Jun
11
Disc Brake Repair
ByWell 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.
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.
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
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6 Comments
October 30th, 2009 at 3:40 am
I was really hoping to find info on how to put new cylinder seals (and dust boots) into/on my (Subaru) front calipers.
Do you have this info posted somewhere on the web?
November 1st, 2009 at 9:59 am
Hi Tom, I dont currently have this posted as of yet but if you cannot find it in a Chiltons or Haynes repair manual then I will walk you through it. Its not that difficult to complete and does not require any special tools either. If you have to have these calipers repaired ASAP then you can replace them with new and rebuild the old ones at your convenience. I hope this helps. Jeff
November 1st, 2009 at 9:16 pm
Hi Jeff, Thanks for your reply.
Well “I went to school” on the worst caliper. One of pistons was so stuck that I had to use the brake systems hydraulic pressure (and really slam on the brakes) to dislodge it.
After a mmajor clean up I managed to pop out the c-clips that held the old boots to the cylinder lips. I put the pistons in the lathe and used 600 grit (wet or dry sandpaper) to pollish the crap off the chrome.
Long story short, beyond refurbing the the pistons and cylinders, putting in and on new seals and boots with plenty of the synthetic grease supplied with the seal kit, I also realized that the slide sleeves that ride in the rubber bushings were immobile. Of course I replaced the bushings with new ones from the seal kit and filled them with syn grease, however I should have been informed enough to check this on every pad change.
I find nothing in the brake pad changing instructions (Haynes) that explains how the caliper must “float” free and also that the pads themselves must not bind in the caliper “frames”.
Maybe these are things you can address in your very informative web site.
Sincerely, Tom Pitt,,,,,
December 9th, 2009 at 12:38 pm
The moog suspension bushing was a nice choice.
November 17th, 2010 at 4:52 am
Hi Jeff, I’m having trouble with my brake system, the front left caliper seems to be grinding against the disc rotor, i’m not too sure as to how this came about. I’ve changed the disc rotor, the caliper and the brake pads, but the caliper is still grinding against the disc rotor. any help will be much appreciated
November 17th, 2010 at 9:26 am
Hi Dylan, there are a few things to look at. First are the slide pins bent that the caliper is riding on. Was the vehicle involved in an accident of any kind that would have bent the steering knuckle or hub assembly and third check the hub bearing to make sure there is no play in it. ( Jack the vehicle up and try to move the tire from side to side and top to bottom) Try these out first and let me know if it helps. Jeff