Primary clutch on SXR EXPLODED

Turk said:
hot clutches are not the 8dn belt; it,s from poor clutching. the 8dn belt is awesome.
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This is your Quote turk: When the 8 dn belt gets hot, it drops rpm's , always has always will. It is alot more noticable with aggresive clutching with lots of wot riding. THE BELT GETS SMOKIN HOT WHICH MAKES IT SOFTER & LOWERS RPM!
 
yammy said:
This is your Quote turk: When the 8 dn belt gets hot, it drops rpm's , always has always will. It is alot more noticable with aggresive clutching with lots of wot riding. THE BELT GETS SMOKIN HOT WHICH MAKES IT SOFTER & LOWERS RPM!
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yes, but isn't he suggesting spot on clutching will reduce belt temps and therefore keep RPM's where they should be? cool running belt and clutches = spot on clutching... or did I miss something? tj
 
Clutches have to be tuned to match the entire setup no matter which belt you are using. Heat is what usually destroys belts. Slippage or twisting is what usually creates heat. Many things can contribute to slippage and twisting. Alignment, offset, side pressure (not enough), binding bushings, weak or broken springs are just a few of these things. The rubber in the 8DN belt has a higher durometer reading which means it is a harder rubber compound. This makes it more durable, but not as sticky which means that it requires more side pressure to avoid slippage.

I sure looks like you ran very hot clutches for a long time. These machines are very durable, but they do require maintenance or they will fail at some point. Parts do wear and when neglected tend to wear faster and faster. Think about the stress the clutches and belt go through every time you hit the throttle.

btw: You are very lucky that you did not get injured when that thing let go. I know of quite a few that were not so lucky, attended the funeral of a couple.

also - Turk knows an incredible amount about clutching, I advise listening to what he has to say closely. Consider posting pics of closeups on the clutch sheaves (both clutches). You will likely get very good advice as a result.
 
I said that & yes it does if your drag racing & clutch testing all afternoon which I do way too much.If your an average trail rider with the occaisonal lake run or racing your buddies the rpm,s dropping are not an issue. I am talking dropping rpm,s making 1000' full throttle runs all day!!!
 
a good thing to do is while you are out riding and you stop for a break....check the heat of your clutches right away....if they are really hot then you have a problem...cleaning your clutches every year is just good maintenance....while you clean you can visually inspect as well...my clutch surfaces get cleaned once a month no matter what.
 
daman said:
1-2mm is the norm on a stock sled,i like 2 yes his is more for sure .
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It could make resonance in the primary sheave and make it explode if its not lined up perfectly! the force will go from side to side on the belt and make a noice as a resonace wave, that will heat up the primary sheave I guess, but its not the heat that make things go to hell, its the resonance waves when it hits the point og zero balance. Importen to understand that heat only make things go slower! And the frekvency in the resonace-waves make things eksplode, or if not eksplode it can produce a lot of noice and heat as well..

thats why I made a comment on that picture.. but its only a theory! ;)
 
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We are aggressive riders and we need our clutches to also be aggressive. we are into and out of the throttle constantly , from corner to corner. We need the response and the rpm's to be up all the time for this to happen. When running the 8dn belt ,the r's fall off ,the clutches heat up and the performance is lost! We don't have that problem when running the 89L or the 8ch belts . the performance is spot on ,and the clutches run a lot cooler , all day long ! Now if you just want to putt around, then ya,the 8dn is the way to go. This is just what my snowmobile experience's have been thru the years. !
 
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after seeing the damage caused here,I think I will get some flat aluminum plateing and mould to the curve of the clutch cover and rivet it to the inside of cover.Then a less of a chance parts would go thru and nail me.Summertime project coming up,you can never be to cautious.I keep my clutches clean and tuned and always check for heat after many runs,just for the heck of it.A habit I guess.My clutches run real cool anyways.
 
toally irrelevant but i really think that belt should be framed and hung in a garage with the attached picture of the remains of the primary. If anyone had a doubted the reliability of a 8DN heres your proof!

Pat
 
Throw a Polaris P-85 on there and be done with it. They are in my opinion more durable then the yamaha and also are cheaper and more plentiful. Find one from a sled with similar cc's and you may not have to tune it at all. I also run the 89-L belt and have never had one blow up and my sheaves stay cool all day. Since I have changed my primary to the Polaris I keep a good eye on it. After 700 miles I have not had any issues. I would definately check engine alignment once it is back together. When i did my secondary swap motor was off a 1/4 or more. I am sure if you ask on here someone may loan you a clutch alignment tool. I borrowed one from here a couple years back and mailed then some money to cover shipping and a couple amsoil products like grease and chain case oil.
 
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I assume that they fit using the same crank as the yamaha clutches? Are the P-85 clutches just stronger? More material??? In the past I have heard that Polaris makes the best clutches, but didn't think anything about it. I actually have a small assortment of polaris clutching components from my pre yamaha days.
 
his clutch is hambuger in the bottom of his belly for a reason... it hasn't anything to do with Yamaha making less robust clutches... a Poo clutch will do the same if given inattention... tj
 
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Sandman is right though about the polaris clutches. Those P85's are inexpensive , easy to tune, and strong.

Not to mention very plentiful.
 
been there. mine blew and completely ripped the footwell out and clutch cover off. also put a hole in my hood. Yeah you had a cracked sheave or you over tightened the six bolts on the clutch cover and cracked it.
 
TJ500 said:
his clutch is hambuger in the bootom of his belly for a reason... it hasn't anything to do with Yamaha making less robust clutches... a Poo clutch will do the same if given inattention... tj
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agreed 100%. a yamaha clutch has no problem standing up to a turbo apex thats trying to make it explode,but its only as strong as the person thats suppose to be taking care of it and that applies to any clutch no matter who makes it.
 
bluemonster1 said:
after seeing the damage caused here,I think I will get some flat aluminum plateing and mould to the curve of the clutch cover and rivet it to the inside of cover.Then a less of a chance parts would go thru and nail me.Summertime project coming up,you can never be to cautious.I keep my clutches clean and tuned and always check for heat after many runs,just for the heck of it.A habit I guess.My clutches run real cool anyways.
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A mod we used to do on the enduro race sled was bolt a piece of rubber belting to the top of the clutch cover. About a 1/4" thick. A little heavier than aluminum but real tough if anything decides to let loose. ;)!
 
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