Brake pad replacment (pesky pistons) - 986 Forum - The Community for Porsche Boxster & Cayman Owners

stateofidleness · 05-30-2011, 03:45 PM

How in the HELL do you get the pistons pushed back in the caliper??
I got everything all dis-assembled, got the new rotors on, everything is going swimmingly...

I opted not to do the fronts only because the fronts looked fine (were good pads, Brembos) and I didn't have the new pins/clips etc (not a big deal). When I got to the rear, they were more worn, so I figured I'd do them while I had it all apart...

Get the old pads out and following numerous tutorials about using a wood block or metal rod to push the pistons back in, they aren't moving at all. I didn't want to rip any seals, but I was pushing pretty hard and they weren't moving at all...

I read one tutorial that said something about opening the bleeder valve, but I REALLY didn't want to have to bleed the brakes and all that if I didn't have to. My pedal feel is great and I don't want to disrupt the harmony

I read something about a tool that can be used for this ( a "pad spacer") but haven't gone to the FLAPS to find one yet. Do they work?

What's the trick here?

ekam · 05-30-2011, 04:31 PM

Use a C-clamp but make sure you cover everything with a piece of cloth so you're not scratching/dinging anything, also open the brake fluid resevior.

kabel · 05-30-2011, 05:19 PM

mechanical leverage is often needed... I bought something similar to this
Brake Pad Separator:
http://www.grainger.com/Grainger/KD-TOOLS-Brake-Pad-Separator-2ZPN2

stateofidleness · 05-30-2011, 07:02 PM

if I open the brake reservoir (the tank in the front, not the caliper right?), do I need to bleed when I'm done?

kabel, did that tool do the trick? would the tool + tank open be the solution?

when I did the "wood" thing, it didn't seem like they wanted to move AT ALL!

I'm having trouble envisioning the C-clamp method on our calipers... how's it setup?

thstone · 05-30-2011, 07:20 PM

+1 on a using a large C-clamp to push the caliper piston back in. Use a thin piece of wood or one of the old brake pads to cover the piston so you have a nice flat surface to push on with the clamp. Cover the back of the caliper with a rag or something soft to avoid damaging the surface of the caliper (especially if they are painted like mine are).

Open the brake fluid resevoir (tank in the front trunk) to lessen the pressure as the fluid is pushed back into the resevoir as you push the piston back into the caliper. Be sure that the resevoir doesn't overflow as you're pushing the piston back in or you'll have a nice brake fluid mess in your front trunk.

It might take some pressure on the piston to get it to move back into the caliper but not a huge amount. Try using a slow and steady pressure so the fluid can flow smoothly back into the resevoir - if you try to give it one big push it ain't gonna move at all.

If you can't get the piston to move at all, then you may have a frozen piston and the caliper will need to be removed and rebuilt. This is pretty rare.

This is a pic of the general idea of using a C-clamp...

stateofidleness · 05-30-2011, 07:26 PM

I can't see how to rig up the C-clamp on the boxster calipers though. I see pictures of it being done on other cars, but the calipers allow the "bar" part to go "through" the middle of the caliper.

thstone · 05-30-2011, 07:31 PM

Try swapping the C-clamp around and place the fixed end inside the caliper on the piston and the screw end on the outside of the caliper. Like this...

Oaktown 986 · 05-30-2011, 08:24 PM

Quote:

Originally Posted by stateofidleness

I can't see how to rig up the C-clamp on the boxster calipers though. I see pictures of it being done on other cars, but the calipers allow the "bar" part to go "through" the middle of the caliper.

Yeah, make sure everything is disassembled and the c clamp fits right in

thstone · 05-30-2011, 09:24 PM

If the caliper is still mounted on the car (you're just changing the pads and not removing the rotors), the C-clamp should still work fine, just put the fixed end of the clamp onto the piston and the threaded end on the back of the caliper.

However, if you can't get the fixed end of the clamp in between the rotor and the piston, then you'll have to try to use something as a lever that will fit between the rotor and the piston to push the caliper back in without damaging the rotor or the piston. A piece of wood can work be used or a screwdriver with a rag on the rotor and a thin piece of wood or metal on the piston.

ekam · 05-31-2011, 03:51 AM

Yea small pieces of wood and a stick to pivot the piston back in should work too.

Or if you're feeling really rich you can get this.

http://www.girodisc.com/Caliper-piston-spreader_p_1926.html

kabel · 05-31-2011, 04:45 AM

+ the pad separator tool works, with the cap off the reservoir or not.
You do not need to bleed if you take the cap off the reservoir.
I have that big c-clamp and used it as well, very cumbersome and the brake pad separator is less expensive and easier to use IMO.
Slow steady pressure like thistone mentioned. I use a paint stick/stirrer to protect either the pad or the piston if I need to.

Funny, I had to use my big c-clamp this weekend to do the pads on the BMW because I forgot I had lent my separator to a buddy.

timothy · 05-31-2011, 05:02 AM

I swap brake pads quite often (track and street); here's the method that works for me. Quite a few use a c-clamp but I've never been a big fan of that approach.
1. Put the old pads back in the caliper
2. Position a set of slip joint pliers in the space above the rotor and between the pads so the jaws touch the tab at the top of each pad.
3. Pull apart on the pliers handles. As the jaws separate they push outward on the pads and pistons are forced back into the calipers.
4. Remove the old pads and insert the new.
5. Reinstall retaining hardware

Jager · 05-31-2011, 07:24 PM

Quote:

Originally Posted by timothy

I swap brake pads quite often (track and street); here's the method that works for me. Quite a few use a c-clamp but I've never been a big fan of that approach.
1. Put the old pads back in the caliper
2. Position a set of slip joint pliers in the space above the rotor and between the pads so the jaws touch the tab at the top of each pad.
3. Pull apart on the pliers handles. As the jaws separate they push outward on the pads and pistons are forced back into the calipers.
4. Remove the old pads and insert the new.
5. Reinstall retaining hardware

My method is very similar to Timothy's except I use this tool (pictured). Makes the job very easy, instead of pulling apart the handles I squeeze them together to separate the pads. I believe Sears carries a similar tool.