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Discussion Starter #1
A while ago, I rebuilt my engine, and after putting everything back together, and getting all my controls adjusted, I started riding it regularly. Soon after the rebuild, I began encountering a problem where when I would press the rear brake pedal while riding, I would hear a "clunk", and the brake pedal would suddenly get tight. At first this happened only occasionally, but now it happens whenever I hit the brake pedal. The clunking is getting louder, and the brake pedal is getting tighter.

I feel like what might be happening is the trailing arm is loose, but after looking at it, I saw that all the bolts were safety-wired in place.

Any idea what is causing this?

Thanks
 

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Sensei
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Don't ride again until you check for de-laminated brake shoe friction material......
 
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Discussion Starter #3
I've never taken my brakes apart, could you give me a link to the proper procedure? Or do I just follow the Shop Manual disassembly instructions?
 

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As long as you follow a factory service manual and not a clymer.

It is not too difficult, generically speaking;;
disconnect brake rod
Remove axle nut
loosen wheel adjustors
remove chain
remove axle
remove wheel
 

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Discussion Starter #5
No specialty tools required?

I've got metric sockets, wrenches, and hex keys, as well as screwdrivers. The shop manual mentions a bearing puller, which I don't have.
 

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I had that same clunking sound on my `69 CL350 and found out I was missing a 70mm washer or spacer (PN 41202286000) seen in the diagram below. I've just recently got everything back together after new spokes, brakes, and a paint job on the hubs so I'm not sure if adding that spacer will get rid of the clunk but I'm hoping so. You might see if you're missing it as well.

spacer.jpg
 

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No specialty tools required?

I've got metric sockets, wrenches, and hex keys, as well as screwdrivers. The shop manual mentions a bearing puller, which I don't have.
No special tools required for just pulling the wheel to check the brakes. If you have a factory tool kit, you can do it sitting along side the road.

I would use the fiche and FSM to make sure everything goes back together properly.
 

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Discussion Starter #8
Ok, so I got my wheel off and brake out, and I definitely have part numbers 2,15,16,and 18. However, there are a few problems:
1) the braking surface on the wheel had a LOT of dust inside. This was dark brown dry powder.
Rear Hub from top.jpg Inside of rear hub braking surface.jpg
I wiped some out with a towel, but got the majority out by laying the wheel flat and softly tapping the final drive sprocket with a hammer. This is the resultant dust
Brake Dust.jpg

2) When I tapped the final drive sprocket, I noticed that the sprocket was loose. It kind of rattled around a bit. I had known that the nuts (#18) that secure the sprocket to the studs (#14) were beaten up, but I didn't know they were so loose.
Final Drive Sprocket wear.jpg
The damage looks like at some point the drive chain had fallen off the final drive sprocket and chewed them up, but this happened with a previous owner, so I can't be sure. Anyway, due to how there are tabs on part number 15 in the fiche that are bent up, I can't really get a good grip with a socket. Further, as I was trying to loosen them, I noticed that the nuts weren't moving, but rather the entire stud was spinning! This can't be good

3) While the brake pads appear worn, they're not delaminated, so I don't really know what's causing my issue.
Rear Brake Pads.jpg

Does anyone have any ideas for me? They're very much appreciated.

Thank you!
 

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The bent up tabs need to be bent down with a flat blade screw driver and hammer, they are the locking tabs to keep the nuts from loosening. The nuts should come off easier then. Looks like you are getting close to the problem finding the loose sprocket, good job tearing into it instead of ignoring it, could have been disastrous.

The dust is normal, comes from the shoes wearing down.

Since it looks like a PO was negligent in it's upkeep, this might be the time to go through everything on the wheel to make sure it is good, cleaning and inspecting.
 

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Discussion Starter #10
I figured out how the sprocket is attached to the studs. Turns out the studs aren't threaded, and the sprocket is supposed to be allowed to move axially between the hub and the c ring. The nuts were definitely loose and chewed up to the point of uselessness though, and needed to be replaced. Everything is dusty, rusty, and greasy, but the pads are in pretty good shape.

The main cause of my problem I think actually is the trailing arm though, because after removing the brake, the trailing arm had 5-10mm of play in it, and sounds very similar when jiggled back and forth to what I had been hearing while riding. Even though the bolts are safety wired in place, they're still loose. I wouldn't have been able to see that without taking the wheel off, so I'm still glad I did this.

I'll wash everything off and reassemble it, and make sure I tighten the trailing arm before putting the wheel back in place.
 

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Replace the rear brakes. They aren't delaminated now, but you don't want them to delaminate later.
Delaminated Rear Brake Shoe 2.jpg
Delaminated Rear Brake Shoe 1.jpg

Mine were not delaminated when I put them in. Luckily I was only doing about 25 MPN when they delaminated and locked up the rear brakes. I had cleaned them, examined them pretty thoroughly when I reinstalled them. I'll never make that mistake again.

Cheap insurance to replace them anyway.

Also, the bolts and nuts on the sprocket do not hold the sprocket on. Thew allow the sprocket to turn the wheel. If you remove the Circlip in the center, the sprocket can come off,
you will see the "bolts slide out of the rubber pockets in the wheel. Thew rubber "holes" are dampers, absorb some of the drive train vibration.
 

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The lock taps keeping the nuts from turning, you bent them out of the way to replace the nuts. I would replace them.

The clunk may be from the front of the torque arm. It may also be the swing arm or a wheel bearing issue...inspection is important here.
 
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