At the end of last year a clunking started to develop in the chaincase. So i took the chaincase apart and the chain was a little bit loose but not much. So i tightened it, and ran it across the field and it seemed to go away. The next day the snow melted and i put her away for the year. Well, after tearing the old track off and putting the new one on, i found the problem. The brake seemed to have a little bit of play and when it was revolving it would move a little making a light clunking noise. At higher speeds it seemed to correct itself, but at low speeds it was a consistent clunk, clunk, clunk...the faster you went the faster the clunk until eventually it stopped at about 30 miles per hour. Anyhow. So i went ahead and decided that the brake must be wore out and went ahead and got a new brake. The brake isnt new, but i put a racing hub on it that is Brand New. Also i order a new sliding key to replace the old one. Figuring...something must be wore a little and is causing this thing to be loose and by replacing the old parts the problem would be fixed.
To make a long story short, I replaced the old brake and sliding key with the new and the brake is still a little loose, and the clunking is still there....I turned the jackshaft as fast as possible from the clutch side and noticed that the frame near the jackshaft bearing was moving slightly. I know this is not right. Which tells me that the jackshaft must be bent slightly because its pulling back and forth.
A little history, the guy i bought it from told me that he hit a concrete block in a ditch in the U.P. The trailing arm on the chaincase side was bent pretty bad and i ended up replacing it. Im wondering if the jackshaft might be bent?? If so, thats not to hard of fix. Or if its just worn out and needs to be replaced. One thing i did find on the secondary was the guy pulled that sleave out and the secondary wasnt running with ANY play. any and all help is greatly appreciated.
To make a long story short, I replaced the old brake and sliding key with the new and the brake is still a little loose, and the clunking is still there....I turned the jackshaft as fast as possible from the clutch side and noticed that the frame near the jackshaft bearing was moving slightly. I know this is not right. Which tells me that the jackshaft must be bent slightly because its pulling back and forth.
A little history, the guy i bought it from told me that he hit a concrete block in a ditch in the U.P. The trailing arm on the chaincase side was bent pretty bad and i ended up replacing it. Im wondering if the jackshaft might be bent?? If so, thats not to hard of fix. Or if its just worn out and needs to be replaced. One thing i did find on the secondary was the guy pulled that sleave out and the secondary wasnt running with ANY play. any and all help is greatly appreciated.
update: Pulled jackshaft out...it appears from what i can see, that there is play in the slot for the sliding key. About 1/32 of an inch. Allowing the brake to slide on the jackshaft back and forth when in motion. Im just gonna replace the jackshaft
i had a belt that was worn out cause the same problem
I had a clunk clunk noise last spring. I bought a new driveshaft and jackshaft bearing and a brand new Yamaha belt hoping one of the above were the problem. It all happened after I shredded my belt doing 100mph. The belt never actually let go, just the top half shredded, I was still able to limp the machine to shore. All that stuff needs to be replaced anyway but if it turns out to be what you said with the brake im gonna be pissed I didn't think to look there first.
.50c its not the brake.......////////
Whammy said:
as long as its not the crank im ok. but i doubt that, like i said the belt didn't actually let go. still had enough grip to limp it to shore.
Sorry SRXR700, at any time feel free to say 
and dont forget to let everyone know that i am a 
. 
but im sure some people want to 
me. lol
and dont forget to let everyone know that i am a . but im sure some people want to me. lol
Bad belt ..... orrrrrrrrr ice in track...........
Mac
Member
I read the forum a lot and never hear anyone at all about discuss brake problems or failures on our Yamaha's. Has to be one of the best engineered systems on the sled. I will guess its not the brake and agree with Whammy. I have over nine thousand hard miles on my Viper and have only changed pads. They didn't even need it I felt guilty. Do you have reverse? I have heard reverse clunks on sleds. Also never heard anyone complain about a bent jack-shaft that is weird. Figure it out and let everyone know. I did once have the set screws on my jack-shaft come loose. I had never checked or torqued them ever. Once the sled ran with loose screws the bearing movement destroyed the shaft wore so bad it had to be replaced. I now check them once or twice a season.
whammy, in my case the brake is the one that is making the clunking noise. its not the belt, not ice, i actually had the secondary off when i was turning the jackshaft. So any belt disputes are out the window. I spun it, spun it, and spun it. Kept listening to all areas around the chaincase and couldnt see or find the clunking culprit until i started playing with the brake. It had some play and it made a clunk when i pulled back on it. Anyhow, i pulled the whole assembly apart and put the brake back on the jackshaft, with sliding key, on my work bench and inspected. Sure enough the brake could slide back and forth on the jackshaft about 1/32 of an inch. looking closer i was able to see that the sliding key was not completely snug in its gap. I have a new jackshaft on order and i will see what happens with a new jackshaft. If this does not fix the problem then im an idiot and i mind as well buy an artic scrap...haha. ill update when i re install
Just got the new jackshaft in today, and the clunking is NO MORE...yee ha....it was the key way on the jackshaft that was loose in the slot that was allowing the brake to move!! Just glad to have this problem solved!!!!!!