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[Lord-Toady]

I have found a paragraph in Snidal's book:



Centering the Operating Cam Bush

The bolt holes in the cover plate for locating the rear brake cam bush are slotted, to enable the brake shoe assembly
be centered in the drum. Before fitting the brake cover plate back into the drum, loosen the locknuts and the cam bush
retainer mounting bolts. Then, fit the cover plate assembly with the new shoes over the spindle into the brake drum
and apply the brake as hard as possible by means of applying toque to the operating lever - a large adjustable wrench
on the end of the lever will be helpful. This will center the shoes in the drum. Then tighten the mounting bolts as much
as possible, remove the cover plate assy, and complete tightening and replace the locknuts. Now check the arc.


The trouble is tightening the those bolts when they are on the inside.

[ric]

Re the bolts, it’s quite possible the design has changed or that mine are that mine are non standard, The brake cam itself has certainly changed over the years as has the brake plate.

[Wheaters]

Strangely enough, it's not unusual for the slave cylinder of a hydraulic drum brake (equivalent of the cam of a rod brake) to be designed to "float". My little car which uses drum brakes at the rear are exactly the same design as Triumph Spitfire and Ford Cortina and they are like this. It ensures that equal pressure is applied to each shoe. With a fixed operating cam or wheel cylinder, as soon as one shoe wears more than the other (and they often do), the braking forces are no longer equal.

Having said that, if the cam plate screws on this brake are done up lightly and the equalisation process is carried out by applying the brake hard as already described, with care I think the drum could be removed without disturbing the cam so that the screws can be fully tightened up.

I think the problem with this bike is that perhaps the cam mechanism has worked far too loose and been "rocking" slightly, which is why the operating face has worn on one corner.

[papasmurf]

Wheaters, practically every car I have ever owned has has floating slave cylinders on the rear, (most were also supposed to be self adjusting as well so the hand brake should have never needed adjusting. (In theory.)
It usually took a big hammer and WD40 ever so often to get them to work properly.
The adjusters also needed over tightening, and then slacking back until the wheel turned freely.

[Wheaters]

Yes, I've worked on a whole host of cars since about 1975 and seen many different types of rear brakes. Later rear drum brakes adjusted via a mechanism linked to the handbrake cable, which was designed to take up "lost" shoe movement using various methods such as a ratcheted arm and sprung pawl. More recently we've had all marks of Ford Fiesta up to Mk 6, Suzukis, small Fiats etc, etc here, all slightly different.

The ones on my trials car have manually adjusted "solid" adjusters and a floating slave cylinder which is held in place in a slot by two interlocking "U" clips on the outside of the brake plate. It takes a minute each side to adjust them via a small spanner and I don't even have to jack the car up to do it; I can reach from the back of the wheels.

[p]

I didn't know the cam bush plates were threaded - I'm really not sure mine are, but if they are, a little screwdriver slot would be easy to cut on the bolt ends with a hacksaw to facilitate tightening enough while removing to do up properly....

[Lord-Toady]

The holes in the cam bush are threaded so cutting a screw slot is a good idea.

[Lord-Toady]

I just spent the better part of the afternoon finishing off and putting the brake back on the bike. I didnt bother cutting slots in the bolts i just did them up a little bit and on the bench used a big adjustable spanner on the brake actuator to expand the shoes and locate the cam bush. I then took the shoes back out and did up the bolts as tight as i safely could with an 11mm spanner. The hardest part was wrestling the wheel back on and i had some trouble with the centre spindle in the brake assembly not wanting to push all the way home into the bearings as it was disturbed while i was putting it back into the frame so had to take it out and clean and grease before driving it home. I went for a short test run around the block adjusting the brake rod as I went and I now have a nice progressive rear brake with no snatching or untoward grinding noises so cheers to all who advised.

[Lord-Toady]

Also because its progressive now with no snatching I can adjust the brake a bit harder than before so have better braking. I had to have loads of play in the pedal before.

[Jamesy]

Forget my post I was referring to the front brake.