Identifying 1940-1948 Ford Brake Drums and Brake Shoes

Ford Hydraulic Brakes Backing Plates 1939 to 1942 Ford

Brake Drums

During the 1940’s, Ford used two distinct styles of 12” brake drum and hub assemblies. Originally, Ford sold brake drums and hubs as an assembly with the drum factory installed on the hub. When purchased in this fashion, it was not necessary to make any distinction between the two styles of drum assemblies. As a hub and drum assembly, either of the two styles can be used on any 1940-1948 Ford Car or 1940-47 1/2 Ton Pickup. It was not possible to purchase brake drums without the hub when buying replacements from Ford. In fact it is not uncommon to find both styles of hub and drum assemblies on the same vehicle if in fact they had been replaced previously during the life of the vehicle with genuine Ford parts.

However, as timed passed, it became customary for aftermarket brake drum manufacturers to simply supply the brake drum without the hub. This was done because brake drums tend to wear at a much greater rate than the hubs themselves, and therefore replacement of the entire assembly was generally an unnecessary and costly practice.

The difference lies in the manner in which the drum is mounted to the drum.

Earlier production assemblies (Generally 1940-1945) utilized a drum that mounted to the outside of the hub, with the hub installed from the interior of the brake drum. These drums have a center hole measuring approximately 3 ¼ ” in diameter and were originally identified by Ford part numbers 21A-1105-A (Front), and 21A-1115-A (Rear).

An alternate version of this drum assembly was eventually replaced by part number 51A-1105-A (Front). These assemblies are identified by a hub that is installed from the outside of the hub, with the hub installed from the exterior of the brake drum. These drums have a center hole that is approximately 4” in diameter. The larger center hole is due to the fact that the entire hub, including the portion of the hub that retains the wheel bearings, must now be passed through the center of the brake drum. On this type of assembly, with the wheel removed, a large circular plate, which is the bolt flange of the hub, will be visible over the face of the drum.

Brake Shoes

Beginning with the introduction of hydraulic brakes in 1939, through the 1948 model year (1939-1947 on ½ Ton Pickups)**, Ford had two distinct styles of brake shoes. Often this can lead to confusion when attempting to purchase replacement brake shoes. The key difference is in the manner in which the shoes are mounted to the backing plate, and in particular, the large anchor hole located at the bottom of each brake shoe.

Earlier production brake shoes (Generally 1940-1942) can be identified by a large, perfectly round hole, approximately 1” in diameter. The brake shoe anchoring bolts that fit through these holes are installed through the backside of the backing plate and are removable from the backing plate, once the retaining nuts are removed.

The Post war models utilized brake shoes that have an irregular shaped anchoring hole, also approximately 1” in diameter. This hole can be identified as having two distinct “flat” sides, as has opposed to being completely round. The brake shoe anchoring pins are permanently affixed to the backing plate and the shoes are retained by cotter pins, as opposed to nuts as with the earlier design.

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