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Brake Secrets


brt650
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hi my 199B has gold did wheels think there off an honda the rear brake drum is on the RH side its has all the mods done when i got it so not sure but i know the brakes are wicked. anybody any idea what honda wheels fit the later bults?

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I don't know if I'm looking at it different but I can't see any advantage having the different locater for the pin on the shoes rather than the original Bultaco offset style if it is shimmed properly so it can't move sideways, the advantage of the other shoe is lost without a larger cam which to me looks a lot of work to get the cam central on the shoe cam plate using the Bultaco backing plate.

BRT whats wrong with Bultaco brakes anyway just pull a bit harder. You really should get rid of that HHHHonda its making you soft.

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I don't think the different diameter of the round shaft for the brake shoes will have any noticeable effect.

The pin sits still so the brake shoes are turning around at the same axis.

The actuator pin with the oval cam press the shoes against the drum.

The main braking power for a single action drum brake as they are mounted on Bultaco, Honda or SWM is done by the leading brake shoe depending of the turning direction of the drum.

Here a sample picture, the right picture shows the drum brake in rest position, the left picture shows the drum brake actuated /engaged:

(The red area is the area where most praking power due to the wedge effect is produced, (the wedge effect depends to the direction in

which the drum / wheel is turning, when the wheel is turning counter clockwise it's the left brake shoe, when the weehl would turn

clockwise it's the right brake shoe)

brake.jpg

As mentioned already you can look up the actuator pin if he is not worn out or will actuate the leading brake shoe slightly first when the drum/wheel is turning forward.

You can inforce the braking power for forward by modification of the oval cam shaft, but this will decrease the braking power when braking backward.

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Thank you for everyone's comments. I have the backing plate away at the moment being sleeved.

With over 2000 views I believe that maybe there are a few issues regarding the brakes that others would like to solve or see solved.

Just on one note though- I think Ross (mrb505) has a valid point . Had I not bought the Honda I would have kept riding the bully with no concerns about the brakes.Anyone want a Honda?

Thank you again for your input.

Cheers

brt650

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  • 1 month later...

Just an update ;

I've fitted Honda brake shoes to the rear. That's fixed that end.

I've fitted Honda shoes on the front , almost.

I'd rather not go any further than that, otherwise I might loose some Bultaco friends.

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No photo's yet mrb505.

But just wondering is a 1985 Honda RTL250s a rare bike?

And if so would it be criminal to fit the forks and wheels out of one into my Bultaco?

Just wondering of course. Not like I would do that.

But just got the tubes back today from the Hard chromers. I'll put them together in the next week or so and I'll send some photo's.

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No photo's yet mrb505.

But just wondering is a 1985 Honda RTL250s a rare bike?

And if so would it be criminal to fit the forks and wheels out of one into my Bultaco?

Just wondering of course. Not like I would do that.

But just got the tubes back today from the Hard chromers. I'll put them together in the next week or so and I'll send some photo's.

Not criminal, but you wouldn't go to heaven !

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I often wondered why you didn't have any of those nice silver BULTACO stickers on that freshly painted tank, now I know why-- Hontaco, Bulda, Sherpa T LR, Sherpar TL,

I give up what is it,

Cheers Greg

PS cant recall any Sherpas coming out with gold rims, geez its gonna look nice, better bring your mum with her airbags to the first event , just to divert attention If you know what I mean.

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feetupfun has dibs on my mum sherpa325 . You''ll have to compete with him.

Anyway, they are off the plentiful Hond RTL250S which I believe they made 240 of them. They crushed some too.

So no-one will miss one more.

Cheers

Brian

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  • 3 years later...

HELP. I had to ride a powerline downhill on a loop Sunday and my 1972 Sherpa T tried to kill me. I looked like a flying chicken coming down the mountain. Finally spied some bushes and fearlessly threw myself in. I had 16 out of 16 cleans when I overshot a hill and went out of bounds because the front brake cannot be sure what it wants to do. I love the Bull but I need brakes that work. I read the entire thread but am not really sure if there was a solution! 

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