Without me trying to find it in a workshop manual , does anyone know the maximum ID measurement, that a stepped drum should be before it becomes a throw away ?

Reason I ask is I have 2 originals here that I have had for years , haven't measured them yet , but i'll take them to a brake shop & get them trued up if they are worth it .

I,m just playing around with some mag wheel sets that I have here to determine whether I need flares on my van or not , I want bolt the drums on and see what it looks like .

Standard size is 7.000".
There are 2 std oversizes that brake shops machine to: +1/32", and then +1/16". Then they supply radius ground bonded shoes to suit.
These days it's maybe cheaper to buy 2 new drums + std shoes from Kc. That's what I did.

So, if yours are at 7.062" now and worn, that's it. Into the skip..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks for that Kev , that helps , i'll check them out tomorrow .

I don't think you can even buy oversize shoes can you?? I have heard of them but never seen or heard of them for sale....

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They are (were?) available here from brake shops- Better Brakes, B&R Brakes, Raybond, etc. They are done on exchange.

It is a complete waste of time machining your drums oversize unless you fit oversize shoes too. By the time std ones bed in to the big drum, they are worn out. Also you will have very little adjustment.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

On exchange Doc... would that have been for the bonded type or riveted type? Assuming riveted?

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They don't care which. They rip the old linings off, bond new thick ones on, then radius grind them to suit the machined drum- 7-1/32" or 7-1/16" diameter.

With a new std shoe set only ~$25 at Karcraft and drums also for $30 - $40 ea, I bet it's now cheaper to buy new instead of doing your old ones up. Material on these new shoes stops better than the bonded ones, I found.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.