SECRETARIAT

09 Cobalt SS. Replacing rear pads and rotors. When you guys screw the piston back into the calipers do you clamp off the rubber brake line & crack the bleeder screw or is it ok to just screw the piston back in as is with the fluid going back into the master cylinder ?
If I don't have to crack the bleeder screw I'd rather not because of the chance of snapping them.
Thanks.

chris88z24

Crack the bleeder but don't clamp off the line.

double clutch

iTrader: (1)

I just take the cap off the master cylinder

SECRETARIAT

What's the danger doing it with the system closed , bleeder not open ? Damage to master cylinder or something else ??

SECRETARIAT

So you keep bleeder closed and remove master cylinder cap. So wouldn't cause any damage to anything in the system ?

chris88z24

You can supposedly ruin the seals in the master cylinder. I'll admit I've done it without opening the bleeders but most experienced techs I've asked have said to open the bleeder. Don't open the master cylinder cap unless you want to contaminate the fluid.

SECRETARIAT

Ya, ruin the seals is what I've heard.
So as long as I only screw the piston back in, with the bleeder open and don't touch the pedal or anything else, I won't have to bleed the system ?

chris88z24

Nope. Although it wouldn't hurt to put new fluid in the reservoir and bleed all 4 brakes + clutch, especially if the fluid is black. The proper order is RR, LF, LR, RF, Clutch.

double clutch

iTrader: (1)

How would it get contaminated?

chris88z24

Air ruins brake fluid.

double clutch

iTrader: (1)

So how would u fill the brake fluid? You have to take the cap off to fill

Grave

iTrader: (7)

It's the moisture in the air. It will not hurt to have the cap off for a few minutes...

To the OP, don't open the bleeders, just screw the piston back in.

double clutch

iTrader: (1)

Yea its not like you have the cap off overnight so dew can get in.

Solaris99

I've never had a problem from backing in the pistons without opening the bleeders. Done it several times on this car.

umrdyldo

iTrader: (1)

So you guys are doing this so you don't have to bleed the system?

Just get a power bleeder. Works so amazing that I just change the fluid out when I do brakes anyway.

The reason many open the bleeder screw is to prevent damage to the ABS module.

Solaris99

Pure laziness for me. I have a Motive power bleeder, but as I would go from track to street pads, I just needed to back the piston in a little. It really is a good idea to open the bleeder. Maybe I was lucky, because I'd have clean fluid when the track pads went on and so the fluid was still pretty clean when the street pads went back on a week later.

umrdyldo

iTrader: (1)

I could see that if moving it a small distance.

blueLNFftw

iTrader: (16)

What power bleeder do you guys use?

I want to invest in one.
Ever use it on the clutch?

umrdyldo

iTrader: (1)

http://goo.gl/LYEmWq

Could probably make an adapter for cheaper with an extra cap, but this is the easiest solution.

I'm not sure about using with the clutch.

This bleeder allowed me to do the entire brake job with no help and flush the whole system with new fluid.

Solaris99

You can use a power bleeder on a clutch, but you must use LOW pressure. I'd start with 5 psi and be patient. With too much pressure you could pop the slave cylinder, which is attached to the throwout bearing, which is inside the bell housing and a huge pain to swap out.

manonahole

Hey I'm having trouble getting the piston back in the caliper, I cracked the bleeder an still it doesnt seem to be going in. Any help is appreciated!

intel

iTrader: (1)

I'm going to go out on a limb here and assume that you are just compressing the rear caliper piston... the rears need to be compressed AND rotated at the same time to get the piston back in the caliper.

You can find an adapter that goes on a socket wrench at a local auto store, should cost you a couple bucks or you can opt for a nicer kit (caliper wind back tool kits) which run around $30-40.

umrdyldo

iTrader: (1)

The trick many of us have found: First you do need the tool to push and rotate the piston. But before to press the piston back in, spin it completely out first. For some reason it makes it easier to compress if it's fully decompressed first.

manonahole

Thanks for the help! I'll have to pick up the proper tool an try again!

chris88z24

Use a pair of pliers lol