Loud clunk after take off

[wingthing88]

I have an interesting problem. I recently replaced all rotors and pads and rebuilt the calipers. Now when I accelerate from a stop I occasionally get a loud clunk that I can feel in the foot pegs and seat this happens more frequently after warmed up on the highway. I've rechecked everything loosened up the rear axle to resettle it used the correct torques checked to make sure the caliper wasn't hanging up and checked the u-joint the noise is still there. Bike has 140k and runs like a top this happens randomly at any rate of acceleration after it's rolling not when you just release the clutch. Not finding any frame cracks either. Any ideas?

[WingAdmin]

Are you able to tell if it is coming from the front or rear of the bike?

[wingthing88]

Feels like the rear. I feel it more in the right foot peg. I’m partially deaf so direction of sound is difficult for me. But I don’t feel anything from the handle bars

[Rambozo]

I take it this wasn't a problem until you did the brake work?
With the rear wheel off the ground and the bike in neutral, use a strap or something to apply the rear brake, and very forcefully attempt to turn the rear wheel forward and backward while observing the caliper and drive system. Any play indicates a problem.

[WingAdmin]

When I started feeling a clunk in my footpegs like you describe, the problem was a worn U-joint. Replacing it fixed the problem. See: viewtopic.php?f=14&t=30309

[ct1500]

I have an interesting problem. I recently replaced all rotors and pads and rebuilt the calipers. Now when I accelerate from a stop I occasionally get a loud clunk that I can feel in the foot pegs and seat this happens more frequently after warmed up on the highway. I've rechecked everything loosened up the rear axle to resettle it used the correct torques checked to make sure the caliper wasn't hanging up and checked the u-joint the noise is still there. Bike has 140k and runs like a top this happens randomly at any rate of acceleration after it's rolling not when you just release the clutch. Not finding any frame cracks either. Any ideas?

Were the swing arm bearing attachment bolts messed with?

[wingthing88]

U-joint looks and feels good. no play in the brakes. swing arm pivots not touched. We have the grandkids over this weekend so it might be a great time to lock myself in the garage and take everything back apart and recheck it and then take a few hundred mile test drive just to make sure.

[tsandvik]

There is a small bushing that is in the front brake where the caliper attaches to the fork.
Mine was missing when I got the bike. Got intermittent clunks.
Could not find a replacement anywhere so had a buddy at a machine shop make me up one.
Problem solved.
Upper attachment point.

[wingthing88]

Good point it could have fallen out and rolled away at some point and I missed it during install. Thanks

[wingthing88]

I have finally made the time to take it back apart. Thankfully I'm not slipping in my old age everything was assembled correctly. So I pulled the final drive to check the u-joint and the joint was like new. However the drive shaft an rear pinion joint came off in one piece. The pinion nut at some point in it's 140k mile life had come loose. I couldn't find the torque spec for the pinion nut so I tightened it down until the final drive quit making noise which equated to about 40 ftlbs. The final drive has always made noise since I've owned the bike when I put it on the center stand and spin the wheel. I put it all back together and went for a ride amazing this bike has never been so quiet. Now I need to find a new drive shaft and pinion joint and the correct assembly process and do it all over right. Many thanks to everyone who responded.