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Tuning Front Brakes?

BlackLightning998

Well Known and Active Website User
VOC Member
#1
Hi,

I picked up from the 5-speed gearbox thread a couple of members like me looking for guidance on how to tune the front brakes. There was one reply and an offer of a telephone number on top of that.

Any chance we can start this dedicated thread and seek the guidance of experienced Vincent owners for their tips on tuning the front brakes for maximum effect?

Replies and tips gratefully received.

Stuart
 
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Tom Gaynor

Well Known and Active Website User
VOC Member
#2
Brakes

Try this website: http://www.francescobazzani.com/freni-e.html

I have a 210 mm Menani on my race bike, functionally identical to the better known Fontana, and slightly cheaper. My (racing) experience of big Japanese brakes (250 mm four shoe) is that they aren't as good as 210 mm Italian ones. On the road it probably wouldn't be noticeable. The 250 mm Fontana would probably stop a speeding locomotive.


If the standard brakes are to work efficiently, both levers should be parallel when both are hard on. Captain Vincent has a neat way to achieve this.
But. Vincent brakes are 7" drums, very resistant to fade ( a 7" brake with 2" wide linings) but lacking the diameter or design features ever to be very powerful. Rudges had 8" drums in 1934. Diameter for stopping power, width for fade resistance.......
Stiffening them up is worthwhile, classically by brazing triangular braces inside the steel plates or by buying "Lightning" plates.
If you stick with the balance beam, put an outrigger plate on. Going to twin cable levers removes the balance beam as a source of lost motion.I've tried both. Functionally it makes no difference. A given pull at the lever results in half that pull at each drum with both methods.

However even with ribbed drums, Lightning plates, turned linings and all, mine were fade resistant but not responsive, particularly in traffic. Discs are (IMHO) the best and cheapest option, a big four-shoe the next best. Both require the contrivance of a speedo drive. So I bought PV 2ls brakes: expensive (compared with making up a double disc system from a breakers), not as good as disc(s) or a big four-shoe, but perform very, very much better than I could ever get my standard brakes to perform. The bicycle still looks like a Vincent, and i didn't have to make my own arrangements for a speedo drive.
 

Vincent Brake

Well Known and Active Website User
VOC Member
#3
Vincent 4LS brakes

Hi out there,
Indeed the only way to brake decently in style in nowadays traffic is possible with those 2 sided 2 LS brakes. I produce them myselve and use them well.
But I have bought an Egli with a D casing, in the front wheel is a YAM (I dare not say the complete word) TZ 350 hub measuring 250 mm. would it be best to go to (what Egli most used I guess) a ceriani 230 mm hub and a Vin rear hub (I could build in me own) or go to menani front 210 rear 180 mm (who have seen this on an Egli (not the Godet) I like to keep parts (seen) on the machine to its time (1969)


Vincent Speet
 

BlackLightning998

Well Known and Active Website User
VOC Member
#4
Hi out there,
Indeed the only way to brake decently in style in nowadays traffic is possible with those 2 sided 2 LS brakes. I produce them myselve and use them well.
But I have bought an Egli with a D casing, in the front wheel is a YAM (I dare not say the complete word) TZ 350 hub measuring 250 mm. would it be best to go to (what Egli most used I guess) a ceriani 230 mm hub and a Vin rear hub (I could build in me own) or go to menani front 210 rear 180 mm (who have seen this on an Egli (not the Godet) I like to keep parts (seen) on the machine to its time (1969)


Vincent Speet
Thanks Tom, Vincent.

For some strange reason I want to try and keep the set up original. I have modern roadbikes, Japanese, Italian and US - so stopping power on discs is well understood - but I am sure that I can get the original twin drum's tuned better for good stopping. The bike has a strengthening plate on the front balance beam that my father and I made for it 30 years ago before the bike was sold - that was one of the ways I identified it from photographs when I found it again.

I'm managed to get the brakes adjusted so they stop the bike, but I now suspect the cables have too much flex in them as the handle just comes back to the bar.

I've picked up a useful tip from Russ at Vinparts about turning the brake plate cam to take up the slack, so that's next on my list to try.

Thanks for your interest.

Cheers

Stuart
 

Tom Gaynor

Well Known and Active Website User
VOC Member
#5
Spongy brakes

Flex (call it lost motion) in the hub can be multiplied eight times, because the radius of action of the cam (say 1/2") is 1/8 the radius of action of the lever (say 4"). Or whatever. This already multiplied lost motion is then multiplied again by the handlebar lever, by about five times. So 1/40" of an inch of lost motion at the cam will amount to 1" lost motion at the hand lever. The greater the mechanical advantage, the greater the potential for sponginess. (True also of hydraulic brakes...) My guess is that you are losing motion in the drum, thus gaining the full 40-fold magnification.
I haven't ever suffered from cable stretch, which isn't to say that others haven't, but compression of the outer is common. Just watch the cable trying to straighten itself out when you pull the lever hard on. Then multiply the change in length by five.
 

BlackLightning998

Well Known and Active Website User
VOC Member
#6
Flex (call it lost motion) in the hub can be multiplied eight times, because the radius of action of the cam (say 1/2") is 1/8 the radius of action of the lever (say 4"). Or whatever. This already multiplied lost motion is then multiplied again by the handlebar lever, by about five times. So 1/40" of an inch of lost motion at the cam will amount to 1" lost motion at the hand lever. The greater the mechanical advantage, the greater the potential for sponginess. (True also of hydraulic brakes...) My guess is that you are losing motion in the drum, thus gaining the full 40-fold magnification.
I haven't ever suffered from cable stretch, which isn't to say that others haven't, but compression of the outer is common. Just watch the cable trying to straighten itself out when you pull the lever hard on. Then multiply the change in length by five.
Hi Tom,

This would sit comfortably with the advice that Russ has given me to take up all the free play on the cam before the shoes hit the drum and then fit the arm and cable onto that - this would minimise the lost motion in the assembly.

I'll keep having a fiddle around and see how I get on - I can sense an improvement since I have been dabbling, so I may get there in the end.

Right now I just don't fancy what it'll be like once the bike is run in, doing 100mph and deciding I need to stop in a hurry!

Thanks for your help.

Stuart
 

Tom Gaynor

Well Known and Active Website User
VOC Member
#7
Brakes

Hi Tom,

This would sit comfortably with the advice that Russ has given me to take up all the free play on the cam before the shoes hit the drum and then fit the arm and cable onto that - this would minimise the lost motion in the assembly.

I'll keep having a fiddle around and see how I get on - I can sense an improvement since I have been dabbling, so I may get there in the end.

Right now I just don't fancy what it'll be like once the bike is run in, doing 100mph and deciding I need to stop in a hurry!

Thanks for your help.

Stuart
What I found was that the problem was the delay between grabbing the lever and getting a result. The result was not sensational, but it was OK. But while from touring speeds I was able to allow for the delay, in traffic I wasn't. The guy in front slows, you need to slow too, immediately, not after 1/2 or 1 wheel revolutions. That was what I could never achieve.
 

BlackLightning998

Well Known and Active Website User
VOC Member
#8
Hi Tom,

Exactly, I find that my riding style has to change and become more anticipative leaving a larger gap in front of me, town riding is not a lot of fun and filtering through traffic is almost a no-no. Mind you, trying to read other drivers behaviour is no bad thing but I would like the welcome reassurance that I could stop rapidly if I really need to. I've been riding modern machinery for the last 20 years so I guess I've been a little spoilt. The good thing is it has saved me some money - I was going to have the master cylinder changed on my Ducati 851 as I thought the brakes weren't brilliant - well compared to the Vincent they are stunning - so they can stay the way they are for now!!!
Glad to see the Scottish Section is so active on the Forum - it is 30 years since I used to go, first Monday of the month, to Carfin and the Church Hall where we met. I was lucky enough to have my first ever ride on/in a Vincent in the Steib chair on George Ramsay's outfit. I've got some super pictures of his Egli at the Kenmore Rally where we used to go for several years - Rab Smith was usually in his tent sleeping off the night before - great bloke and you could not ask for nicer, (Bike was a bit oily though in those days but it ran well).

I always remember a guy called John (King, I think) who has an immaculate Shadow (he had the Steib for it from new) and he had done some tidying up on it including replacing the oil lines - but didn't want to damage the ferrules at the end so had not crimped them. He came with it on a trailer. Started the bike to let everyone hear it - it soon wasn't so shiny as uncrimped ferrules aren't very good at keeping the oil in!!

Happy days for a teenager.

Cheers and thanks again for your interest.

Stuart
Cheers for now
 
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tonythecat

Well Known and Active Website User
Non-VOC Member
#9
Tuning Front Brakes.

I am suprised no one has mentioned the heavy duty front brake cable as supplied by Conway Motors this transformed the brakes on my Rapide, it is a really strong outer cable which does not compress at all, so all the energy is trasferred to the brake arm.
 

john998

Well Known and Active Website User
VOC Member
#10
Front brakes.

Hello, I have always felt that nearly every Vincent that I have ridden had better brakes than my own. This disqualifies me by and large from this discussion.
That said I once spent a lot of time on a set of front brakes, AM4s turned to fit re-machined drums, stiffened plates, heavier cables, the whole 9 yards. On the road they where an improvement, one race at Cadwell and I was back to normal ie. Passable.
The mention of the Kenmore rally, just before my first attendance, called forth a smile. Rab is well described, and both he and George Ramsay will be missed. We do not seem to have produce characters like them now.
John.
 

piggywig

Well Known and Active Website User
Non-VOC Member
#11
Front Brake Improvement.

Black Lightning 998,
Have read with interest the various suggestions to your question, specifically, how to improve the standard setup rather than go to exotic brakes.My ownership of the same B Shadow covers 45 years of very long distance touring with heavily laden bike and from trial and error I now have completely non-spongy brake that performs well. Brake drums are skimmed and softer linings (I know they wear out quicker) hand lapped to drums to initially eliminate high spots, labourious but effective and necessary to actually get the new shoes into the drums. Twin pull lever and two long heavy duty cables made to exact length to fit after taking up the slack on the levers. Balance beam left as is. Adjusters can now be taken up to get the linings very close to drums, both exactly the same.(If you have made the inners wires too long they will have to be shortened now.) When all is finally in place some running in will finally bed in things at which time readjustment can be done. Very little lost motion with this set-up,and although you need a good hefty hand to operate, the brakes will be fully on after about 10mm. of movement at the lever (nipple end) and another 3-4 mm is as much movement as the mightiest hand will achieve. Lever end will never get near the bar as in original set-up. There will be plenty of doubters and nay sayers on all this but my very heavy bike has never run into the back of anything or careered off a mountain road. Not in the same class as modern twin discs but a huge improvement.
 

methamon

Well Known and Active Website User
Non-VOC Member
#12
OK here is my two pennorth.

The original main cable was a heavy duty item and someone has mentioned that something similar is available - this will resist compression of the outer.
A circular drum helps, as does shoes machined circular, ie removing point contact.
Rivitted linings whilst original are suspect. I bought some a couple of years ago and wolud not again as there were visible gaps between the lining and the shoe.............................bonded must be better.
Dave Hills mentioned a mod once which sounded interesting, he had ridden someone elses bike and that someone had reduced the radius of the shoe actuating cams (NOT ENOUGH FOR THEM TO RISK GOING OVER CENTRE). The increased mechanical advantage had apparently produced astonishing results.
One word of warning. Do not over adjust (ie leave inadequate clearance between shoes and drums) as I did. Everything was just fine on the drive; it was far from fine when having used the brakes a few times en route I pulled up at the MOT station. The bike immediately became the source of much attention for the wrong reasons.....as smoke was billowing up from the front end.
 

BlackLightning998

Well Known and Active Website User
VOC Member
#13
Thanks to everyone so far, so here I go.

I've put on very heavy grade cables, looks like very little distortion now and I've adjusted everything up so the the balance beam is nice and level, the actuating arms are pretty much aligned and the shoes are set close up to the drum, (she has new shadow drums and new shoes with bonded linings having just been re-built by someone else - I've stripped them out and had a good look - the shows seem to be sitting ontot the drum fairly well).

The lever pull is now impressive - I can get it back well towards the bar but that takes a pretty significant effort - the brakes seem to be very well on with little pull.

Off out to the Bill Little event in Swindon tomorrow - so we shall see.

Thanks to all who've replied so far - keep you posted.

Stuart
 

piggywig

Well Known and Active Website User
Non-VOC Member
#14
Tuning Front Brakes

Stuart,
I have followed with interest your adventures in the quest for front brake improvement.
Last word from you on the subject, unless I have missed something, you were 'off to Bill Little event in Swindon' with your nicely set up brakes.There has been good advice offered from all quarters, so how did all the adjusting improve things?
Did you find the pot of gold??
Col. :rolleyes:
 

clevtrev

Well Known and Active Website User
VOC Member
#15
Thanks Tom, Vincent.

For some strange reason I want to try and keep the set up original. I have modern roadbikes, Japanese, Italian and US - so stopping power on discs is well understood - but I am sure that I can get the original twin drum's tuned better for good stopping. The bike has a strengthening plate on the front balance beam that my father and I made for it 30 years ago before the bike was sold - that was one of the ways I identified it from photographs when I found it again.

I'm managed to get the brakes adjusted so they stop the bike, but I now suspect the cables have too much flex in them as the handle just comes back to the bar.

I've picked up a useful tip from Russ at Vinparts about turning the brake plate cam to take up the slack, so that's next on my list to try.

Thanks for your interest.

Cheers

Stuart
It`s not the cables that are flexing, it`s the shoe bending.
 

vin998

Well Known and Active Website User
VOC Member
#16
Tuning Front Brakes

Trev,

I was wondered about the shoes "bending" before Trev mentioned it, because when stationary and applying the front brake the brake arms appear to move a bit after the brake is fully applied. This is when the spongness is felt at the handlebar. This was on brakes where the lining was turned to fit the drum when originally fitted. Now I cannot remember if the extra brake arm movement happened when the brakes were new 10000 miles ago, but they do now.

Anybody know if the linings are wearing unevenly or if the shoes are just too weak or is something else going on?

Have you found a cure to your bending shoes Trev?

Cheers
Simon.
 

BlackLightning998

Well Known and Active Website User
VOC Member
#17
Hi Col.,

You're right - I went off to Bill Little's event and what a difference the cables have made just on their own. I have since fitted springs to both brake shoe arms, the bike only had one on the left when I got it and then I have made up a little return spring on the balance arm on the left hand side too to hold it in tension when in neutral position, I have seen a few other bikes with this little mod and it certainly helps the balance arm return to the neutral position easily. The brakes are performing really well, now stopping the bike properly although after each run I am having to adjust the cables which I suspect is the brand new shoes bedding in - they now only have 2500 miles on them and I have read and been told that they may need as much as 5000 to settle properly. I have had the shoes out to check and they are wearing nicely across the surface so no need to have them spun to match the drums I think.
So (fingers crossed) I think I may have found that pot of gold:
1 - Proper thick cables.
2 - All parts in good serviceable condition and operating as intended, cables oiled and keep them that way.
3 - Springs on both actuating arms.
4 - Little spring mod to return the balance beam to neutral.
5 - Remember the little screw under the balance beam is on an eccentric - if you can't get it adjusted up the try rotating it and you will get more/less free play on the right hand side.
6 - Bed in the shoes - make sure they are touching across the surface area.
7 - Keep persevering.
8 - Find a nice empty road, get up to 60mph plus and try them - often, helps bed them in and improves your confidence with the bike.

Cheers and hope it helps.

Stuart






Stuart,
I have followed with interest your adventures in the quest for front brake improvement.
Last word from you on the subject, unless I have missed something, you were 'off to Bill Little event in Swindon' with your nicely set up brakes.There has been good advice offered from all quarters, so how did all the adjusting improve things?
Did you find the pot of gold??
Col. :rolleyes:
 

Pete Appleton

Well Known and Active Website User
VOC Forum Administrator
VOC Member
#18
Spongy cables

I am interested to see so many people having good experiences with heavier duty cables. My experience was quite the reverse.

When I built my rapide I used new, ribbed, drums. Had the shoes fitted with modern bonded on linings. Profiled the shoes to fit the drums.

When it came to the cable Vinparts were out of stock so I bought a cable from another supplier. (I have slagged them off quite a bit already lately so I won't mention any names)

The cable was very well made and looked much better than standard. The outer casing was massive and the inner also reassuringly large. The result was frighteningly bad brakes which could be pulled back to the bar with no great effort. 1000 miles of bedding in did little to improve this. A close look showed that most of the sponginess was due to the straightening of the outer casing under load.

By this time Russell had some more stock in so I tried one of his. By contrast the Vinparts cable looked far less heavy duty but transformed the brake action to only mildly worrying which is probably the best you can expect.

It is unfortunate that the larger the diameter of your outer cable the more the coils must open up to allow it to bend. This then allows more compression under load. It seems to me that although a large heavy duty cable is reasuring as you reach the end of the mountain straight you can never take advantage of the extra strength because it hits the bars before you can get a good pull on it.

Has anyone else tried this comparison? It is too easy to try changing everything at once and then you are never really sure what cured the problem. Maybe I am just talking rubbish

Pete
 

Comet Rider

Well Known and Active Website User
VOC Member
#19
Brake cables

Hi Pete,
You are definately not talking rubbish.
I've had the opertunity to look at a broken original 50's HD cable and a modern one.
On the original the outer was made from a heavy duty square section wire, which means no compression of the outer, wheras the new one was not square insection, and had much more "compressability"

Neil

I can't comment on Russ's as I've never had one, but knowing Russ it's down to finding the right supplier.:D
 

BlackLightning998

Well Known and Active Website User
VOC Member
#20
Heavy Duty Cable

Mine was quite straight forward as Dad taught me to substitute parts one at a time. Set up was bad brakes, changed the lightweight cable for heavy duty - result was transformed brakes with nothing else done.

Cables the answer for me - heavy duty every time. In terms of profile and quality - not sure as I was given them by a friend who bought them from Kempton (about £45) - but they do the job properly.

Stuart
 
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