Question About Pre-war vs. Post-war Brakes

[JerseyHarold]

I saw a '37 Plymouth in someone's yard the other day and got to thinking about the differences between pre-war and post-war brakes.

As I understand it, the pre-war brakes had stepped wheel cylinders and single cylinders for the front wheels, which are difficult to find and expensive when you do.

Would post-war (P15 through 1954) backing plates fit the axles and spindles of the earlier cars? This would make it much easier to get parts. Does this idea have any merit?

Harold

[oldodge41]

My '41 Dodge (prewar) has the stepped cylinders. I recently replaced my rear end with a modern unit but still have the stepped cylinders on the front. I have wondered if it would be possible to use the newer (post war) cylinders from the rear of these cars on the front of mine. These cylinders are available at reasonable prices through auto supplies. The stepped ones are available from specialty shops at specialty prices. I have also wondered about modifying the front brakes to a floating type rather than the anchored type by adding the pins and springs thru the backing plates / shoes and adding the adjuster between the heel of the shoes. I think it might work but I really haven't even mocked anything up to try the fit. With the availability of disk conversions and subsequent replacement parts I will probably go that route. As for your actual question about swapping backing plates, I don't know. I don't particularly care for that brake setup and actually prefer the single master cylinder setup I have now over that one. We had a 48 Chrysler with the dual cylinders on the front and to me it was just double the amount to go bad.............Tim

[JerseyHarold]

I think the backing plates are stamped to handle a specific type of cylinder and shoe so I don't know whether converting to full-floating shoes would be an easy task.

I was wondering if the bolt pattern to attach the backing plates is the same pre- and post-war. If it is, changeover should be fairly easy.

[Niel Hoback]

I have given some thought also to converting to floating brake shoes. I notice that floating brake shoes use the wheel cylinder mount to stop the shoes from rotating around in the drum. Our cylinders are mounted by two small screws through the backing plate. I don't think that is enough to stop the wheel under severe pressure. Wheel cylinders for floating shoes have a large circular shoulder that fits tightly into a hole in the backing plate.

The answer could be to change to cylinders of the same bore from a floating shoe designed system and then just make the correct size hole in the original backing plate.

There also may be a problem with the piston pushrod to the shoe. Maybe not.

I really think that somehow this can be done, and I think it will be easy when someone finally figures it out.

[Jim Yergin]

I saw a '37 Plymouth in someone's yard the other day and got to thinking about the differences between pre-war and post-war brakes.

As I understand it, the pre-war brakes had stepped wheel cylinders and single cylinders for the front wheels, which are difficult to find and expensive when you do.

Would post-war (P15 through 1954) backing plates fit the axles and spindles of the earlier cars? This would make it much easier to get parts. Does this idea have any merit?

Harold

When I bought my '41 P12, the front wheels had the post-war style brake cylinder set-up. I think to use them you have to change the spindle uprights so that you can use the correct backing plate. The original '41 spindle uprights have four bolt holes for the backing plate and the post-war ones have three.

Jim Yergin

[moose]

When I bought my '41 P12, the front wheels had the post-war style brake cylinder set-up. I think to use them you have to change the spindle uprights so that you can use the correct backing plate. The original '41 spindle uprights have four bolt holes for the backing plate and the post-war ones have three.

Jim Yergin

On my A hot rod, I have a 37 DeSoto front axle with spindles and brakes from a 50 or 51. The kingpins are the same size, and the spindles(early 4 bolt, later 3 bolt) swapped over easily. The original brakes from the axle were no good, and I had all the parts for the newer style on the shelf(from my 55-switched to discs by olddaddy) The later brake parts are cheaper and easier to find.

[JerseyHarold]

So from the posts above, it looks like the fronts are a relatively easy swap if you have the suspension uprights and backing plates from a post-war car. Is the bolt pattern the same for attaching newer rear backing plates to an early axle?

[Robert Horne]

I saw a '37 Plymouth in someone's yard the other day and got to thinking about the differences between pre-war and post-war brakes.

As I understand it, the pre-war brakes had stepped wheel cylinders and single cylinders for the front wheels, which are difficult to find and expensive when you do.

Would post-war (P15 through 1954) backing plates fit the axles and spindles of the earlier cars? This would make it much easier to get parts. Does this idea have any merit?

Harold

On my 38 Coupe, I have the stepped wheel cylinders front and rear. The front takes 2 different cups, and the rears take 2 different cups. I believe the reason is because all the brake shoes are the same length. I used Ford brake linings to reline my Plymouth shoes. I use a master cylinder from a 1986 Dodge to replace my orignal master cylinder. Your idea has alot of merit also. I never thought about just changing the complete backing plate assembly. thanks for posting......Bob......