Tuning Front Brakes?

piggywig

Well Known and Active Forum User
Non-VOC Member
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

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Non-VOC Member
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

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VOC Member
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 Forum User
Non-VOC Member
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 Forum User
VOC Member
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.
 

Simon Dinsdale

VOC Machine Registrar
VOC Member
VOC Forum Moderator
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 Forum User
VOC Member
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

VOC Hon. Editor
Staff member
VOC Member
VOC Forum Administrator
VOC Forum Moderator
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 Forum User
VOC Member
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 Forum User
VOC Member
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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