks like the weight froze and at high rpm she let loose with the results shown. Ever change out the weight bushings? Does what's left of the weight move freely? Is it possible your roller was so worn out the weight climbed over it? That break doesn't look like it's from excessive belt heat. They normally appear on the sheave face

 

[Beenba]

I agree with canoehead. With 8600miles, it could even be possible the tip of the weight wore thin and cracked off allowing it to slip past the roller.

It is unlikely, but the weight may have been cracked from day one and then let go once it got thin enough.

Were you wide open throttle when this happened?

 

[mdkuni]

As mentioned, the clutch was rebuilt 2,000 miles ago. Rollers, weights, sheaves, etc were all replaced. Everything but the spider and spring.

I was not wide open when she let go. Was probably doing 40 mph and got back on the gas. Twice before it blew it seemed to struggle a bit engaging from a stop. It would rev high (higher than normal) before engaging.

 

[mach9]

Not sure of your options from here.
But if you are thinking of an aftermarket primary.
I tried the the PB80 for my nytro xtx and really liked it.
Simple to use, very quiet and performed just as good if not better than the stock yammie primary.

 

[mdkuni]

In the past 8 years I have put over 44,000 on stock primary's. My clutches have never gone more than 7,000 without being rebuilt (they are rebuilt every year) and I have never had a single failure. I guess that is a pretty good track record. Although I would prefer zero failures! Hopefully Yamaha will be covering this one as it is under warranty.

 

[BADSLED]

I have witnessed clutch failures before but due to issues with weights. Are you using OEM Yamaha weights? Have you ever engaged the clutch by revving up motor without belt installed?

 

[mdkuni]

100% OEM. I did not rev the sled without the belt.