Front brake pistons - how hard should they be?

Ok, I realize this may seem a bit off... but I just gotta ask.

Yesterday, I thought I'd check the front brake pads for wear. while they were out of the assy, I was stupid/intrigued enough to pull on the brake lever.. you know, just to see if the piston moved and whatnot.
It did... but wouldn't move back in... not a fraction of an inch!
I had to bleed out the right brake caliper, take off the assy, and hammer the piston back in. Of course, now I don't have enough DOT3 to refill, but that will be taken care of on Monday.

1) how hard are the pistons supposed to be? I mean, they're supposed to return to a certain location after releasing the handle right?
2) what is the procedure for removing the pistons for inspection? The Haynes manual had some pictures, but no real explanation...

 

If you had to HAMMER the piston back in it's time for a rebuild.

The pistons can be removed the way you already did using brake fluid pressure (a bit messy) or you can pull the caliper, drain, and use a grease gun to push the piston out.

The bleed screw has the same end as a grease fitting, if you block the pipe union hole you can pump the caliper full of grease and gently force the piston out. You can try compressed air but it's never worked for me.

All that's in there are two rubber seals sitting in channels in the caliper. Getting those channels CLEAN without damaging them is the biggest challenge.

 

Thanks. I had a hunch about them being too stiff. Once cleaned, they may even affect mpg in a positive manner =)

 

I have good luck with dental picks and green scotchbrite pads getting the innards cleaned out.

x2 on the grease gun.

 

I use a lot of those bamboo barbeque skewers, you can easily resharpen them or cut the end at any necessary angle. They come in quite handy for all sorts of "non-marring tool" situations.

I also used a tiny brass wire brush in my Dremel, as well as Scotchbrite. You can also get Scotchbrite buffs for the Dremel now, they're way cool.

 

i used compressed air to take apart. leaving the bleeder closed and blowing into the bigger brake line hole.

dremel with the soft wire wheel to clean up the insides.

a c- clamp to compress back in when replacing the brakes. never opening the bleeder. the fluid pushes back into the master cylinder.

 

I also noticed that there is a lot of gunk inside the piston chamber. Is this a proof of having used something other than DOT3 fluid, or does it naturally occur if the fluid hasn't been changed for a while? (the fluid was not dark)

 

If you use compressed air to get the pistons out, keep your fingers away from the pistons.

Don't ask me how i found out.........

 

I've seen it turn to LIGHT-colored jelly before.

 

Here's what I accomplished yesterday:

I got the piston out by pumping brake fluid into the caliper. I let all the metal parts soak in denatured alcohol for a while before polishing them up with the Dremel black soft bristle brush and used some soft wire brush on the hard parts. The inside of the piston bore were cleaned using WD-40, finger power, wooden toothsticks, and steel wool.
The piston itself looked good, and I was actually surprised how easy it was to rub it clean by hand using WD-40.
The only parts that need replacing are the dust seals and one of the rubber boots around the caliper shoe (the one you insert the flat headed pin into).
Then it was the entire ordeal of getting the piston back in.. Unlike before cleaning, this time it just slid inside with gentle thumb pressure.

Today, I'll do the same with the left caliper...