I’m in the process of cleaning and rebuilding the calipers on my project car. I have them apart and have been scrubbing the parts while I await the new seals. And, I have a couple questions:

When I reassemble them I need to have the pistons pushed in far enough that I can get the new pads in. To do that on the rear calipers, does that mean I have to twist the piston clockwise all the way? Are they sort of self adjusting? I guess what has me wondering is how they screw onto the rod that has the stack of concaved discs on it. Lastly, I’ve seen some people say to use grease on the pistons and other say to only use brake fluid when reinstalling the pistons. It does look like the new seals kits come with packages of grease.

 

First off, it's important to mention that this is regarding an SE, as the brake calipers are specific to the model given their 4-wheel VENTED rotors. You seem to be describing the rear calipers and the stacks of disk washers, as this is the parking brake function on rear SE calipers (*maybe others, too). The Caliper Pistons must be rotated back into the caliper after rebuild, and there's a special tool for that. It's a smallish cube with various sides that have protrusions and cut-outs to fit different piston faces. On the SE rears, you'll not there are 2 cut-outs that a piston tool will fit into, and a ratchet wrench then turns the tool cube, which turns the piston inward. Here's a picture for reference; (*this isn't an SE caliper, but you get the idea)

As to compressing the stacked disk washers, you'll notice that the spring bail holds a camming lever in position over the threaded shaft and the stacked disks. When you rotate the caliper piston, it rotates the threaded rod, and is how the Parking Brake function self adjusts for rear brake pad wear. You can use a bench vice and some chock blocks to compress the camming lever so you can take it apart, and put it back together. There are 2×O-rings down in that mechanism that come with the Caliper Rebuild Kit for the rear which must be replaced, or they'll bypass brake fluid into the rubber boot and make a mess.

When you put the Parking Brake mechanism back together, coat the internal threaded rod, stacked washers, and camming lever LIBERALLY with Brake Caliper Grease, and cover the mechanism of the Bail Spring with it as well before you install the big rubber boot. Water gets in here and is trapped, often leading to rusty mess and these parts are NLA...

For more detail on that, scroll down and read these Related Topics (*which should be 2nd nature for you by now, as this has been covered a few times before);


Have at it, and post back with pics if you get stuck somewhere. Good luck,

 

There's a specific grease to use with the piston seals that won't make them swell. I think "rubber grease" is the search term to use.
Brake fluid is fine if the caliper is going back on the car shortly. Brake fluid absorbs water so if it's used for assembly then the caliper sits on the shelf for months it may rust the piston and bore.