What you need to perform a rear brake job/repair

You will need the following parts and tools to perform this repair;

• 1-Brake shoe kit
• 2-Wheel cylinders
• 1-Hardware spring kit
• 1-Can of brake clean
• High temp brake lube
• 1-Bottle of brake fluid
• 1-Can of PB blaster
• 2-Brake spring tools
• 1-Wire brush
• 1-5/16″ bleeder wrench
• 1-Flat blade/standard screw driver
• 1- 3/8″ Ratchet
• 1-3″” extension
• 1-10mm socket

Price comparison

Do it yourself-2-Drums $40 each
1-Brake shoe kit $25
2-Wheel cylinders $13 each
1-Hardware spring kit $12
1-Brake fluid $4
Total = $147 in parts (plus tax)

Repair shop cost -$298 in parts
$240 in labor (3 hrs @ $80 per hr)
total=$538 plus tax

Important! Prepare the Vehicle for Brake Repair

For help with jacking up a vehicle and removing the wheels refer to the following posts;

Note: refer to How to use a jack and jack stands
Note: refer to Remove and install a wheel

Let’s get started on the rear drum brakes

Remove the rear drum from the axle/hub assembly.

Sometimes rear drums can rust onto the hub and extra force may be needed to remove them.

Here is the rear drum assembly with the drum removed.

In this case the customer concern is, the brakes pulse when applied at highway speeds and a vibration is coming from the rear of the vehicle.

Scenario for brake pulse

When movable brake parts age and are exposed to a variety of weather conditions rust becomes a big factor in shortening the life of these parts.
Parts that would normally move become seized and the brakes stay partially applied causing them to heat up and warp the drums. This results in premature wear and brake failure. This brake pulsation is a common occurrence for drum style brakes.
Brake drums can be machined to eliminate an out of round shape from brakes staying engaged and warping the drums. It’s more cost effective and less time consuming to replace the drums especially for the do it yourself type person.

How brakes work

If you need a break down of how automotive brakes work, refer to Automotive Braking Systems 101-Part 1

Evaluation of the brakes

The hydraulic portion of these brakes has a leak. Although it’s not a severe leak, it’s still a leak. This leak could fail with a complete and total loss of the brakes.

It’s a good thing this brake concern lead to an inspection and found this problem before it left the customer stranded or caused an accident.

Parts to Replace

Here is an itemized list of needed parts to repair this job.

• 2-Rear brake drums
• 1-Rear brake shoe kit
• 2- Rear wheel cylinders
• 1 -Spring hardware kit
• 1 –Bottle of DOT 3 brake fluid

Tear Down

Here are a few tools that are much needed to perform this job.

These are all spring removal tools which I will show you how to use through out this post.

Start by using this aerosol brake spray cleaner to help remove any brake dust that can become airborne and inhaled.

Make sure to use a suitable fluid catch/drain pan for the job.

Don’t forget to wear your safety glasses!

Once this is cleaned, start by removing the brake shoes. Remove the hold down springs and retainers.

Remove the emergency brake adjuster spring and lock.

Remove the lower spring that connects both shoes together.

Pull out the lower emergency brake pivot bar.

Remove the upper spring that connects both shoes.

Pull out the front brake shoe.

Pull out the threaded brake shoe adjuster.

When removing the rear shoe, the emergency brake cable will need to be detached from the pivot arm.

Pull the cable out of the pivot arm and remove the rear shoe.

Clean the backing plate with a wire brush

Here’s a helpful spray to use when removing bolts and brake lines to prevent damaging these components.

PB blaster is the best penetrating spray to use on rusty parts.

There are 2 hold down bolts and 1 fluid line to the brake wheel cylinders that need to be sprayed.

After spraying, start by loosening the brake line and removing the two 10 mm wheel cylinder mounting bolts.

Note:

Sometimes these brake lines are seized. To prevent braking the line and having to replace or repair the hydraulic line, you can perform this old trick that I picked up years ago.

Pull the wheel cylinder towards you. This allows you to unscrew or spin the wheel cylinder counter clockwise for removal to avoid breaking the line.

Remove the old leaking wheel cylinder.

Prepare to install wheel cylinder

Now that this is done, prepare to install the new wheel cylinder.

Loosen the bleeder screw before installation. This allows the fluid to fill up and prevent air locking the wheel cylinder when installing the brake shoes.
Install the wheel cylinder and tighten the mounting bolts.

Once installed, close the bleeder screw. Lube the six backing plate contact points where the brake shoes contact when installed.

This will allow the shoes to properly slide with no friction, hanging up, or squeaking noises.

Use a special brake lube or anti-seize for any place where metal parts rub together.

Installing the Brake Shoes

Here you will have to transfer over the necessary parts that operate the emergency brake. (Each shoe has a part to switch over) The forward shoe has a bracket that pivots.

Remove the E-clip, lube and install into the new brake shoe.

Here’s a scary find that I found during this brake job. The emergency brake parts were seized up and wouldn’t have worked if the emergency brake was used. With a leaking wheel cylinder, this vehicle was on borrowed time.

When purchasing the brake parts, make sure to get a spring kit. The old springs get weak and could break if reused. The cost is minimal and will prevent future problems.

Switch over the pulling arm from the old shoe to the new rear brake shoe and lube with grease to allow a smooth operation when applied.

Assemble the rear brake shoe and install new springs.

Lube and screw the brake adjuster inward for installation.

Install the adjuster between the shoes.

Install the spring that holds the adjuster in place.

Install the adjuster lock and spring.

Note:

If you forget or have difficulty remembering exactly where all the springs go, use the opposite side as a mirror image. This is why it’s good to only tear down one side at a time.

Install the lower emergency brake pivot bar

Install the holding spring and recheck or compare to the opposite side for proper fit.

After finishing the assembly of the rear brakes, use brake clean on a shop rag to remove the grease that might have inadvertently got on the shoes while handling during installation.

Clean the new brake drum as well. When stored at the parts store they are lightly oiled to prevent rust from forming on the metal surface.

Slide the drum in place and check for a slight amount of drag.

Note:

The adjuster can be turned manually to increase the drag when turning by hand. A good rule of thumb is to pump the brakes with the drum installed then turn the drum by hand and there should be very little effort.
When driving and operating the brakes, they are designed to self adjust as they wear in upon daily driving.

Bleeding the brakes

There are a few ways to bleed out the trapped air from the hydraulic brakes.

The first is to use a vacuum type evacuator like this standup model.

Install the hose and pump the handle. Open the bleeder screw and a vacuum will pull the fluid through the system eliminating any air that might be trapped.

The second is to use a hand held vacuum pump which operates just like the larger model.

The third way is to have someone pump and hold the brake pedal while you open and reclose the bleeder screw letting out the trapped air. Be sure to keep the brake fluid topped up when bleeding the hydraulic system and use the brake clean spray and shop rags to clean up spilt brake fluid.

Test the emergency brake for proper operation and make sure they don’t stay applied. Reinstall the wheels, torque the lug nuts, and perform your test drive.

Note:

Most brakes will take approximately 50 to 100 miles to fully seat in. For the most part, they should feel like new brakes right away.

How They Work

Brakes work on the principle of hydraulics. When you apply pressure to the brake pedal, this braking force will multiply based on the piston diameter at the master cylinder at each corner or wheel of the car. This is how you are able to stop a 3000 pound vehicle with a small amount of force from your foot.

Side note about Hydraulics

At Sci-Culture.com you can learn about how force, area, and pressure work with hydraulics in an automotive braking system.

Parts of the typical Non-ABS Brake System

Start with your foot and move through the system to get familiar with each component and what its purpose is. Here is an animated illustration of a non-ABS brake system to help you visualize and learn where these parts are located in and around a vehicle..

Brake Pedal

The Brake pedal is where you apply pressure in order to stop the vehicle. (The mechanical advantage)

The pressure is applied to a component called the master cylinder. With the brake pedal mounted in the pedal cluster assembly…

The pedal arm has a pivot point for forward and backwards movement. This pushes a metal rod from the inside of the vehicle through the fire wall and brake booster into the master cylinder. These components are located in the engine compartment area.

The master cylinder is the main fluid control area where the pressure that is applied is distributed to each part on the vehicle. (The hydraulic advantage)

Master Cylinder

The master cylinder has two chambers inside it where small pistons and seals push the fluid in two directions, to the front and to the rear. Here are 2 plugs in this new master cylinder, one is for the front fluid distribution and the other is for rear.

This Auto Zone brake fluid is a special fluid that is used only in the brake systems and is not meant for any other system in your car.

Brake fluid has a synthetic base with a very high temperature/heat range. These two things allow protection from moisture in the system and to keep the fluid from boiling, considering the extreme temperatures that are generated from the friction between the brake pads and rotors when stopping your car. Note: most brake fluids have a boiling point of 450°F. (Fahrenheit)

Power Brake Booster

Even though brakes are hydraulically operated and perform using a great deal of pressure to stop vehicles with a large amount of weight, power brake boosters offer an assist which eases the amount of force need to stop the vehicle.

There are two types of power brake boosters used on vehicles today, vacuum and hydraulic assist.

Type 1

Engines naturally produce a vacuum that can be harnessed and used to provide an extra amount of force to the master cylinder when applying the brakes.

Here is a master cylinder and brake booster together. Notice the vacuum supply hose from the engine, it has a one way check valve (white) to keep vacuum stored after the vehicle is shut off. This allows vacuum to be readily available to use for the power assist on the next start up.

Type 2

Hydraulic assist works off a two chambered belt driven pump. Mounted and driven off of the engine, the one chamber operates the power steering to ease the turning effort and the other operates the power assist for braking effort.

“Hydraulic Booster Photo”

Combination Valve

The next component in line is the combination valve. With brakes applied, the pressure now travels through this valve sending the fluid to each corner of the car. The main purpose is to divide the front brakes from rear. This is to prevent total brake failure if there is a pressure loss on one axle. You’ll still have brakes on the one remaining axle. The valve also has a sensor which signals a warning light if a pressure problem occurs.

Combination valves are an early pressure control design. Once vehicles started using anti-lock brake systems (ABS) they incorporated the pressure control into a hydraulic pump. The pump is controlled by an electronic brake control module.
(More on ABS in Automotive Brakes-Part 2)

Brake Lines

The fluid now travels through brake lines approximately 3/16 of an inch in diameter. The fluid is being sent to each corner of the car to a specific type of brake assembly that helps to stop the car.

Brake Designs

There are two types of brake designs. They are drum and disc style braking systems.

Drum type

There are 3 main parts to this type of brake assembly. These 3 parts are:

Wheel Cylinder

Brake Shoes

Brake Drums

The fluid comes into the drum type brakes to a component called a wheel cylinder.

This cylinder is where the hydraulic pressure is pushed to. Similar to the master cylinder, the wheel cylinder has one chamber with two pistons and seals.

Within the brake assembly, there are two brake shoes that have a special fiber and metallic substance to help aid in the stopping of the vehicle.

The pressure in the wheel cylinder forces out the shoes which are mounted to a flat backing plate by springs and lock pins.

The pins keep the shoes mounted against the backing plate while the springs allow the shoes to move in and out within the drum assembly.

When the brakes are applied

The shoes contact the inner surface of the drum and slowly stop the vehicle. When the brakes are released, the springs pull the shoes away from the drums allowing the brakes to disengage.

Drum Brake Application

See an animated drum brake system hydraulics illustration.

Disc Type

There are 3 main parts to this type of brake assembly also. These 3 parts are:

Floating Brake Caliper

The brake fluid comes into the disc brake assembly to the caliper. The caliper is a c-shaped housing with one or more pistons in it. The floating caliper design refers to how its mounted above the rotor, slides on 2 pins, and floats back and forth when the brakes are applied. The most common design is a single piston caliper. Other types are dual piston and four piston calipers.

Brake Pads

The brake pads are made up of a special fiber and metallic material that helps to stop the vehicle while still having a long life span. Brake pads are commonly referred to as semi-metallic. The softer fiber material helps to dissipate heat while the metallic chips give it strength. There is a smaller amount of metal so that they don’t retain as much heat. These two materials bond together to form the brake pad.

Brake Pad Sensors

Brake pads have 2 types of wear indicators. The most common type has a thin metal tab mounted on it with a pre-determined depth that contacts the rotor surface and makes a squealing noise to alert you before they are completely worn out. The other type is a sensor that cuts through or contacts the rotor surface grounding out a warning light in the instrument cluster to get your attention when worn.

Brake Rotors

When the brakes are applied, the pistons within the caliper housing squeeze the brake pads against the brake rotor slowing the vehicle to a stop.

Disc Brake Application

See an animated disc brake system hydraulics illustration.

Just as any type of automotive system has evolved over the years the brakes, although similar in nature have been designed and re-designed again and again. These changes evolve into more modern and updated designs that work better and are safer for today’s vehicles.

The two types of disc brakes that are commonly used are vented and non-vented.

Vented Rotors

Vented rotors are used on all front brake assemblies and some rear brakes of today’s vehicles to help bring in air that will cool off the rotors when they heat up. Due to the amount of braking force needed and weight transfer that is applied to the front rotors, the friction builds heat and the heat creates two problems. Problem 1; heat warps rotors. Problem 2; excessive heat can put stress on the brake fluid (especially if its old fluid) and when it reaches it’s boiling point it creates brake fade. Brake fade is a condition where the pedal drops or fades toward the floor when holding pressure or trying to stop. This is why it’s important to keep your brakes cool.

Vented Rotor

Here is an end view that shows the rotor vanes for cooling down the temperature and to prevent warping and fading. Depending on how severe the rotors may be warped, they can be machined on a lathe. If they fall below a minimum thickness specification they will need to be replaced. A majority of manufactures make rotors at or just above the minimum specifications and machining or resurfacing would be out of the question. Resurfaced rotors tend to warp a little bit faster than new rotors due to the smaller amount of material remaining on the rotor.

Non-vented Rotors

Non-vented rotors are used on rear brakes. There is less friction and heat generated from rear brakes so the extra cooling is not needed.

All manufactures have used both types of braking systems and a variety of combinations and mixing the two systems.

(Drum front and rear, drum rear and disc front, front and rear disc, and rear vented or non-vented)

This is the basics of how the hydraulic brakes work, but not the end.
The emergency brake or hand brake operates using the same components in the hydraulic system, with one exception. There is a mechanical advantage or over ride built within these systems.

Emergency Brake

Generally speaking, the Emergency brake is considered a secondary braking system. If the primary system fails in any way you have a back up system to help stop the vehicle and prevent an accident from happening.

When applying the emergency brake in a drum brake system

The cable pulls a lever within the brake shoes to push them into the drum allowing the vehicle to stop.

There are two types of rear disc emergency brake set ups. If you have rear disc brakes, one type has the cable pull a lever.

Disc caliper E-brake photo

The lever pulls a ratcheting mechanism inside the caliper housing under the piston. This operation squeezes the pads without using hydraulic pressure.

The other type has an internal drum within the rotor that operates like standard drum brakes.

Rotor/drum E-brake photo

The cable pulls the shoes into the drum without hydraulic operation. The importance in this is that if there is a sudden loss in brake pressure you can use the “emergency brake” to mechanically apply the rear brakes and bring your car to a stop safely.

Review notes:

Use the key terms list below to refresh your memory about Brakes 101 and proceed to the brake quiz to test your knowledge.

Key Brake Terms

(Key terms in bold through this post)

Brake Quiz

Now that you completed the Brakes 101 – part 1 section, test your knowledge with a brake quiz to see what you’ve learned.

Note:

Now that your through with Automotive Brakes 101-Part 1, you can refer back to System 101 for more automotive topics

Coming soon

Automotive Brakes 101-Part 2 (ABS functions)
Automotive Brakes 101-Part 3 (Performance upgrades)
Automotive Brakes 101-Part 4 (Electrical-ABS fault tracing)

Enjoy. [Via Discovery Turbo]

This article will show you how to diagnose and replace front brake pads and rotors. I will also give recommendations on some little tricks here and there that will help with making the repair a long lasting repair.

If you know how to change your brakes already, and are just curious about how much money you can save by changing them yourself, jump to the end of this ‘Replace front brake pads and rotors’ post to see the price breakdown.

Let’s Begin

The repair begins here with the vehicle jacked up, supported on jack stands and the wheels removed. Don’t know anything about jacking up your car, check out our How to use a jack and jack stands tutorial.

This is a 2000 Mercury Villager front disc brake view with vented rotors

The reason for replacing the pads and rotors on this vehicle is because of a brake pulse or vibration when applying the brakes at highway speeds, and the pads have been on this vehicle for 72,000 miles, Wow!

This tool allows you to do a comparison of the brake pad thickness – From 8 to 12mm green or good , from 4 to 6mm yellow or caution! (breaks at or below 50%), and from 2 to 3mm red or warning!! (less than 20% remaining).

I’ve had customers ask, why would you replace brakes that have 20% remaining? I always answer their question with a question, would you drive your kids around with little to no brakes left on your car?

But I want to get my money’s worth!

Some people look at it as, when the brakes wear down into the metal then I’ll replace them, I want to get my money’s worth.

Here’s the difference between 3mm and 12mm pad thickness.

If you were to replace the pads between 4 and 6mm, chances are that you might save warping the rotors because the pads help to dissipate the heat form the rotor with thicker pads.

If the pads are 2 to 3mm, the heat transfers quicker into the metal backing of the pad which retains heat causing hot spots on the rotors causing them to warp. The brakes also take a longer time or distance to stop, which can increase the odds of having an accident when needing to stop in a hurry.

This is not a tool that most technicians use due to the fact that most people in this business have an eye for break wear and can make an estimate knowing “good from bad”. But it serves the illustration well and gives you an idea of what a safe brake pad thickness is.

Time to change the brake pads

The photo on the left is what a disc brake assembly looks like with the wheel removed. Notice the bolt holes used for removing the rotor from the hub.

The first part to remove is the brake caliper. There are two mounting bolts that take a T-35 torx socket to remove.

After removing the bolts pry the caliper off the rotor and secure out of the work area. (Use wire to tie onto the shock or lay on top of the rotor backing plate)

Note: Do not let the caliper hang from the brake hose, or damage to the hose may occur!!

The bolts used to remove the rotors are 8mm x 1.25mm.

Tighten down evenly until the rotor separates from the hub and remove the rotor.
Use a brake caliper compressor tool to compress the piston back into the caliper. ($15 or less at your local parts store)

Remove the caliper mounting bolts, clean and lube with a high temperature grease, and reinstall into caliper.

Install the new rotor, and brake pads onto the caliper. Make sure not to get grease onto the pads or rotor surface.

Apply a high temperature brake lube to all of the metal parts that need to slide. (Pad backing edges and caliper mount bracket)

Reinstall the caliper, bolts, and wheel.

Make sure to pump up the brake pedal several times before attempting to test drive. The new pads and rotors will need to be driven around 50 to 100 miles to set in.

We hope you found this tutorial helpful. As always, we’ll leave you with a cost breakdown of what the work would cost at an auto shop vs. doing the repair yourself.

Your cost comparison – Shop vs. Do it yourself

If you purchased the parts to repair yourself
Brake rotors $30 each(aftermarket), Pads $50 (factory original)

If you paid a repair shop
Labor time, 2 hours @ $80 per hour, plus 100% mark up on parts

Cost at a repair shop
$380 plus tax, 12 month warrantee

Cost to do it yourself
$110 plus tax, Lifetime pad warrantee