Half-width Brake

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Leejm
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Re: Half-width Brake

Postby Leejm » Tue Jan 05, 2016 8:03 pm

I also read in the book of the ariel to adjust the fulcrum until it won't turn no more. Which is completely wrong in my book. The brake will always be on if you do that. I set my brakes up by spinning the wheel and adjust the fulcrum at the same time until I heard rubbing and then backed off one notch at a time until no rubbing and then backed off one more notch.
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simon.holyfield
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Re: Half-width Brake

Postby simon.holyfield » Tue Jan 05, 2016 8:34 pm

nevhunter wrote:... I am now using heat proof paint now on the drum, when I build a wheel. Nev


I found that one the hard way!
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
http://ariel-square-four.blogspot.com

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simon.holyfield
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Re: Half-width Brake

Postby simon.holyfield » Tue Jan 05, 2016 8:37 pm

Leejm wrote:I also read in the Book of the Ariel to adjust the fulcrum until it won't turn no more. Which is completely wrong in my book. The brake will always be on if you do that. I set my brakes up by spinning the wheel and adjust the fulcrum at the same time until I heard rubbing and then backed off one notch at a time until no rubbing and then backed off one more notch.


I have just set up the drum by adjusting the cable to give the play I want, and secondly using the adjuster to tighten the brake until the wheel locks when spun on the front stand; then I back off the adjuster.

This seems to give the play I want, no rubbing, and there should be no bending moment on the shoes because the cable/cam end will make contact first.

What do you think? I have not tried it on the road yet.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
http://ariel-square-four.blogspot.com

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Re: Half-width Brake

Postby Vincent.vanGinneke » Tue Jan 05, 2016 9:05 pm

Glueing a full circle of emery grade 120 in the drum and walking up and down the street a couple of times while applying the brake slightly worked for me.

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Leejm
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Re: Half-width Brake

Postby Leejm » Tue Jan 05, 2016 9:05 pm

The middle of the shoes needs to touch first in theory not either end first. So you get most contact and even wear! If you follow what waller says you get neither! And hot brakes. I read before on here people having problems with overheating brakes. Due to following waller advice.
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Re: Half-width Brake

Postby nevhunter » Tue Jan 05, 2016 10:49 pm

Being able to adjust the fulcrum outwards means you can wear the shoe friction material evenly. It's the big advantage of the later ARIEL brake set-up. After adjustment it will contact harder near the fulcrum if you are going to achieve even wear on the shoe. From original setting I hardly ever adjust at the cable. There shouldn't be drag with the brake not applied, but I just turn the square clockwise until it drags and back off till it doesn't. The non leading shoe should have softer lining material or have some removed to allow even wear. The trailing shoe can hold the cam back from applying the force needed on the leading shoe, if the leading shoe has worn the most. (which is common). Nev

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Re: Half-width Brake

Postby Simon.Gardiner » Wed Jan 06, 2016 12:44 am

You're supposed to use the fulcrum adjustment to get the brake to be pulling fully on when the lever-arm is at right angles to the cable (therefore getting maximum purchase through the lever-arm).
Cable adjustment is then used to get a comfortable level of free play at the handlebar (and obviously without the brake rubbing).

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

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Re: Half-width Brake

Postby simon.holyfield » Thu Feb 15, 2018 9:53 pm

As part of winter maintenance, I have my front wheel off for new bearings, a new tube and a look at the brake. It appears that I still haven't got it right.

Take a look at this:

IMG_20180215_203058.jpg


To me, this is indicating that I haven't got the adjuster tight enough - there is about 40% contact on both shoes, at the cam end - in both shoes, there is no contact at the adjuster end. Here is the other shoe:

IMG_20180215_203109.jpg


What do you think? In both cases you can see where the lining is worn by contact with the drum. The brake is nothing like as effective as the one on my W/NG, which is obviously a much lighter bike but the brake has much more feel.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'30 Model A
http://ariel-square-four.blogspot.com

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Leejm
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Re: Half-width Brake

Postby Leejm » Thu Feb 15, 2018 10:12 pm

The way I did my brakes was to Turn the adjuster from completely off till the wheel locked counting the clicks as I turned the adjuster. Then backed off half the amount of clicks. Then I adjusted the cable end the idea behind this is that both ends are adjusted up by the same amount to keep the shoes square to the drum to get as much contact as possible. If you adjust it all at one end or the other you will only get a small contact between the shoe and drum. this idea seems to work well and both brakes work very good Lee
1948 NH, BSA D10 SPORTS. 1953 VHA, 1951 KH rigid project.

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Re: Half-width Brake

Postby DaveH » Fri Feb 16, 2018 6:05 am

The front brake on my '52 Square Four was completely ineffective, even though I'd sent the shoes off for relining. The handlebar lever would go all the way to the bar with hardly any actual braking. There turned out to be several problems:

- The exchange relined shoes were wrong, 1" wide not 1.1/8" as specified for the Square Four

- The shoes at rest were skewed sideways, probably due to cam wear. This meant they initially contacted the drum only along their edges.

- The new linings were 3/16" thick, apparently standard, but the fulcrum adjuster had to be turned in quite a ways before the shoes contacted the drum.

What I did to resolve all this:

- Obtained 1/4" thick lining material, and installed it on shoes of correct width.

- Assembled the brake plate with the fulcrum adjuster entirely out, mounted it in a lathe and turned the linings to a diameter .020" less the drum ID (my drum was 7.035", not sure if that's standard or indicates wear). This was based on advice from Vintage Brake. The thicker linings were necessary, as 3/16" linings would have left greater clearance without turning. My 7" mini-lathe had just enough capacity to accept the assembled brake plate.

- Replaced the brake cam (surprisingly inexpensive).

The brake is now entirely satisfactory (for a vintage bike) - it has a firm feel and respectable stopping power. There's also plenty of room to take up wear with the adjuster, since it's fully out now.
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