Uni joint in shaft shot. Output shaft from gearbox shot....

[Ross]

My bike is a 1986 R80 mono.

I have a clunk in my rear wheel.

When I rotate the wheel I can feel it clunk about 5 times for that rotation. I can hear it too.

I have checked the bolts from the tranny output to the driveshaft and they are all tight.

Removed rear wheel and then tried to turn the crowngear with the wheel bolts in to give me something to grab. Very tight and no clunk.

Put wheel back on and again clunk.

I assume its the driveshaft?

or crown wheel bearing going?

There is NO side to side movement felt through the wheel.

So to pull the driveshaft besides taking the swing arm out of the frame and unbolting the diff is there any special tool I would need to get the drive shaft out of the swing arm?

[Bamboo812]

You will need something to compress the spring so you can remove/install the cir-clip (get a new one, they're cheap) Cycle Works makes a tool for $39 or you can try what this guy on ADVrider did, with a shade tree option as well: http://advrider.com/index.php?threads/c ... ue.411323/

[Ross]

Just tried rotating the back wheel while in different gears with the clutch pulled in and the clunk goes away.

So it only clunks when in neutral.

[ME 109]

My final drive clunked. It was the gearbox.

Remove the 4 driveshaft/gearbox bolts and see if the wheel spins freely.

[Ross]

My final drive clunked. It was the gearbox.

Remove the 4 driveshaft/gearbox bolts and see if the wheel spins freely.

I can feel the clunk at both the uni joint and in the diff. If I wiggle the wheel and hold the gear box up near the uni joint I can hardly feel the clunk. Which makes me think it is not the gearbox. But will check the output shaft when the swing arm and drive shaft come out.

[jagarra]

Charlie, since you said yours was from the tranny, was it because shifting mechanism got worn and sloppy and the neutral position shifted so that gears were nicking each other?

[khittner1]

Whatever the source of the clunk, it can undoubtedly be fixed by welding or riveting on some recycled steel.

[Ross]

This morning I adjusted the rear shock. I had wound it out a few months back to make the back end come up higher. My thoughts were that maybe on the main stand the rear wheel drops too low and that the shaft is hitting the housing at that angle. It was not. Sat on it two up and moved the bike (paddled) and it still makes the clunking.

I pulled the boot back from around the uni and checked that. The uni and the shaft at that end looks brand new. There is no movement on the uni joints at all that i can detect from pushing on them.

Had a listen to the shaft and diff while turning the wheel with a bit of tube up to my ear. The noise/clunk is loudest from the diff to were the cush drive/spring is. So maybe its the spring?

The only way to tell will be to pull it apart.

[Ross]

Whatever the source of the clunk, it can undoubtedly be fixed by welding or riveting on some recycled steel.

I am a viking when it comes to this.

[ME 109]

Charlie, since you said yours was from the tranny, was it because shifting mechanism got worn and sloppy and the neutral position shifted so that gears were nicking each other?

my clunk was due to a failed output shaft bearing, but there was also other things going on with the output shaft.
Symptoms were.....either the output shaft was being jacked backwards by the tall 5th gear, or the shimming was wrong, or the rear bearing failed.
I don't think it was the shimming, I don't think the bearing failed and caused the other problems, and the shaft being jacked backwards is a guess based on the damage evident.
That was one year ago that I rebuilt the box. So far so good, but I never pinpointed the exact cause of the failure.