Never seen it... transmission U-Joint sheared off...

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wildweasel_pt

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Im sorry for not having pics but today i saw something unbelievable... I know a guy that is a friend of a friend that bought a Vmax and asked me if i could take a look at it to see if i could see anything suspicious or in need of repair/replace, summing it up he wanted me to check it out. He was complaining that the bike was dripping oil by the left footpeg. First i thought to myself that it could be the middle drive gasket or the lower bolt that could be leaking, or the gear shifter rod seal leaking oil. I kneeled and looked around and found oil dripping in the frame around that area. I got suspicious because i couldn't find the source, it was really oily, then suddenly i saw the rubber boot that goes over the U-Joint kinda greasy underneath where the dripping hole is. i found that awkward and got my hands on it (so to speak) and i felt loose parts inside. I thought - what the hell?!? Can't be... he went to get the bike and brought it riding for 100 miles. So i removed the boot from the engine flange where the seating spring is and found the darn U-Joint nut loose inside the boot. Took me a while to remove it with the bike assembled and in the meantime i was thinking how was it possible that the nut would come loose when its all so tight. When i removed it i saw something that got me worried and amazed. The fricking stud sheared of flush and perpendicular to the nuts mating face. What amazed me even more was the fact that everything was in place and the nut was just going for the ride on the rubber tumbler. It was scarred due to being banged repeatedly by the U-joint that never came loose. I took it for a SLOW test ride and felt a bit of vibration when throttling up but besides that was behaving normally. I wonder for how long has that been like that... The oil leak was coming from there due the fact the U-joint just wasn't bolted to the engine side pinion... What a mess... The drive shaft was ok supposedly... What you guys think about this?
 
Yep! Been there before! Not a common problem though! There was a change in the thread size (larger) but can't remember the year. They must have had some problems to need to do that.

Sean
 
This is a '91 European version. I got awed looking at that... I thought the shaft was supposed to go first. That bolt is hardened and its like M14 or M15. A bit of a surprise to me though... Especially the fact that it was just sitting there and fumbling around inside the boot with the UJoint rotating in place, that was what amazed me the most...
 
It's actually more common for this to happen on the rear diff! A number of guys on the forum had that happen too.

Sean
 
Well this bike came to my hands again. I'll have to replace the middle gear output shaft/pinion (upper number 4 on the pic) and im wondering if i need to remove the engine from the frame. Haynes says it doesn't need to but im not convinced on that. The threaded tip where the UJoint nut screws sheared off so that darn thing needs to be replaced. Any hints or help is appreciated because this is something i never did before. Thanks all in advance... BTW regarding that is just the output shaft the cases don't need to be split right?

middledrivegear.png
 
It seems that the rear end of the drive train can be easily removed without messing with the engine case. It looks i need to check for cracks on the case that may be causing the oil leak.
 

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