Changing the brake pads on a 99+ GAGT

[Foxy]

This thread is intended to supplement the existing brake thread located here:
http://www.gaownersclub.com/forum/showthread.php?s=&threadid=25853

The 99+ GAGT is slightly different than the older cars described in the above thread in that it has no Torx bits.

Tools You Need:
-Jacks/Jackstand
-Torque Wrench (3/4" for lug nuts)
-Tire Iron (to get lug nuts off)
-13mm ratchet/wrench
-Anti-squeal (available at Advance Auto, etc - approx $5)
-4" C-clamp (5" might be better, but 4" will work - just barely)

What to do
First, jack up and secure the car. Make sure to use jackstands and not just a jack. You will not be able to do this job with just ramps as the wheels need to come off.

Pop the hood and open the cap for the brake fluid reservoir. It's in the rear of the engine bay, sort of in front of the driver.

Spray the rear of the new pads with anti-squeal. You don't need to cover the whole rear of the pad - just the center really. It needs about 10 minutes to cure.

Take off the wheels, and get under the car. Look at the backside of the caliper (this is the rear one, but the front looks pretty much the same, only slightly bigger):

http://img.photobucket.com/albums/v306/RiddleFox/cars/gabrakes/P6250004.jpg

Circled in red are the 13mm bolts that hold the caliper to the bracket. Undo them. If they are stuck on tight, Liquid Wrench or something might help. The bolts will come all the way out.

Take the caliper off of the rotor. Note which pad has the little metal squealer that indicates when pads are low.

http://img.photobucket.com/albums/v306/RiddleFox/cars/gabrakes/P6250006.jpg

Push the pads to the center and pull them out (outside pad first, inside one next). Put in the new brake pad for the inside, taking care to keep the squealer on the same side (I think it's the inside). Using your C-clamp, compress the piston:
http://img.photobucket.com/albums/v306/RiddleFox/cars/gabrakes/P6250007.jpg
(I was bad and put the c-clamp straight on the brake pad.. it might be better to put a thin piece of wood between the two. It didn't seem to affect braking though)

Put in the outside pad, put the caliper back on, and put everything back together. Torque the wheels down to 100 ft/lbs.

Do all the wheels you need to. The procedure is the same.

Put the lid back on the brake reservoir. Lower the car off of the jacks.

Break in your new pads.

[Foxy]

Taken from another thread:
When you're breaking in a pad/rotor, what you're doing is 'smearing' a thin layer of the pad material over the rotor. There's basically two kinds of friction being created when you mash the brakes - adherent and abrasive. Abrasive is bad; when you have two dissimilar materials rubbing against each other, they'll wear away each other. Adherent means that the two materials are sticking to each other - rub the sticky part of two post-it notes together, and you'll see.

Breaking in basically transfers a layer of pad material to the rotor, so that you'll get more adhesive friction than abrasive (though this depends greatly on the pad compound). This means your rotors will last longer (though, eventually, too much pad material might transfer over and you'll have to replace ment eventually, or the rotors might just crack, etc).

The transfer layer must be even - a variation of a few thousandths of an inch can be felt and will be diagnosed as "warped rotors."

So, in order to get the transfer layer created, you must bring your pads up to a temperature where they will 'smear' the rotor easily. Usually for street pads, that temperature is somewhere in the 100-600 degree range (compare race pads that get up to 1600+ degrees). This is why break-in consists of a number of stops from 60-5 mph - this heats up your brakes, and gets the transfer layer created. You do it a number of times to not only heat your brakes, but ensure that the layer is smooth.

However, a critical step is also to let your brakes cool properly! After you do the stops, drive around without touching your brakes for a few minutes to let the system cool. Why? If you do your hard braking and then come up to a light and sit with your brakes on, the pads will brake into that one spot and the transfer layer will be thicker than in other places on the rotor. This causes vibration - bad!

To begin, do a few stops from 60-40mph to slowly bring the brake system up to temperature. After that, I'd say that maybe 5-7 stops from about 50 or 60 mph down to 5mph at about 75% effort (if 0 is not touching the brakes and 100% = ABS kicks in) in rapid succession ought to do it for you. If your brakes get 'soft' or 'mushy,' then you've done about all that you should do and stop the braking.

Then drive around for 5 minutes or so to let the brakes cool (drive around in circles in a parking lot if you have to - just don't stop and let the pads rest on the hot rotor). After you do this, it's usually recommended to do it once more, just to be sure.

You can tell the system is bedded in when there is an even grey layer of material on your rotors where your pads rub. If it's still shiny, it's probably not broken in. If you can see the pads, the edges of it near the rotor should look 'ashy' from the paint burning off.

A pain, but it's fun working in your new brakes :) Just make sure you're somewhere isolated and safe!

Also, many brake systems like being worked out every once in a while, just to make sure that there's a good even layer of material transferred over. Again, don't stop when the rotors are still hot, or you'll make an uneven spot.

My rotors - the face of the rotor used to be the light silver color that the hat of the rotor is, before I bedded the brakes - see the color difference from the pad's transfer layer?:
http://img.photobucket.com/albums/v306/RiddleFox/Impreza/chips.jpg

Look at the 10 o'clock position on this rotor - see the pad imprint? That's what happens if you stop without letting the system cool, and that is what will cause vibrations under braking:
http://sportcompactcarweb.com/projectcars/0209scc_projwrx03_z.jpg