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#260247 - 06/20/09 7:08 pm How to make conical brakes work
royalenfieldxxx Offline
BritBike Forum member

Registered: 12/17/06
Posts: 255
Loc: Calgary, Canada
How can the conical brakes on my '71 Tbolt be set up to give decent stopping power. Right now they are pathetic. eek

Thanks

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#260248 - 06/20/09 7:28 pm Re: How to make conical brakes work [Re: royalenfieldxxx]
DMadigan Offline
BritBike Forum member

Registered: 01/09/04
Posts: 2621
Loc: ca, us
You need to have the drum round and the shoes match the drum. Skim the drum then fit the backing plate. Turn the cam until the shoes make contact and mark the position. Put the backing plate in the lathe and move the cam just beyond the marked position and skim the shoes to the same diameter as the drum. If most of the lining is not touched, move the cam a little more.

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#260253 - 06/20/09 7:56 pm Re: How to make conical brakes work [Re: DMadigan]
raf940 Offline
BritBike Forum member

Registered: 03/02/06
Posts: 3330
Loc: gastonia nc
hi.there were instructions on this forum a while back about gluing thin strips of coarse sandpaper to the drum, then putting the backing plate in, then as you held a little pressure on the actuating arms to have the shoes touch the paper then spin the wheel it would do a 'poor man's' shoe arching job...i tried it and it seemed to help
_________________________
1972 Triumph T120
1968 BSA A65
1968 MGB Roadster
1979 Chevrolet Camaro Berlinetta
1969 Honda Mini Trail
2004 Honda Shadow Aero
1972 BSA Thunderbolt
1975 yamaha xs650b
1974 Norton Commando (calvin's other bike that lives here)

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#260266 - 06/20/09 9:30 pm Re: How to make conical brakes work [Re: raf940]
royalenfieldxxx Offline
BritBike Forum member

Registered: 12/17/06
Posts: 255
Loc: Calgary, Canada
Thanks for the responses. Is it possible to turn the drum without taking the wheel apart or the tire off? Is there better, modern brake shoes that give more friction?

Brian

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#260278 - 06/20/09 11:14 pm Re: How to make conical brakes work [Re: royalenfieldxxx]
Shane in Oz Offline
BritBike Forum member

Registered: 10/04/01
Posts: 656
Loc: Sydney, Oz
The main thing which seems to go wrong with the comical hub tls brakes is that the previous owners have neglected them for 38 years, and they've turned into sls brakes frown
This is usually a case of not greasing the pivots, so the rear is fixed and only the front turns. Check that both the front and rear levers turn when you pull the brake on.

Ron T's dissertation on setting up conical hub brakes is far better than any description I could give, so you should read that and follow his steps.

One other thing to be aware of with the comical hub brakes. They're an automotive style self-servo brake, so respond best to firm initial application.

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#260281 - 06/20/09 11:20 pm Re: How to make conical brakes work [Re: royalenfieldxxx]
ca7a Offline
BritBike Forum member

Registered: 03/09/05
Posts: 731
Loc: Asheville, North Carolina
Yes, Brian, it is possible to turn the drum without demounting the rim, but you'll need a lathe with a swing large enough to accommodate the entire wheel. They exist in machine shops that cater to off-road equipment and the like.

I like the idea that raf940 suggests. It's simple and elegant. Except that it doesn't circularize the drum, which is what you need to do to start with. Use his method with abrasive strips attached to the shoe linings, first. Then you can use his method to do the linings.

Before you start, however, make sure the spokes are evenly tensioned and then measure the drum runout - you might find that the drum is actually pretty well circular!

Also, check that the existing linings are sufficiently thick and not contaminated with oil before you decide to switch them over to another compound; and, if you do decide to, check with a reputable vintage brake supplier before you leap,

David

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#260287 - 06/20/09 11:41 pm Re: How to make conical brakes work [Re: ca7a]
raf940 Offline
BritBike Forum member

Registered: 03/02/06
Posts: 3330
Loc: gastonia nc
i'm putting new tires on my 72 T120 this week so i reckon i might as well tune up the front brake while the wheel is off...
_________________________
1972 Triumph T120
1968 BSA A65
1968 MGB Roadster
1979 Chevrolet Camaro Berlinetta
1969 Honda Mini Trail
2004 Honda Shadow Aero
1972 BSA Thunderbolt
1975 yamaha xs650b
1974 Norton Commando (calvin's other bike that lives here)

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#260329 - 06/21/09 6:01 am Re: How to make conical brakes work [Re: raf940]
Nick Offline
BritBike Forum member

Registered: 04/14/02
Posts: 555
Loc: Out There!
Probably no need to turn the drum. Get some glue-backed sandpaper (used on electric sanders, etc.). Cut the strips to match your drum and paste to the drum surface. After disassembling the brake plate, cleaning everything up and reassembling it, mount the shoes on the plate, and assemble the wheel. Then mount the wheel in the forks. To ensure that the brake drum is centered with the hub, before tightening anything up, spin the wheel slowly and apply the front brake. Then tighten the wheel mounting hardware without releasing the front brake. (This technique should always be used when installing drum brake wheels on a bike as it ensures concentricity between the drum and the brake plate.) Now, very slowly turn the wheel by hand while actuating the brakes and let the sandpaper do its work. Don't overdo it, or you'll wear out the shoes.
Of course, also make sure that both cams are moving the same amount and causing their respective shoes to contact the drum simultaneously.
Do it right and you'll be pleasantly surprised at how effective your braking action will be.
_________________________
When people who should have known better cautioned me about the dangers of motorcycle racing, I always told them that a fear of death is nothing more than a fear of life in disguise.

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#260343 - 06/21/09 10:08 am Re: How to make conical brakes work [Re: Nick]
Ger Online   content
BritBike Forum member

Registered: 09/23/05
Posts: 4427
Loc: Netherlands, Rotterdam area.
Something I found usefull. And believe me: a well adjusted conical hub front brake is a pleasure to ride with; a real stopper.

[click]
_________________________
Ger B
BSA A-65T 1971, nicknamed "De fiets" (the bicycle);
Triumph Trophy 900 1996, nicknamed "Dat andere ding" (that other thing).

http://www.mijnalbum.nl/Grotefoto-T4S7BCBJ.jpg
http://www.mijnalbum.nl/Grotefoto-Q4QIECV7.jpg

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#260347 - 06/21/09 10:47 am Re: How to make conical brakes work [Re: Ger]
nisse Offline
BritBike Forum member

Registered: 12/06/06
Posts: 51
Loc: sweden
I havnīt done anything to the front but turning the adjusters in the drum and keep the wire welloiled

And when I grab the handle I can easy get my rearwheel in the air if I want.

The rear isnīt a brake itīs a brakelightswich

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#260363 - 06/21/09 2:17 pm Re: How to make conical brakes work [Re: nisse]
royalenfieldxxx Offline
BritBike Forum member

Registered: 12/17/06
Posts: 255
Loc: Calgary, Canada
I really appreciate all the great responses. Knowing that this brake is good when properly set up tells me that mine has potential. I am going to take mine apart and take a close look at everything.

I like the sand paper idea because it is something I can do myself and it will not cast much.

After Shane's comment I went out and tried the brake to see if both cams are working and although they both move the rear one does not move very much. So maybe it is stiff.

I will keep you all posted.

Brian

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#260368 - 06/21/09 3:18 pm Re: How to make conical brakes work [Re: royalenfieldxxx]
johnnyrvf Offline
BritBike Forum member

Registered: 08/16/06
Posts: 730
Loc: Dordogne, SW France
Convert it to hydraulic operation, it works as designed then. Johnny.
_________________________
What d'ya mean it won't rev to 10?
1965 BSA A65D Lightning Rocket
1976 K*w*s*ki Z900.
1978 Triumph Bonn3ville (930 T160 Powered T140)
1988 H*nd* RC30
1990 Moto Guzzi California 3
1993 Y*m*h* TDM 850

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#260487 - 06/22/09 1:46 pm Re: How to make conical brakes work [Re: johnnyrvf]
BSA_WM20 Offline
BritBike Forum member

Registered: 05/05/04
Posts: 2836
Loc: Sydney Australia
To work properly the shoes must be a bigger radius than the drum so that when the leading edge strikes the drum it can dig in and cause the shoe to flex on to the drum.
This is what a mechanical self servo brake dose. It is also what a drum clutch dose.
Sanding the shoes to the same ( actually slightly smaller ) diameter by glueing paper to the drum will not get the radii correct unless you have a hydraulic cylinder in ter pressing on the shoes a several tonnes/ inch .
Your hand can not do this or any where near that force regardless of how yo play with the effective leverage length.
This is why you really need to get them done properly.
the good news is that new linings are almost the exact correct radius directly out of the box so only need to be properly adjusted.
My conicals locked up my front wheel at 70 mph on a sound dry bitumen road with about 80 kg of camping gear strapped on board.
One up around town I could easily raise the rear wheel.
The important thing to remember that you adjust the brakes first useing the adjusters in the drum then take up the slack with the adjusters in the cable.
The outer must not be fastened to the frame any where.
If there is a front brake switch, remove it.
Look for a cable with a very heavy outer case.
It is better to put a new inner in an old outer than to use the really thin loosely wound pattern rubbish that suppliers buy from China risking our lives to put a few more bucks in their pockets.
The rear lever must be very free in its operation or it will drag on the drum and cause fade. Racers used to wind light clock springs ( like on the rear lever) and fit them to the outer lever on the front brake to keep it off the drum.

They respond best to a quick jabbing motion rather than a long slow squeeze ( which is why the levers are so short)
_________________________
Bike Beesa
Trevor

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#260492 - 06/22/09 2:40 pm Re: How to make conical brakes work [Re: BSA_WM20]
Lannis Online   content
Life member

Registered: 07/28/01
Posts: 8269
Loc: Old Pop in an Oak
Originally Posted By: BSA_WM20
To work properly the shoes must be a bigger radius than the drum so that when the leading edge strikes the drum it can dig in and cause the shoe to flex on to the drum.
This is what a mechanical self servo brake dose. It is also what a drum clutch dose.
Sanding the shoes to the same ( actually slightly smaller ) diameter by glueing paper to the drum will not get the radii correct unless you have a hydraulic cylinder in ter pressing on the shoes a several tonnes/ inch .


In theory, what you describe is probably the best way to get optimum braking power out of TLS BSA brakes.

However, on my A65, I've used the sandpaper-in-the-drum method, and have chirped the front tire on a hard stop to avoid a dog. The brake has good feel and will lock up the wheel - I'm certainly happy with it, even if there's more available. I'm on my last set of "frictionmat.com" shoes, which is an excellent brake shoe material, although they are not available any more. Not sure who I'll go to for the next set.

Lannis
_________________________
"What's the plan?"

"Plan? There ain't no plan!"

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#260537 - 06/22/09 8:08 pm Re: How to make conical brakes work [Re: Lannis]
Alex Online   content
BritBike Forum member

Registered: 09/05/02
Posts: 7443
Loc: NorCal
I guess I'll add my mustard to this sandwich as well since I have had a little experience with this when setting this brake up for my production racer. I ended up out-braking a BMW with disc brakes in a race.

1. New industrial brake linings from McMaster-Carr (Semi-metallic woven strips) riveted on.
2. Shoes radiused in using 60 grit aluminum oxide paper stuck to the inside of the drum with double-stick carpet tape. I did this with each shoe individually by hand, not on the backing plate since the new shoes would not clear with the sandpaper in there. BTW, from both personal experience and finite element modeling, I've concluded that having the shoe a slightly smaller radius than the drum is pretty much irrelevant under heavy braking since the shoe's radius INCREASES with braking load when it has to.
3. Check drum for roundness. Even on a re-laced wheel, it was still within .002" in my case.
4. Mounting sequence. As mentioned above, tighten cap nuts and stay bolts only with the brake under load.
5. Heavy duty cable (MAP sells a nice one), no inline brake switch routed to avoid large radii.
6. Properly adjusted cam adjusters on the shoes.
7. Well lubricated lever pivot, cable, and cable end at the lever. Often overlooked is that a fair amount of pull is lost when the barrel shaped end in the lever binds and twists the cable...not to mention eventually breaking it.

I think that's most everything. Granted this was not for a street application and the conical brake, due to having a lower mechanical advantage will take more force to apply, but I did not find this excessive even under extreme conditions. I also found that, besides being about 8 lbs lighter than its iron predecessor, the conical brake does not fade nearly as badly.

Anyway...much of the above was either gained from advice by the above mentioned Ron T and Don Roe while other stuff was either dumb luck or persistence and hard work. Hope my experience can help someone.
_________________________
A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
sixtyseventy Lightboltrocket road racer...and many more.

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#260541 - 06/22/09 8:15 pm Re: How to make conical brakes work [Re: Alex]
Lannis Online   content
Life member

Registered: 07/28/01
Posts: 8269
Loc: Old Pop in an Oak
Originally Posted By: Alex
I guess I'll add my mustard to this sandwich as well since I have had a little experience with this when setting this brake up for my production racer. I ended up out-braking a BMW with disc brakes in a race.

1. New industrial brake linings from McMaster-Carr (Semi-metallic woven strips) riveted on.
2. Shoes radiused in using 60 grit aluminum oxide paper stuck to the inside of the drum with double-stick carpet tape.


Alex -

Thanks for the pointer on the McMaster Carr material, I wouldn't have wanted to experiment with an unknown material. Now it's NOT unknown!

I used 100 grit paper, and left off the tape, I just contact-cemented it straight to the drum. Using the thinner paper and no tape allowed me to fit the shoes on the backing plate and made it a little easier. Bit of cleanup afterward but you have to do that anyway to get all the grit out so it doesn't end up in the wheel bearings ....

Lannis
_________________________
"What's the plan?"

"Plan? There ain't no plan!"

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#260612 - 06/23/09 5:54 am Re: How to make conical brakes work [Re: royalenfieldxxx]
DavidP Offline
BritBike Forum member

Registered: 10/21/08
Posts: 3681
Loc: Gnashville
Originally Posted By: royalenfieldxxx
How can the conical brakes on my '71 Tbolt be set up to give decent stopping power. Right now they are pathetic. eek

Thanks

Remove conical front end.
Attach late-model Triumph front end with disc brake. The only time I was ever satisfied with a drum is when I had a 650 drum on a 500 Triumph.
Forget about the rear, it's only good for adjusting your attitude in turns.
_________________________
A good friend will bail you out of jail.
A great friend will be in the cell with you saying, "Damn, that was fun!"

71 A65L

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#260622 - 06/23/09 7:33 am Re: How to make conical brakes work [Re: DavidP]
Ger Online   content
BritBike Forum member

Registered: 09/23/05
Posts: 4427
Loc: Netherlands, Rotterdam area.
So what you say, David is: Spend a thousend quid to solve a 5 quid problem?

Technology makes it easy to make things expensive...
_________________________
Ger B
BSA A-65T 1971, nicknamed "De fiets" (the bicycle);
Triumph Trophy 900 1996, nicknamed "Dat andere ding" (that other thing).

http://www.mijnalbum.nl/Grotefoto-T4S7BCBJ.jpg
http://www.mijnalbum.nl/Grotefoto-Q4QIECV7.jpg

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#260625 - 06/23/09 8:11 am Re: How to make conical brakes work [Re: Ger]
BSA_WM20 Offline
BritBike Forum member

Registered: 05/05/04
Posts: 2836
Loc: Sydney Australia
Yes and the point the Alex made.
The drum on the handlebar end should be the free floating type where the drum rotates on a soldered on pear or a swaged ball, similar to those multi use cables that you get with 2 pears and a bag of drums & balls non of which will fit properly.
_________________________
Bike Beesa
Trevor

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#261548 - 06/28/09 5:34 am Re: How to make conical brakes work [Re: Ger]
DavidP Offline
BritBike Forum member

Registered: 10/21/08
Posts: 3681
Loc: Gnashville
Originally Posted By: Ger
So what you say, David is: Spend a thousend quid to solve a 5 quid problem?


Not half of what some folks spend to get 20 more horse power from the engine without more stopping power.

BTW: It's only a 5-quid fix if you already have a couple of thousand quid worth of machine tools (and a lot of free time) at you disposal.
_________________________
A good friend will bail you out of jail.
A great friend will be in the cell with you saying, "Damn, that was fun!"

71 A65L

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#261566 - 06/28/09 9:24 am Re: How to make conical brakes work [Re: DavidP]
nisse Offline
BritBike Forum member

Registered: 12/06/06
Posts: 51
Loc: sweden
Agree with David in that the amateurs spends too much on power without realising that handling and brakes are more important

And If I had that kind of money to spend on brakes Iīd buy a Fontana not a disk. donīt think disks looks good on a BSA

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#261569 - 06/28/09 9:48 am Re: How to make conical brakes work [Re: nisse]
Ger Online   content
BritBike Forum member

Registered: 09/23/05
Posts: 4427
Loc: Netherlands, Rotterdam area.
AFA I understand, the original poster wants his brake to work on a standard A-65, not on a beefed up racing machine.
The suggestion to build on a completely different front end is therfore a bit over the top.
A normal conical brake is a perfect brake which does not need a couple of 1000 dollars worth of machine tools to be maintained and adjusted properly.
BTW: it has been used in racing wink
_________________________
Ger B
BSA A-65T 1971, nicknamed "De fiets" (the bicycle);
Triumph Trophy 900 1996, nicknamed "Dat andere ding" (that other thing).

http://www.mijnalbum.nl/Grotefoto-T4S7BCBJ.jpg
http://www.mijnalbum.nl/Grotefoto-Q4QIECV7.jpg

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#261570 - 06/28/09 10:21 am Re: How to make conical brakes work [Re: Ger]
nisse Offline
BritBike Forum member

Registered: 12/06/06
Posts: 51
Loc: sweden
I agree itīs a good brake when right adjusted and maintained

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#261761 - 06/29/09 10:53 am Re: How to make conical brakes work [Re: royalenfieldxxx]
Rich B Online   confused
BritBike Forum member

Registered: 08/04/01
Posts: 4381
Loc: Stone Creek OH USA
This works for me with conical brakes:

1. Use sand paper adhered to the drum with rubber cement, rotate the wheel and bed the shoes to the drum. Clean the mess up after you are done.
2. Install the wheel, leave the fork caps loose along with the torque reaction bolt. Apply the brakes firmly. Either have a helper hold the brakes on or use a bungie to lock down the front brake. Tighten the fork caps in a criss cross pattern until they are tight, then tighten the torque reaction bolt. Release the brakes.
3. With the brake cable completel.y slack, remove the dust plug in the drum, adjust the front micram adjuster until the brake locks, back off until it is just free to turn. Repeat for the rear micram.
4. Adjust the cable at the bars.
5. When adjustment is needed, always adjust the micram adjusters first. Cable last. Always adjust the micrams with the cable completely slack.
_________________________
Life is too short to drink cheap, bad beer.

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#261960 - 06/30/09 2:18 am Re: How to make conical brakes work [Re: Rich B]
royalenfieldxxx Offline
BritBike Forum member

Registered: 12/17/06
Posts: 255
Loc: Calgary, Canada
OK I thought I would go through the adjustment described by Rich B steps 2 to 5 before I took anything apart. When I took the rubber cap of the drum and turned the big slotted screws clockwise as far as they would go I only got a bit of drag. But I tried to make them both the same. Does that mean my shoes are getting pretty thin?

Also when I had the bolts loosened off and the brake applied hard and then tightened up the 8 fork bolts the torque arm tab had a small gap with the backing plate. So I put shims in the gap and tightened down the bolt. Does that sound right?

Anyways it did make a marked improvement over what I had before. I will take it all apart though and put new shoes on if necessary.

Thanks for all the great advise.

Brian

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