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Join Date: Nov 2007
Location: Chandler, Arizona
if it is the rear splines, then you will need a new (or used) coupling and a complete rear final drive gear case assembly with good splines on th pinion shaft, which mates with the coupler, and the ring gear, which engages with the rear wheel. It's the gearcase that is usually expensive.
It would seem from all the posts on here about it, that most of the Vulcan 750s ever made destroyed their final drive. That would help explain why there are so few still around after 22 straight years of production. Most people think that the only maintenance a shaft drive needs is to change the final drive gear oil. I used to think the same thing until getting a Vulcan 750. I found the thing about lubing the splines in the owners manual, and looked it up in the Clymer service manual. But according to the owners manual, it did not need to be done for several thousand miles, and I waited until the mileage specified in the manual to do it. They neglected to tell me that they had not done the spline lube at the factory, so by the time mine was due, I already had some spline damage. I was not happy. But I cleaned up the splines with a file, lubed them well, then did it every 10,000 miles thereafter. It made it past 80,000 miles, when I traded it.
Most motorcycle shaft drives are very poorly designed. There is no reason why they need maintenance, beyond changing the gear oil. The rear splines should be lubed by the gear oil, and the front splines should be lubed by the engine oil. Cars have always done it that way, so it has been proven to work.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike