11in Front drums, How thick?

[Wollfen]

I have a set of front drums that are the 11in variety found in the late sixties C-bodies. I have been looking at the thickness of them to determine if they can be machined as there appears to be less than a 1/4in of meat left. Whats the minimum these things can be and also what do they start out being thickness wise?

 

[commando1]

The min. diameter should be cast right onto the drum, no?

 

[polara71]

The min. diameter should be cast right onto the drum, no?

Really? Never knew that or even heard of that

 

[Wollfen]

Im wondering whats the minimum thickness of metal is acceptable after machining before you trash it and get a new one. i have second set of drums that only have 1/16 of an inch left in them and i would say they are beyond use now.

 

[jake]

Stans right, Every drum I had turned, the minium thickness is cast right on it.

 

[Wollfen]

Oh you mean as in words, the minmum thickness can be read, gotcha, i will check that out tomorrow.

 

[commando1]

Learned that back in 1965...

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[1978 NYB]

 

[1978 NYB]

The min. diameter should be cast right onto the drum, no?

Yep, Auto Shop 1969

 

[1978 NYB]

Any automotive machine shop will have a book/chart that will have drum and rotor specs.

 

[71ChargerSE]

11" will have an inside diameter 11.060 "machine to" and 11.090 discard.

 

[Zymurgy]

I'm still kicking myself, I ruined one of my original drums, so I bought one new drum, and I had the other 3 turned. My old ones where thicker than the new one.

 

[commando1]

My old ones where thicker than the new one.

Thanks for confirming my suspicions.

 

[Zymurgy]

Thanks for confirming my suspicions.

The old ones heavier all around. I stupidly pressed the hubs back into the drums with no back support. I started with the old drums and they popped in with no damage to the drums. However when I did this to the new drum I cracked it and ruined it, so I ended up buying 2 new drums.

 

[Fratzog]

I wonder if those cast diameter #s are guidelines or carved in stone safety rules. I can see manufacturers minimizing the diameter to increase demand.

 

[commando1]

I never though of you as the conspiracy theorist type, Fred.
Myself, I wouldn't cut beyond what is cast in iron.....

 

[Fratzog]

Probably wise...

 

[commando1]

It IS the brakes after all...