brakes

[RDfella]

Chaterlea,

good luck with your vee twin. The motor looks much like the old dog-eared japanese. Have a 350 single one of those (1936) in a '46 B31 frame that I fitted with girder forks for a period look. Another project I must finish before the reaper arrives. I've spent a lot of time working on cam profiles (not with computer programmes) but when you look at those old J A P profiles you realise they had it right way back then. Plenty of grunt and mid-range makes for a great riding experience.
 PS - why does posting Hagon J A P end up as Hagon Japanese? Bloody spell checker I suppose.

[RDfella]

Getting back to brakes, here's a pic I took today of the M21. Note my tls conversion of the 8" s/s BSA drum brake. A quick grab of the lever will bottom the front forks. Guess I was expecting too much from a Triumph backplate on the BSA hub.
And once again, my typing of J  A  P in reply to Chaterlea has been changed to 'Japanese' Arrrgh.

[muskrat]

My 7"ss front on my plunger is woeful, the 7" Ariel fw on the Cafe is a lot better. Brakes only slow you down anyway!
When japanese (or any word) gets the red squiggle, right click it an click "add to dictionary".
Cheers   

[chaterlea25]

Hi RD,
I forgot that big brother does not like abbreviations that could in some places be taken as "offensive" 
You have to put in the  full stops or write J.A.Prestwich

Yes the project engine has 20's style heads but the bottom end is based on the Mk2 postwar V twin engine that were used in ??? formula racing

John

[chaterlea25]

Hi Muskie,
The word J.A.P without the full stops does not alert the red squiggle
the letters change after you press "post"

John

[duTch]

 

If you use the outer cable on one and the inner on the other (as I did on my 8” tls conversion) you get twice the leverage compared with sharing the leverage as is the case by linking them.

 RD, Do you mean kinda like the way OIF/Comical ones operate ?

[BSA_54A10]

One thing I find surprising is the way the cams are linked. If you use the outer cable on one and the inner on the other (as I did on my 8” tls conversion) you get twice the leverage compared with sharing the leverage as is the case by linking them.

You only have the force your finger & wrist can apply, regardless of how it is applied.
The leverage come from the difference in the arc your hand to the pivot and he cable nipple to the pivot.
Then the length of the brake arm.

If you could pull 100  lbs ( which you can't ) a single moving wire gives you 100 lbs at the cam which if things are good = 50 at each lever
The Comcal set up will also give you 50 at each lever.

What a properly set up comical does is give you better control and move the brake shoes a lot quicker
A quick application causes the floating shoes to bite into the drum and get maximum self servo effect.

Clowns with no understanding of physics and inability to read the instructions decided they needed longer levers which actually made the brake substantially worse.

[duTch]

 I find that the actual 'pull' force on my Comical cable is not much at all- especially compared to the clutch cable 'pull' force...I realised this when I was removing the F-brake cable and the pissant sweged-on blob came off the end....

[Joolstacho]

If only Physics was that simple!

[muskrat]

G'day all.
Gee, I thought it was all about leverage! I lengthened the front brake lever by an inch. Made a moderate 7" into a good stopper.
Cheers

[RDfella]

muskrat -  lengthening the cam lever will give an advantage - more travel on the handlebar lever but more torque on the cam working the shoes. Had to shorten the lever on my B31's 8" s/s as it was locking the front wheel when getting over-enthusiastic into a corner.
Referring to BSA 54A10's comments, what I was proposing with the extremely feeble brake I presently have, is removing the tie rod and using a system as shown on my (modified) M21 front brake, where the outer cable is mounted on one cam lever and the inner on the other. Accoring to my calculations, that would double the force pulling on each lever.
Or maybe that's why today's boots have rubber soles - more grip for stopping the bike than the leather-soled I preferred for racing. When I returned to hillclimbing after a long absence, the only leather-soled boots I could find were horse riding ones.

[worntorn]

Rd , do you have the correct later BSA hub?
I tried the late 2LS in the A10 hub for awhile.
It didn't work well.
The later hub has the wider contact area needed for the 2 ls setup.
With A10 hub and 2 ls you have brake lining contacting spoke ends.

[Tomcat]

G'day RD fella,
I had a 1970 Thunderbolt with original TLS front brake and it was brilliant, probably due to original asbestos linings? Nowadays I have a '68 TLS on my Super Rocket and it is sh1t. I've put it down to generic car type lining material that is PC today. As I don't ride in traffic much and am used to pre planning stopping on old motorcycles I haven't bothered to fix it.
But then again as Musky says "Brakes just slow you down!"
Cheers TC

[JulianS]

My own experience over 40years of the BSA TLS setup fitted to my A10 is that it is a very good brake, provided you use the correct hub, as mentioned by worntorn, use decent linings of appropriate thickness if hub skimmed and set the tie bar as per instructions.

The A10 hub has a brake surface 1 1/8 inches wide and straight spokes, the A65 hub has a brake surface 1 5/8 wide with a substantial spoke flange which resists distortion.

The original A65 lining was a Ferodo AM14 moulded material but also available in MZ41 a woven lining with included zinc wire to resist fade. A good brake specialist should be able to select a suitable modern material. At one time a non asbestos lining called MZ Gold was available to replicate MZ41 it is possible that a similar alternative is still available - used in classic Alfa cars. Too soft a material will not help but will probably look like the surface has smeared if examined after use.

Photo shows the old MZ41 (top each photo) and AM14 A65 linings.

[RDfella]

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.