Author Topic: Why is my front brake still useless?  (Read 1665 times)

Offline RogerSB

  • 1960 Golden Flash, Plymouth, Devon, England
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Re: Why is my front brake still useless?
« Reply #30 on: 29.01. 2019 11:49 »
I recall stopping at the top of a steep descent on a B road in the Dales. There was a sign at the top the read " Steep hill, 25% grade"
Glen

Widecombe Hill (the one Tom's mare collapsed and died on and the one Swarfcut mentioned) is a steep hill (I believe up to 22% in places). I have a friend who lives there and been there a few times. However not on my BSA, always by car.

The comment I'd like to make about our BSAs and brakes is that it may not be prudent or safe (maybe, even cannot) ride a +50 year old British motorcycle like you can a modern one in today's traffic and on faster roads. As always, it's horses for courses.

I owned and rode, as daily transport, a couple of GFs in the mid 60s and well into the 70s and they were very capable transport and could easily hold their own in the traffic and on the roads of the day. In the 80s I bought a new Honda CX500, which had powerful hydraulic twin disc brakes and was shaft driven and was a world apart from the BSA and Matchless I owned (and also rode) during that time (see photo).  Today, for me, it's the pleasure of owning and riding a BSA and the very quaintness of it that I enjoy and I ride it with that in mind, maybe that's why I haven't felt the need to complain about its brakes.

1960 Golden Flash

Online RDfella

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Re: Why is my front brake still useless?
« Reply #31 on: 29.01. 2019 14:34 »
Roger - you're so right. Having ridden modern bikes we then tend to expect the same from our classic ones. Trouble is though, with today's traffic one still needs to be safe and the 'appointment to stop' required with older bikes just doesn't cut it. Maybe it's my mind failing after all these years, but I think classic brakes are generally worse now than they were in the 60's and 70's. I'm sure we used to get brakes working at least reasonably back then, but then we didn't have cardboard masquerading as lining material. Having read of all the mods carried out in this thread (and being in the same situation myself with my GF brakes) I'm even more convinced the problem is today's brake lining material.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online chaterlea25

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Re: Why is my front brake still useless?
« Reply #32 on: 29.01. 2019 16:57 »
Hi All,
Yes lining material is the key to good brakes
This subject has been raised time and time again  *sad2*
I have had good results with a soft non woven lining, its dark grey in colour, unfortunately the shop closed some while ago (Supreme)
Recently a Friend has been getting shoes lined at a local place here in Ireland, they are using material that is the same or similar to Supreme's stuff?? They reline shoes for classic rally cars with it
Talking with him the other day he was filing away some more of the leading shoe edge to make the front brake on his Flash less severe *eek*
I found the pattern floating shoes to be worse than useless *warn*
Get the rear cable,  lever angles sorted and the correct thickness linings and the rear brake works well
99.99% of pattern rear cables are SH1T  *razz*

John
1961 Super Rocket
1963 RGS (ongoing)

Online Greybeard

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Re: Why is my front brake still useless?
« Reply #33 on: 29.01. 2019 17:10 »
....filing away some more of the leading shoe edge to make the front brake on his Flash less severe...
*countdown*
Maybe your friend is a thrill seeker.

Online edboy

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Re: Why is my front brake still useless?
« Reply #34 on: 29.01. 2019 18:08 »
what always strikes me is how the rear brake can lock the wheel but the front feels spongy. maybe its the cable size and length?

Online Kickaha

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Re: Why is my front brake still useless?
« Reply #35 on: 29.01. 2019 18:36 »
I ask again, are there different powder coating finishes available?

Yes there are, there are different heat ranges and they have powder coat capable of doing heads and barrels
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Offline mikeb

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Re: Why is my front brake still useless?
« Reply #36 on: 29.01. 2019 18:53 »
Swarfy yes that extra arm is between ugly and strange but with split pins should it be scary? Ie, dangerous? I made it as I didn't want to mod and solder the brake cable etc.
I might try marking the drum and shoes with pen/pencil to see how much contact is actually occurring. Any tips on suitable markers that won't then affect the friction surfaces?
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Offline RogerSB

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Re: Why is my front brake still useless?
« Reply #37 on: 29.01. 2019 20:33 »
what always strikes me is how the rear brake can lock the wheel but the front feels spongy. maybe its the cable size and length?

The front brake is the more important brake.  As a motorcycle instructor and examiner throughout the 1980s for the Royal Automobile Club & Auto Cycle Union and later for the British Motorcycle Federation training schemes we always tought the importance of applying the front brake harder than the rear and just before the rear.  This would become most important to do automatically if ever faced with an emergency where there's no time to think about it. This is to avoid skidding and possibly losing control completely. We were not allowed to take riders out on the road until they could perform an emergency stop correctly and under some control. It can be easy to skid the rear but not so easy to skid the front - - - but if banked over and turning you're in big trouble regardless.


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Offline Swarfcut

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Re: Why is my front brake still useless?
« Reply #38 on: 30.01. 2019 10:26 »
   MikeB.... No, from an engineering aspect it is fine. I just get a bit jittery in the irrational belief that the cable will get stuck between the backplate and the fork leg. Sod's Law an'all.   Kid's coloured chalks could be used to mark the linings to find the high spots.

 Swarfy.

Online chaterlea25

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Re: Why is my front brake still useless?
« Reply #39 on: 30.01. 2019 16:05 »
Hi GB,
His problem was that the front brake was
"Too Good" and tended to lock up on wet or greasy surfaces  *eek* *eek* *eek*

John
1961 Super Rocket
1963 RGS (ongoing)

Online KiwiGF

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Re: Why is my front brake still useless?
« Reply #40 on: 30.01. 2019 18:24 »
Swarfy yes that extra arm is between ugly and strange but with split pins should it be scary? Ie, dangerous? I made it as I didn't want to mod and solder the brake cable etc.
I might try marking the drum and shoes with pen/pencil to see how much contact is actually occurring. Any tips on suitable markers that won't then affect the friction surfaces?

Hi Mike, maybe we’ll be discussing this at the National Rally in a few weeks! I agree with previous comment that it’s worth REALLY making sure the leading shoe contacts first, by adding a temp spacer, or building up the cam face by weld I did. I’ve had good feedback from other riders of my B31 on the front brake as “much better than mine  *eek* ”. Including from a gold star owner. It will lock the wheel at slow speeds but is a lighter bike of course.

Its accepted pretty generally that more than 75% of your braking comes from the leading shoe (due to the servo effect) so IMHO that’s what one needs to concentrate on, one thing is I’ve not put much thought into is the effect of reducing the leading shoes contact length, maybe this can increase the servo effect? Is it worth trying? (Noting this reduces lining contact area, but increases pressure on the lining).

My gut feel is that removing the part of the friction lining on the leading shoe, nearest the cam, would increase the servo effect? Can someone confirm that? I’m thinking you need to get closer to the “brake grabbing” effect....albeit if you don’t like that effect you may have to get new shoes....as you can’t replace removed friction material!

I note trailing shoes can also have shoes with reduced lining length, I’m not sure why but probably to try to prevent them wearing in a way that prevents the leading shoe working properly, as there is no significant servo effect on trailing shoes.

Another “variable” is the chamfer on the lining, is the servo effect increased with no chamfer? Anyone know? ( I suspect it’s reduced, as no chamfer can cause bad grabbing).

On lining contact area maximising, it appears trying to get an even contact might be a good thing to do but more a “nice to have” ...I say that as sanding the shoes to get perfect contact only made only a small difference to my brake (albeit it reduced the “sponginess” a great deal), and “physics” says friction is proportional to contact area and pressure so if you increase the area you reduce the pressure and maybe end up no further forward  *dunno* . I definitely see advantages in spreading the generated heat over the whole friction lining though, as local overheating of the lining may result in a low friction co efficient. Getting the brake to work well is not simple physics though, as shoes flex, linings compress, brake plates flex, drums flex, all of which affects the evenness of force over the lining, probably making it a bit of a “black art”. A SLS brake is inherently “flawed” as one end moves more than the other!

Accepted wisdom around here is that “soft” linings work best on our brakes, and that modern linings are “hard” to suit higher pressures from hydraulic pistons. I’ve no direct experience of this but I suspect some wassel aftermarket bonded shoes I bought are “hard” hence that’s the cause of my useless rear brake (as well as them being too small in diameter, and so thin sanding them to the correct diameter would make them virtually worn out!).

It’s also occurred to that a old school brake specialist would know how to set up a SLS brake to work well, and make the customer happy, but maybe as the linings wear the trailing shoe gradually comes more into contact and reduces the brakes performance, and the specialists knows that!

New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

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Online duTch

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Re: Why is my front brake still useless?
« Reply #41 on: 30.01. 2019 19:02 »

 For what it's worth, I bought some shoes for my Plunger rear a couple of years or so ago, and they seem to work fine and has even skidded up sometimes but can't say if they soft or hard....bought from Trojan Classics in Sydney;

 http://trojanclassics.com/

 or eBay shop;

 http://www.ebaystores.com.au/TrojanClassicMotorcycles/Control-cables-/_i.html?submit=Search&_fsub=2366346014&_nkw=67-8681&_sid=95114404&
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Online morris

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Re: Why is my front brake still useless?
« Reply #42 on: 30.01. 2019 19:52 »

 For what it's worth, I bought some shoes for my Plunger rear a couple of years or so ago, and they seem to work fine and has even skidded up sometimes but can't say if they soft or hard....bought from Trojan Classics in Sydney;

 http://trojanclassics.com/

 or eBay shop;

 http://www.ebaystores.com.au/TrojanClassicMotorcycles/Control-cables-/_i.html?submit=Search&_fsub=2366346014&_nkw=67-8681&_sid=95114404&
Huh?
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Offline mikeb

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Re: Why is my front brake still useless?
« Reply #43 on: 30.01. 2019 20:21 »
Quote
Huh?
which end of those do you fit the steel pads??
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Offline mikeb

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Re: Why is my front brake still useless?
« Reply #44 on: 30.01. 2019 20:41 »
KiwiGF - yes, another 'dark art'.  I will be at the rally (for the day ride and dinner) and hopefully on the a10 so we can discuss it further then. my b33 (plunger) with reversed front brake arm stops better than the a10 tho maybe just as its a lighter bike. i rode my modern yesterday after riding the a10 more recently and just about broke my wrists stopping at the first corner. if only...

Roger - unfortunately I've never mastered the gentle riding and do tend to ride the bsa's like moderns. i've enjoyed passing porsches and harleys on my b33 - rather adolescent great fun. the good part is 60mph on my bsa feels like about 140kpm on the modern and you don't even get a speeding ticket!

Swarfy - i share some anxiety about this linkage. messing around with brake mechanisms doesn't sound wise to me, even if it looks 'failsafe'. I posted that pic to see if anyone would freak out so i do appreciate your comments.

i'll have a go with the chalk and see what i find

cheers

Mike
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS