Front brake improvement. Photos added July 2014

[SPRIDDLER]

Whilst I had the wheel out to do some serviceing yesterday I took the opportunity to photo the mod which I made 6 months ago to the front brake lining on my '54 G3LS. Two pics:
Showing which is Leading and which is Trailing shoe. Arrows show direction of wheel rotation. Leading edge of leading shoe is adjacent to cam.:

100_1398 (640x480).jpg

Chalked area of lining removed:

100_1399 (640x480).jpg

I had been researching both the theory and bar room waffle (which is the leading or trailing shoe?.. so forth) behind this mod for some time. However, ignoring the long-winded science/physics involved I can only say that my practical experience is that it's worth doing: Better initial 'bite' without grabbing, more powerful retardation with less strength needed in the hand and fingers thus reducing fatigue/cramp on long hilly rides.
It goes without saying that the brake needs to be correctly set up as well - i.e. the lower brake actuating lever should be at the most advantageous angle (i.e. 90 deg) to the cable when the shoes touch the drum; shoes/backplate centralised before tightening the backplate locknut, and cable undamaged and run without sharp bends etc. etc.
Well, it has worked for me.

[GSAX1]

Nice photos Spriddler! Thanks for sharing.

I have two questions:

* Is the brake more "spongy"?
* Does it need more frequent adjustment?

Michael

[mike.dowling]

I did this mod on my Francis Barnett which has the same brakes as the Lightweights and I can assure you it really doe's work. I went from wondering if I would past the MOT to be amazed how quickly I could stop, MOT result brilliant.
I have done 2500 miles and no problems , very little adjustment required in that time.
Well worth doing, will do the Model 16 over the winter.
Regards
Mike d.

[rex.webb]

All seems to good to be true ?.BUT i must try it on one of my bikes asap.
Ride with Care and Live Long.

[SPRIDDLER]

quote:
* Is the brake more "spongy"?
* Does it need more frequent adjustment?


No, not at all spongy - mind you I've had (cheap) pattern cables with 'flimsy' outers which were wound of thinner steel and tended to compress spppprrring-like over the metre or so length, thus absorbing effort and making the action feel spongy.
I don't think I've adjusted that brake more than twice in 6 months (probably 3 to 4000 miles) and as you can see there's loads of lining left on the shoe.

You may notice that I've also chamfered the ends of the linings at 45 deg but as I always do that I can't say what effect it has had. And
there's also a very shallow cut showing near the end of the reduced lining. To get to the one and a half inches removed I took off about a quarter of an inch at a time, refitted the wheel and tried it out on the road. I had planned to cut that extra bit off but chickened out!

[jonhal]

I have seen this mod at the Ariel club for the Arrow, seems to work. Also extending the brake arm a tad will give more leveridge. One other thing is to change the brake shoe fixed pivot for a second brake cam. This seems to allow the shoes to float and be forced into the hub when the brakes are applied. Needs carefull trial and error, I did this on my Arrow and I was nearly pitched over the handlebars! The hub also got very hot, they were too good.

[armstrongdreadnought]

Hi all.
Something else worth mentioning about cam operated brakes is that the cam should turn in the opposite direction to wheel rotation. Most do, but even the manufacturers got it wrong sometimes.
The reason is that although both shoes move out when the brake is applied, one shoe touches first because of the expander geometry, and this should be the leading shoe.

Theoretically, the trailing shoe does no work until the leading shoe has worn down a bit, so a little play in the expander housing is a good thing.

[oliver]

Hiya - what I do, for what it's worth - on the basis that the trailing shoe just stops the leading shoe digging in (and also generates uneccessary heat) - is to shim up the leading shoe only using a thin washer under the thrust pin.

As a cautionary note, I would advise that if you do get the brake working well, that you ensure the brake plate centre nut is done up tight. Mine was slack and sloppy and snatched (and broke my wrist).

One other point which I didn't realise until late on - all full width hubs and late '53 single-sided hubs have better working brakes than earlier models because the operating arm points forward and the cam receives a touch of servo action from the rotation of the drum. The rear-facing lever tends to push the leading shoe away from the drum. I had this confirmed by non other than Bob Manns who turned up (to our astonishment and delight) at a Dorset clubnight a few years back.

REgards.

[Ian809MB]

I'm a bit new to this forum thingy and would like to know how I can see Spriddler's photos of the brake mod.
Cheers Ian

[Ludwig]

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Regards Ludwig