Jeff's DIY

Advice on doing your own diagnosis and repair

Advice from the book Can I Do It Myself?



Replacing Brake Pads and Shoes

So you want to save money by doing your own brake job? Well, you can if you're handy, but if not you may get frustrated. Unfortunately, there are so many different designs that it would take a monster tip to cover even a fraction of them.

This tip is designed to help you decide whether or not you should attempt to change your brakes and to provide some tips for those who are up for the challenge.

This tip does not address system faults. If you have dashboard indicators lit, see the tips on brake or ABS fault indicator lights.

Here are some resources and challenges to consider before deciding to change your brakes:
A repair manual for the car/truck is highly recommended, because new brakes do not come with instructions. You may find a manual at your local library or find brake R&R procedures online.
For disk brakes, the calipers are removed using a wide variety of tools. The bolts may be torx head, allen head, or hex head, among others. They are occasionally hard to get out. For rear disk brakes, some designs require special knowledge to reset the parking brake adjustment.
Drum brakes have several challenges, including the difficulty of assembly without specialized drum brake tools, a wide variety of complicated configurations, and the potential for the drums sticking on the hubs due to lip formation on the edge of the drum.

Tips if you decide to DIY:
Front disc brakes
1. Set parking brake or block rear wheels, jack up the front of the car, and place jack stands under the frame. You may want to loosen the lug nuts on the front wheels before jacking the wheels off the ground.
2. Check the level of brake fluid in the reservoir. If full, remove 2-3 ounces of fluid, if possible, to avoid overflowing the reservoir when the brake caliper pistons are collapsed back into their cylinders.
3. Remove front wheels and place in a way so that you remember which one goes on which side. This is also a good time to inspect your tires for even wear. Also, if you have a full set of four jack stands, consider rotating wheels from front to back.
4. Work on one side at a time. In case you get confused about how to reassemble, you can refer to the other side.
5. Determine what type of bolts hold your caliper to the wheel hub, and loosen the two bolts holding the caliper on. Some calipers are designed to hinge open on a pivot, such that only the top bolt will come out.
6. If you do not have a large c-clamp to collapse the caliper piston back into its cylinder, consider using a large screwdriver to pry between the inner pad and the rotor to collapse the piston into the caliper. If you do this, be careful not to scratch the rotor.
7. Pull the caliper out of its bracket and use a coat hanger to hang it from the spring/strut so as not to put tension on the hose.
8. Remove and inspect the old pads for wear. Replace all pads if any are worn out. As a rule of thumb, replace when the lining has less than 1/8" of material before the rivet or bond, or if any warning tang was near the rotor.
9. If you haven't collapsed the piston yet, do so now using one of the old pads over the piston to apply your c-clamp.
10. Inspect the rotor for damage. If there is significant damage or if the brakes had been vibrating before the brake job, have the rotors resurfaced.
11. Replace pads. Apply quieting compound on outside of new pads if provided with the pads. Also reinstall quieting plates and/or any clips that the design uses to hold the pads in position.
12. Reinstall the caliper.
13. Repeat procedure on the other wheel.
14. Replace wheels, remove stands, and let the car down.
15. Pump the brake pedal to bring the pads up to the disks for use.

Rear Brakes
1. If car is front wheel drive, set transmission in park or manual transmission in reverse and block the front wheels.
2. You may want to loosen the lug nuts on the wheels before jacking the wheels off the ground.
3. Remove wheels and place in a way so that you remember which one goes on which side. This is also a good time to inspect your tires for even wear.
4. Work on one side at a time. If you get confused about how to reassemble, you can refer to the other side.
Rear Disk Brakes
Follow above procedure for front disk brakes, but ensure to use any special procedure in your repair manual required to adjust the parking brake.
Rear Drum Brakes
1. Check your manual to determine if the bearing must be removed before the drum will come off--remove bearing if necessary.
2. Remove the drum. If it sticks, try rotating while pulling. If necessary, remove the rubber plug from the access hole in the back of the hub and use a screwdriver to back the shoes down. Refer to your manual on how to back off the self-adjuster for your particular design.
3. Inspect drums for damage and wear lip. Have drums resurfaced if necessary or desired.
4. Inspect the shoes for wear. 1/8" of liner may last 50K miles. Note if there is a difference in the length of the linings on the 2 shoes.
5. Inspect brake cylinder for leakage--pull open the boots on each side. If more than a drop of brake fluid is released or if desired, replace the cylinder (procedure not covered in this tip).
6. If shoes are worn out, remove shoes--first remove upper return springs, noting how they were attached. Use a brake spring tool, if available, else use pliers or vice grips. Arrange springs in order nearby as you remove them. Use hold-down spring tool (or pliers) to remove hold-down springs. Note position and configuration of self-adjuster components and remove them from the shoes. Note how the parking brake mechanism is attached to one of the shoes and unhook from the shoe. If there are any pins or other hardware on the old shoes that did not come with the new shoes, remove those as well. Also, ensure the self-adjuster is free to rotate/adjust or free up and lubricate as needed. Replace any damaged or corroded brake parts with a brake hardware kit as necessary or desired.
7. Note which shoe is the front versus the back shoe, and assemble new shoes with any hardware that is required.
8. Attach parking brake mechanism to shoe.
9. Attach shoes to the hub using hold-down springs. Use hold-down spring tool, if available.
10. Replace parking brake hardware and self-adjusting mechanism.
11. Replace all return springs using brake spring tool, if available, else use pliers or vice grips.
12. Repeat procedure on the other wheel.
13. Replace drum and check for adjustment. There should be rubbing but not significant drag on the drum. Adjust self-adjuster to get the shoes up close to the drum. Some extra clearance is OK, as the brakes will self-adjust later.
14. Repack and replace bearing, if removed. Tighten bearing nut as specified in repair manual.
15. Replace wheels and lower vehicle.
16. Check brake pedal travel. If excessive, drive car in reverse and repeatedly apply brakes to adjust brake shoes until pedal travel is normal.
17. Check parking brake for normal operation.


Brake Indicator Light Stays On--Why?

As you know, the Brake light on your instrument panel tells you when your parking brake is set, right? But, in most cars, this light is also used to indicate a fault in the brake system. In the case of a fault, the light will stay on even when the parking brake is released. I will go through several common reasons for the light to stay on and some troubleshooting procedures to help you resolve the problem.

1. Parking brake switch broken or misaligned.
Your parking brake has a switch, usually at the base of the handle, that turns on the light when you set the brake. The common design is a button that pushes in when the brake is completely released. If you can find this switch, try pulling the connector from it. If the connector has only one terminal, ground it to the body of the car to see if that will put the light out. If it has 2 terminals, connect them using a paper clip.
If grounding or shorting the connector puts out the light, your switch is bad--replace it.
If this doesn't put the light out, it is possible that there is an open in the wiring. If you can trace the wire and short it at the other end, you can further eliminate the possibility that this is your problem.

2. Low brake fluid level.

Check the brake fluid reservoir for adequate fluid level. If the level is low, add brake fluid and inspect the car for leakage. If the level is only a little bit low, it may be due to normal wear of the disk brake pads.
But if you have to frequently add brake fluid, you have a leak. Places to look for common leaks are as follows:
a. All four wheels under the hubs.
b. Under the master cylinder in front of the driver inside the engine compartment.
c. At the clutch slave cylinder if you have a manual transmission without a separate clutch reservoir. The picture below shows a brake fluid reservoir and a hydraulic clutch reservoir side by side:

Brake and clutch reservoirs


3. Leaks.

If you have a leak at one or more slave cylinders or calipers, the slave must be replaced and the system bled of all air. Leaks may also occur at junction blocks or at the ABS module, or even in a brake line that has corroded through. Due to the wide variety of brake systems and configurations, I will not cover repair procedures but will provide a few tips.
First make sure you identify the exact location of the leak. For example, on a disk caliper, if the leak is at the bleeder or line connection, you may be able to stop it by tightening the fitting. If the leak is coming from the piston, replace the caliper.
With drum brakes, a slave leak can be verified by pulling open the rubber boot on each side on the cylinder. If you get a good drop or two there, replace the brake cylinder.

Note: A key tip to limiting your bleeding effort is to have the new part ready to install before disconnecting the brake line. Then quickly install the new part before losing fluid from the brake line.
Bleeding: Once the system has been opened by replacing a slave or caliper or if air entered the system due to an empty reservoir, air must be bled from the system.

Bleeding the brakes.
Always use a catch pan when bleeding, and a hose on the bleeder if you prefer, to direct the fluid into the pan. Clean up any spilled fluid, as brake fluid is corrosive.

If the problem was at a particular wheel, you can probably just bleed the one wheel. But, if the reservoir ran dry, you will have to do a full bleed.
A full bleed is always done wheel by wheel beginning with the wheel furthest from the master cylinder and proceeding to the wheel closest to the master.

Some cars will gravity bleed by just opening the bleeder valve at the top of the slave (and keeping the reservoir full) until all bubbles have passed and you have a purely liquid flow. If the line will not gravity-bleed, have a second person pump the brake pedal and hold it down while you open and close the bleeder valve. Do this repeatedly until no air comes out of the bleeder.

If your car is equipped with a proportioning valve, a better procedure is to start with the pedal up, open the bleeder, push the pedal down, close the bleeder, allow the pedal to retract, wait 5 seconds, repeat.

If your pedal is still soft after bleeding, it is possible that you have a bubble in the ABS system. Check with your dealer or repair manual on how to bleed the particular ABS system or have the system bled professionally.

If after repairing a leak and bleeding the system your brake indicator does not extinguish, you may have a stuck proportioning valve. Many designs employ a proportioning valve to prevent the back wheels from locking up. The valve is often integral to a tandem master cylinder (but can be separate) and can incorporate a switch that will light your brake indicator when there is a leak in the system. If the leak is repaired and the system is bled properly, the switch should reset on its own. Try removing the connector at the proportioning valve to see if that will extinguish the light. If it does, the switch has failed closed due either to a broken valve spring or a short. Replace the valve and bleed the system.

4. Sinking pedal, no leaks.

If your car has no brake fluid leaks but the pedal sinks under constant pressure, your master cylinder has failed and must be replaced. Make sure to bench bleed the new master cylinder and plug the ports before installing. Also be careful to limit the fluid dripping from the lines as the old master is removed. If there was no air introduced to the system, you may not need to bleed the system after replacing the master cylinder. If the pedal is soft, try just bleeding at the master cylinder line nuts. If this doesn't work, you'll need to do a full bleed.


If these repairs are successful, your light should extinguish on its own.


ABS and Traction Control Lights Stay On

Are these lights staying on? If yes, your car has a fault in the system that senses wheel speed and changes the way the car automatically responds to slippery road conditions. Often, successful troubleshooting of these faults will require the use of a special scanner; however, there are a couple of failure modes that a backyard mechanic can discover and correct.

If your ABS AND your brake light (on the instrument panel) are both on, it is likely your basic brake operation has a fault. In this case, please refer first to the tip on Brake Light Indicator.

First, let's understand how these systems work. The car/truck must have a sensor at each wheel to know for sure if any wheels are slipping. The usual method is to use a tone ring and sensor as shown below.

Wheel speed sensor


The signal from each of the 4 sensors is evaluated by the ABS system, which, if the brakes are applied, will essentially pump the brakes for you to prevent skidding. If the brakes are not applied but you have traction control, the traction control system will limit the differential behavior of the drive wheels to help you get traction. If you don't have traction control, the ABS system may alert you to wheel slippage with a "low trac" light. The logic and electronics associated with the reactive systems is different on different models, and that is why troubleshooting those parts of the system requires special scanners and training.

OK, so what can you do about getting those lights off without paying a specialist big bucks?

You can inspect the wheels for damaged tone rings, broken sensor wires or connectors, and misaligned sensors. The tone ring is usually visible at the end of the CV boot on a drive axle or behind the rotor on a non-drive wheel. For wheels with drum brakes, the tone ring may be inside the drum.

Spin the wheel looking closely at the tone ring for any missing or chipped teeth or a break in the ring. Check the sensor alignment to the tone ring and also the distance. If you can find the specs on the air gap, measure and adjust as necessary. If you can find specs for the sensor, check it with an ohmmeter for shorts and opens. There are a few more details on sensor diagnostics at the following page: Check the connectors and trace the wires all the way to the ABS module to inspect for damage. Due to the variety of systems and conditions, I'm not going to try to cover repair procedures.

If you found anything wrong and corrected it, hopefully your light(s) will go out.


How to Swap Out a Brake Booster Without Breaking a Sweat

Do you hear a hissing sound under the dash when you push the brake pedal? Does your pedal go down and not stop the car? Yep, the diaphragm in your booster is torn and you will have to replace the booster. Here is the quick and dirty on this job.

There are a couple of warnings to give you up front. You may need line wrenches to loosen the hydraulic fittings on the master cylinder. A line wrench is like a box end wrench with a cut in it to fit over a line. Using open end wrenches can result in a stripped fitting. Never use a vice grip on a line fitting, unless you plan to replace both the line and the fitting. The second warning is on brake fluid. It is corrosive, so don't get it on your paint, and make sure you clean it up.

Now for the procedure--I always try to do it without disconnecting the brake lines from the master cylinder, if possible, as this can be difficult and almost always requires the extra step of bleeding the system. Below is a picture of a typical master cylinder and booster.

Brake booster


In this case, they routed the A/C evaporator lines right in front of the master cylinder, so we'll never get this booster out without removing the master cylinder. Remove the nuts holding the master cylinder and also the cable from the reservoir level sensor. One nut is visible in the upper right of the pic below. The sensor cable is right thru the middle of the pic, and one of the hydraulic fittings is on the left.

View under brake reservoir


Here the cable is removed revealing the other hydraulic fitting.

Clear view under reservoir


If the pushrod is loose, remove it and set aside. Pull the master cylinder forward off the studs. See if you can push it down such that the booster will clear it coming off. Just be careful not to kink the hydraulic lines. Remove the vacuum line from the booster--it should pull straight out. A pic of the vacuum connection is below. You can also see the other nut holding the master cylinder onto the booster.

Vacuum line on booster


Go under the dash and remove the 4 nuts holding the booster. Check for and remove any pin that may hold the booster pushrod to the brake arm. Back under the hood, pull the booster forward and see if it will clear the master cylinder. If not, have the new booster ready to go in, remove the lines using line wrenches, remove the master cylinder and turn it so as to keep the fluid from leaking out of the ports. Set it down and swap out the boosters. Quickly get the master cylinder back in and the lines connected. Don't forget the pushrod if you took it out, and make sure it's properly resting in the push recesses. Tighten the lines just until they stop leaking. Replace the booster nuts and pin you may have removed--tighten the nuts. Also tighten the master cylinder nuts and reconnect the sensor cable. Now, if you had to remove the master cylinder, have an assistant help you bleed it at the fittings. Have them pump and hold the brake pedal down while you loosen and then re-tighten the fittings one at a time. If any air comes out, repeat on that fitting until only oil comes out. Clean up any fluid and test drive the car. If the brakes are soft, you may have to bleed the brakes at the wheels to get any remaining air out of the system.

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