'73-'74 atc 70 question

[johnso75]

on the honda '73-'74 atc 70 the rear drive hub has a grove in it on the oppisite side of the sprocket. looks like for a belt or something. What is it for? Thanks

[oneroom42]

hmm....any pics of this?

[jensenracing77]

it is only for cooling of the brake drum. it wasn't really needed but looks good when they are cleaned up real good.