1943 Dodge WC51 Rebuilding Brake Wheel Cylinders

The ending photo in the Master Cylinder Repair blog kinda hinted that diving into brake wheel cylinder repair was a chore that needed to jump to the top of the Dodge's to-do list. Here's the photo again:

Today I pulled the offending left rear wheel off and psyched myself up for the chore of getting the brake drum off. They're never easy, but I guess I should Never Say Never. Who would have guessed it would be relatively easy? So the three large countersunk screws seen in the photo below fasten the drum to the hub. I unscrewed the three screws (they weren't super tight) and noticed there are three corresponding threaded holes in the drum to screw the three screws into so the drum can easily be pressed off the wheel studs by tightening the screws. I loosened the brake shoes using the adjustments on the backing plate and the drum slid off with little drama.

I used this big-head stubby Craftsman screwdriver (below) to deal with the three screws. It's from my dad. It's probably from the late '60. The only time I ever saw him use it (and what I used it for when I was old enough) was to open the old style 1-quart oil cans (that you only see in an antique store and my basement anymore). The containers were a thick cardboard middle section with a tin bottom and top. This screwdriver was the right size to poke holes in the lid to pour out the oil into a car engine. Now that I have the screwdriver, it gets used quite often in other ways, and it was the perfect size for those large brake drum screws.

Things don't look too terrible in here. The brake linings have a lot of meat left.

That is one massive brake drum. The brakes are 14" diameter by 1-3/4" wide.

This wheel cylinder's rear piston has some crystalline mess growing in it. This rear piston is slightly free to move but the front piston is rusted and seized in place, which is one reason I had such poor braking performance when I drove the truck to the recent tractor show. I'm guessing more wheel cylinder pistons are stuck in this same manner (future me says yes, six out of eight of the pistons were stuck).

This next photo shows the brake shoe top and bottom adjusters. The top snail-shaped adjusters can only move the "toe" (top) of the shoes out toward the drum or in away from the drum. The bottom adjusters look round but are essentially an eccentric cam and can move the "heel" (bottom) of the shoes in/out and up/down to a small degree. It's really a lot simpler to see them in action that try to describe how they work.

My brake cylinder hone was my dad's when I was a kid in the 1960s, and the stones were quite worn out so I bought some new ones.

This photo below shows the cylinder after a little honing with the old stones.

This next photo is after the new honing stones did their job. New rubber cups and spring went in, then the pistons, and finally rubber dust boots went on.

The massive brake drum looks fine. Good, because new ones are not cheap, at north of $187 apiece before tax and shipping as of this writing. It is a bit of a shock that new brake drums are still available, but they do fit the later Dodge M37 and Power Wagon with the same 5 x 6-7/8 bolt pattern.

Now that the left rear brake is done (other than bleeding), I am now on to the right rear brake. Its brake lining looks good also.

Both pistons were seized in the cylinder on this side so this brake wasn't working at all. The front rubber cup was leaking and the piston was covered in nasty goop. It took some propane heat and "gentle" persuasion with a hammer and large socket to break both pistons free. I started on the front leaky piston first since it looked like it would be easier to get out.

Yep, that one is very stuck.

The cylinder looked fine after honing so everything went back together with new rubber cups and spring.

After finishing up the right rear brake job, I adjusted the shoes, put the tire back on, and then called it a night. The next morning I came into the garage to find a lot of brake fluid leaking from the right rear brake. Hmm, that's not too promising. So I removed the tire and brake drum, disassembled the wheel cylinder, and honed the two sides a lot more (photo below).

I put the wheel cylinder back together, put the shoes back in place with the spring, and slipped the drum on most of the way, to hold the shoes from spreading apart. I then bled the line and brake fluid gushed out again. Back apart came the wheel cylinder and more honing. Back together, but this time I just put a ratchet strap around the shoes to hold them in place, so I could see where the leak was, if any. Yep, another gusher. Something was definitely not right but I didn't know what, so I called it a day again.

At that point I decided I'd just buy new wheel cylinders, as I figured they'd be maybe $30 at the most. Nope. The cheapest was $44 apiece plus shipping/tax, so that would be over $200 for four cylinders. I then got onto a Facebook Military Vehicle forum I'm subscribed to and searched for anything that might help.

Well, come to find out, because the wheel cylinders are stepped inside (1-1/4" bore on the front side and 1-3/8" bore on the back side), there's a step inside the cylinder (you can see it in the above photo) and with the top shoe adjusters all the way in, the front brake shoe pushes the 1-1/4" rubber cup far enough back in the bore that the rubber cup drops out of the small bore and the seal is lost, so brake fluid can just run out the front of the wheel cylinder. You'd think Chrysler wouldn't have made it so the adjusters could allow the shoes to push the piston/cup in so far.

The solution to this issue, per the FB forum guys, is to crank out the top shoe adjusters maybe halfway so the shoes can't push the 1-1/4" cup into the 1-3/8" bore. I did that the next morning and everything worked great.

On to the left front brake. Cobwebs adorned this brake drum like the previous two. By the way, that is a Superwinch locking hub, probably from the 1980s.

Both pistons were seized tight in the wheel cylinder so I decided to pull the cylinder and work on it on the bench. I had to grind a cheap 1/2" box wrench down so I could loosen the two wheel cylinder bolts, as the steering gear was in the way to fit a full width wrench in (and an open end wrench was goobering up the bolt's hex head). Here's a photo showing the lack of room.

The photo below is me applying heat to the wheel cylinder, to hopefully break things loose.

After much heating, pounding on the pistons, heating, pounding, scraping, pounding, I finally got one piston out. Once one is out, it's a breeze to knock the second piston out.

Below is a photo of the completed wheel cylinder. I hadn't noticed on the rear wheel cylinders that they are marked with the rubber cup size. The markings are on the bottom side of the cylinder so that's why I didn't see them.

Left front parts all back together.

On to the fourth and final right front brake. Both pistons were seized on this side too. Well, ok, this front piston did show slight signs of movement but there was so much crustiness that I decided to pull this cylinder off also and work on it on the bench. Good thing I did, as it was the most difficult one to get the pistons out of.

Yep, that's stuck.

I don't know why I took this photo below but here's the wheel cylinder in all its glory, just before removing it. Actually, you can see part of the funky shock absorber used on the truck. It's the arm thingymadoodle at the top center of the photo with a link down to the axle. I wonder if the shocks actually still do anything. I don't imagine you'd notice much difference if they worked or didn't work, with the suspension so stiff.

At this point, after getting the guts out of the wheel cylinder, I realized the new stones I'd bought for this job were completely worn out. The new worn-out stones are on the right. The old stones from the early 1970s are on the left. They are worn out also but are in slightly better condition than the new ones.

This photo below shows the hone. K-D No. 265, made in the USA and "Pat. Applied For" wording.

This next photo is the right front wheel cylinder all done after getting new stones for the hone - again.

This photo shows the rubber brake hose, with several cracks in the outer casing. I ordered new rubber lines from Midwest Military, and they should be here in a week maybe. I'm sure that will be another taxing job to be done, but there is no alternative. The hoses are a ticking timebomb waiting to go off.

Right front wheel cylinder is back in place.

Each brake drum has a slot in the side of it to stick a feeler gauge in so as to assist in adjusting the brake shoes. This right front drum is the only one that still has the cover clip and screw. I'm guessing the other three drums' screws broke off and nobody bothered to fix them. I didn't bother either.

The lug wrench that came with this truck is shown below (I had to come up with a suitable bar to use as a handle). The wrench is made by Budd, the same company that made the wheels and brake drums. This wrench has a large hex (1-1/2") on the left for the lug nuts and a slightly smaller hex (1-1/16") on the right for the combat rim nuts.

This photo below shows the truck up on the lift. I have to use blocking to reach the frame of the truck, as the truck's wheelbase is so short that the front and rear tires touch the center lift platforms and I wouldn't be able to get the tires/wheels off with the tires pressing against the platforms. With the blocking so tall, I can only do one axle at a time.

The truck is now back together and I took it for a test drive. The brakes worked like a charm. To summarize, out of eight brake shoes on the truck (two for each wheel), one or possibly two shoes were somewhat operational before I rebuilt the wheel cylinders. No wonder the truck barely slowed down when I drove it to and from the tractor show last month. I did plan ahead and anticipated every stop and was never in any danger of running into anything (the truck is just so slow), but it is good to have operating brakes now.

I'd like to mention how I adjusted the brake shoes. I didn't use a 0.006" feeler gauge like the shop manual says to use. I just went by feel. First step was to back off all four adjusters. Next I would adjust one top adjuster until the shoe started dragging on the drum, and then back off the adjuster a little bit until the drum spun again. Next I would adjust the lower adjuster until the brake dragged, and back off a little until the drum spun. Repeat for the second shoe.

7/23/2025 update: Ok, so today I was at a fellow tractor club member's garage sale. Guess what they had that I couldn't live without, and just five days after I finished up this wheel cylinder job? Still in its original packaging. And it was a buck. Who knows when I'll ever need it but I'd be nuts to pass it up.