1940 brake drum and wheel sizes

[Charles2]

On my 1940 Special 4-dr, a previous owner changed the wheels from 16" to 15" and installed L78-15 tires. I have a couple of questions about this. First, was this done with the original brake drums and backing plates or were these changed to go with the new wheels? The drums and backing plates appear to be original and one of the three hub-to-drum rivets on the front, and hub-to-drum bolts on the rear, have been removed to accomodate the 15" wheels. The inside diameter of the brake drums is almost exactly 12"; just a tad under, maybe -1/64", and the OD at the widest part is 13-3/32". So, if I decide to go back to 16" wheels, will I be able to use the brakes I have? My second question is this: Can anyone tell me what the minimum drum thickness or maximum inside drum diameter for turning might be? The drum walls seem a bit thin by modern car standards. I live in hilly country and don't want the brakes fading with normal use. Any information will be welcome. Thanks.

[palbuick]

It was quite common years ago to switch to 15" wheels , on the early buicks with original 16" rims and tires. Any 15" buick Rim from 1941 through 1955 would fit without any alteration(except removing the guide pin on drum). Even the 53 Skylark wire rims would fit on the 40. If you want to go back to the original 16" rims, make sure that you get the 1939-1940 rims only, as they were designed for the 39-40 hubcaps only. As for the brake drums , full them off and take to a good machine shop and let them measure the inside to see if they can be cut again.

Jim Schilf / palbuick@aol.com