Most people who have drum brakes in their Land Cruisers hate them, especially the older models which have drums all the way around. Why is this? Well, they take more maintenance than disks, and if the maintenance isn't done properly or regularly, they can be a real pain. Also, drum brakes don't work very well right after a water crossing, and they heat up more than disks under heavy loading, such as when trailering.
But, with proper maintenance, you can stand your Cruiser on it's nose, lock up all four wheels without too much effort, without double pumping or pulling to one side.
Here's what I have learned in 19 years of driving, maintaining and repairing Land Cruisers:
To start with your Master Cylinder must be in good condition. If it leaks to the outside world, it's history. Also if you press down, and after getting firm pedal it then slowly sinks to the floor, fluid is leaking past the seal inside and it's toast. Rebuilds and rebuild kits are a dicey proposition. If not done properly, they won't last long. Also many times the inside of the cylinder may contain pits on the surface from corrosion. Simply honing the inside surface of the cylinder won't go deep enough to remove the pitting, and it will just leak past the seal again, as well as wear out the seal prematurely. Your best bet is to get a new Toyota OEM replacement. Next best bet is a new (not rebuilt) high quality aftermarket Japanese replacement. For aftermarket replacement parts, I have had good success with NAPA, but spotty results with some of the other larger nationwide chains.
Whenever you replace your master cylinder, you must bench bleed it first. This can be done on a workbench, as the term implies, or while it is bolted in the Land Cruiser. Bench bleeding gets the air bubbles out of the guts of it; if not done braking will be impaired (soft pedal) and it will be really difficult to bleed the rest of the system. Basically, you get these fittings which are threaded like your brake line hydraulic flare fittings (10mmx1.00mm), and they have a barb for a small tube. You thread them to the brake line outlets, then push on the tube (usually about 6-8" long), and then position the end of the tube in each reservoir. Fill the reservoir(s) and push in the end of the M/C with a dowel or large screwdriver to pump the piston. Fluid will be consumed from the reservoir(s) and used to fill the inside of the M/C, as air is then expelled through the tubes and back into the reservoir(s). Don't let the reservoir(s) become empty. Keep pumping until no more air comes out the tubes.
Then bolt your M/C back into your Cruiser and connect the brake lines to it. Whenever a new master cylinder is installed, the brake height usually has to be adjusted too. There is a locknut on the rod where it connects to the pedal lever. Loosen the locknut, then rotate the rod with pliers until the brake pedal is at the right height. You must now bleed the system to remove whatever small amount of air got in during installation, but the amount will be small and manageable. Always start bleeding farthest from the M/C and work your way closer. There are 8 wheel cylinders, and each must be bled.
I have found that those handy bleeding kits that come with a small plastic reservoir, a special cap that has barbs through it for tubing, tubing and adapters for various sized bleed nipples is a really handy tool, much easier to use than the jar-and-tubing method you see in the manuals. They cost about $5-$8 in the auto department of discount retailers or the large auto parts chains. When bleeding, have your assistant start pressing down on the brake pedal BEFORE you loosen the bleed nipple. Then open it, let fluid out, then close it back up before your assistant starts raising the brake pedal back up. This way the chances for air re-entering are minimized. Keep bleeding until the fluid is clean, clear, and free of bubbles. Have your assistant check the level of brake fluid in the reservoir(s) about every 3-5 strokes of the brake pedal. NEVER let the reservoir empty, or else you will have to start all over again, including bench bleeding.
It is an excellent idea to bleed your brake system about once a year or so, whether you have done any brake work or not. Brake fluid is hygroscopic (absorbs water from the air), and the water will eventually corrode the internal surfaces of the brake hydraulic system.
Wheel cylinder adjustment is critical to drum brake equipped Land Cruisers. As mentioned above, there are 8 of them and it takes a lot of fluid to move all 8 of them any appreciable distance. For front disk brake equipped Land Cruisers, manufactured 9/75 and up, the 4 rear wheel cylinders must still be properly adjusted or else as the shoes wear the front disks will start doing all of the work, leading to premature wear on the front disk components and unsafe stopping in an emergency. In a Cruiser with drums on all 4 wheels, it is very common to have to double or even triple pump the brake pedal before firm pedal is achieved. This is because it is taking all that fluid to get the wheel cylinders to expand enough to make all 8 shoes make firm contact with the inside of the drums. The solution is proper adjustment of the wheel cylinders.
To adjust, chock a wheel that will remain on the ground, and jack up the wheel to be adjusted just enough so that the whell can spin freely. On the axle side of the brake there will be a small slot for adjustment, one in front of the axle and one in the rear, one for each cylinder. On some nicer cruisers the slot will still be covered with a rubber plug, but usually they are long ago history. If the plug is still there, you have to remove it to get the adjusting tool into the slot to turn the cylinder adjusters.
To tighten (expand) the shoes, the end of the adjustment tool should move away from the axle. To contract the shoes, the end of the adjustment tool should move toward the axle.
I have done this job using screwdrivers as the adjustment tools, but it is rather difficult as the end interferes with some of the stuff under there, like the shocks in the rear and the steering arm and hydraulic fittings in the front. I have found that a special brake adjustment tool, about $3-$5 at a parts store, works WAY better than screwdrivers.
Tighten a few clicks, then spin the wheel. No interference, tighten some more. Continue until the shoes are just starting to drag on the inside of the drum. As you spin the wheel, you may notice that it drags for a some of the rotation and spins free for the rest of the way. This means that your drums are out of round and must be turned. It costs about $8 per drum at NAPA and usually they can do all 4 drums in an hour if they aren't too busy. If your drums have already been turned one too many times there won't be enough material left to mill away and you must obtain new drums or used ones which have something left to turn.
Another instance in which you must have new or turned drums is whenever shoes are replaced. Don't even bother putting new shoes on an old drum that is not round and true. The new shoes will be true and the old drums will be conical. The result is that you will not be able to properly adjust your brakes.
After you have gotten the first cylinder adjusted, then tighten the second one on that wheel. Every so often go stomp on the brakes to center the shoes. The Hayne's manual says to tighten until they start to drag, then back off 5 clicks. I have tried this and it simply does not work, you will be double pumping for sure. My neighbor suggested backing off 2 clicks. I tried that and it still wasn't enough. Finally, I found out that if you leave them right where they start to drag, you will have good brakes. The shoes will wear into the diameter of the inside of the drums after a few week's use, then you adjust them one more time, and they'll be good for many thousand miles.
When working on brakes, often brake fluid is spilled on the inside of the brakes or elsewhere. Do not use mineral spirits to try to clean it up. It will attack the special compounds they use on the seals for the hydraulics. Only use special brake cleaning products like Brakleen.
There's more, but that's the important stuff. Email me if you have a specific question, I'll give it my best shot!