1955 Roadmaster brake drums

[McGreaham]

Hello all, I have a question about the proper size of brake drums for a 1955 Buick Roadmaster series 70.  My mechanic stated that the drums on the car are front 2 1/2 and rear 2 1/4.  I purchased replacements from Cars and they shipped drums that were front 2 3/4 rear 2 1/2.  Their catalog lists the size of the drums at 2 1/2 and 2 1/4.  I contacted them for a return and they are telling me that what they sent is correct.  I don't believe them but want to get feedback from the group before I escalate this up the chain.  Any info would be appreciated.  Thanks.

[billbuickgs]

Shop manual lists 2.50 front and 2.25 rear . I think that is the brake shoe width  ??????

Hope someone has the answer to this .

Bill

[avgwarhawk]

What Bill has posted seems logical.  Brake shoes are 2.50 and 2.25.   There needs to be some space between the  shoe and the drum or it will rub.      Hence drum is 2.75 and 2.50.  

Edited October 17, 2017 by avgwarhawk (see edit history)

[Frank DuVal]

Are you measuring the outside of the drum width, or the width of the inside swept surface (the machined surface the shoe presses against)?

[Beemon]

You also have to consider the surface that is used to seal around the lip of the backing plate. Depending on wear of the anchor points of the shoe, you'd want some play on both sides. 1/8" play on both sides of the shoe sounds ballpark to me.

[old-tank]

Take the new and old drums to a local mechanic and get another opinion as to interchange.  Reproduction drums look a lot different from originals, but should fit.

[McGreaham]

21 hours ago, Frank DuVal said:

Are you measuring the outside of the drum width, or the width of the inside swept surface (the machined surface the shoe presses against)?

The width of the inside swept surface.