On the way home from an offroad trip in my Toyota, I noticed that 4runner brakes were squeeking. When I removed the brake calipers to replace the brake pads, I found that the passenger side pads were warn to the spring clips, and the driver's side pads had plenty left on them.
Just as everyone always says you should do, I decided to replace the pads in both sides at once. When it came time to push the pistons back into the drivers side calipers, I couldn't do it. 2 of the 4 pistons were siezed. I called the parts shop and got prices on a rebuilt caliper (much cheaper than a new caliper), and started thinking about trying to rebuild the Toyota brake caliper myself.
After searching diligently online, here is what I've found....basically nothing. Everyone who asks the question on an offroad or Toyota forum is quickly shut down. The common response is "Its your brakes. I prefer to pay the money for a rebuilt so that I know it will work. Plus it comes with a warranty." I've played around with plenty of other brake components on my Toyota 4x4, so why should I stop now?
And then I found this comment on the http://www.yotatech.com/ forum: "remember most toys have 4 piston fixed calipers so it might be a little more involved than rebuilding your typical 1 or 2 piston sliding caliper." Ah, I hadn't thought of that.
All of the 'How to rebuild a brake caliper' videos and tutorials I found online are showing floating calipers with one or 2 pistons on only one side of the caliper.
Replacing the seals on a brake caliper in a lexus (the closest I could find to Toyota)http://www.lexls.com/tutorials/brake/fbcaliper.html
Here's a good video showing how to use compressed air to pop the calipers out of the piston: