Twin leading brake

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Re: Twin leading brake

Postby SPRIDDLER » Mon Apr 29, 2019 8:12 am

dave16mct wrote:A member a few years ago used to offer a service to modify your standard brake plate, making it twin leading shoe. I think his name was Dagger. Ex chairman Malcolm has one on his CSR.
Dave.

That fine engineer and long time club member Malcolm Saggers (RIP) produced a hydraulic twin leading shoe conversion of the standard AMC front brake.
See here in Tech Articles:
http://www.jampot.com/article_read.asp?id=250
I poke badgers with spoons.

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Re: Twin leading brake

Postby bob121 » Mon Apr 29, 2019 2:00 pm

That was an interesting read. Although I don't want to go hydraulic. I've looked at the plate and have an idea of how it can be done. I'll pick up a plate sometime and have a play.

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Re: Twin leading brake

Postby bob121 » Mon Apr 29, 2019 6:34 pm

Andy51 wrote:If you look on the club website photos (I do not know how to post links on my iPad) under pictures/bikes/classic road machines/TLS front brake you will see a very professionally made 2LS conversion to the standard AMC 7 in front brake by a member called Poul. The brakeplate work looks difficult but 'do able' on a lathe and milling machine, but the machining of the cam is brilliant but looks extremely difficult. I am currently working on fitting a Honda CB 250/350 2LS brakeplate (180mm) into a '55 on AMC hub, but it isn't that simple - will report progress in due course. I have just completed work on fitting a BSA single sided 8 in hub into teledraulic forks (needs new axle making) as they were reckoned to be one of the better brakes of their era. PM me for details. Andy


Similar to what I had in mind. Although I was thinking of just using two std cams. I was also thinking of rotating the plate so the torque arm was to rear but still keeping the cable mount to the front. Thank you for pointing out those photos. They will help to mentally run through options before doing any work.

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Re: Twin leading brake

Postby robcurrie » Tue Apr 30, 2019 4:10 am

bob121 wrote:Similar to what I had in mind. Although I was thinking of just using two std cams. I was also thinking of rotating the plate so the torque arm was to rear but still keeping the cable mount to the front. Thank you for pointing out those photos. They will help to mentally run through options before doing any work.


Do I understand correctly that you want to put the torque arm in compression instead of tension? If so, then you will be making a dangerous mistake as has often been pointed out on this forum.

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Re: Twin leading brake

Postby bob121 » Tue Apr 30, 2019 8:51 am

robcurrie wrote:
Do I understand correctly that you want to put the torque arm in compression instead of tension? If so, then you will be making a dangerous mistake as has often been pointed out on this forum.

Rob C


Just considering the possibility. I've only got a picture in my head at the moment. Only been thinking about it for the last week. Either way, I think the torque arm would have to be replaced with one that has more material surrounding the anchor point.

That's why these posts are helpful. A good sounding board before starting.

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Re: Twin leading brake

Postby Martin.S » Tue Apr 30, 2019 11:11 am

No - not just beefing up around the hole. Take a piece of paper and hold it between finger and thumb of each hand and then try and pull, the paper is now under tension and will not rip, now push your hands together - the paper was then under compression and it has collapsed - you don't want that happening to your torque arm!!

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Re: Twin leading brake

Postby bob121 » Mon May 20, 2019 2:37 pm

Got fed up this morning, so I took the aj out. Ended up at the sarecens head in Ross-on-wye. Via Worcester, Evesham, Tewkesbury and Gloucester. Shot back up the m50 and m5. Looks like I need to retorque the head. There's some oil sat on the engine, but not much. Not bad for an 150 mile round trip.

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Re: Twin leading brake

Postby bob121 » Tue May 21, 2019 6:06 pm

Worked out today that I averaged 62mpg yesterday. Don't think that's too bad. Spent most of the time at 50-60 mph, apart from the motorway. That was 60-80. On an engine that's only done a thousand miles.

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Re: Twin leading brake

Postby mdt-son » Fri Aug 09, 2019 2:52 pm

bob121 wrote: Either way, I think the torque arm would have to be replaced with one that has more material surrounding the anchor point.

You should take a look at the torque arm fitted on Teledraulic forks for 1967-69 G80CS and P11 models. It may be the answer to your requirements.

-Knut

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Re: Twin leading brake

Postby mdt-son » Fri Aug 09, 2019 3:02 pm

bob121 wrote:That was an interesting read. Although I don't want to go hydraulic.

Why not? Malcolm Sagger's 2LS hydraulic conversion is brilliant and ensures much more friction force than can be produced by a mechanical brake - ever.
The only drawback to a disc brake is fading on long and steep downhill roads, but how often do you really need no-fade performance?
On the upside is instant stopping force in the wet, which can't be said of a disc brake. Much more useful, IMHO.

It wonders me that no one is offering this conversion today.

-Knut

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