Final Drive Spring

[senrak]

Hi Guys,
I once again need help from this knowlegable group. No where in my repair manual is this found, and I've only seen it mentioned in this forum once in passing.
When I separated the final drive from the driveshaft housing/swingarm, out fell this spring. It doesn't look like it belongs there. Does anyone have an explaination?

http://i470.photobucket.com/albums/r...FinalDrive.jpg

[CaptonZap]

Hi Guys,
I once again need help from this knowlegable group. No where in my repair manual is this found, and I've only seen it mentioned in this forum once in passing.
When I separated the final drive from the driveshaft housing/swingarm, out fell this spring. It doesn't look like it belongs there. Does anyone have an explaination?

http://i470.photobucket.com/albums/r...FinalDrive.jpg

Yes.

If you look in the back end of the drive shaft, you will see a cavity, and at the bottom, a round hole, just slightly larger than the spring. It goes in there.
It presses the drive shaft forward, when properly installed, and keeps the forward spline fully engaged with the U-joint.
Due to the geometry of the drive shaft assembly, the distance between the U-joint and the rear drive input spline changes slightly, with swing arm travel, which requires that one end of the shaft or the other has to slide. Yamaha engineers chose the back end, and tensioned it with a spring. If the front spline has the wire spring clip installed in the groove, you might not suffer catastrophic failure if you do not install the back spring, but why take the chance?
Pack the spring and cavity with moly grease, and ride with an easy mind.
CZ
p.s. Nice cleanup on the parts. At least I hope you cleaned it up for the picture. If it was that clean when you took it apart, you may have other problems, like worn splines.
After reassembly, don't forget to pump in a third or more of one of the small (100cc) tubes of grease. That is in addition to a liberal quantity applied before reassembly.
I think Habba Fleight has the small tubes of Moly grease.

[DGXSER]

That spring will also fit snugly on or in the bolt in the center of the final drive. Just pulled one off yesterday, spring stayed on the FD the entire time.

CZ has you covered on why its there, to push the driveshaft into the U-joint as the swing arm moves up and down.

[senrak]

Okay,
Thanks again. Makes perfect sense to me. I just went out and took a closer look and the spring does fit snuggly on the end of that bolt and nicely in the drive shaft. Somehow, when I took it apart and the spring just fell out on the floor, it didn't seem right. And then, when I couldn't find it mentioned in the yamaha manual. Dah.
Have been cleaning and painting. Splines are perfect and there was plenty of grease. I will replace with fresh moly at assembly.
Thanks again!