Author Topic: 8" single sided front brake  (Read 2557 times)

Offline Adler

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Re: 8" single sided front brake
« Reply #15 on: 07.04. 2024 22:44 »
... I meant the Zündapp K800 which had the rear brake lever rotation with the wheel. The KS600 had it against it again. Pls apologize.

Best regards, Manfred
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1950 A10 GF Plunger (and some German motorbikes from '33 to '54)

Online limeyrob

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Re: 8" single sided front brake
« Reply #16 on: 15.04. 2024 22:38 »
My experience with drum braked cars is that its worth getting modern high friction linings fitted. Its not that expensive - I seem to recall about £80 and the improvement can be huge.  Most modern linings are very hard and optimized for low wear - 100k miles plus. But on an old vehicles a brake life of 10k miles would be fine if it was 2 or 3x better at stopping.
I drive a Land Rover with TLS drums on the front and SLS on the rear. I fitted new linings when I got it and the brakes were terrible, after 10 k they weren't even bedded in and looked set for 200k.  I changed to high friction, they bedded in in 100 miles and at 10k were about 10% worn but it stops like a modern car now.  Do a search for someone who relines the classic race cars and bikes.
There's actually a Brexit angle to this (honest), the EU mandated the standard for aftermarket brake shoes and pads and all the parts makers follow it but to pass the linings must pass a wear test, but no friction test so blame the EU *smile*
Slough 59 GF/SR

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Re: 8" single sided front brake
« Reply #17 on: 16.04. 2024 09:49 »
Had my front shoes relined with modern material and it has made a big difference, they certainly squeal when applied with gusto!
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Offline Adler

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Re: 8" single sided front brake
« Reply #18 on: 17.06. 2024 21:32 »
Dear Forum,
I have a little task for a rainy day for those who like to play and think oneself into something (which I assume, there are a few of those among you ...  ;)):
1. put the bike on a stand where the front wheel is rotating free
2. give the wheel a good turn and pull the hand brake lever until the wheel stops
 - do this several times to be able to reproduce the procedure
3. give the wheel a turn in the opposite direction and pull the hand brake lever again
4. Compare the effort for braking the forward and the rearward rotating wheel
5. repeat the procedure for the rear wheel.
My assumption: it is (at least a bit) easier to stop the wheel when the brake lever at the brake plate is rotating against the wheel rotation.
Have fun.
Best regards, Manfred

Germany SE (Bavaria)
1950 A10 GF Plunger (and some German motorbikes from '33 to '54)

Offline KiwiGF

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Re: 8" single sided front brake
« Reply #19 on: 17.06. 2024 21:50 »
Dear Forum,
I have a little task for a rainy day for those who like to play and think oneself into something (which I assume, there are a few of those among you ...  ;)):
1. put the bike on a stand where the front wheel is rotating free
2. give the wheel a good turn and pull the hand brake lever until the wheel stops
 - do this several times to be able to reproduce the procedure
3. give the wheel a turn in the opposite direction and pull the hand brake lever again
4. Compare the effort for braking the forward and the rearward rotating wheel
5. repeat the procedure for the rear wheel.
My assumption: it is (at least a bit) easier to stop the wheel when the brake lever at the brake plate is rotating against the wheel rotation.
Have fun.
Best regards, Manfred

Yep due to the cam design one shoe moves more than the other, and it is best if the one that moves more, is the leading shoe, BSA designed it the other way around though.

Existing wear pattern on the shoes impacts the result of this test as well though….

I have fitted thin pads on the leading shoe to make sure it touches the drum first, but that is only a temporary fix until the wear returns the brake to being poor again.
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Re: 8" single sided front brake
« Reply #20 on: 17.06. 2024 23:05 »
Adler i rotated the front brake plate to the same position a lot of gold star racers had them years ago, it does make a better brake

Online Triton Thrasher

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Re: 8" single sided front brake
« Reply #21 on: 18.06. 2024 08:33 »
I’ve probably posted this before.  It’s something I read in a Vintage Motor Cycle Club item.

This brake on another popular motorcycle marque has lining material removed from the trailing end of the trailing shoe.  The wheel spindle hole in the backplate has been enlarged to allow the plate to be centred.



With that bit of lining removed, the cam is not stopped so abruptly from turning when the trailing shoe meets the drum, so a bit more force can be applied to the leading shoe.

I’m not recommending anyone tries it: lots of guys in sheds have modified/messed up their brakes and crashed.

Online limeyrob

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Re: 8" single sided front brake
« Reply #22 on: 18.06. 2024 09:42 »
On cars (1950's) with drum brakes the front part of the trailing shoe is also cut away by about 1/4 of the length.  This ups the force on the trailing shoe so it does more braking.  Braking is only friction coefficient x force x radius of drum, there's no area component.  Area stops fade by dissipating more heat.
Slough 59 GF/SR

Offline Topdad

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Re: 8" single sided front brake
« Reply #23 on: 19.06. 2024 09:02 »
Wasn't this called "self servo action " back un the day ?
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Online Triton Thrasher

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Re: 8" single sided front brake
« Reply #24 on: 19.06. 2024 09:55 »
The action of a leading shoe being pulled harder on by the drum is often called self-servo, yes.

Online limeyrob

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Re: 8" single sided front brake
« Reply #25 on: 19.06. 2024 11:26 »
Self servo is a double edged sword.  My daily driver is a 2 1/4ton Land Rover camper with twin leading shoe brakes on the front and single on the rear.  It absolutely needs the self servo effect to stop and it stops well.  But get the tinyest bit of condensation one one brake on a damp morning and expect to do an unplanned U turn on the first stop. It doesn't help that its randomly left or right. Self servo needs friction and if that's not there you loose the servo effect.  SLS are a lot more tolerant of variations.  Putting in high friction linings really benefits TLS as it ups the self servo, although having recently invested in some modern high friction linings I would say fit them to everything, they really work!
And of course TLS don't work going backwards, I rolled rather a long way back down a hill on an A65 trying to get my foot on the back brake without sacrificing the girlfriend....In the end I was stopped by a parked car  *whistle*
Slough 59 GF/SR

Online Triton Thrasher

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Re: 8" single sided front brake
« Reply #26 on: 19.06. 2024 11:51 »
One of the reasons I usually state that I’m not advising anyone to modify their brake is that people have been killed by too much self-servo effect locking the front wheel.

Online Worty

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Re: 8" single sided front brake
« Reply #27 on: 19.06. 2024 18:45 »
Dear Forum,
I have a little task for a rainy day for those who like to play and think oneself into something (which I assume, there are a few of those among you ...  ;)):
1. put the bike on a stand where the front wheel is rotating free
2. give the wheel a good turn and pull the hand brake lever until the wheel stops
 - do this several times to be able to reproduce the procedure
3. give the wheel a turn in the opposite direction and pull the hand brake lever again
4. Compare the effort for braking the forward and the rearward rotating wheel
5. repeat the procedure for the rear wheel.
My assumption: it is (at least a bit) easier to stop the wheel when the brake lever at the brake plate is rotating against the wheel rotation.
Have fun.
Best regards, Manfred

This is what I've just done with my GF.  Not initially for better braking, but better adjustment.  I've found the brake is better as you've described, as does Bergs. 

TT, that's really sad, but surely one tests the brakes carefully to ascertain the stopping characteristics??
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Online Triton Thrasher

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Re: 8" single sided front brake
« Reply #28 on: 19.06. 2024 18:52 »
surely one tests the brakes carefully to ascertain the stopping characteristics??

You never know what people will do or not do.

Offline olev

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Re: 8" single sided front brake
« Reply #29 on: 20.06. 2024 06:37 »
The venom I had back in the bad old days had a forward facing front brake lever.
I can't remember how it stopped but I'm still here.
Velocette really knew their sh!t.
I'd still have that thing if I'd ever mastered how to kick start it.
cheers