 Tech Article #3 - Brake pad change
Brake pads are probably one of the things most people send their vehicles to the shop for. Either lack of know-how or lack of time. Here is how to alleviate one of those dilemas.
Tools Required:
Sockets or wrenches
A set of pliers
a regular screwdriver
A tire lug wrench
Disc brake quiet
4" C-clamp or brake caliper piston tool.
Brake cleaner
Brake pads are always to be replaced in pairs (both fronts, both rears [if applicable]) Use the lug wrench to brake the lugs free as if you were changing a tire... just the initial torqe dont take them off yet. This keeps the wheel from spining. Jack up the vehicle and place jackstands under it. continue removing the lug nuts until you can take off the tire.
A quick run-down on the braking system.. The circular disc is called the rotor.. this is clamped upon by the brake pads to stop the car. The pads are housed inside the caliper and it is the caliper that provides the hydraulic pressure to stop you by having a piston extend. Natuarlly, the piston will be further out, the more the pads are worn.
The caliper is held in place usually in 2 mounting points. The caliper could be mounted with 1)bolts which require a socket or wrench, or 2)it coud have a special bolt on it that would be either male or female, and either torx or hex-shaped. Torx, is the 6-pointed star-looking bit that is sold at all auto parts stores. or 3) Ford uses a special kind of pin that looks like a pencil but its make of rubber surrounded by metal on two sides. They just squish down and slide in/out.
Once you get the pins out, pull the caliper off the rotor. the pads may fall out but no big deal. If not, use the screwdriver to pry them out. Look at the pads and see how worn they are compared to the new ones. Some pads are rivited on, some are glued.. either work. With the caliper off, set the caliper aside. *note* do not let the caliper just hang by the brake hose.. this will stretch the fibers in the hose and can cause it to collaps and your brakes will fail. Either set it up where it wont fall, or zip-tie it up out of the way.
The rotors should always be resurfaced (turned) when doing a brake job... if the rotors are good and no bad grooves in them, you can get away with it. but i recommend turning them. (*see below for rotor removal*)
Take the new pads and lay them face down on a clean surface (metal side up) Use the disc brake quiet (spray is easiest) and lightly coat the backs of the pads. If the pads come with shims, lay the shims on now and hit them again with the spray... make sure not to get any on the fronts where the rotor sits. Wait until they get tacky which should be about a minute... while waiting, on the caliper,notice the protruding piston. On most pistons you can just compress the piston and it will go back in.. on the newer ones you have to spin the pistons to get them to go back in...Unless you have someone that knows for sure , you can purchase a caliper tool for about $5 at the auto parts store. If you dont need it, you can return it. The tool is fairly easy... find the right side of it and put in in the piston and spin. To compress the piston, use an old brake pad, and put the C-clamp over the pad and the back of the caliper. Very slowly tighten the clamp until the piston is flush... If you go two fast, it will back flood the master cylinder and fluid will spill out. Not really a problem but brake fluid eats paint and rubber parts so be cautious.. if it comes out, before you take off, just put the master cylinder cap back on.
Now that you have the caliper back to normal, take out the old pads and put the new pads in place... notice the pads are curve at the top as is the caliper.. and one pad may have a metal hinge looking thing on it.. this goes inside the piston. If you forget, you can look at the other side, but i don't think its possible to put them in wrong and have it fit. with the pads in, push them in to make sure they stick. then just put the caliper back on and bolt it up. (or slide the pins in.) There is no adjustment to be made and the rotors may be stiff but they will soon get a wear pattern. Do the same for the other side and you are good to go. Important note, regardless if you spilled some or not, check your brake Master Cylinder. It is located under the hood on the other side of where the brake pedal is.. there is a big round disc behind it called the brake booster.. this uses vacum to assit braking.. the booster is "power brakes" other wise it would be hard to stop. On the master cylinder there should be a full line or max and min. make sure you are good on fluid.. you never want this to run dry. Then you get air in your lines and its a big mess. Remember about brake fluid and paint!
When putting your wheels back on, tighten them up very well but not put so much power behind it that you break the lugs (studs). You are now done with a pad change.
For rotor replacment or resurfacing, the rotors can be either held on with a nut, or just slide on and off held by the caliper and the wheel. I cant say for sure when this changed but I believe cars with 4-wheel disc brakes have the rotors that slide on and off. There may be little E-clips on each wheel lug that holds it on. just pop these off with a screwdriver... you'll never use them again. These types of cars have a hub assembly behind the rotors. What that means is that the spindle to the rotor has a big bearing that spins.. if this goes out, you replace the entire thing.. no muss no fuss.
Now, for the older vehicles and still some trucks, the rotor is held on buy the spindle nut...generally about 1" - 1 1/2", they require a big socket. Once the nut is off, you can pull the rotor off along with an inner and outer wheel bearing. this is what these rotors ride on to spin so fluently. You can either re-use or use new bearings... either way, you have to re-pack them. You will need some bearing grease found at the parts store (its also a good idea to get new bearing seals as well).You can pick up a bearing packer which forces grease through the bearings or you can put a glob of grease in your hand and using the side of the bearing, roll it in the grease to fill all the little cracks and crevices in the bearing. With that done clean your hands as best as possible, install the bearing seal on the spindle, then the inner bearing, then the rotor, then the outher bearing making sure that its tight on the outer and inner bearings... then just install the washer and spindle nut and the cotter pin and you are set.. use brake clean to clean off any grease or fingerprints..
Now you have changed your brakes and saved money!
PM me or reply to this message if you have any questions or comments.
Last edited by GTRaptor; 12-03-2002 at 03:55 AM.
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