I write about maintaining and troubleshooting cars as well as jet skis and lawn mowers!
Today let's look at replacing the drum brake cylinder or "wheel cylinder" on a 1983 Buick Skylark. As always, I will go into a little more specific detail for my lady friends that are looking forward to taking their car repair into their own hands. This may appear to be a difficult job, but it's as easy as changing the oil in your car. It really is.
Different Brake Cylinders and What They Do
Sixty percent of the stopping power of a car is produced by the front brakes, which can be either disc brakes (most often) or drum brakes. A car may have disc brakes in both the front and back; another common combination is disc brakes on the front and drum brakes on the back.
Either braking system setup is run by a single master cylinder located under the hood on the driver's side. Every time your foot presses on the brake pedal it forces fluid in the master cylinder through thin lines that weave through a vehicle's framework until each line reaches its respective wheel (front right, front left, rear right, rear left, though not in that exact order).
On disc brakes, when the fluid reaches the wheel, it goes into a "caliper" that distributes the fluid to each side of the disc brake that presses the pad in onto the spinning disc or rotor. With disc brakes, the braking pad never completely separates from the disk. There's always a very slight drag.
On drum brakes, when the fluid reaches the wheel, it goes into another cylinder, the wheel cylinder, that presses the brake shoe out onto the wheel drum to slow the vehicle down.
This process happens every time you step on your brakes. You can imagine the wear and tear the braking system goes through!
Disc & Drum Brakes
Tools and Other Things You Will Need
First, make sure you have a vehicle manual on hand for the vehicle model and year you're working on. You will need to look up the specifications for the bolts, which are very important.
Second, we need a few things from the parts store:
- The correct wheel cylinder for the year, make and model of your car. The parts guy may need to order them for you. Sometimes calling ahead will expedite the process. Napa and most auto parts stores will order parts for you over the phone with a credit card.
- Brake cleaner. Do not use WD-40 to clean any brake parts whatsoever. WD-40 is a lubricant; brakes want friction, not lubrication.
- A rag to wipe your hands; brakes are filthy.
- A jack
- A jack stand
- Various wrenches and sockets ranging from 8mm to 5/8ths inch
- A breaker bar
- Torx head. This is like a screwdriver, except it has a star-shaped hole on the tip instead of a cross or a blade. You will want a socket type. It will be around a half-inch size. A set of socket torx is cheap and comes in handy.
- A torque wrench. This measures how tight a bolt or nut is.
Let's Change That Cylinder! Getting Ready
- Park on level ground.
- Block the front tires with a wedge.
- Using the breaker bar and appropriate socket, loosen all the lug nuts just a bit. When the tire is off the ground, it is very difficult to loosen these.
- Lift the car with the jack and set it on the jack stand. Make sure it is secure.
- Now remove the lug nuts the rest of the way and set them somewhere safe. Set the tire aside.
- Remove the drum. The drum may need a couple of taps from behind with a hammer to get it loose enough to remove. Once it's off, you will see the braking mechanism.
Removing the Wheel Cylinder
To get the wheel cylinder out, we need to remove a few things.
- Remove the right side hold-down pin and spring.
- Remove the upper and lower spring.
- Remove the brake shoe adjuster. Now set the brake shoe aside.
- On the back side of the cylinder, there is either a ring holding the cylinder in place or two screws. Either pull the "wings" out on the ring to remove it, or unscrew the screws.
- Notice the holes in the wheel mount. Two are ovals and one is a large circle. The large circle is the hole we will be using to remove the torx screws. Spin the wheel mount around to align each torx head with the large circle.
- These are on there tight, so get our your breaker bar as well and loosen the top torx until they are loose enough to wedgy the cylinder out.
Putting the New Cylinder In
Put the new cylinder in. The ring on the back can be a bugger to get on because its an odd position and you have squeeze hard to make the "wings" set into place.
Tighten the four torx to the specified torque in your manual.
Follow the removal steps backwards to almost complete the job; then bleed the brake system (see below).
Bleeding the Brake System
For safety, you must bleed the brake system before driving, to remove any bubbles that interfere with the flow and pressure of the brake fluid. Either you need someone to help you or you need a special brake bleeder tool that eliminates the need for an assistant.
- Place a tube on the bleeder valve on the back of the cylinder (above the brake line) and have an assistant press down on the brake pedal while you open the bleeder to allow air to escape with some of the fluid.
- Close the bleeder valve and have your assistant release the brake.
- Again, open the bleeder valve while your assistant presses down the brake pedal, repeat these steps. Periodically check the master cylinder under the hood during this process to be sure it is full of fluid.
- Continue until no bubbles are released when the pedal is depressed.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Aurelio Locsin from Orange County, CA on August 14, 2012:
This sounds a bit daunting for me to try on my own. Nevertheless, voting this Up and Interesting.