replacing the rear brake pads
Time needed: between a half-hour and an hour
One final word of advice: my bike had three years of crap nested in amongst the brake pads, making this an extremely dirty procedure. Don't wear your favorite dress suit.
Now that you're laying on the floor, contemplating napping, remove the brake pad cover. It just pops off. Don't put your face near it -- removing mine unleashed a waterfall of three-year-old dirt, pebbles, and pine needles (!).
Here's what you've got now. Two brake pads, two clips, two pins, and two cotter pins. It's all very straightforward; the trickiest part is just rolling around on the floor getting to it. I'm sure it's easier when you're not also trying to take useful photos while upside down and holding tools.
Find your two tiny little cotter pin ends and remove them. They'll come out with just a tug; no tools required. There's one on each pin.
Next, grab your needlenosed pliers and slide out the pins. This will cause the clips to sproing out and hit you in the face, but that's the price we pay for saving money by doing our own maintenance. Don't lose the two clips.
Once the pins are out, one of two things will happen. Either the brake pads will fall out and give you a heart attack, or they'll be stuck. If the latter, you'll have to tug them out with pliers and then push the pistons back into the calipers. If you don't, you won't have a chance in hell of getting the new pads in.
What do you think? Did I need to replace the brake pads?
If you need to push the pistons back into the calipers, the best way I've found is with rib joint pliers. It's a bit of a pain, so if anyone has any other tips, let me know. It's sort of a crappy picture, what with lying on the floor and trying to photograph upwards and all, but basically, you just want to squeeze that piston back in. You won't hurt it. Put a rag between the brake caliper and the pliers if you care about things like the paint coating on the caliper.
Note: Discerning Reader Brian writes: " i ended up placing the old pad over the piston and using my thumbs to press it against the piston. i was able to push both pistons back without too much trouble and with no worry of scratching the caliper. this was of course done after takign the caliper off the bike( i just took out the 3 bolts and left in the brake line)."
Note: Discerning Reader Adrian writes: "I'd also suggest a recommendation to make sure that the pistons are clean before pushing them back in. If they're not clean enough, the pistons may not retract properly after the first use and drag on the brake rotor."
Try to slide the new brake pad up next to the brake disc. If you have to force it at all, or if it won't seat all the way, you need to squeeze the piston in more. Yes, it sucks. If that piston really won't get in there, it's easiest to remove the caliper from the wheel so that you can turn it to get the best angle with your pliers. Just make sure to put it back before continuing with your brake pad installation. Once you can fit both new pads into the caliper, you're ready for the actual installation.
Take the new pads out again and slide the clips onto them -- the main part of the clip should be on the back of the pad, wrapping over to the pad side. They won't stay on the pads by themselves, so be sure to hold them when you pick up the pads from now on.
Now, go grab your flathead screwdriver. You'll be really pissed if you don't have it handy here in a second.
This is probably the most annoying part of the installation. The basic idea is that you want to slide the pad up into the caliper and then, while holding the clip on, insert the pin. Look at each pin and find the little hole. You want the hole to be towards the outside.
I found it easiest to install the closest pad first. Start with the righthand pin; it's easy to get the first pin in because you can sort of move the clip around on the pad. Don't forget to install the pin so that the little hole is on the side closest to you.
Once your first pin is through the pad, keep holding the clip on (it'll want to fall off -- thanks, gravity!) and grab your handy flathead screwdriver (see, I told you you'd want it handy). The idea now is to wedge the screwdriver up next to the pad so that it pushes the clip arm up enough to clear the pin hole. With your third hand, grab the second pin and try to line it up while also holding the clip and pushing it out of the way with the screwdriver. Who designs this stuff? This is not fit for human manipulation.
Trust me, eventually, you'll get it. The pins don't want to line up, and the clip will sproing back out and hit you in the eye (I probably should have suggested wearing goggles if you're not a nerdy glasses-wearing four-eyes like me) a few times. But prevail and you will succeed.
Ha! You still have to do the same thing to the other pad!
Now go find where you put those tiny little cotter pins. Remember how I told you to install the pins with the hole on your side? This is why. Slide the straight edge of the cotter pins through the holes, pushing until you feel it click into place.
Look at how nice those brand new pads look.
Don't forget to put the little plastic cover back on, so that it can continue to collect crap and dirt until your next brake pad swap.
Now, this last step is especially important if you had to squeeze the pistons back into the calipers: step on the rear brake pedal a few times. You want to make sure that those pistons are contacting the new pads. It's a little less important with the rear pads -- you do do most of your braking with your front brake, right? -- but it would still be an unpleasant discovery when faced with a left-turning UPS truck or something. I usually sit on the bike, walk it forward a little, and then stomp on the rear brake to make sure that it does, in fact, stop the bike.
As always when replacing brake pads, go a little easy on them for the first 50 miles or so. They have a glazing compound that doesn't grab immediately. I'll ride my rear brake up to a stop light more often after I've replaced the pads, just to "break them in" a little bit.