Topic: 1972 CB750 rear drum brake specifications

[kschwarz]

Hi -
trying to replace my rear wheel, as the rim got rusty and the brakes werent very powerful.  The wheel was laced ito a 16" rim, and needs to replaced with the same setup.  Finding a decent wheel or hub for a 39 year old bike is proving problematic.  I bouht a replacemnt (used craigs list) but I thought I had measured it correctly, but the brake lining appears too worn- the brake when adjusted so it has some stopping power will prove to be dragging, and the brake pedal ends up hitting the exhaust pipe. no braking.  i used to be able to lock the rear wheel.  (the brake plate has new brake shoes).

I believe the maximum wear on the brake lining is 7.025"  this is from my clymer manual
Does any one know the nominal lining distance  on a new wheel.  (6.9" maybe?)

I made some thin metal guages at the machine shop at work, the have a cut out in the middle to fit over the bearing cut out, so in the future I can measure the inner diameter of any decent wheel I can find- but so far most of the wheels I see are worn or way too rusty

any help appreciated!

[Old Scrambler]

You have likely picked up what someone thought was from a CB750 but 'maybe' was from another model or brand of the era. Look up the part number and copy (compare) the casting numbers from the inside of your HONDA hub. New brake linings are available.

Regarding the foot-lever.........when you drastically adjust at the rear you will have to move the lever one spline on the actuator shaft.  By the way.........those HD rims and spokes are highly prone to rust and a used wheel may be suspect at the spoke nipples. An original rim with a modern tire is approximately the same height. 

[VTCBike750]

You have likely picked up what someone thought was from a CB750 but 'maybe' was from another model or brand of the era. Look up the part number and copy (compare) the casting numbers from the inside of your HONDA hub. New brake linings are available.   

Are you talking about brake shoe linings or a lining for the hub?

I have a few questions about my rear brakes.

[VTCBike750]

From what I've read, arent the punch marks are supposed to line up? Mine are off set one step. The brakes only work when set up this way. Ive tried adjusting. I checked the brake pedal, those punch marks are lined up properly. Is this something I should be concerned about?


Maybe someone can give me some insight on the hub's diameter. It has a diameter of 181 mm and is fairly smooth, no gouges or ruts. Does anyone know what is the inside diameter of a new hub?  The Clymer manual says at 183 mm the rear wheel hub needs replacement. Is the hub close to wearing out? Maybe thats why those punch marks dont line up? Any ideas? The pads are 7 mm thick. Well reassembled things and the rear brakes work well, just wondering if they are wearing out.