Brake Drums

Workshop Overview

The workshop opens with a reminder that mechanical brakes tend to deteriorate gradually, making periodic inspection and adjustment important. The handout reviews the complete brake system: drums, hubs, races, bearings, studs, backing plates, shoes, linings, springs, cams, levers, linkages, and brake adjustment.

The workshop agenda focuses on original steel drums versus newer cast iron drums, hub components, brake-drum equipment, and a drum-turning demonstration.

Questions to Ask During Inspection

• Are the drums steel or cast iron?
• When were the drums last removed for inspection?
• How are the brake linings wearing?
• Do the brakes squeal, fade, pull to one side, or fail to stop the car as quickly as expected?
• Will the emergency brake hold the car on a slope or stop it if needed?

Original Steel Brake Drums

The handout describes the original drums as stamped steel with forged-steel hubs and reinforcing bands.

Diameter

Measure drum diameter with a brake-drum micrometer. The handout gives a new diameter of 11.000 in. and uses the following evaluation ranges:

Thickness

The handout says a new steel drum is about 0.150 in. thick and notes a minimum acceptable thickness of approximately 0.120-0.130 in., depending on the source consulted.

Newer Cast Iron Drums

The handout notes that Ford introduced cast iron drums in August/September 1931, with spoked front drums and non-spoked rear drums.

• New replacement drums cited in the handout are manufactured slightly undersize so they can be trued to 11.000 in.
• Used cast iron drums, after turning, are to remain at 11.060 in. or less according to the workshop notes.

Hubs, Races & Bearings

For rear hubs, the workshop identifies shoulder-style hubs with 1928-29 cars and grooved hubs with 1930-31 cars. The handout also shows a tapered hub design for comparison.

Front Hubs

• Two races are used: a larger inner race and a smaller outer race.
• Races must be pressed securely into place and must not move.
• Inspect race surfaces for wear or pitting.

Rear Hubs

• The bearing race is integral with the hub.
• Some wear is common; inspect carefully for excessive wear or pitting.
• The axle key must fit securely in its slot without play or wobble.

Wheel Studs

• The handout states that original-style studs for steel drums are no longer made.
• Cast-iron-drum studs have a longer shaft because of the thicker drum; new studs must be modified if used with a steel drum.
• The workshop specifies swedging studs into place with a hydraulic press at 20 tons of pressure.
• Do not braze or weld wheel studs into place.

Evaluation & Solutions

Two Quick Tests for Steel Drums

1. Drum diameter must not exceed 11.060 in.
2. Wheel studs must not be welded in place. The handout says drums with welded studs should be discarded.

Hub Inspection

• Front: races must remain firmly seated and bearing surfaces must be in good condition.
• Rear: remove the snap ring, grease seal, and roller bearing to inspect the race surface. The axle key must also be firm with no wobble or play.

Solutions Presented in the Workshop

1. Turn steel drums if they pass the workshop's evaluation tests.
2. Purchase new cast iron drums and hubs.
3. Install good-quality used hubs into new cast iron drums.
4. Install a rear-hub repair kit into an original hub.

Removing Your Brake Drums

Front drums should come off relatively easily. For rear drums, the handout lists the following tools:

• Pliers for the cotter key
• 15/16-in. socket or wrench for the axle nut
• A hub puller that properly fits the hub
• Wrench for the hub puller
• A method to keep the drum from rotating while loosening the axle nut
• Two screwdrivers for the snap ring
• A vise and slide hammer, and possibly other tools, for grease-seal removal

Reinstalling Your Brake Drums

Front

• If races need replacement, install the new races with a press.
• Wheel-bearing grease
• Inner bearing A-1201 and outer bearing A-1216
• Bearing retainer A-1195
• Flat washer and reused axle nut
• 1 1/8-in. socket or wrench
• New cotter key

Rear

• Wheel-bearing grease and bearing A-1225
• Rear axle key A-4243
• Axle shims A-4235-SH as needed
• Replace grease seal A-1175 and fiber washer A-4244
• Snap ring A-1180 if replacement is needed
• Reuse the flat washer and axle nut if serviceable
• 15/16-in. socket or wrench and a new cotter key

Brake Adjustment

After new drums and hubs are installed, the handout calls for adjusting the brakes and checking the adjustment again after approximately 50-100 miles.

Workshop references include the Model A Ford Mechanics Handbook, Vol. I by Les Andrews; Model A Ford Service Bulletins; How to Restore Your Model A, Volume 1; and Model A Ford Construction, Operation, Repair for the Restorer.

For the club's dedicated adjustment procedure, see Model A Ford Brake Adjustment.