Drum Brake Stone Damage

Just remember when grinding drums there is a max diameter they may be ground out to.

On most the max allowable is cast into the outer edge of the drum.

"Don’t know how common it is or what would happen if you left it, but I reckon it would be worth people with drum brakes checking them out from time to time"


That is a very much overlooked part of car maintenance and countless drums have been destroyed by it. I always try to avoid driving in mud, particularly the sloppy type. When I do I remove the drums as soon as I get home (or well before that if I will be away for long periods) and there is always rolls of mud built up in front of the leading edges of the shoes. If left there it just keeps working itself past the shoes and tears them and the drum to pieces.

Found a cure that works for my c/t. Spotwelded 40 x 2.6mm fms bar onto the forward edge of the backing plate extending from 11 o,clock to 5 o.clock so covering the cooling air gap . Silicone any gaps & go where you like. Total clean out every year though. Important to leave slight gap at the bottom end so that any flukey grains can drop out.

Cheers John