Possible u-joint problem

[gmonty]

I was riding my '85 Aspy about a month ago when I noticed a knocking noise coming from the right side of the bike. Not knowing what it was I parked the bike and had to come back and get it the next day(I didn't think night riding with a possible failure in the near future was the best idea). Anyways I got it home and have taken it for a few test rides. It knocks only when in gear. I thought it was the differential at first but after running it in gear on the center stand with the wheel both on and off I think the issue is something else. Just a side note, the rattle is much worse when I put the bike in gear with the tire off. Also note that the knock is in every gear and gets louder the higher I go through the gears. My research through the forums has led me to the hypothesis that the u-joint is going bad. I have pulled the boot back and looked at it. I saw nothing that would make me think it is the problem though. Any thoughts?

[gmonty]

To add to this, my bike just cranked over 18,000 miles. It is in very good condition. I also do not think it is an engine issue because when it is in neutral I can rev to the red line with full throttle and hear no knocks.

[JamesA]

The symptoms sound familiar. If you can get the rear wheel off the ground and observe the u-joint while you or your assistant chuck the wheel forward and backward, you may see suspicious up and down or sideways motion-which is causing the rattle ( it does speed up in relation to road speed, right? ) instead of a smooth rotation. I had to replace my u-joint a couple of years ago. At that time, I learned that they are not rebuildable and Honda does not supply them as a replacement part. I was lucky to find one on ebay, taking a chance that there was not enough miles on it to find myself making the repair again right away. I just read an article in Motorcyclist magazine about a motorcycle salvage company in Ventura, CA: Tri County Motorcycle Salvage. You could try them. Anyway, if you do have to replace it and can get a spare, one female spline end is longer than the other. Notice which way it faces when you take the old one out. As I recall, there is a spring in there somewhere. Collect all your patience before starting. Good luck.

[DenverWinger]

For what it's worth there's a thread on our sister site about rebuilding a 1200 Universal Joint.

https://www.goldwingfacts.com/forums/2- ... epair.html

The meat of how to do it is an attached PDF in post #10

Not that likely to be a u-joint problem if only 18k miles though. As you are going thru the gears and increasing speed, does the knock slow down after shifting to next gear (match engine RPM) or does it continue to increase with speed regardless of gear (match drive line speed)?