Front Coaster Brake Mad Scientist Crazy (wear a helmet)

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gone_fishin

Guest
how much cable-travel is used on a front drum brake?

if the answer to that is "a lot"...is there a special lever or cable arrangement?

i need "a lot" for a project i have going.
 


azbill

Active Member
Joined
Dec 15, 2006
Messages
3,721
I will try to measure it for you, but it works with my dual pull lever
(v-brake on rear)
looks like approx 1/4"...give or take 1/16"
hope thay helps ya :D
 
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G

gone_fishin

Guest
it does, but it ain't the answer i wanted to hear :LOL:

thanks :)
 
A

Alaskavan

Guest
That brings to mind another question. How much pressure is usually applied to a coaster brake to engage it firmly?
 
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G

gone_fishin

Guest
quite a bit when you're trying to stop the whole bike at speed...but i've learned that you can get about the same effect as an average side-pull-brake when using a hand-lever on a coaster hub. a hand-lever isn't strong enough to lock a coaster, tho.

yes, we are this-close to a working front coaster brake, the tests show a hand-lever will apply enough pressure for good speed-control and "standing." it's pretty nice so far, but we've learned there's a mechanical necessity to utilizing a full 3-4" (1/3) travel (rotation) of the arm (sprocket) in order to hold an adjustment. we need more cable-travel, and have an idea for a muliplying-lever at mid-point. this will also reduce the amount of pull i can apply, a good thing, but might make it a tad touchy as a trade-off.

btw-this whizzer front end is made with amazing quality...just sayin' :)
 

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Alaskavan

Guest
A wild thought, but is there a way you can alter the internal mechanism to reduce the required rotation? Probably a dumb question.
 
G

gone_fishin

Guest
not dumb...at least i didn't feel dumb when i was searching that same question, but i haven't found anything yet that says we could do that.

look at it this way...how far does the crank move the rear-sprocket from full-release to a full-engagement? that's what we need for predictability (and safety)

right now, when i release the brake and it moves in the "pedal" direction, the internals rotate along with it & that changes the adjustment by that amount of travel. after a fresh adjustment, 1st pull is perfect, 2nd pull is sloppy, 3rd pull does nothing. lather, rinse, repeat...frustrating :(
 
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Alaskavan

Guest
Okay. Been probly about 40 years since I had one apart to look at. That's a scary thought. Anyway, I don't have any other thoughts. Wish I did.
 
G

gone_fishin

Guest
Alaskavan said:
Anyway, I don't have any other thoughts. Wish I did.
you know, taken out of context...that could look pretty bad for you ;)

i been racking my brain all week only to keep coming back to the same conclusions.
 
D

DougC

Guest
A wild thought, but is there a way you can alter the internal mechanism to reduce the required rotation? Probably a dumb question.
I haven't ever done it, but I understand that there is a way, by putting extra washers in it somewhere.

What some kids do with coaster-brake rear wheels when they want a freewheel (a freewheel is where there's no coaster-brake action, and you can back-peal freely) is they convert it into what's called a "free-coaster". They remove the brake cone shoes, and then they place washers in it somehow to tighten-up the amount of rotational slack between coasting and pedaling (which would be the amount of rotational slack between braking and pedaling, if the brake was still in there).

So there does seem to be a way.

http://www.google.com/search?num=30&hl=en&c2coff=1&safe=off&q=convert+coaster+freecoaster&btnG=Search
~
 
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