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Jun

Disc Brake Repair

By Jeff Williams · Comments (4)

Well lets start with the basics before we learn how to fix them. Your brake system is made up of many components. The very basic brake system uses a brake booster that is attached to a master cylinder. The master cylinder feeds ( hydraulic fluid ) brake fluid through a combo valve that feeds the rear wheel cylinders ( Drum Brakes ) while another set of lines off of the combo valve feeds the calipers ( Disc Brakes ) in the front.

Most cars and light truck have a front disc brake system installed into them. The rears as they are called are either drum design or rotors as well. You can look through the rim to find out what you have.

Disc Brake systems contain at least three parts. The Rotor or disc as it is sometimes called. The caliper assembly which is what you have to remove to get to the brake pads, and of course the brake pads themselves. The hydraulic system that most brake systems use can be a little complicated ,so watch the video to understand it better.

The Brake pedal is directly connected to the master cylinder via a push rod the travels through the fire wall. Pedal pulsation is caused by warped rotors. A soft or ” Spongy ” pedal can mean to much air in the brake lines and a pedal that drops slowly when you are holding down the brake pedal can mean leaking seals in the master cylinder.

The Master cylinder has a reservoir on top of it that holds the brake fluid. You can check it by looking at the side of it and seeing where the fluid line is at . You should keep it between the Min and Max level. If the fluid level drops down to low then a sensor on the reservoir will send a message to you on the dash

You may even see one of these depending on make and model.

As far as repairing your own disc brakes, I have created a short list of things you can do yourself to make the process a little easier.

First is Safety. Always support your vehicle the proper way and use something to block the wheels so the car cannot move. Jack stands are a must and make sure they are placed in the right position under the vehicle.

Remove the front tires to gain access to the brake system. Never use just a scissor jack to hold up a vehicle if you plan on getting under it.

Next remove the caliper bracket from the steering knuckle. Then remove the caliper assembly from the caliper bracket.

On some cars you can simply remove one bolt from the caliper assembly and swing the caliper up to gain access to the brake pads.

Once you have access to the rotors, pull them off and inspect them for signs of wear like ,cracking, bluing scoring or high ridges at the edges. You can have them resurfaced at most brake shops and even at some parts houses.If your rotors are to thin, you may have to replace them. Remember to always replace in pairs.

If new rotors are to be used. invest in some brake clean to remove the shipping oil on your new rotors.
Next you will have to push then brake piston back into the caliper. You can use a C clamp or even a large pair of channel locks. Use one of the old brake pads to act as a backing for the spreader tool.

If you plan on doing this a lot then invest in a good spreader tool. You’ll be glad you did. The make several and most can be found at your local parts house.

After you install the rotors onto the hub the simply put everything back on they way you removed it. You should consult with an after market repair manual for the torquing specs. That is very important. Haynes and Chilton make some good ones and can found almost anywhere. Even your public Library has them.

The last thing you should do is bleed the system. This can done a lot faster if there are two people doing it. Have one person behind the wheel with the engine running while the other person opens and closes the bleeder valve. Make sure your friend does not lift his foot up while you open the valve . Air will be pulled into the system and you will have to start the process again. Always start from the furthest point from the master cylinder.

If you are working alone then use a catch bottle with a rubber line attached to the bleeder valve. Add a little fluid to the bottle first so that the line is submerged at all times, thus preventing air from entering the system.
Don’t forget to keep the master cylinder full of brake fluid as you are working. The last thing you need is a dry master cylinder that is allowing air into the entire system.

Well that’s about it in a nut shell. I know that I left a lot out but you have the basics.

If you would like to learn more about ” How to Do It Yourself ” brake jobs then I recommend our latest DVD on Front Disc Brakes. We use a Honda Civic as an example but the info can be used on any front disc vehicle.

Just click on the DVD at the top of the page and you’ll be fixing your own brakes like a Pro in no time.

So until next time, this is Jeff Williams saying ” Thanks for stopping by “and if this article has been helpful to you then please click on the coffee cup icon below and help us keep this web site going. Thanks for your help. Jeff

If you like this post, buy me a cup of coffee.

Categories : Auto Brake Repair, Auto Mechanic Tips and Training

Comments (4)

May

Check Engine Light – Code Readers

By Jeff Williams · Comments (4)

If you have ever seen one of these pop up on your dash then I know that for most of you the thought of catastrophic engine failure along with a hefty repair bill has entered you mind.

Well I am here to shed some light on this subject and give you some clues as to what this light means and it is trying to tell you .

If you see a “check engine” or a “service engine soon” light in your instrument cluster; your car has stored a diagnostic trouble code. Which means the computer system on your vehicle has detected a problem within various systems it controls. Your car has many different sensors that monitor the various vehicle systems.

If the trouble code light has been illuminated then your vehicle enters into a “limp mode” . This means it is running on a program that causes poor mileage and increased emissions.

To find out what trouble code or codes were stored then you must use a code reader or Scan Tool . Most scan tools will tell you all of the codes that are stored in the PCM and most of the time in the order they were stored.

Now code readers come in a large variety of shapes and sizes but I would recommend the Actron for quick easy scans at a very low price but remember that you get what you pay for and in this case you will have to look the code up to find out its definition.

Now if you plan on working on your own vehicle quite a bit then I highly recommend paying for a subscription to www.alldata.com. Its one of the best web sites for the do it your selfers and they supply a lot of info that you cant get any where else. It will cost you about $ 26.00 dollars for your first vehicle and $ 16.00 for every vehicle after that and the subscription lasts for one year. Its well worth it and they give you all the TSBs or Technical Service Bulletins, Which are very helpful in diagnosing your problem.

Now for the rest of you that prefer something a little more sophisticated, there are scan tools that are OEM specific that have the manufactures programs installed in them, but they can cost up wards of 5 to 8 thousand dollars, not including attachments.

I personally like to use the OTC Genysis Scan tool for pulling codes . Its easy to use and upgrades wont cost a fortune.

Now most scan tools are user friendly and all 1996 and newer vehicles utilize a “D” style plug-in connector that connects to the code reader. On most vehicles the connector is located at the driver’s compartment. Once the code reader is plugged in you can retrieve trouble codes the engine computer has stored in its memory. These codes are the same codes the dealer and repair shops use to diagnose and repair your vehicle, as well as clearing the trouble codes from the computers memory.

Remember that an engine trouble code reader is an easy tool to use and is a worth while investment for future repairs.

First locate your vehicle’s computer connector (ALDL) or Data Link Connector , most are on the lower driver’s side. In some vehicles you might need to look around a little, on the passenger’s side, and around the center console under a plastic cover. For more information, check your owner’s manual.

Connect your code reader to the under dash Data Link connector. The code reader will automatically turn on and prompt you to the next step for code retrieval. Once the code has been identified look up the identification on the trouble code chart supplied with your code reader.

After repair has been made, clear the trouble codes and re-check system. After codes have been cleared the computer system is ready for internal testing, this means that while the car or truck is in operation and the on board computer is performing tests. These tests are called “monitors” and most cars have between 4 and 8 monitor systems. The computer goes through its testing procedure in about 40 to 60 miles.

Most on Board Computers are called ECMs ( Electronic Control Modules ) or on the 1996 and newer models they are called PCMs ( Powertrain Control Modules ) and they usually look like this. The job of the ECM or PCM is to monitor the input and output signals produced by various sensors in the system. The ECM or PCM then adjusts the system as necessary.

Sensors can include: oxygen sensor, coolant sensor, mass air flow sensor, air intake sensor, crankshaft angle sensor, throttle position sensor, camshaft angle sensor and knock sensor. The ECM operating program consists of information cells. These cells hold the code for proper engine operation, if information is outside the cell parameters, a MIL (malfunction indicator lamp) or “check engine light” is illuminated on the dash.

Once a “check engine” or a “service engine soon” light in your dash has illuminated, the ECM has stored at least one diagnostic trouble code. This means the computer system on your vehicle has detected a problem with the various systems it controls. Your car or truck has many different sensors that monitor the various vehicle systems.

If the trouble code light has been illuminated your vehicle enters into “limp mode” this means it is running on a special program that causes poor mileage.Trust me if you are running on “limp mode” it will feel like your car is about to stall.

The ECM outputs a 5 volt reference to most sensors to drive the monitoring circuits. The ECM also controls the radiator cooling fan, air pump controls, fuel pump, EVAP system and more depending on the vehicle.

Manufacturers have different trouble codes for each vehicle and some can be very generic. Check with a good after market repair manual if your code reader cannot give you the definition of your code so you can know where to start looking.

And remember that a code definition doesnt mean that a specific sensor is bad. Check it out before replacing it or you could be throwing your money away.

Well I hope this has answered a few questions about that mysterious “ Check Engine Light “ and if you have any more questions, I would like to hear from you. Just leave a comment by clicking on the contact us tab at the top of the page and I will try to answer it for you as soon as possible.

Until next time , this is ASE Master Mechanic Jeff Williams saying ” Thanks for Stopping By ” and if this web site has been helpful to you then please help us keep it running by clicking on the coffee cup icon below. Your support is greatly appreciated. Jeff

If you like this post, buy me a cup of coffee.