Rear Drum Arm Directional?

[Nessman]

I've exhausted my quota of stoopit questions so I had to figure out this one by myself.

Replaced rear wheel bearings (and swingarm bushings), while I was in there I disassembled the brake hub to lube the pivot shaft and cam. Upon reassembly the axle slipped through the bearings easily but would bind through the brake hub. I had the wheel on-off many times trying to get the brakes to quit dragging.

Solution? pull the whole thing apart and rotate the brake cam 180deg.

All good now.

Are they directional or was that just an odd coincidence?

Matt...almost there.

 

[angus67]

Coincedence. But you need to figure out why so it won't lock up on you. My 1979 drums arm was bent. A little heat and VCR and hammer bent it straight

 

[gggGary]

There is a thick washer/cam on some years of the brake shoe pivot shaft. If it is installed "wrong side out" it causes the shaft to sit too far in, binding the brake shoes. Yeah I figured THAT out the hard way. We are not alone, several others have found this out.

 

[JRP01]

Yupper. Once again the forum and gggGary wisdom (is that oxymoronic?) saved me a bunch a time. Could not figure out where that rear brake drag was coming from.

 

[gggGary]

Huh?? Wah??

 

[gggGary]

And yes early brake cams are directional, about 76 or 77? they changed the profile so they would work either way. This is only an issue if you are going all custom and trying to flip the arm for a "top" pull set up.
A nice 5T image of the late model shaft with the plate installed correctly. from this thread http://www.xs650.com/threads/how-difficult-is-it-to-replace-the-rear-drum-brakes.25632/

5T calls this a 74 you can see the difference in the cam shapes

 

[59Tebo]

Redundant. Not oxymoronic.

 

[kshansen]

Had to take a look at a couple brake backing plates a 1972 and a 1983. A quick look and don't see any obvious difference in the shape of the cam itself but did notice that the 1972 the washer under the cam is thin, say 0.015 thick, where the washer on the 1983 something closer to 3/16 inch thick.

 

[5twins]

There are quite a few detail differences between the '70-'73 plates and the later ones, both cosmetic and concerning the parts. Details are here .....

http://www.xs650.com/threads/650-rear-drum-brake-plates.51046/

 

[gggGary]

Redundant. Not oxymoronic.

Redundant. Not oxymoronic.

Yeah, most days I feel pretty redundant.....

 

[59Tebo]

No, I meant "gggGary" and "wisdom" in the same sentence, were redundant!

 

[JRP01]

I figured that was what you meant. I can never pass up a chance to give him a hard time. We go back a ways.

 

[angus67]

Nice avatar of gggary in his prime. How far back?

 

[gggGary]

I took that pic of JP on my first XS about 1975? Hate to admit this but we've been in trouble together for way too close to half a century.

 

[JRP01]

It probably has been over half a century. Mind boggling.