Topic: What is the drum surface supposed to be?

[mycb750k6]

I just got a nice 16" rear wheel for my CB750 but the drum surface is a bit rusty. I cleaned it up with 000 steel wool but was wondering what the surface should really be for best breaking. I could easily make it really smooth with some effort but is that the right thing to do. Should it have a rough surface for best bite and if so how to attain that? I never worked in a garage so I have no idea.

[cb650]

I use 60 or 80 grit sandpaper by hand.

[OldSchool_IsCool]

Your brake shoes will impart their own surfacing preference.  Just clean the surface up, check for severe pitting or gouges, make sure it's still in speck (181 millimeters for a 550).  Install, adjust and let the parts get to know each other.

[gane]

My, This will sound "homespun" but...  if you can see metal w/ steel wool, go no further. wash residuals, break glaze off old shoes assemble. note rear brake arm position at proper adjustment, & use.  Use will do two things. 1st, remove residual rust without causing "holidays" & 2nd reveal possible any prior distortion of drum. The "drum liner" is a mild steel insert residing in hub. and is hardy, However they can wear out/ become "out of round". Pitting/grooves (caused by escaped springs)  can be dismissed if inner dia, is within spec.  Out of round (after rust is knocked off) will be discerned by pulsing pedal. tapered bore by shoes traveling/clicking back into place. After discerning state of hub, Hopefully fine, replace shoes w/new....  Why? because the friction materiael was glued to shoe core 30 years ago. and can do a # of things, IE be fine, or, break off bits (common), break off completly, leaving you without rear brake, (still not so bad,) or break free, jam and lock rear wheel. Bad... IMHO. Pedal actuated drum brakes are fine. Smooth application, quiet, long lived, and (at least on Honda 4's)easily sufficient to lock wheel at any time. The only shortcoming I can think of is the possibilty of "fade", and thats a toss-up if you consider the possibility of brake fluid temps in disc models. my 2 cents.G

[754]

I do believe it is cast iron, not steel on the drum surface.

 If you want a nicely centred brake assembly, partially tighten the axle nut, the push hard on the brake pedal, & while holding pedal down, then tighten axle. This will centre the shoes, and prevent one contacting first or dragging....

[JBMorse]

I do believe it is cast iron, not steel on the drum surface.

 If you want a nicely centred brake assembly, partially tighten the axle nut, the push hard on the brake pedal, & while holding pedal down, then tighten axle. This will centre the shoes, and prevent one contacting first or dragging....

Good trick!  I'll have to remember it when I clean/inspect my rear drum.  Thanks!