How do I retract a brake piston?

[pnwtii]

I finished bleeding the brake system, all seems well. But since I have the rear disc, I had to remove the calipers while the line was still attached to bleed them. Now that it's done, I have the pads in contact with each other, and the piston extended. There's no way I can get it over the rotor like this. How do I get it back?

Thanks to those who helped with bleeding tips, and to those who already had their posts in the archives, it was a lot of help.

[KFunk]

The normal way is with a big C-clamp, and an old brake pad.

First take off the cap from the brake reservoir, so you can relieve the pressure there. Some people use a turkey baster to remove a little brake fluid, so it won't spill over.

Then squeeze the piston back in with the C-clamp, while using the old brake pad in between the piston and the clamp (so you get good leverage and don't scratch things up. As you squeeze, the brake fluid will go up in the reservoir.

With some kinds of brake pistons, you actually have to rotate the piston to screw it back in... doubt yours is like that.

Before you drive the car any, be sure you press the brakes a few times to get the piston to come out and tighten up against the rotor. If not, then you're gonna have an unpleasant surprise.

[MBH297]

Take the lid of the Brake fluid bottle & gently push a screwdriver between the two pistons, when there is sufficent gap put a piece of wood between them and twist untill they are home.

[TJW]

Prise apart as said earlier but slightly loosen the bleed valve on that caliper, with the valve uppermost, then you can observe and clean spillage as you go.

No need to get fluid on your paintwork.

[robspeed]

The normal way is with a big C-clamp, and an old brake pad.

First take off the cap from the brake reservoir, so you can relieve the pressure there. Some people use a turkey baster to remove a little brake fluid, so it won't spill over.

Then squeeze the piston back in with the C-clamp, while using the old brake pad in between the piston and the clamp (so you get good leverage and don't scratch things up. As you squeeze, the brake fluid will go up in the reservoir.

With some kinds of brake pistons, you actually have to rotate the piston to screw it back in... doubt yours is like that.

Before you drive the car any, be sure you press the brakes a few times to get the piston to come out and tighten up against the rotor. If not, then you're gonna have an unpleasant surprise.

id agree with kfunk,, but add: COVER THE MASTER CYLINDER WITH A RAG OR SOMETHING!! you do NOT want brake fluid accidentally shooting onto the paint,,, ANYWHERE!! ;-)

[pnwtii]

With some kinds of brake pistons, you actually have to rotate the piston to screw it back in... doubt yours is like that.

You were right on that one. I called Ireland for advice when the clamp didn't work, and Jeremy confirmed that a clockwise rotation was needed to retract them. Good to know if anybody else is looking into their kits.

[KFunk]

hmmm, good to know for others that can afford that kit (which isn't me).

Is that the one with the e-brake mechanism built into it?

I think the stock rear disks on my miata were the same way, so I'm wondering if maybe the e-brake mechanism necessitates the screw-type piston for some reason. I have no idea why, though.