Band brake help

[bem70]

Newbie question. Brake drum outer diameter is 4 inches. So do I order a 4 inch band and 4 inch drum? Also mine is rod not cable and did not have cutter pin. Only the end smashed a bit. That's the old band and drum. Does drum look like it needs replacement? Ty in advance for any advice

 

[Denny]

I would just replace the band. But that’s me. And yes if there’s a hole in the pin put a cotterpin in it.

 

[bem70]

Thanks. There is no hole for a cotter pin. They just had rod hammered on the end. Should I drill a hole and add one or just crimp band on rod aftergetting ends over edge of rod?

 

[Hellion]

Thanks. There is no hole for a cotter pin. They just had rod hammered on the end. Should I drill a hole and add one or just crimp band on rod aftergetting ends over edge of rod?

You can use a bent nail to hold the brake rod to the band but that's redneck. The preferred method is a hardened clevis pin, usually 1/4" diameter with a cotter pin on the end, so it doesn't "walk out".

Typical setup in this illustration:



#74 is the clevis pin
#65 washer
#73 cotter pin

The peg that is welded to the frame to hold the stationary end of the brake band usually has a hole in it for another cotter pin to hold it to the frame, but the band brake assembly is usually held captive by proximity to the wheel, sprocket and drum -- no real place for it to go.

You could also use a 1/4" bolt with a nylock nut on the end or a regular nut and blue threadlocker.

 

[Hellion]

A lot of brake material still exists on your current brake band, but the ends are bent. You could theoretically and feasibly unbend it so it pulls straight and true...

 

[Denny]

A lot of brake material still exists on your current brake band, but the ends are bent. You could theoretically and feasibly unbend it so it pulls straight and true...

Hellion, I looked at that too but unfortunately with as bent up as it is I think the brake lining will start to flake off. Better off replacing it.

 

[Hellion]

...but unfortunately with as bent up as it is I think the brake lining will start to flake off

I agree then. Unfortunately that is what you get sometimes from "previous owner Bubba", real what-the-heck-happened inexplicable damage to an otherwise good part with lots of life left in it.

Make sure the band is matched with the brake drum size, like this one for example:

BAND BRAKE, 1″ WIDE for 4″ OD DRUM, with PIN » Azusaparts

azusaparts.com

Some vendors don't know what they have or what they are selling.

 

[Functional Artist]

Here is another brake rod-to-brake band, connecting method
...for karts with rod actuated brake bands

* Note that the end of the brake rod (or cable)
...needs to be, connected to, the "actuating" side/end of the brake band

So, when the brakes are applied
...the "closing or clamping action" of the brake band
...goes the same way
...as the rotation, of the brake drum/axle

Which should enhance the braking action
...& NOT be "working" against it

This method also, allows some "fine tuning" adjustment of the brake band

 

[bem70]

Ty sir. My issue is how to put brake band on frame. Should I drill hole for a pin or spread our band to get over the knuckles like they had it? I don't want to mess up new parts or braking.

 

[Hellion]

Ty sir. My issue is how to put brake band on frame. Should I drill hole for a pin or spread our band to get over the knuckles like they had it? I don't want to mess up new parts or braking.

I see the end of the brake band pin/rod has been peened over in all three photos, making the installation of a new band difficult (maybe) if the tolerances are tight. If you have trouble installing it, I would grind the peened-over metal (the mushroom) off with a grinder, die grinder or even a bastard file.

I suppose the pin on the brake rod will suffice but you could drill a hole (about 1/8" diameter) into the frame mounted pin/rod so both ends of the band are secure.

No need for a return spring in that area, the springiness of the brake band should be enough but make sure the brake band springs back with your foot off the pedal and the pedal itself back to neutral or straight and vertical (more or less). Also ensure you have full travel at the pedal, no binding. Some light brake band "drag" on the drum is normal.

 

[Hellion]

It looks like the brake pin welded to the frame is slightly bent as well as the end of the long brake rod. It could be a camera illusion or 'fisheye' effect but make sure the parts are all 90° and straight so that the brake rod pulls the brake band in a straight line so that the brake liner makes full contact with the drum for maximum braking effectiveness. Hope this all makes sense.

 

[Denny]

I would just take a file and clean up the end of the pin. Then drill a hole for a hitch pin, roll pin or cotter pin to retain the drum.

 

[Hellion]

If you look at Functional Artist's photo in post #8 and the exploded parts view I posted, you will see or visualize that the brake band is pulled in the direction of the brake drum's rotation and in so doing it cinches itself around the drum as you apply the brakes, requiring less effort. I think this is described as a self-energizing brake system. F-A described it perfectly but didn't say what it’s called. I wasn’t so sure myself.

Most of the examples I found describe self-energizing brakes in terms of automotive style drum brakes (with the brake shoes on the inside of the drum).

Self-energizing means it boosts the braking force. I think they're one of the most effective brakes for go karts, easily locking up the axle and leaving skid marks.

 

[Denny]

Self-energizing means it boosts the braking force. I think they're one of the most effective brakes for go karts, easily locking up the axle and leaving skid marks.

Just like in your underwear!