I have a set of original Bennett brakes that I want to put on my 15 Speedster. (Actually, I'm not sure how much of this car is really 15, but that's how it's registered, so that's what I call it.)
The brake mechanisms are in good shape, but the drums are rough. I have some modern car drums that are very close is size that I'll be able to machine down to use. My question has to do with the inner drum diameter (for the parking brake). The current drums on the car measure 8". The Bennett drums are 8-1/8". The parking brake shoes are lined with linings that are mounted with flat head screws. The screws are not much recessed into the lining, if at all. I suppose that make sense if these are only used as a parking brake.
I'm concerned that if I match the 8-1/8" dimension of the Bennett drums, the parking brake will no longer work.
What is the correct inside diameter for these brake drums? What is the correct lining thickness on the parking brake shoes?
Why not buy new parking brake drums?
I agree with Stephen. I'm pretty sure the Bennetts originally used the stock Ford drums. The parking/emergency brake was not effected by the installation of the Bennetts. Your best bet is to get a pair of correct Ford drums.
Maybe I should mention why I feel it is better to buy new parking brake drums. The shoes are designed to be used with the 8" drums and using a slightly larger drum may cause the shoes not to make full contact with the drums. Also, using a larger drum would require the shoes to be spread more when setting the parking brake which may cause the brake to shoes to break apart prematurely.
The problem when using the original 1909-25 Ford drums as a service brake besides the small size is they're made of pressed steel. Almost all other cars has cast iron drums which gives better friction and handles the heat from braking better, thus less risk for brake fade.
The original parking brakes never had any lining, the ones you have may be one of many brands of accessory brake shoes offered over the years.
From your posting it seems the modern brake drums you've got are slightly larger in outer diameter than the original drum's outer diameter of 8-1/8". What's the inner diameter of the modern drums?
Cast iron needs to have more material thickness for strength than pressed sheet metal, so maybe you have to modify your accessory brake shoes to fit inside the modern drums?
The actual original Bennett Brakes had their own drums and they are wider than the ford drum by about 1/4". I don't recall if there is a difference on the inside diameter and can't get to them to measure the ones I know of, but I do remember they are cast and wider.
Yes, the Bennett drums are wider so the Bennett bands will not work on the stock drums. Using only a tape measure at the moment, the (very pitted) Bennett drums that I have appear to have an ID of 1-1/6" and an OD of 8-7/16". They are almost 1-3/4" wide, although the flat friction area is about 1-1/2".
The modern drums also appear to be 8-1/8" ID. They are thicker so I could turn them down to whatever I need for OD. They also are wider so can be cut to match.
My concern is the ID. The shoes on the car appear to work with an 8" ID drum. As Stephen mentioned, they may not work correctly (or at all) with a larger ID.
Seems I do have some sort of aftermarket brake shoes. Interesting that the linings are held on with screws, not rivets.
Still not sure what my next step is. I might be able to shim out the current brakes to work with the slightly larger drums, or maybe new linings would be enough thicker to make up the difference.
You might be able to put lining on a set of original cast iron shoes. The lined cast iron shoes have a recess the lining goes in. Just installing lining on the shoes may give you that extra diameter you need.