Originally posted by sparky2263
The max diameter was put on there because the lining to drum contact would be minimal once the drum reached a certain diameter, NOT because of some danger of drum breakage (but you probably think setting batteries on the ground will kill them). Arcing the shoe ensures full contact of the friction material.

Somehow when mfgs. started putting max. diameters on drums people started this myth of drum breakage (that was never a problem before).

I'm not real big on old wives tales.

this is what my drum manf. and the st of VA. says and i dont belive its a old wives tales either. i cant belive your telling people on a open forum that dont know any better its ok to go over the max. on these drums. i dont want you working on my brakes.

Any time the brake drums are removed for brake service, the braking surface diameter should be checked with a suitable brake drum micrometer at several points to determine if they are within the safe oversize limit stamped on the brake drum outer surface. If the braking surface diameter exceeds specifications, the drum must be replaced. If the braking surface diameter is within specifications, drums should be cleaned and inspected for cracks, scores, deep grooves, taper, out of round and heat spotting. If drums are cracked or heat spotted, they must be replaced.