Twin leading shoe brake queries.

Singles, twins and fours.
allan.walker
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Twin leading shoe brake queries.

Postby allan.walker » Tue Nov 12, 2019 3:00 pm

EDIT:
I've had another look at the brake plate and discovered my initial analysis was incorrect (a senior moment.....) I have therefore amended the text below.

I recently purchased a modified front brake plate for an Ariel alloy full-width hub.
Supposedly, it is twin leading shoe, but.....
Whoever did the work removed the fulcrum adjuster and replaced it with a second brake cam spindle. On the outside of the plate, the two arms are connected by an adjustable rod. So far, so good.....

On the inside, both shoes float. Each shoe has one original flat end and the other end has a machined wedge-shaped abutment fitted to it.

Does this particular modification look familiar to anyone? Has anyone got one like this?

Every TLS brake I have had in the past had one end moved by the brake cam whilst the other end rested against a fixed post (either floating, or the shoe had a semi-circular recess which rested on a pivot post.) On this one, the cams have been made 'single- sided' so that the 'trailing'end of the shoe rests against a cylindrical part of the cam spindle, opposite to the cam 'lobe.'

I have not tried the brake on my bike yet. I am too concerned about the engineering fundamentals to take that risk! I understand that there have been TLS conversions made for the fw hub, but I have never seen one 'in the flesh,' or any photographs of the internals.
Can anyone shed any light on this apparent oddity that I have acquired, please? I apologise for the lack of photos; I assume that it is possible to post them on here but I have yet to discover how!
Last edited by allan.walker on Wed Nov 13, 2019 10:39 am, edited 1 time in total.

allan.walker
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Re: Twin leading shoe or twin trailing or what??

Postby allan.walker » Tue Nov 12, 2019 5:10 pm

I've just found the instructions on uploading pictures, so I'll venture into the garage tomorrow and take some.

Watch this space...... :?

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paul.jameson
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Re: Twin leading shoe or twin trailing or what??

Postby paul.jameson » Tue Nov 12, 2019 7:31 pm

If it is simply an original Ariel brake plate which has been modified it is likely to give trouble anyway, due to being very thin around where the brake anchor arm bolt is. Failure here is common, which accounts for the widespread efforts to produce more reliable brakes on the alloy hubs.
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Re: Twin leading shoe or twin trailing or what??

Postby nevhunter » Tue Nov 12, 2019 9:28 pm

I'm with Paul on this. It's not safe to fiddle with those brake plates. Start from scratch with a properly designed twin shoe, if that's the way you want to go. I'd recommend a good inspection of all original ones in use too for wear, corrosion and cracks. Nev

john.whiting
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Re: Twin leading shoe or twin trailing or what??

Postby john.whiting » Wed Nov 13, 2019 3:41 am

Even with just a single cam,they are sort of twin leading shoe,due to the girling design.......the FW ally front had a reputation for grabbing ,and BSA junked the design after just one season,and went to the cast iron hub.

allan.walker
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Re: Twin leading shoe brake queries.

Postby allan.walker » Wed Nov 13, 2019 10:47 am

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allan.walker
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Re: Twin leading shoe brake queries.

Postby allan.walker » Wed Nov 13, 2019 10:52 am

I have read various reports about the fragility of the Ariel fwh brake plate. At this stage I'd just like to see if this thing is workable or not! If all else fails, it will be a case of finding a different wheel/hub with a TLS brake.

allan.walker
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Re: Twin leading shoe or twin trailing or what??

Postby allan.walker » Wed Nov 13, 2019 10:57 am

john.whiting wrote:Even with just a single cam,they are sort of twin leading shoe,due to the girling design.......the FW ally front had a reputation for grabbing ,and BSA junked the design after just one season,and went to the cast iron hub.


Hi John.
I'm not sure that I understand this. I realise that the fulcrum adjustment is an oddity in the motorbike world, but, once adjusted, that end of the shoes is basically 'fixed' when the brake is operated - the other ends of the shoes being spread by the cam.
Doesn't this mean it is just a single leading shoe brake (or am I missing something? :oops: )

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Re: Twin leading shoe or twin trailing or what??

Postby allan.walker » Wed Nov 13, 2019 10:59 am

paul.jameson wrote:If it is simply an original Ariel brake plate which has been modified it is likely to give trouble anyway, due to being very thin around where the brake anchor arm bolt is. Failure here is common, which accounts for the widespread efforts to produce more reliable brakes on the alloy hubs.


It is certainly an original Ariel plate (casting numbers inside, etc.)

Have any of the efforts to produce a more reliable brake actually been effective at all?

john.whiting
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Re: Twin leading shoe brake queries.

Postby john.whiting » Wed Nov 13, 2019 12:04 pm

Looks quite well done,not yer average bodge....or are the bodgers getting scientific...........I d just stick a couple of crumpled newspapers inside the helmet for extra protection and try it on the road....Or would I ?.......was at the medicos today to get flu and pneumonia shot, he clocked the helmet ,and informed me that if I break a bone at my age,I have only a 25% chance of surviving....I said me knees are too crook to walk,so Ill take the odds.


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