Cable brake questions

[Master Hack]

The reason is not for strength. It's a replica of a 1932 Ford frame, which has a very specific appearance. In other words, it's built like that for looks.

That's cool and there have been other replicas here and all have been works of art. The point was the weight. No way a little mechanical brake is gunna be satisfactory. That 6" brake is for a sub 200# cart (SWAG). So I'm guessing you will be adding a body at some point? More weight...
Save yourself some grief and ditch the mechanical brakes for hydraulic. BTW a drum brake will probably be worse.
The above is just the opinion of a grumpy old man, there may or may not any basis in fact.

 

[Hellion]

That 6" brake is for a sub 200# cart

That's a good point and maybe two brakes would be better. I was reading past DIYGK posts on the topic; the mechanical disc brake seems to have major fans and major detractors. Lots of people use "locking up the axle" as the measure of effectiveness and some (most?) of the guys who said that were in the neighborhood of 150 lbs wet.

I have not thought about disc rotor size in conjunction with karts, probably because these you can't go too big before you're dragging it on the ground. Also, some of these vendor supplied discs often look like they are galvanized or zinc plated which does not bode well for effectiveness.