Lockheed 11 inch brake drum
 

I am surmising that the diametral limit for reboring (to correct an out-of-round drum) is 11.080 inch, which allows for a further .040 inch of wear, before a service limit of 11.120 inch is reached. I have not found any reference to the maximum allowable wear limit of this brake drum in any Bristol workshop manual. I suppose I am asking if a drum that has reached 11.120 inch ID which is otherwise in very good condition, can still be used with oversized brake linings. I would be pleased to hear from anyone who knows better. Thanks, vincent

Vincent ,
What drums are you referring to ??

Alloy drums of the 403 with cast iron linings, I suggest .060 max oversize, as when the liner is too thin it tends to crack and even loosens in the alloy drums.

Cast iron drums could be taken out more but a brake specialist should know what the appropriate government safety regulation is regarding the max. oversize they can be machined. This could vary state to state in Australia.
I also suggest the largest oversized drums be fitted on the rear axle and the smallest on the front axle.

There are also government safety regulations on machining of disc rotors .

Geoff