Re: Increasing Drum brake performance

black twingle /
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J Campbell, that little rotating piece is called a "cam." Increasing the size, or the ramping of a brake cam will change how powerfully, and how quickly your brakes engage, respectively.

So far, that's a good plan, but putting an unsecured piece of metal inside your brake drums is a Very Bad Idea. Even if you shim your brake cam to get better performance out of it (and somehow avoid over-shimming so as not to burst or crack your hub) you can't just leave that shim there - you need to do _something_ to secure it in place.

The perfect implementation of your plan would be to remove the cam, weld on some extra metal, and then file it down until it is exactly the right shape to engage the shoes on the inside of the hub shell.

At the very least, use some glue, or a tapped-and-faced hole, or a flattened-thimble-like covering that bolts to the flat side of the cam, or...

+++

Increasing the length of the lever arm on the brake hub itself will make your hand lever move more (you'll have to pull it farther, and have less adjustment room) to make your brake shoes move a shorter distance more powerfully.

Colin, if your brakes are in good tune, and you haul on the hand lever without bottoming out at the handle bar this would give you more braking power (and probably better braking response).

Brake drum lever arm failures are among the primary reasons old motorbikes were recalled. I'd suggest finding a bigger lever arm, or building an entirely new, larger lever arm (basically, don't try bolting on an extension to the existing arm).

+++

Do we just assume that Colin knows to de-glaze the insides of his hubs? Colin, do you know to de-glaze the inside of your hubs?

As brake shoes wear, they leave a burnt deposit on the inside of the hub shell (they shouldn't, but they do). Brake cleaner gets this off, as does sandpaper. You are not supposed to use sandpaper for some reason (asbestos? Brake surface scratches? I don't remember).

+++

Doesn't the Sachs use a coaster brake? Coaster brakes have a sprocket with a threaded cone. When the sprocket is rotated backwards - when you pedal backwards - the cone "unscrews" from a pair of brake shoes inside the hub - in effect, the sprocket replaces the brake cam as the actuating method.

I think that this means that you can roll a Sachs with a coaster brake backwards without the pedals turning. I am not sure how useful that would be.

This single post is part of a larger thread. Start from the top or view this post in context.
Subject Written By Posted
  Increasing Drum brake performanceTopic by: Colinswoop . Colinswoop . 02/23/09 02:25PM
  Re: Increasing Drum brake performanceRe: King Drunky JCams King Drunky JCams 02/23/09 02:40PM
  Re: Increasing Drum brake performanceRe: Colinswoop . Colinswoop . 02/23/09 05:55PM
  Re: Increasing Drum brake performanceRe: Emperor Swagustus Emperor Swagustus 02/23/09 03:11PM
  Re: Increasing Drum brake performanceRe: steve steve 02/23/09 04:18PM
  Re: Increasing Drum brake performanceRe: black twingle black twingle 02/23/09 05:56PM
  Re: Increasing Drum brake performanceRe: Mark Mark 02/23/09 06:08PM
  Re: Increasing Drum brake performanceRe: Colinswoop . Colinswoop . 02/23/09 11:36PM
  Re: Increasing Drum brake performanceRe: Chris Rice Chris Rice 02/24/09 12:34AM
  Re: Increasing Drum brake performanceRe: steve steve 02/24/09 12:53AM
  Re: Increasing Drum brake performanceRe: heather heather 02/24/09 02:24PM
  Re: Increasing Drum brake performanceRe: steve steve 02/24/09 02:37PM
  Re: Increasing Drum brake performanceRe: heather heather 02/24/09 03:01PM
  Re: Increasing Drum brake performanceRe: King Drunky JCams King Drunky JCams 02/24/09 03:10PM
  Re: Increasing Drum brake performanceRe: Zeke Zeke 02/24/09 03:28PM
  Re: Increasing Drum brake performanceRe: Eric P Eric P 02/24/09 09:32PM
  Re: Increasing Drum brake performanceRe: Downhill Harvey (OFMC) Downhill Harvey (OFMC) 02/24/09 10:07PM
  Re: Increasing Drum brake performanceRe: W Coop W Coop 02/25/09 12:04AM
  Re: Increasing Drum brake performanceRe: Flagrant - Flagrant - 02/25/09 02:59AM
  Re: Increasing Drum brake performanceRe: Graham Motzing Graham Motzing 02/25/09 03:39AM
  Re: Increasing Drum brake performanceRe: Sunset Paul Sunset Paul 02/25/09 06:33AM
  Re: Increasing Drum brake performanceRe: black twingle black twingle 02/25/09 12:30PM
  Re: Increasing Drum brake performanceRe: heather heather 02/26/09 01:01PM
  Re: Increasing Drum brake performanceRe: Emperor Swagustus Emperor Swagustus 02/26/09 01:17PM
  Re: Increasing Drum brake performanceRe: Flagrant - Flagrant - 02/26/09 01:40PM
  Re: Increasing Drum brake performanceRe: King Drunky JCams King Drunky JCams 02/26/09 01:43PM
  Re: Increasing Drum brake performanceRe: Mike Bartell Mike Bartell 02/26/09 04:20PM
  Re: Increasing Drum brake performanceRe: leee leee 03/03/09 04:45PM
  Re: Increasing Drum brake performanceRe: Mike Bartell Mike Bartell 03/03/09 04:55PM
  Re: Increasing Drum brake performanceRe: black twingle black twingle 03/03/09 06:15PM
  Re: Increasing Drum brake performanceRe: Mike Bartell Mike Bartell 03/03/09 11:08PM
  Re: Increasing Drum brake performanceRe: Matt Bengry Matt Bengry 03/04/09 12:01AM
  Re: Increasing Drum brake performanceRe: heather heather 03/04/09 03:42AM
  Re: Increasing Drum brake performanceRe: brendanM brendanM 03/04/09 04:05AM
  Re: Increasing Drum brake performanceRe: dallas dallas 03/04/09 10:22AM
  Re: Increasing Drum brake performanceRe: Flagrant - Flagrant - 03/04/09 01:05PM
  Re: Increasing Drum brake performanceRe: Charles Cole (OFMC) Charles Cole (OFMC) 03/04/09 02:25PM
  Re: Increasing Drum brake performanceRe: NickCB NickCB 03/04/09 03:37PM
  Re: Increasing Drum brake performanceRe: ; . ; . 03/05/09 10:24AM
  Re: Increasing Drum brake performanceRe: ; . ; . 03/05/09 07:34PM
  Re: Increasing Drum brake performanceRe: James G James G 03/05/09 10:08PM
  Re: Increasing Drum brake performanceRe: black twingle black twingle 03/06/09 11:39AM
  Re: Increasing Drum brake performanceRe: James G James G 03/06/09 12:02PM
  Re: Increasing Drum brake performanceRe: MIke applewhite MIke applewhite 03/07/09 12:23AM
  Re: Increasing Drum brake performanceRe: ; . ; . 03/09/09 07:32PM

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