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Here is a diagram:
Here is a picture of right rear:
You will need a drum puller to remove the rear brake drum. It is mounted onto the end of the axle shaft with a large nut.The drum hub fits on the tapered end of the axle shaft with a key way. The nut is removed,put on backwards with the castellated end in, until the flat of the nut is flush with the end of the axle to protect the threads on the shaft end. Then the puller is bolted to the drum, the center screw of the puller contacts the end of the axle and the puller is hit with a hammer which tightens the center screw and pulls the drum off. It takes some hitting,then you will hear a pop and find the center of the drum against the nut when the drum breaks free. Then just take the nut off and pull the drum of by hand. Good luck.
Adjusting '39-'42 Ford Brakes:
Here's the tool:
I used to hate these brakes because of the adjustable double anchor when I was a mechanic in the mid fifties. Then a fellow mechanic showed me a Ford Service bulletin. Ever since then, I have preferred these to the '46-'48 units since I can get a better adjustment.
These are Lockheed brakes which use eccentric washers in conjunction with non-eccentric anchor pins to position the shoes. The top of the shoe is controlled by an eccentric cam (usually 11/16") located near the top of the shoe. The anchor pins, located at the bottom of the backing plate, control the shoe position by turning the eccentric washers at the bottom of the shoe. These anchor pins have locating on the elongated 1/4" adjuster. The locating marks may be a dot or an arrow, I'm assuming everything is in good condition and not rusty or frozen.
Step 1: Loosen the anchor pin large lock nuts (usually 3/4") on both shoes of one wheel just barley enough to permit turning the 1/4" anchor pin adjusters. Now, turn both of the 1/4" adjusters so the locator marks face directly towards each other. This next point is important .... All further adjustments are made by turning the anchor pins (1/4") and eccentric (11/16") downwards.
Step 2: Back off the upper eccentric cam adjusters on both shoes until the wheel rotates freely.
Step 3: Now turn one of the upper eccentric (11/16") until the wheel cannot be turned.
Step 4: Now turn it's 1/4" anchor pin adjuster downward until the wheel just turns freely. This lowers the shoe and moves the toe of the shoe away from the drum and results in fuller shoe contact.
Step 5: Now go back to Step 3 and do it and step 4 again to the same shoe. Repeat as necessary until turning the 1/4" anchor pin adjuster will no longer free up the wheel. Back off both anchor pin adjuster and upper eccentric just enough so the wheel has a slight drag. Tighten the anchor pin lock nut (3/4") without letting the anchor pin adjuster move. Now do the other shoe the same way.
If you've worn the shoes badly at the top, it'll take some time to wear the heel enough so you get full brake shoe contact.
When adjusting brakes, always turn the wheel in the same direction the wheel would turn when the car travels forward.
Additional Information regarding the Adjustment of Early Brakes.
Adjusting the upper hex bolts to set shoe clearance is the easy part. The confusing part is the lower anchors on 39-42's. The Service Bulletin sends you through a procedure to follow, but does not explain why or what needs to be achieved.
The purpose of the lower anchors, which are eccentrics, is to properly position/center the linings in the drums, so that full lining contact can occur. OF FIRST IMPORTANCE is to have the new linings arc ground to fit the arc of the drums, which may be different on each drum, depending on the oversize of the drum. If this is not done, you are rolling the dice on whether the lining is too large of an arc (and will only contact the drum at the ends) or too small (and will only contact the drum at the center of the lining)- in either case, full contact cannot occur regardless of the anchor adjustment. Note also that the lower anchor adjustment is only required when installing new linings.
Once the anchor studs are set and the lock nuts are tightened, the shoes will not move out of center with the drums, and thereafter only the upper adjustment need be performed to compensate for lining wear.
In a nutshell, assemble the anchors with the dots facing each other as a starting point. Make sure that the drum turns freely, then adjust the uppers until they don't, then back them off until they do.
Have a helper apply about 30lbs of pressure to the brake pedal while (with the lock nut loosened) turning the flat on the anchor stud in each direction to cause the lining to impact the drum in both directions, then set the anchor in about the middle of that travel, hold the stud while tightening the lock nut. This essentially centers the lining up/down in the drum, allowing it to make full contact
when the brakes are applied. This operation is done to each anchor/shoe/lining separately. When all have been done, again adjust the upper (clearance) hex heads until the shoes are just barely off of the drums.
Road test and readjust as necessary to make it stop good and straight.
It is also important to have at least 1/16" of free travel of the Mcyl pushrod before it starts moving the Mcyl piston; otherwise, the brakes will not fully release, will get hot and will lock up.
The above is not exactly the same procedure as provided elsewhere, but it is what I do and it seems to work well. If you keep in mind what you are trying to accomplish, it makes sense.
The short shoe is the primary shoe and always goes facing the front, the long shoe is the secondary and always goes facing the rear. If you will look at the second picture you will see it is labeled "right rear". He is correct, most people who have the old style convert to the later model hydraulic type for better braking.
DRUM BRAKE EVOLUTION
To understand the how we must first discuss the why. Brake technology has made quite a few advances in the last 100 years, but even back in the 1940s, Ford adapted changes to the way brakes were designed, much to the resistance of Henry Ford.
Henry Ford was fond of his mechanical brakes, and his marketing touted "Solid steel from pedal to wheel". These mechanical rod operated brakes persisted until 1939, well behind Ford's competitors. The problem with the brakes is that they required frequent adjustment, and were just plain dangerous at speed. They featured 12 inch diameter drums that could easily put a car into a spin if one brake rod was tighter than another. High speed stops proved to be hair raising experiences, and many felt that the new hydraulic or "juice" brakes introduced in 1939 to the Ford product line was a step up in safety and performance.
The first and by far the most important design improvement was the change from rods to hydraulic fluid to actuate the brake shoes. Although the design was originally invented in 1924, Ford resisted utilizing the design until 1939, with the backing plates, shoes, and drum assembly that in many ways the is same design used on cars today. There were a few key design issues that took some years of production to be recognized and improved upon. Along with other idiosyncrasies, Ford's new adopted hydraulic design was a work in progress. The brakes required more pedal effort to stop the car than our modern drum brakes, a break in period, and even in some cases machine grinding to fit correctly.
Back in the 1940's and 1950's our hot rodding fore-fathers had limited resources and little access to sophisticated machinery, so often a "bolt on solution" was the most popular. From the way Ford designed their cars, these brake alternatives were just that.
The second major design improvement was the way the shoes were mounted on the backing plate. The 1940 brake shoes pivoted on a pin at the bottom and where actuated by a slave cylinder at the top. This design is known as "single leading shoe" or "leading and trailing shoe brakes". When brake force is applied, both shoes pivot at the bottom attachment bolt and press against the drum with equal pressure. Shoe contact tended to stay in one spot and the wear was uneven. Pedal effort was high because none of the rotational force was used to help make the shoes press harder to the drum surface.
To improve shoe to drum contact, the 1940 design utilized a pair of cams on the shoe pivots that moved each shoe in or out to eliminate high spots. Either lock nuts on the backing plate side of the brakes, or spring tension bolts allowed for adjustments to be made.