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[Clive The Motorcycling God]

Without doubt Beezabryan and TimNZ that is the case.
Get the dammed floating bush thingy set right and you should get excellent rear wheel braking without buying the longer arm. I bought one before I did any research with only small improvement. Then I took the wheel out. Bite the bullet !!!!! and get the back wheel out and sort it. Pays dividends.

[brokeLad]

Thanks for all opinions. It seems the general consensus is to free the floating bush, apply brake and then tighten down presuming both shoes are in contact with hub………rather than leaving the bush floating?

My sixty5 has brake pedal on the right with link going across chassis to the lever on the left….I'm guessing this could also be affecting efficiency?

[jefrs]

brokeLad, unless your full weight and then some is capable of bending the brake lever and twisting the transverse pivot, I doubt your across-the-bike RHS brake pedal is the problem. There is some 'spring' in the system but my full 100kg/15-stone cannot bend the long lever on my C5, strength and stiffness of the parts seems to be adequate.

The rear brake should be capable of locking the back wheel with the clutch in, or you're fighting a lot of horses. If you are needing to use undue pressure then something is wrong, and it's not the leverage from the pedal.


The pedal has a 'mechanical advantage' and should only require a light touch to put the brake on. Then it's down to friction - both shoes have to kiss the drum.

It's no good only having the tip of the lead shoe doing anything. Is there a chance the linings are shot or glazed?



Brake linings are not the place to skimp on quality.

[ric]

One of the problems is bad machining of the components. I had a brake cam that wasn't machined parallel to the main body so the shoes would twist upon opening so only the edges of the shoe would make contact with the drum. It's replacement had just one face parallel, so a slight improvement and easy to rectify. I've also had a bush carrier that wasn't faced square to the main body. With quality like this it's almost impossible (without access to machinery) to get a decent brake

A 50p box of chalks has proven to be the best investment I made to identify any problems and end up with an efficient rear brake. Be warned though, I had the rear tyre slip on the rim under severe testing which tore the valve holder and left me with a flat tyre.

[jefrs]

Well I've been inside the brake now and loosened off the bolts freeing up the pivot. Before I did that it was only applying the trailing shoe. I've also moved the lever arm back a notch or two to lessen it's mechanical advantage.

Shorter brake arm, less brake pedal travel!



Now however the pivot mechanism drops under its own weight as we go along, however the shoes never contact the drum when the brake is off. The upper shoe is the leading shoe, so the mechanism falls under gravity towards the trailing shoe; by rights the trailing shoe shoe contact the drum slightly ahead in normal operation. In operation the brake goes firm and actually stops the bike, like 300% better efficiency; the lead shoe is working

But I may then have left the pivot bolts too loose. I now reckon they should be pinched up just enough so the pivot stays put over lumps and bumps, cannot be moved 'by hand' but can be moved under the full weight of your foot - so the shoes centralise and stay put. That means I would be able to tighten the rod adjuster some more before the shoes touch the drum.

[jefrs]

tpyo "shoe shoe contact" = "shoe should contact" doh!

[PeteF]

Your right, you can tighten the pivot reasonably firmly but your boot will still move it. Once it's centralised it hardly has to move again except for wear in the linings.

[jefrs]

One thing not noticed in the 'previous thread' is that the outer two nuts are lock nuts, the pivot body is threaded, so you can set the tension needed. Lubrication on the mechanism is, like a cars slave cylinder, a thin smear of copper grease (because this stuff stays put), also used on the shoe fulcrum.



Tightening the outer two nuts just serves to lock the bolts in place not hold the pivot block in place, over-tightening them 'as much as possible' will just result in shearing the bolt off. Nyloc nuts I tried are too tall for the exposed thread on the bolts (the nylon part does not engage thread), plus they serve no purpose today. The lower of the two bolts is longer to anchor the return spring.