The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: RDfella on 02.08. 2018 21:16
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Hello fellas.
The A10 GF saga continues. Full restoration of engine, frame, gearbox and tinware was a nightmare at every stage. What wasn’t worn out was either bodged, missing or broken. Anyway, took it for its first test ride yesterday. Frame handles well - one of the best of the dozens of bikes I’ve owned / ridden over many years. Gearbox is fine. Engine has an intermittent annoying chain-like rattle. Not the dynamo or primary chain. Will have to look into that.
But the brakes. What brakes? I wasn’t impressed with the standard sls full-width setup, so made a tls conversion. Wasn’t keen on the sponginess so opted to fit a Triumph tls backplate unit. I had skimmed the drum, and it is still round despite the usual struggle to force a modern mis-shapen rim into a reasonable circle. The linings are new and a good fit. The linkage is properly adjusted, yet the brake is next to useless - the rear brake has considerably more stopping power than the front.
My M21 has a single-sided BSA 8” drum with tls conversion. It will bottom the forks. My B31 with sls single-sided BSA 8” drum will lock the front wheel. But this Triumph / BSA set-up on my GF wouldn’t skid on gravel. I appreciate that the older and no longer obtainable woven asbestos linings had far superior stopping power compared with modern materials, but this is unsafe. Anyone had similar issues, or should I change the wheels for something better? Those wheels are absurdly heavy and I could find far superior items, but I was trying to keep the bike as original as possible.
I realise brakes have been covered elsewhere, but a quick trawl didn't really throw up anything other than the consensus that these full-width brakes are rubbish.
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G'day RDfella.
Those brakes should be a LOT better than the standard. Something definitely amiss. Been 40 years since I had one so can't really shed light but I'm sure a member will be along to do so. Good luck.
Cheers
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Our A10 has the same setup as yours and the brake is good. There must be summat up.
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^^what the other guys said ^^....I had one on mine on first rebirth, and as far as I recall it worked ok.....
** The same TLS was also fitted to '68-'70 BSA twins (may have different stamp numbers), so you can at least pretend it's one of these *smile*
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The BSA/Triumph full width TLS is usually a fine brake, it can feel spongy but the stopping power is still there.
Some modern grey anonymous linings leave much to be desired.
You can get woven asbestos free linings fitted by a number of suppliers including Villiers services;
https://villiersservices.co.uk/index.php?main_page=page&id=9&chapter=4
With a skimmed hub you need thicker linings or just the leading edges will contact the drum.
The original A10 full width hub with straight spokes does loose strength when skimmed. The BSA/Triumph hub with verticle spoke flange is much stronger and resists distortion.
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The 'racer's trick' is to set the brakeplate up on a lathe, shim the operating lever(s) a touch so the shoes are JUST opened a mm or 2, then machine the shoes so they will be dead circular WHEN THEY CONTACT the drum track. If you examine the shoes as is, you'll probably see that they are only contacting over limited areas. You might need to start with oversize linings.
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.... ** The same TLS was also fitted to '68-'70 BSA twins (may have different stamp numbers), so you can at least pretend it's one of these *smile*.
For what it's worth, and I'm sure you're aware, I better note that the '68 TLS is slightly different to the later ones #37-3462 (like mine- Just checked), but don't know if the Try- hard ones are same #number
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Hi RD,
The rear cable operated brake has a poor reputation usually because it has been set up badly and because of the wrong length cables being fitted
Your bikes rear cable /arm angle do not look too bad though?
The pattern shoes available are crap *ex*
Originally the A10 rear linings were thicker than "normal", thin linings will make the lever angle wrong
The shoes need centering in the drum, loosening the pivot nut and re tightening with the brake applied
I used to get Supreme motorcycles to fit the softest non woven linings they had to original shoes
get them oversize and machine them to size
Sadly Supreme are no more, but I found a company nearer home that have the same material *smile*
They use it to reline shoes for classic rally cars
The only thing I can think of about the TLS front is the quality of the linings??
John
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Mechanical brakes have to dig into the drum to use the momentum of the drum rotating to force the shoes into the drum.
There is no way a human hand or foot can apply enough energy to stop a motorcycle.
Thus the shoes are radiused to a slightly digger diameter than the drum.
When the leading edge his the drum, the drum forces it to flex and press against the drum.
Think about the last time you were driving a car and the engine cut out so the power booster was not working.
Two feet on the brake and all your muscle power barely slows the car down.
Hydraulic brakes are ground to the same radius as the drum because they are being forced into the drum by 300 to 3000 psi
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Think about the last time you were driving a car and the engine cut out so the power booster was not working.
Two feet on the brake and all your muscle power barely slows the car down....
well...um..hasn't happened in a while, but you're now bringing in Power assisted(boosted) that's a bit of a different equation...?
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Thanks for those replies. fellas.
Consensus appears to be linings. As I said in my original post, I’m no fan of modern lining material and have never found any to match the effectiveness of woven metal-reinforced asbestos. Having said that, this brake is not just bad, it’s appalling. I’d expect a new installation to be poor (it’s only done 4 miles so far) and to improve over a couple of hundred miles, but this starting point is so low it’s never going to be acceptable / safe. It’s even worse than BSA’s lousy 7” single-sider. Maybe an agricultural supplier somewhere has some NOS asbestos linings of appropriate thickness that I can cut to suit. Any suggestions in that area appreciated.
In the meantime I’ll pull the front brake – again – and see if I can improve anything. 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.
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Took a bit of fiddling and now my Super Rocket has excellent brakes front and rear.
TLS front.
New cheapo eBay shoes on the rear will lock the wheel on pavement .
I used stick on Emory to true drums and shoes.
This got rid of all pulsation and greatly improved the brake effect.
Glen
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Hi RD,
It’s even worse than BSA’s lousy 7” single-sider.
I will have to disagree with that statement *fight*
I have a 7in. BSA hub wheel fitted to my 500 Ariel HT5 that's in road trim
It used to have green Ferodo linings in it which gave an excellent brake
I had the shoes relined with woven material and turned the shoes to suit the drum diameter,
The result was very dangerous, it would lock up the front wheel event though the shoes were well chamfered
Long story short was the linings did not work at all in the rain and soon buckled between the rivits *eek*
Supreme replace the linings with the soft non woven material I mentioned and once these were machined to fit
the brake was and is brilliant,
Mostly the Ariel is ridden two up with a combined weight of probably 24 stone *eek*
Works for me
John
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chaterlea - we'll have to agree to disagree. Know from your posts that you know a lot more than you let on, but my experience with 7" s/s has been not good. Started racing a B31 in the early sixties in hill climbs and sandracing. No matter what I did to its 7" it was at best poor - hence my fitting the 8" which works great. Will lock the wheel if you get too ambitious! My son now races it when he gets time. Similar experience with my M21. Agreed the added weight / speed of its vee twin engine puts extra demand on the brakes, but it was again vey poor and it now has a tls conversion on another 8" s/s. Personally I prefer iron drums, either alone (eg 7") or in alloy, as I've seen 8" cast iron ones crack.
On a PS, the B31 and my Weslake (and the Hagon japanese I had at one time) are on methanol. I always liked motors on dope - they seemed to respond better, or is that just my immagination?
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Hi RD,
Notabother *smile*
I have an A65 single sided iron hub with a Taylor Dow TLS brake on the front of my SR
(it has the slightly narrower shoes though ) It works well but needed a lot of setting up due to inaccurate machining first day *ex*
About 10 years ago I smashed my right wrist and it has never been a strong as it was before, so I need to have the brakes as good as possible
I found a B44 single sided hub in USA some years ago that will be fitted to the B33.9 under construction
(must investigate a TLS setup as £6-700 for a replica would hurt)
(B31 frame and hybrid big fin goldie engine, STD box and so on)
Know from your posts that you know a lot more than you let on
Dunno about that *????* I have not made my own engine like you have *respect* *respect* *respect*
Although a future project is a set of castings (some part machined) to build one of these quasi japanese V twin replica engine ( I hope the project will be more subtle on the cycle parts side though)
http://lamb-engineering.com/spirit-of-endeavour
John
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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.
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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.
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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
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Hi RD,
I forgot that big brother does not like abbreviations that could in some places be taken as "offensive" *eek*
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
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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
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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 ?
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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.
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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....
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If only Physics was that simple!
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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
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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.
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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.
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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
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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.
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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.
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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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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
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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
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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.
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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.
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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.
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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...
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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
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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
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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.
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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.
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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
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A65 wheel cleaned up
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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.
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No they are both clamp types just dont have the lower clamp shown, photo shows A65 brake, hub and forks fitted to my A10.