Drum brake adjustment?

Actually it's quite common, but the cause can be elusive. With the drum off, look at the "parking brake strut bar" between the two shoes, right below the wheel cylinder. You'll see there's an anti-rattle spring on one end. Use your thumb to push against that spring. The bar should move a good 1/8th inch. If it's tight, look at the parking brake lever attached to the back of the rear shoe. That should be fully retracted so it's hidden from sight behind that shoe frame. It's most likely pulled forward due to a stuck parking brake cable. Another clue is that lever will move forward and back as you flex the parking brake cable right behind that brake assembly.

If the parking brake cable is just sluggish, use a large pry bar to retract the lever. At that point the play in the strut bar should return. If this doesn't help, post a photo of one of the brakes with the drum removed.

If it does help, do not try to lubricate the sticking cable. It must be replaced. When performing safety inspections on trade-ins at a very nice new-car dealership, we were only allowed to replace parking brake cables, or cut them. Cutting them was legal as long as it was disclosed on the window sticker. Even if lubricating them appeared to get them working properly, it was well-known that vehicle was going to come back sooner or later on a tow truck with a stuck cable.

If that strut bar is tight, also look at the anchor pin on top. Both brake shoes must be against that pin. If the parking brake is stuck partially applied, one or both shoes will be held away from that pin. When you push that shoe up to the pin, it will cause the other shoe to move away.

This drawing is of a different design, but the parts I described are the same as yours.

Dandy photos. Look at the parking brake lever on the right side and see how far back it is, hidden behind the rear shoe.

On the left side, it's pulled forward all the way to the fully-applied position. That's what took up the free play in the strut bar. Also notice on top, the rear, or "trailing" shoe is not touching the anchor pin on top. If you push that shoe up to that pin, you'll see the front, or "leading" shoe move away from the pin. Another sign of an applied parking brake.

I also noticed the star-wheel adjusters on both sides are turned down, or shortened almost as far as possible. Even with new shoes and new drums, they're normally adjusted out roughly a 1/4" of threads showing. With worn drums, and even more so with drums that have been machined, those adjusters will be extended a lot more. Shortening them as much as you have is in response to the tops of the shoes being held out too far. That's the only way to get the drums on.

On most vehicles there's three parking brake cables we're concerned with. Those are the two rear cables, one going into each backing plate, and the front one coming down from the parking brake pedal. There's also, at a minimum, one intermediate, or connecting cable that ties all the other three together. We don't worry about that connecting cable unless it's broken. It isn't in a casing so it can't stick. With the two rear cables, first look at the front end where the casing is snapped into a metal bracket welded to the frame. If this sticking is fairly new, right where the cable comes out of the casing, you'll see about an inch long section that's shiny, or cleaner than the rest of that cable. That shiny area shows the part that's supposed to be retracted back into the casing. Use a pry bar on the driver's side to force the parking brake lever back behind the rear shoe, to its retracted position. If you can't do that, that cable is rusted tight and must be replaced. Another clue to a rusted rear cable is if you flex the casing by hand, you'll see the parking brake lever move back and forth a little. It's doing that because the cable is not free to slide around inside the casing.

On the right side, grab that cable ahead of the casing, where it's exposed, and tug on that. What should happen is the parking brake lever gets pulled forward, then it retracts under spring pressure when you release the cable. If that movement takes place freely, that cable is okay.

If you're able to pry the left lever back to its retracted position, look at the right lever now. If it is still retracted, as in your photo, the intermediate cable was likely drooping, and now it's tight. More likely, if forcing the left lever back causes the right lever to move forward, there's too much tension on those cables. Either the front cable is sticking, in which case the parking brake pedal would not retract on its own, or the cable adjustment is too tight.

The cable coming down from the parking brake pedal can become tight too. The only thing pulling it up is the four brake shoe return springs. Check that front cable by working the pedal. If it doesn't return, have a helper hold up on the release lever while you work the cable from underneath.

If all the cables appear to be working freely, but the pedal doesn't return completely, the shoe return springs may be weak. All of the hardware comes as a complete kit for both wheels. You'll usually have springs left over. There will be two or three variations for some applications. Use the replacement springs of the same color. Those colors denote the springs' tension. With those extra springs, one kit covers a number of different variations such as drum diameter and body type, (truck, station wagon, sedan, etc.).

Another common complaint when the parking brake cable is sticking is extremely easy rear wheel lockup and tire skidding under rather light brake pedal pressure. The rear brake doesn't apply smoothly and gradually like it should.

For the benefit of others researching this topic, another common mistake has to do with where each shoe is installed. In most cases the right and left pairs will be identical, but the leading and trailing shoes are different. The leading shoe has a shorter lining. It's only job, when driving forward, is to grab the drum and try to rotate with it. As it does, it pushes on the star-wheel adjuster which pushes the bottom of the rear shoe into the drum. At the same time, the piston on the wheel cylinder pushes the top of the rear shoe into the drum. This common setup is called a "duo-servo" design. Two forces are pushing the rear shoe into the drum. That rear shoe does almost all of the stopping, so it has a longer lining. The common mistakes are someone will pair up the identical shorter linings and put them on one side, and the two with longer linings on the other side. That can cause an elusive brake pull. Another mistake is to put both longer linings on the front in the misguided thought they do more of the stopping. In fact, the shorter linings on the rear will wear out very quickly. In your photos, you can see the length difference in the linings at the top. You have the shoes installed correctly.

One notable exception to the shoes being identical has to do with older rear-wheel-drive Chrysler vehicles. They used a pin for the self-adjuster lever that had to be tapped into each rear shoe. If you had to install the pins provided, the two rear shoes were identical. If the new shoes came with those pins already pressed in, you had to put them on the proper sides.

Another common exception, before someone gets excited, is a lot of smaller cars do not use this duo-servo design. They often have a fixed anchor at the bottom of the backing plate. Going forward, only the leading shoe does the stopping. The trailing shoe sees very little wear as it only does its thing when backing up. The nice thing with these is the leading and trailing shoes are usually identical. When the leading shoes are almost worn out, the two shoes on each side can be switched to get double the life out of the set.

To add to the excitement, I added some callouts to your left photo to help me explain this better. If it's too difficult to see, copy and paste it into a typing program where it can be expanded. I use MS Word for this.

"A" shows the gap between the end of the strut bar and the frame of the rear shoe. It's much larger on the left brake, indicating that parking brake is applied.

"B" shows the same condition. The lever is pulled as far forward as possible.

"C" shows where the rear shoe hasn't retracted back to the anchor pin. They can't move out any further on top, so under hard braking, the bottoms of the shoes get pushed out which activates the self-adjuster. That makes that brake self-adjust up too high until the shoes are dragging.

I added "D" in case you need to replace a cable. There's three or four tangs that must be squeezed in to let the cable be pulled out of the backing plate. If the cable is being replaced, it's faster and easier to just bend those tangs to break them off. To access those in back, use a pair of pliers behind the backing plate to rotate the casing until you can get to them.

The red and blue brackets at the top are the same length. The red one shows how much shorter that lining is on the shoe toward the front of the truck, (leading shoe).

Let me know what you find with these cables. The rest of the job looks fine.

There is a way to replace the cables without removing other parts. The easiest way to start, if you have an air-powered cutoff tool, is to cut all the way through the casing. Cut near its center so both halves give you something to hold onto. If you can find a way to hold the parking lever in the applied position, as it is now on the left side, that will help. Break off the tangs on the ends of the casing. (If you're really emotionally-involved with the old cables and want to keep them, you have to press one tang, then push the cable sideways a little to start that one coming out of the hole, then move on to the next tang and do the same thing). When all three or four are pressed, the cable can be pulled out of the backing plate or frame bracket. I'll give you the whole five minutes for that simple task, as it too can give a guy trouble doing it that way.

Another way I've seen work is to cut and remove enough of the cable so it can be removed at those casing ends, then push just the right size deep socket over the tangs to press all of them in at the same time. Personally, I wouldn't expect that to work, and it would take me too much time to find the right socket.

Once the casing is pulled out of the hole in the backing plate, slide it off the cable if possible. The goal is to get enough slack in it so that long spring on the end of the cable is free to slide back and forth a good inch or more. Have the new cable ready, use the old cable to pull the parking brake lever applied, then use a pry bar or large screwdriver to hold it there. With the slack in the cable and the spring free to slide, push the cable rearward to unhook the metal "bullet" from the lever. This simple task can be more frustrating than you'd expect. You'll likely need another pry bar to unseat that bullet, then life isn't complete until the first pry bar slips off and the parking brake lever retracts. After a few choice swear words, pull the old cable out, then feed the new one in but not far enough to seat those tangs.

You may have noticed the new cable has a light film of grease on it. For what it is meant to do, (prevent the same rust-related failure), that is an insult. I like to coat both ends with Spray White Lube. That's a lithium-based grease that has a liquid that seeps into tight places and takes the grease with it. Later, the juice evaporates and leaves the grease behind. It's also great for door hinges. "Spray White Lube" is actually Chrysler's name for their product, but you can find this at any hardware store or auto parts store under many different names. Slide the cable back and forth a little through the casing to get some of that grease inside the ends of it.

With the front end of the cable not connected yet, you're free to push it rearward far enough to hook the end onto the lever. By not having the casing snapped into place yet, you can get plenty of slack so the long spring on the cable doesn't get in the way. Once you get the cable attached to the lever, go to the front end of the cable and pull it out of the casing. That will take up the free play and begin the squeeze the spring. That spring keeps the bullet from popping off the lever. Now you can snap the casing into the backing plate. Don't panic if even that gives you a little trouble. Once one of them is in place, wobble the casing around until the others pop into place.

I think you'll find the rest of the procedure to be intuitively obvious. Feed the cable through the bracket on the frame and snap those tangs into place.

On the right side where the parking brake lever is retracted already, you'll need to pull it forward to remove and attach the end of that cable. I would break off the tangs on the casing, then use that casing to pull the lever forward. If nothing else works, use a large pick with a 90-degree bend to hook the lever and pull it forward. Attach the new cable the same way as you did on the left side.

With both rear cables snapped into place, check for smooth operation of the front cable. Push the parking brake pedal down, then have a helper hold the release lever. From underneath, you should be able to pull on the front cable by hand to pull the pedal back up. If you can't do that by hand, the brake shoe return springs won't be able to either. If you have to replace that front cable, I'll find the instructions and post them for you. There's too many variations to remember them all. I can suggest that GM is more interested in assembling vehicles quickly on the assembly line with little regard to what has to be taken apart later. Look at it with that attitude when trying to figure out how something comes apart.

With all the cables handled and working freely, one of them is going to be adjustable. Usually there's a long threaded rod on the end of the front cable, but it could be on one of the rear cables instead. Once in a while, especially on Ford trucks, you'll find a mess of hooks and hangers holding the parking brake cable away from the driveshaft, hot exhaust parts, and things like that. It might be a good idea to take a few pictures in case one of those hooks falls off and you're not sure where it goes.

If the threaded adjuster is on the front cable and you don't have to replace that one, the adjusting nut is likely to be rusted tight. You might free it up with a propane torch, but usually you need an acetylene torch. They actually make very deep six-point sockets for that nut. You'll find them on the tool trucks, like Snapon, Mac, and Matco. The people at any repair shop can tell you when they are on the schedule each week, or give you the salesmen's' phone numbers. Of course, when you're only doing occasionally, you can use a box wrench too. Hold the smooth end of the threaded shaft with a vice-grip pliers, then turn the heated nut.

A really good product to use on that threaded shaft is "anti-seize compound". The can has a brush under the lid to apply this grease. It will prevent the nut from rusting tight way better than any other grease. A word of caution though. Do not use this on lug nut studs. Doing so can get a mechanic fired because it's almost a certainty the nuts will work loose, leading to a potential lawsuit. A very light film of grease is okay on wheel studs, but then run the nuts on by hand, not with air-powered tools. With too much grease, and air tools, that grease will build up in front of the nut, then get flung out onto the curved friction surfaces. Those friction surfaces must be clean and dry to hold the lug nuts from working loose.

When adjusting the parking brake cable, check if the pedal comes back fully on its own. It will push very easily when the drums aren't installed yet. Keep in mind the pedal won't go so far to the floor once the drums are installed. Also, don't get excited if the pedal doesn't like to come up all the way with a lot of force. That will improve once the drums are in place. If you do this with the drums off, don't press the regular "service" brake pedal when the parking brake is applied. Doing so provides no resistance to the wheel cylinder and one of those could blow apart. If that happens, this is another time to not panic. I can write another chapter on how we always used to rebuild wheel cylinders.

For my last caution, related to the wheel cylinders, during any brake system service, do not push the brake pedal more than halfway to the floor. This is especially true when pedal-bleeding the hydraulic system. It also applies to any vehicle more than about a year old. Crud and corrosion build up in the lower halves of the bores in the master cylinder where the pistons don't normally travel. Pushing the pedal further than normal runs the rubber lip seals over that crud and can rip them. That shows up as a slowly-sinking brake pedal, and it commonly takes two or three days to show up.

See how far this gets you, then let me know how this turns out, or if you have more questions.