Just getting into the brake system on my '94 Explorer Sport and I guess I assumed it was disc brakes all around, but now I'm hearing about 91-94's having drum brakes for the rear?
Is this true?
Great (if true)... now I'll need to study up on drum brakes like I did with disc brakes! I haven't seen any "helpful articles" or tips on rear drum brake maintenance. Did I miss the thread in my searches?
Thanks,
JP
Drum brakes have a few more moving parts to keep track of. They are not difficult, but they do take a few tricks of the trade to make working on them easier. I'll post links to KD Tools along the way -- using the RIGHT tool for drum brakes makes the job amazingly easy.
First tip -- always work on just one side at a time. That way, you can look at the other side to see how the springs and levers go back in place once you remove them on the side you are working on.
To pull the drum -- as drums wear, they often wear a groove inside the shell of the drum, where the brake shoes rub. That means that there is often a lip that will stop the drum from pulling off of the brake shoes. The trick here is to back off the shoes by using a brake adjusting tool (sometimes called a spoon) to back off the star-adjuster wheel and to reduce the overall diameter of the brake shoes.
http://www.kd-tools.com/287.htm
In order to actually turn the star wheel in the correct direction, you will also need to insert a thin screwdriver or pick to push back the spring-loaded anti-reverse guard (through the rubber plugged access hole in the rear of the drum, right below the wheel cylinder) that allows it to ratchet in only one direction. One tool pushes away the guard, the other backs off the star. How do you tell which is the right direction? It goes the other way from the way it moves easily when you push it with the spoon (in other words, it will move to adjust "out" freely -- you'll hear a click as you push it -- but it will not go the other way until you press the guard out of the way. That is the right way to back off the brakes.)
Once backed off, the drum should slide off. If it doesn't, one of two things is happening. Either you cannot back off the pads far enough to let it slide off -- OR -- the drum is frozen onto the axle shaft (they are very closely fit and often seize up!). The trick here is to hit on the EDGE of the drum (toward the axle centerline) NOT on the face or the rear of the drum. If you picture the brake drum as a musical bass drum in a marching band, you do not want to hit either head -- instead, you spin the drum sideways and hit the side. toward the center of the drum. This works best. At times, the drum will simply be frozen in place. Use PB Blaster lube, and sometimes a BIG hammer. Expect to ruin ALL of the parts inside the drum. Just replace everything, springs and all (They are cheap!).
Once the drum is slid off, you will see two shoes. Look at them carefully, one is the leading shoe and one the trailing. One typically has more material than the other -- it matters. The design of most drum brakes is "self-energizing" in that a longer shoe pulls the brakes tighter once it engages to assist with braking force. These shoes are held in place with a bewildering array of springs, clips, and wires. Again, pay close attention -- take a picture if you need to. This stuff must go back exactly in the same order to work.
Start by removing the main spring. You can get a special tool for this process that makes the job super easy. I like this one:
http://www.kd-tools.com/280.htm You use the fat end of the tool, push it over the post, then the little finger on the tool will lift off the spring as you rotate the tool. Use the opposite end to reinstall the springs later, slide the thin end through the spring, put the end over the post, and then lever the springs into place. Don't try brake jobs without this tool!
Once the main springs are released, release the springs holding the "nails" in place. These work best with this tool:
http://www.kd-tools.com/2774.htm Push the cup against the spring retaining plate, give it a twist until the wide spot on the nail fits through the slot on the retaining plate and it will come apart. Reverse for installation. The tool makes it possible to push, turn, and see at the same time.
Now, your brake shoes will be about to fall off except for the emergency brake cable and the lower spring that still holds them together. Just wiggle them around do dislodge the lower spring, then twist them until the e-brake cable comes out. In some cases, you may also have to un-bend a horseshoe clip in order to release it from the e-brake lever. Just use a screwdriver and a pliers to un-bend this clip and remove it.
Now, your brakes are disassembled. Clean everything with brake cleaner spray (only!). Don't blow off the dust with air -- it can be hard on the lungs.
Check to make sure that your axle seals are not leaking into the brake housing area. If they are, replace them (another write up for another day). Also make sure that the wheel cylinder is in good shape. If you are even close to being doubtful, just replace them. They typically sell for under $15 a side -- well worth it to have good brakes. You will have to bleed the brakes, and typically the bleeder screws are rusted shut, and replacing the wheel cylinder is the easiest way to fix that problem.
Assembly is the reverse of removal. First the lower spring and e-brake bracket and cable. Then the adjuster mechanism in the center (Lube all the rub points with white lithium grease -- use sparingly so it doesn't get on the shoes!). Insert the nails and spring retainer plates. Then the main springs and viola, you are done.
Oh, the drum should probably be "turned". Take it to a mechanic or parts house that has that capability (most do) and take off the minimum to clean it up. If they cannot be turned, expect to purchase new drums.
