Brake piston compress/bleed and FLAPS question - 986 Forum - The Community for Porsche Boxster & Cayman Owners

stateofidleness · 08-12-2011, 07:07 PM

Gents,
Going to re-attempt my brake pad swap tomorrow. The first time resulted in failure as I could not get the pistons compressed (at all!). I'll be picking up a tool for this tomorrow, but also was wondering some things..

If the tool fails to work, what can I expect by opening the cap to the reservoir, and also, if I open the "bleeder valve" on the caliper itself, does this mean I'll need to bleed the brakes? I really want to avoid having to bleed the brakes as I have newer fluid in it and it brakes great at the moment.

Last question, does the local FLAPS carry a correct "cabin" filter for our cars or do I need to order it online/stealership it?

thanks!

thstone · 08-12-2011, 09:55 PM

Yes, open the cap to the brake fluid reservoir first. Otherwise, the pressure may not allow the fluid to flow back into the reservoir. Keep an eye on the fluid level as you push in the pistons to avoid any brake fluid overflow!

Use a slow yet firm and steady pressure on the piston and it should retract slowly back into the caliper. Be sure to apply even pressure acros the piston and not to just push on one edge. Use a flat, thin piece of wood or metal to provide a wide and even surface to push in the piston evenly.

Don't open the bleeder valve on the caliper. Not needed if you follow the above advice.

stateofidleness · 08-12-2011, 09:59 PM

Good deal. Doing the reservoir cap thing, in theory I shouldn't need to replace any fluid afterwards either right? Is there a way to "refill" each caliper after I'm done with each wheel?

Not real sure what my sequence of steps should be. I'll be replacing both fronts and rears at the same time.

tonycarreon · 08-13-2011, 02:40 AM

just did mine a few days ago...

do one wheel at a time (natch) and one side at a time. by that i mean remove a wheel, remove the pin, bolt, spring. use a screwdriver to get one pad looose. use the pad to push the piston in some. remove a pad. push back the piston, put the new pad in, then move to the next pad. i did the "inside" pad then the "outside" pad. start with the wheel furthest from the reservoir - rear passenger then rear driver, then front passenger, finally front driver. keep an eye on the brake fluid because it will probably rise...

don't open the bleeder valve. just pump the brakes a few times and things will be back to normal.

thstone · 08-13-2011, 08:37 AM

The fluid in the reservoir is used by the braking system to "add" fluid as the brake pads wear (they get thinner). This maintains fluid in the system at all times.

When you replace the worn (thinner) brake pads, you'll need to push the caliper piston back into the caliper so you can get the new (thick) pads to slide into place between the rotor and the piston. When you push the piston back into the caliper, brake fluid will be moved back into the reservoir.

There is no need to replace the fluid in the caliper - it is continually maintained "full" by the reservoir.

ekam · 08-13-2011, 08:50 AM

I'd watch the reservoir if it's already in the MAX mark before you push the pistons back in I'd get some of those fluid out first.

stateofidleness · 08-13-2011, 09:54 AM

yep mine looks pretty full. another dumb question, i have the black cap off but there looks to be some kind of plastic "debris" catch or something just underneath it that I can't get out. Is that supposed to come out or am I supposed to take the entire "cap" off the reservoir (like the 4-5" yellowy cover underneath the black cap)?

thstone · 08-13-2011, 10:21 AM

Just take the black cap off the reservoir - the purpose being just to release any back pressure when the fluid from the piston is pushed back up the line and into the reservoir.

The filtering thingy is hard to get out. Just leave it in there (along with the top portion of the reservoir). If you get close to overflowing the reservoir and need to remove some fluid, use a small tube or a straw and suck some out.

tonycarreon · 08-13-2011, 11:04 AM

Quote:

Originally Posted by thstone

use a small tube or a straw and suck some out.

i used a turkey baster... much better than accidentally drinking brake fluid.

stateofidleness · 08-13-2011, 03:13 PM

I ended up taking out the filter thingy (wasn't too hard after all), and used a syringe to take out a bit of the fluid and temp store it. that was the missing "ingredient" to getting the pistons back in. I used the tool from AutoZone ($8) and it was worth it. Made the job easier.

Got all 4 corners done, started her up and the pedal went to the floor. Pump it one time and it was "back to normal". Bedded them a bit and then gave her a bath

The hardest part of the whole job was gathering all the tools needed!

EDIT: p.s., the FLAPS doesn't carry the cabin air filter, it's a special order item... bah