Catastophic Clutch Failure! Old Dog Learns New Lesson....

The thing to watch for in the future is cracks in the primary sheave. Usually the stationary sheave is the one that cracks. Heat from excessive belt slippage causes this as was mentioned. Over-rev does not always cause excessive heat depending on the cause of the over- rev. Lots of things can cause excessive slippage. Worn belt, snow intake, dirt, oil, water etc.


I don't know what shape the primary is in but I'll bet there is still a lot of good stuff you can salvage. The weights are probably good as well as the rollers and even the spider.

A person has to be careful with sleds with reverse. Backing up heats the primary and drive belt right away because there's very little secondary load.

These Yamaha sleds are easy to fix with respect to clutches. Lots of interchangeability. Just get it calibrated correctly
And you're back in business.

Good luck.
 
SWEDE said:
You've probably been overevving that sled and in turn slipping the belt for years. This puts tremendous heat into the clutch and eventually they blow apart.
Click to expand...

Heads up to a perfect call!
Talked to my son today who is the only other person who has driven this sled and he said it consistently ran up to 9,000 RPMs.
Kudos, you nailed it
 
Sorry to be a little argumentative here, but overreving the motor will not in itself slip the belt or cause the primary to fail. If you put triple pipes on the red head motor, you deliberately run it around 9000 rpm. It's not slipping the belt. The clutches are simply calibrated to run at that rpm because that's where it makes the most power. We have run Vmax4s well over 10,000 rpm and never blew up a primary. I ruined one once when I had to drive the sled off a lake on bare ground slowly up a steep grade. The primary clutch got extremely hot. When I shut the sled off, I heard a distinct "ting" sound. I opened the hood and looked at the primary. It was cracked. If I would have run that sled much after that, the cracked sheave would have flown apart. Just like in this case. We've never ruined one specifically because of rpm. Clutches can be slightly cracked a long time before they fail. Cracks always start from the spider outwards. Periodic inspection is key.

You certainly have to find out why the sled overrevs. That is key to top performance. The belt was certainly slipped on your sled at some time and heated the primary up. Most primary clutches are ruined by slipping the belt at low speed when the drive belt is low in the primary. When the belt is low in the primary it is grabbing very little of the belt. Examples are when the track is frozen down, you're stuck in deep snow etc.

Just trying to be helpful. I hope everything works out well for you.
 
Rick-Mi said:
Heads up to a perfect call!
Talked to my son today who is the only other person who has driven this sled and he said it consistently ran up to 9,000 RPMs.
Kudos, you nailed it
Click to expand...

They all seem to Rev up to or close to 9000rpms in stock form. That was NOT the cause of your failure. When I baught mine 4 years ago (@9000kms) it reved the same way until I added 2.8 g to each tip to load the engine back down to the proper revs.
 
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Appreciate the additional advice Vincent and Weatherbyman. Believe me, I've learned a lot in the last week and will be doing a lot of inspection and routine clutch maintenance from here on out.

I supposedly have lined up a primary and secondary clutch from the same model, year and displacement. Don't have details yet, but was told I might need some new internal parts. I don't know if that is for tuning or wear. We'll see where it goes from here....

Tried to post a pic for you guys to see the damage, but keep getting a red exclamation error symbol. First it said the file was too large, so I resized it down to 664 x374 75 KB and then some other unrecognizable error. I give up....
 
Make sure that you know what machine the clutch came off.
Will be easy to give you direction to see if you need to change anything internally or not.
 
rick thank you for this interesting read I have been running every Yamaha sled built since I was about 7. I now have several ventures, vmaxs, exciters, inviter, enticer, rx warrior. I have never had a clutch blow apart, and don't want to after reading this, I need to go through some primaries and learn how to service them.
 
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