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by Mal Marsden - 06/16/22 7:00 pm
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So I built a 1974 B50mx to race in vintage mx and I love the bike but the front brake is miserable. Now I am use to modern mx brakes so I don't really have anything to compare it too but I still feel it should be better than it is. I had the brake shoes relined when I built the bike up and the drum all looked good. I also think the angle looks ok on the brake arm so I don't really know if there is anything else I can do. Like I said I love riding the bike but with the way the front brake is I don't think I can race it like that! Any help would be appreciated.
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That arm at rest is in the wrong position, when the hand lever is operated the arm angle to the cable should still be over 90 degrees. It won't make much difference but worth trying turning the lever over if the hole is serrated and engaging it further back so it pointing to the ground more.

Or

With the lower use of imperial thickness linings the aftermarket is using metric thickness and fitting say 6mm thick instead of 1/4" thick linings, so you start with new shoes with 1/2 worn linings which also only touch on one end.

So what brand shoes did you buy ?

This is why Villers services and Saftek are the go to places for shoe relining, the lining thickness can be custom or the OEM imperial thickness.

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This is not a recommendation. Modifying your brakes can be dangerous.

On this Norton backplate, lining material has been removed from the trailing end of the trailing shoe, by a mad experimentalist.

It allows the cam to put more pressure on the leading shoe, instead of the cam being stopped from turning by the trailing shoe contacting the drum. That cam jamming effect is a characteristic of non-floating SLS brakes, and ones that float the wrong way.

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did the shoes get arced to match the drum?

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Originally Posted by kommando
That arm at rest is in the wrong position, when the hand lever is operated the arm angle to the cable should still be over 90 degrees. It won't make much difference but worth trying turning the lever over if the hole is serrated and engaging it further back so it pointing to the ground more.

Or

With the lower use of imperial thickness linings the aftermarket is using metric thickness and fitting say 6mm thick instead of 1/4" thick linings, so you start with new shoes with 1/2 worn linings which also only touch on one end.

So what brand shoes did you buy ?

This is why Villers services and Saftek are the go to places for shoe relining, the lining thickness can be custom or the OEM imperial thickness.
Yeah, thanks for the advice. Unfortunately I need a longer inner cable to be able to reposition the brake arm as I am already out of adjustment.

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Originally Posted by Mitch
did the shoes get arced to match the drum?
Does that mean matching the radius of the drum and the shoes? I did not do that but will take the wheel out to check.

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In the picture where we can see the brake cable entering the lug that holds the cable ferrule there might be a problem. It appears that the ferrule on the end of the cable barely rests on top of the lug. It is supposed to fit in the lug its full length. The ferrule at the end of your cable is too big in diameter. I can imagine your cable popping off the lug in its present precarious situation and then there would be no front brake. Or is your ferrule a stepped set up where an equal amount is inside the lug? I just can't tell from the picture.

The free play on a correctly made cable is 4" (take off the adjuster at the lever end first!). Does your brake cable have an in line adjuster (it is supposed to)? I can't tell from the picture. I just looked at my B50MX and the brake lever on your brake plate looks about right for its placement, so that isn't your problem. And like others have said the arc of the shoes may not match the drum.


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getting drums turned and/or relining brake shoes will almost certainly result in a miss-match. you may only have 30% contact. shops used to have a machine to grind brake shoes to match the drum but it is very hard to find someone that does it anymore. there are home remedies, some as simple as putting sandpaper in the drum and working the shoe by hand. there are also some home made machines and fixtures. plenty stuff on u-toob

start with sandpaper and double sided tape in the drum, magic marker some lines on the shoes, put it together and scuff it a bit and you'll see how good the fit is

Last edited by Mitch; 05/25/22 4:08 am.
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I think the real answer is a different front brake. The larger conical front brake is a bit stronger but it still isn't great. The real benefit is that it fits right in the forks you already have. I have the larger brake on my B50 with extended arms and original shoes. It works but it isn't as good as my T140 with a single disk.

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That looks great! What year bike is it from? Not sure if it would be allowed in my pre 74 class.

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Originally Posted by johnu
That looks great! What year bike is it from? Not sure if it would be allowed in my pre 74 class.

B50 goldstars had that brake setup as standard. It was only the A65 which had the short arms.


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That brake came standard on the 1971-72 B50SS. It was also used on the 1971-72 Triumph 650 twins and 750 triples as well as the 1971-72 BSA 650 twins and 750 triples. It will bolt right up to your forks with no modifications. It isn't recognized as a great brake though. I would call it adequate on a 300 lb B50 and dangerous on a 400+ lb triple. Here it is on my B50 mashup.

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Thanks Scott, that's a beautiful bike:)

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Just out of interest the front conical brake is also a straight swap for the 6" SLS front brake originally fitted to the 1973/74 Triumph Trophy Trail.
This is because the fork lowers are identical to those on the BSA B50.
The conical front brake is not a great brake IMHO-- however if set up properly it can be adequate on a 500, barely adequate on a 650 and totally inadequate on a triple.
People say that set up so and so it is a good brake.
That may be the case but the problem on a relatively fast and heavy bike like a Trident is brake fade.
A few hard stops through twisty road sections and the front brake lever seems to get closer and closer to the grip.
Definitely not confidence inspiring!

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When properly adjusted , which this one is not, they will lock the front wheel of an A65L doing 80 mph in a 30 zone even when fully laden with 50 Kg of camping gear approaching a police car .
George Heggie had no problems with them on his A75 that he raced both in the day in production class & latter on in Historic racing .


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There are a couple of things I would do as follows:-
- check the handlebar brake lever, ideally, the distance between the pivot bolt and nipple should be 7/8" but could be larger if a different lever has been used. The 7/8" lever gives greater leverage and thereby improves braking.
- try using a PTFE lined brake cable with a flat wound outer, these provide much sturdier feel and help improve braking, Venhill UK sell kits.

Sometimes flipping the brake plate lever around changes the angle of attack, so something else to try.

It looks like the brake shoes are of the pivot type which means that full contact may not be obtained, it might be possible to convert them to fully floating by machining off the crescent and adding steel brake pivot pad, or finding a set of 6" shoes off another bike?

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Originally Posted by gunner
There are a couple of things I would do as follows:-
- check the handlebar brake lever, ideally, the distance between the pivot bolt and nipple should be 7/8" but could be larger if a different lever has been used. The 7/8" lever gives greater leverage and thereby improves braking.
- try using a PTFE lined brake cable with a flat wound outer, these provide much sturdier feel and help improve braking, Venhill UK sell kits.

It looks like the brake shoes are of the pivot type which means that full contact may not be obtained, it might be possible to convert them to fully floating by machining off the crescent and adding steel brake pivot pad, or finding a set of 6" shoes off another bike?


The levers with the Lucas switch gear attached don’t have 7/8” pivots, I’d have to measure to tell you what they have but I did check to see if they did when I was building my own. Fitting the longer brake arms gives the same effect as having a smaller distance between the fulcrum and “effort” points.

The Venhill cable kits are really good! I use them for clutch and brake on most my bikes, I say most because even the underspeced cable that they came with is still much sturdier than the venhill outer. Original cables are lined.
- The twins came with the shorter brake arms because because the notion that the shorter lever will have a greater amount of lift on the shoes… however it needs hands like Charles Atlas for it to work as so, the design was originally for a hydraulic system and this was a cost saving exercise.

The shoes on my mates B50T, (6”) are ok, they have some decent linings in from PES and work ok proving you ride with added caution.

Modern brake cables aren’t the best, I have one from tricor which is well made but sadly will place the levers in the same position as Original Scott’s. If you set the brake properly where by you detach the cable and adjust the micram adjusters then set. Then you’ll never fit the cable.
I have mine hanging up in the garage. I bought a NOS B50SS cable instead and now have enough free length in the cable for it all to work as it should.


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Don’t know about the conical TLS being poor on a triple, the pre OIF TLS isn’t anything to boast about on a triple. Though the same brake can easily lock the front end on a twin


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IME on a triple the conical front brake fades much more than the 1968-70 TLS brake.

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They fade because the inner tends to move a lot more than the outer
George fitted a clock spring to pull the outer arm back to stop it skimming on the drum thus overheating the drum & glazing the pad
He did this to my A65 and it worked too well.
On the race bike he fitted 2 clock springs and did away with the spring between the levers .
The brake is self energizing but will only do this if you jab the brake on quickly , hense the short arms for faster shoe movement and the shoes make as close to a simutaneous contact as possible .
If pulled on slowly the shoes will not dig into the drum so don't self energize and you only have your hand strength
What is vital to make them work properly is to always adjust the bake at the drum, never ever at the lever the adjuster there is purely & simply there to take the slack out of the cable AFTER THE BRAKE HAS BEEN ADJUSTED , some thing that period testers and users seemed to be totally unable to do
So they bagged the brake as useless and every armchair expert has done the same since then
When fully applied the arms should be not quite square to the cable , exactly the same as every other cable operated brake or clutch so the above photo has a badly adjusted brake which would be dead lucky to stop a fart &/or a stretched cable
Same as a hydraulic brake you tighten the adjusters one at a time till they stop the wheel turning then back off 2 to 3 clicks
When both are done you adjust the cable a little slack and jab the brake on acouple of times to centeralize the shoes then check the adjustment
It is vital that both shoes hit the drum at the same time so the adjustment may need to be done several times
When finished take up the slack.
If the arms go past square to the cable then the cable is stretched & needs to be shortened or replaced .

It is a difficult brake to get working 100% and the idiot in line brake switch does not help , Mine got tossed almost the fist time I rode it .
It also requires a very tightly wound outer that has the turns of flat wire actually touching both sides otherwise they become a big plastic covered spring
The Wassell cables are to be avoided at all costs because the outer turns are widely spaced .
A lot of the aftermarket cables were made using cheap & readily availible speedo cable outers which are again not suitable for this brake .
The local cable makers Conwire used to wind their own outers because they could not get a good enough off the shelf outer
And of course there are the people who do not understand how the brake works so they tie the outer tight against the frame to neaten up the bike
BSA put the two loose cable guides in there for a reason, the outer has to be able to moove to work properly .

No arguement that it was a cheap work around for the abandoned hydraulic operation but it is a good & very powerful brake when set up properly.
Down side is it needs very regular adjustments particularly as the inner slowly unwinds so is always getting longer


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