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[jawa-enfield]

This is a pic of how small i machined the brake cams.. about or less then 50% of original width. so the pressure on the drum must be twice as hard..
Ver soft/graspy linings.. made to fit on diameter and the drum hardly brakes.
Strange thing is, after adjusting first attempt to brake is hopefull, after that braking gets less and less and no, brake does NOT drag, brake comes freely loose every time.

[p]

Whilst the nut is off, very slight dressing with a file will enable the box spanner in toolkit intended for rear wheel to fit.....
Surely because of the conical nut all this business of centreing whilst tightening etc is of limited use, doesn't it always self centre itself anyway? (if it's machined wrong - it will remain wrong?)

[jawa-enfield]

The 2 nuts i had, one original, one from our host, do NOT fit or match the conical shape in de brake plate at all..
I happened to find one which did fit- in theory it should centre itself to some degree..

[stinkwheel]

Surely because of the conical nut all this business of centreing whilst tightening etc is of limited use, doesn't it always self centre itself anyway?

Short answer. No.

This is one of those situations where theory does not match reality.

I suspect because the definitions of "round" and "centered" are being pushed beyond breaking point. If you don't physically centre the thing (relative to the shoes and drum, rather than the hub centre axis and brakeplate), it's perfectly capable of being far enough out to put the cams over-centre and lock the brake on.

[trophyvase]

Can someone explain the mechanical logic of this:
about or less then 50% of original width. so the pressure on the drum must be twice as hard..

I'd have thought the opposite was the case.
'Give me a lever and a place to stand and I will move the earth'
Cut the cam away until there is no cam and there will be no pressure on the drum.
Enlarge the cam to one foot width and more pressure of the drum.

??????

[trophyvase]

BTW – and NOT my findings but those of a mathematician (which I am NOT!)

Archimedes would need a lever that was 10/23 1023 [that can't be written right on this forum] meters long – that is a distance of 10 million light years. That lever would then need to be moved a distance of 10/20 1020 meters to move the earth just 1 mm. If the lever was moved at the speed of light it would take 10 thousand years to push it that far – enough to move the earth just that 1mm.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[stinkwheel]

I'd have thought the opposite was the case.
'Give me a lever and a place to stand and I will move the earth'
Cut the cam away until there is no cam and there will be no pressure on the drum.
Enlarge the cam to one foot width and more pressure of the drum.

??????

It's about reduction gearing, the ratio between the brake arm and the cam. Long brake arm attached to a short cam = easier to apply more pressure but a larger arc of movement to move the shoe the same distance. Think of a bicycle crank. If you make the crank (brtake arm) longer or the sprocket (cam) smaller, the bike is easier to pedal.

Yes, if you had a cam a foot long, and managed to move it through the same arc, it would apply an enormous pressure but you couldn't use it. To use the bicycle analogy, you could fit a 100 tooth front sprocket and it would in theory go super fast, however you wouldn't be able to move off the spot. Whereas if I fitted a 20 tooth sprocket, it wouldn't go very fast but I could apply an enormous anount of pressure to the rear wheel and ride up Hardknott pass.

[jawa-enfield]

Just informing yo; front brake is still very unstable... after adjsuting at one of the 3 methods (with normal bike, all 3 methods come out at the same point, with the enfield it does not. Which way adjustemnt it 'wants'is trial and error every time)
at first, braking is almost reasonable, then after a few hundred km's or so, brake gets lazy again.. and yes, it has free play/does not drag.

I have reason to belive that besides very big tolerances in the holes of the braking cams, these holes(at least one of them) are drilled not straight, pushing the lining under a angle againt the drum. This can explain the wear only on the outer half of a (new) lining and the variation in adjusting it.
Plan is to drill the holes straight and press bronze bushes in them.

This might be the last thing i try to get the brake normal working,.
I really love my enfield diesel, but for over 12 years i am trying to get the brake in order.. 3 hubs, 4 plates, many, many different lingings, things on the lathe, of the lathe, makes no diffewrence.

[jawa-enfield]

Summary;
Brake does not work well,
If it almost does work well, braking gets less over time and yes, brake returns good and no drag.
When you adjust the brake with the extension-lever method (Snidal?) you get a total different point of adjustment when you do it by hearing, with the latter method, you get the end result of ca 5 full turns 'thighter' of the connecting rod. And THAT does not make sense? (with an other bike/brake, you get about the same adjustment)

After a while, when braking worsens, it demands a totally different adjustment. Which was of adjusting gives the best result, you cannot predict.

Despite the linings made on radius on the brake plate, 1 of the linings touches the drum under an angle (what also is higly illogic)

Some of you claim to have a reasonable or good working front brake.

Which year of wheel, which type of brake plate, which cam width and what kind of linings do you use?
I have tried 2 wheels, 3 brake plates and 8 different linings.. The drum does not respond different to any lining.

[Jamesy]

That front TLS I could never get working anywhere near as good as a disc break.I got it reasonable but not good enough for me.Funny the rear drum brake was really good.There was a New Zealand member whos name I forget who used to bet he could get it working good as disc brakes.