Hey! Just wondering if anyone could give me a heads up on my drive line? I am experiencing a thud that sounds like a ball peen hammer tapping the final drive case when I let the clutch out. I can also hear the noise when adding throttle or letting off the throttle, just not as loud. I put it on the center stand and jacked the back wheel off the ground, put it in 1st gear, opened up the drive shaft boot and took out all the slop in one direction. I then turned the wheel the other direction and noted the amount of slop in the final drive and the transmission. The final drive has about 3/4 of an inch before it contacts the transmission, the transmission has about 1/2 inch slop. My question: Is this normal slop?

Notes: 1983 R100RT: Measurements for final drive taken on the side of the tire, on the output flange for the transmission. I inspected the splines at both ends of the final drive and the transmission splines when I replaced the swing arm bearings. All appeared serviceable. I also replaced the drive line fluids at that time. I checked the drive shaft flange bolts and they are tight. I've put 1,000 miles on the bike since doing the work/purchase. I don't know for sure, but I think this is a problem that is getting noticeably louder as I don't recall hearing it when I first put the bike into service.