Author Topic: brakes  (Read 1279 times)

Online muskrat

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Re: brakes
« Reply #30 on: 05.08. 2018 21:20 »
G'day RD.
I would think 40% more break shoe contact would make a big difference. Never done this mod myself but I have a hub & breaks in a box for use one day.
Cheers
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Australia
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Online chaterlea25

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Re: brakes
« Reply #31 on: 05.08. 2018 22:08 »
Hi RD,
There's an ebay seller from France who has lots and lots of NOS brake linings for old Brit bikes
https://www.ebay.co.uk/str/GP-Motos-Anciennes?_trksid=p2047675.l2563
He has a lot more than advertised on ebay and also travels to UK autojumbles

John
1961 Super Rocket
1963 RGS (ongoing)

Offline worntorn

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Re: brakes
« Reply #32 on: 05.08. 2018 23:10 »
Yes, it's the '58 A10 hub, with T120 backplate. The spokes are well away from the linings and anyway, width should not have too much affect - diameter (eg 8" v 7") is more important. Am in agreement about lining material - never found any of the modern materials any good, whereas the old asbestos ones were generally fine. Just can't seem to find suitable material at all these days. What one gets looks and feels like cardboard.

Tried it that way and it did not work well at all, which seems to be what you are finding.
Switched to proper matching drum and brakeplate, presto , excellent brake.

Glen

Online JulianS

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Re: brakes
« Reply #33 on: 06.08. 2018 09:13 »
I dont think the A10 hub is strong enough to resist distortion, especially when skimmed. That verticle spoke flange makes it more rigid as well as cooling better. See photos of hubs below.

The shoe area does make a difference, especially to cooling and lever pressure, but the main thing is contact - a skimmed hub and standard linings will give poor initial contact, just the leading edges of the linings until they wear to conform to hub diameter.

NOS ferdodo linings come up on ebay very regularly - the Ferodo reference for the TLS lining to fit the drilled original shoe is BS/24/1.

Online Joolstacho

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Re: brakes
« Reply #34 on: 06.08. 2018 09:49 »
Yeah, look, we all know (well, anyone with any experience) -knows that a well bedded-in brake makes ALL the difference.
This is why machining the assembled shoes makes a big difference - basically all it's doing is shortcutting the initial wear mileage (where it's all slightly out of whack), so the shoes contact the brakedrum track with maximum CONTACT AREA.
If you think 'servo effect' is going to do it for you, well, in my opinion, you're living on a different planet to me. Servo action will always be better with a bigger contact area yes?

All other things being equal, the shoes need to contact the brakedrum with as much contact area as possible. It's too simple.
Shoe material is of course another matter. But don't worry about that until you have good contact area.

The '68 -'69 Triumph/BSA TLS setup is the go. To get it on an A10 you need the later fork sliders.

Online RDfella

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Re: brakes
« Reply #35 on: 06.08. 2018 10:50 »
Lots of good info from you guys. My experience of what to expect from vertical twin BSA's is limited - had a rigid A7 in the early sixties and a 6t (triumph) engined Triton in the 70's but otherwise all my bikes have been singles or vee twins.
Reason I've gone down the route I have is because I wanted to keep the bike as original as possible. With my setup, only the backplate needs to be changes to get back to standard. Otherwise, as other have noted, it's not only a different wheel but a change of sliders too. If I was going that route, I'd have changed both wheels not only for better brakes, but to save weight. Those wheels with cast iron hubs weigh twice that of most other wheels. To be frank, those hubs must be an Umberslade 'expert' design as I can't understand why BSA would fit such a lemon.
At present I'm minded to persevere and see if I can get some better linings. Don't agree with the idea that width makes a difference, though. Might help cooling and wear, but no real effect on braking effort. Braking effort is a function of friction of the linings on the drum (or disc). ie the coefficient of friction of the two materials x weight (the force of the lining on the drum or disc). Surface area doesn't come into the equation. Or so I was taught when working at F.V.R.D.E. in the 60's.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online Joolstacho

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Re: brakes
« Reply #36 on: 06.08. 2018 11:07 »
So mate, how does the width have no bearing on this?
"Braking effort is a function of friction of the linings on the drum"
Friction area?

Oooh I just want to add, some of England's best brakedrums are solid, heavy cast iron drums. Don't be too quick to label them as "lemons". (Think dimensional stability under temperature variations).

When I feel the weight of my cast iron Velocette VM front drum I think... "jeezus, why so heavy fer gawd's sake?!!!" But then when I ride it, I realise just how good a simple single leading shoe 7" brake can be, I forgive the weight, - those engineers knew their stuff, Velo did have the 'engineering class' to make the hub in 2 halves... braking side cast iron, the other half, aluminium.

One of the problems (IMHO) with the conical TLS brake is that it had a shrunk-in iron liner in an alloy hub housing, -and then they compounded the problem by having cruddy pressed steel brakeshoes, with all the heat distortion that comes with all that.
And then (insult upon injury)... they put in a bluddy brake switch inline in the cable, so you had to squeeze out that 'play' before the cable even had any effect at all on the cam levers!

And we wonder why...

Online bsa-bill

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Re: brakes
« Reply #37 on: 06.08. 2018 11:40 »
Quote
Braking effort is a function of friction of the linings on the drum"

Just guessing, but think for a given effort (lbs at the lever) a wider area will have less friction per square inch than a narrow one but over a larger area, then you have heat generated / dispersed, mmm not exactly  E=MC thingy but just a bit beyond my long division
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline worntorn

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Re: brakes
« Reply #38 on: 06.08. 2018 17:02 »
I didn't change the sliders, just built up the brake plate stay boss with aluminum Tig and milled to true.
You need to do this or change sliders regardless of whether you use the correct width hub or the A10 hub.
Using the 2ls brake plate as is with the stock A10 forks is a recipe for disaster.
The 2ls stay is barely held from turning by the A10 forks, just hanging on by a tiny bit.

At least that is how my setup lined up.

Glen

Online RDfella

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Re: brakes
« Reply #39 on: 06.08. 2018 20:17 »
worntorn - so the only difference is the backplate / slider contact area? I saw the contact area was unsafe and so I remedied that - machined out the original lug in the backplate and got a friend (my TIG welding is ghastly) to weld a new, longer, alloy lug that I had made in its place. I then machined the slot for a good fit. Doe this mean that the later A65 hub will fit? I was presuming it was because it was mounted as on the B series and RGS, where the axle screws in instead of clamping up.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online JulianS

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Re: brakes
« Reply #40 on: 06.08. 2018 20:41 »
Had the alter A65 hub fitted to my A10 for over 40 years, all that was needed was for the brake plate to be built up to give sufficient engagement with the fork lug.

The A65 lug is longer.

Photo 1968 type A65 fork top, A10 beneath.

Offline worntorn

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Re: brakes
« Reply #41 on: 06.08. 2018 21:03 »
Rd, my experience with the brake is same as Julian's except I added to the brakeplate as you have done.
Works fine with the A65 wheel.
I was fortunate in that I purchased a complete A65 wheel for $100. As mentioned, I tried with just the 2 ls plate in the A10 wheel, but that didn't work well at all.
The A65 wheel was quite rusty but cleaned up  Ok

Offline worntorn

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Re: brakes
« Reply #42 on: 06.08. 2018 21:06 »
A65 wheel cleaned up

Online RDfella

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Re: brakes
« Reply #43 on: 06.08. 2018 21:25 »
Forgive my confusion (I said I wasn't au fait with BSA twins) but the photos Julian shows are both screw-in sliders. My A10 has the clamp type. Different axle. The screw-in type is what I know is fitted to most B series and, I believe, the RGS when the 8 in s/s brake was fitted. Hence my query about changing sliders.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online JulianS

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Re: brakes
« Reply #44 on: 06.08. 2018 22:46 »
No they are both clamp types just dont have the lower clamp shown, photo shows A65 brake, hub and forks fitted to my A10.