C2: Max allowable brake drum surface diameter

[James W.]

Does anyone have the specs for what the maximum allowable diameter can be for 63/64 Corvette brake drums?

Thanks,

James West
Omaha, NE.

[John M.]

Re: C2: Max allowable brake drum surface diameter

I think that it is 11.060"

[Duke W.]

Re: C2: Max allowable brake drum surface diameter

Actually, it's 11.090". The max diameter is debossed in the castings beginning in the late sixties. This was a FMVSS that went into effect, I believe, on 1/1/68, so original drums do not have this placard.

Functionally correct replacement drums are relatively inexpensive and readily available, so I would personally recommend that you replace the drums if a cleanup cut takes the final ID to 11.060" or greater, especially on the front, and drums should alway be replaced in pairs on either end.

The drums aren't visible during judging other than the edge of the inside flange from under the car, so you don't have to worry about have "correct" casting numbers.

Duke