Like most everything else on the pickup, this system requires a complete overhaul. First, GM vehicles didn't have dual brake master cylinders (one circuit for the front wheels, the other for the rear) until later in the 1960s, so for safety that needs to be updated. We went through this on the Impala as well, and the updated parts are readily available, so that's not a big deal. It does mean the lines to the wheels need to be replumbed, but we wanted to replace them anyway.

We are, however, not installing an update kit to convert the front wheels to disc brakes as we did on the Impala, and that means we must now confront the ineffable horror that is drum brakes.

These are so called because instead of rotor discs with calipers that pinch them, drum brakes have a metal drum over the wheel hubs, like so:

(This is a bit of a sneak preview, since that's a new drum. You can see the rusty old one on the floor under the truck.)

Inside the drum, check out... this fuckin' thing.

In principle, a drum brake is pretty simple. Pressure on the brake pedal, relayed hydraulically by the master cylinder, causes the wheel cylinder (that barrel-looking object mounted sideways near the top) to push outward on the two shoes, which makes their bearing surfaces drag against the inside of the drum, converting the wheel's rotational energy into heat.

In practice, even a relatively simple brake like this one from the mid-1960s is a maze of return springs, retainer springs, levers, self-adjusters, manual adjusters, and, on a rear wheel like this one, the mechanisms that make the parking brake work independently of the hydraulics. Putting one together is like that stage of a LEGO build where to seat one brick, you have to exert pressure against some other part that is then inclined to pop off. It's ever so slightly maddening.

In this lower view, you can see the adjuster (at the bottom, with the gear teeth on it) and the arm that makes it work (on the left, with the long spring on its face and the shorter spring standing it off from the bottom). The p-brake actuator, basically a sprung cable running up to the front of the cab, is hidden behind that. This is a self-adjusting brake system, so with the drum on, that arm engages with the gear teeth on the adjuster. When the brakes are applied, if they have to travel farther than one sweep of the arm to engage with the drum, the bottom of the arm trips the adjuster, advancing its cog one tooth and forcing the shoes apart a little bit. This compensates for wear on the shoes and keeps the brakes effective until the shoes are too worn to work at all.

You can see from all the extended threads on the adjuster that this set of shoes is just about done--the extender is almost all the way out.

Another anatomical note: those circular objects at roughly four and eight o'clock are the retainers that hold the shoes in place. They have a pin that runs through from behind, with a spring behind them that keeps the retainer cap tense against the end of the pin. To remove and install them, you need a special tool like a screwdriver with a little cage at the end instead of a point. My father and I have never known the name of this tool, and it's the canonical example in my head of his long-standing habit of putting his hand out and saying, "Gimme the....... thing, willya?" Learning which "thing" he meant was my earliest education in working on cars. :)

Here's another view of the adjuster mechanism and the spring that holds the shoes together at the bottom. From this angle you can see that other spring running across in back, which is the sprung end of the parking brake cable. There's one of those on each rear wheel; they join together farther forward, and the single cable they merge into then runs up to the hand lever in the cab.

With new shoes and springs installed, the whole business looks a lot cleaner. The makers of the new hardware kit we used were kind enough to color-code the springs to make telling which one goes where a little easier. Note the yellow one on the rear retainer pin.

Up front, things are mostly a bit simpler, since there's no p-brake mechanism to worry about, but one thing is significantly different in a way that threw us off a bunch. On the rear wheels, since this truck was made long before independent rear suspension was a thing in pickups, the rear wheel cylinders are connected directly to hard lines, so they're screwed directly to the backing plates and the whole system is rigid. Up front, where the wheels have to be able to steer the vehicle, the wheel cylinders are connected to the hard lines with short sections of rubber tubing. I guess for this reason, the way they're retained on the backing plates is a little different.

See that shiny washer behind the nut at the top of the cylinder? That's called a French locking washer. It's basically a normal washer, only a bit thinner. Once the nut (which is actually a complicated peg thing with a nut-like hex surface on part of it, but anyway) is in place, part of the washer is folded backward over the mounting boss behind it, and part is folded forward over one flat of the nut, which keeps anything involved from rotating in either direction.

Except here's the thing: it doesn't appear that you can get French locking washers in the correct size any more. We ordered what we thought were new ones from a parts supplier, but when they came, both the inside and outside diameters were too small. Dad's theory is that they're actually for a passenger car's slightly smaller, lighter front brakes.

This meant we had to try and make our own, but normal washers are way too thick for the bending part to work. We hit on the idea of tracking down some wide, thin washers of a type commonly called "fender washers" because they used to be used in attaching auto body panels back in the day, but the problem with those is that the holes are quite small for the large size of the washer. This meant we had to find a pair that had the right OD and then drill out the holes to the correct ID using a step drill.

There were two problems with this. One was that we didn't have any fender washers. The other was that we didn't have a step drill.

Oh, and the third of two was that the hardware store a mile away was closed on Saturday, so we had to go to the one ten miles away... twice, because someone got the wrong size washers the first time. :)

Still, perseverance wins out, and we did eventually get the dang washers figured out. By then we were out of time for the day, so reassembling the front wheels will have to wait a bit longer.

--G.
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Benjamin D. Hutchins, Co-Founder, Editor-in-Chief, & Forum Mod
Eyrie Productions, Unlimited http://www.eyrie-productions.com/
zgryphon at that email service Google has
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