Single width brakes shoes and cams

[Keith.owen]

Hi,
I have collected various bits along the way and have noted that:
The width of brakes shoes varies.
In my box of bits I have two widths of cast shoe and one type of steel shoe.

Also, I have a number of brake cams all of different lengths extending from the shaft outwards, so would have a different mechanical advantage. Also, some have the squared section, over which the lever is seated, at an angle to the cam whilst another has this in line with it.

Can anyone identify their different uses.

I have a rear brake plate (rigid) in which the cast adjuster body id riveted to the plate and seems to be accompanied by narrower brake shoes. So is this a pre-war assembly?

Also, me being me, I am tempted to ask if anyone things there could be some advantage to be gained by fitting the cams with the shorter reach to a front brake, possibly getting more leverage / stopping power?

Any thought?

BR,
Keith

[nevhunter]

Just make the trailing shoe wear faster, then it won't hold the Leading shoe from gripping. Original Rivetted shoes had one soft one, which could also be a bit shorter. Makes a BIG difference. .

[Keith.owen]

Hi Nev,
Thankyou for this important piece of information.

This is very much worth considering (particularly with modern traffic conditions)>

Keith

[Roger Gwynn]

The length of the cam will not affect the leverage, the length of the brake arm will. Longer arm =more leverage and more movement.
See Draganfly wheels page for the story of lots of brake shoes, when they changed etc.
The riveted on adjuster block is from 1932-34 and from 1942 is bolted on.
Properly set up brakes work well enough. Follow Nev's advice either a softer or shorter by about 1/13 lining on the trailing shoe.
The longer cams are either early rears or girder ones.

[simon.holyfield]

Follow Nev's advice either a softer or shorter by about 1/13 lining on the trailing shoe.
The longer cams are either early rears or girder ones.

So, file back 1/13 of the length of the lining so that it's ineffective?

[Roger Gwynn]

Yes, on a single leading shoe brake the trailing shoe is less effective than the leading shoe so wears more slowly thus preventing the leading shoe from contacting the drum effectively. The aim is to make them wear at the same rate either by making the trailing shoe softer or shorter. The VOC did a big bit of research, as they would, and came up with recommendation for a softer lining. The article may be available somewhere.

[will_curry]

Is this the article?

[Roger Gwynn]

The V was for Vincent not Velocette. The Vincent one went on for numerous pages with graphs showing variations in coefficient of friction against temperature for various materials. It was like a PhD thesis. I think Rob is wrong in removing the material from the leading edge of the trailing shoe as this part does contribute to the braking, whereas the trailing end contributes very little except to prevent the rest of the shoe touching the drum. I stand to be corrected by someone whose brain is working better than mine. Cue long discussion....

[nevhunter]

Removing it from the leading edge of the Trailing shoe Increases the Leverage and braking effect of the rest of that shoe and also allows more wear to keep pressure on the Leading shoe. One consideration is, is the "Trailing" shoe itself strong enough to not bend or break? You can very successfully tweak these brakes if you Know what to do. Nev

[Keith.owen]

Hi,
Not sure what is meant by Nev when he says 1/13 of the lining?

Obviously remove some lining, but how much?

Keith