Brake bleeding

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Oct 13, 2011 | 07:27 PM

#21

bigvette1

Drifting

Joined: Jan 2002

Posts: 1,645

Likes: 11

From: Schaumburg IL

If you have bled the brakes and they still go soft and especially using a power bleeder there is something else wrong.

I would suspect another caliper or even the one you replaced sucking air around the "O" ring seal for one of the pistons. These buggers can be just big air pumps. Also, if you have a rotor out of round the calipers will act as air pumps and suck air also. Do you have a runout gauge? You may need to ck the rotors for runout and if one is >.005" try reindexing to another position. If that does not work you would have to get it turned to true the rotor. C3 brakes can be real problems to get tuned and bled.

Oct 18, 2011 | 09:35 AM

#22

Mark Hawkins

Instructor

Joined: Apr 2011

Posts: 137

Likes: 0

From: Goose Creek SC

Quote:

Originally Posted by dbwright15

Well,, we bled both rears, both inner and outer caliper and the brakes still went soft. I do have a motive products power bleeder and im putting it to use next. We'll bleed all brakes front and rear.

Hey, I came across this thread because I too am having problems bleeding my rear calipers. I replaced both rear calipers and rotors. Now, I went the Advance Auto route on the calipers. I noticed that the outer side of the caliper had two "O" rings, however the inner half only had 1 "O" ring. I called the local Advance store and they said that this was normal because the halves can be used with other halves. Not sure if I like that or not. Anyway, are you still not being able to get a harder pedal? I will try the hammer test. Yes, I wish I had a power bleeder. I might be taking my '81 to a local shop if I can't get a better pedal.

Oct 18, 2011 | 12:48 PM

#23

bigvette1

Drifting

Joined: Jan 2002

Posts: 1,645

Likes: 11

From: Schaumburg IL

When you say goes soft, does that mean it will not hold peddle pressure for at least 1/2 minute stepping on it. If not, there is definitely a problem. Or is it just what feels like a mushy peddle, but does not go to the floor?. GM brakes are not a totally hard peddle.

It sounds like you are doing everything right at this point. If it is soft and will not hold there is still air in the lines somewhere. Did you by chance let the master cyl go dry in the bleeding and introduce air? Or have you considered the MC is not up to par?

Oct 18, 2011 | 05:28 PM

#24

silver79

Racer

Joined: Jul 2001

Posts: 483

Likes: 3

From: d.d.o quebec

Quote:

Originally Posted by dbwright15

understood... we'll bleed both rears, left then right, and see where we are then. If theres a break/crack id think we see some fluid leaving the master cylinder or a puddle somewhere.

I rebuilt both front brakes, bled them with help of my wife. No problem make sure that the master cylinder has fresh oil and keep the cap on. You don't need to bleed all the brakes only the on you worked on.

Oct 18, 2011 | 07:33 PM

#25

Mark Hawkins

Instructor

Joined: Apr 2011

Posts: 137

Likes: 0

From: Goose Creek SC

Quote:

Originally Posted by silver79

Hey, you stated that the cap needs to be on. I did not know this. This is my first time brake bleeding and I even have the GM Service Manual and it did not say anything about having the cap on...you're talking about the cap on the Master Cylinder correct?

If this is a major factor, then i've screwed up...no wonder I can't get a hard pedal.

Oct 18, 2011 | 11:28 PM

#26

bigvette1

Drifting

Joined: Jan 2002

Posts: 1,645

Likes: 11

From: Schaumburg IL

I have bled a lot of brakes and did not know this either. I think though it is a good idea as the fluid won't splash to squirt.

Mar 9, 2012 | 09:20 AM

#27

73Corvette

Le Mans Master

Joined: Feb 2012

Posts: 6,644

Likes: 479

From: OK

I have never tried to bleed brakes with the cap to the master off...
Did have considerable trouble bleeding brakes though on my chevelle...
someone at some point had switched sides with the calipers so they were upside down......bleeders down.... I don't know how I had any brakes at all
switched them and BAM I had brakes.

Mar 9, 2012 | 10:22 AM

#28

Silenttrouble

Intermediate

Joined: Jan 2012

Posts: 46

Likes: 0

Just a thought but I did all of my calipers and was having issues not getting a hard petal.

Not that you would be as stupid as I was but the brass washer thing that goes on the brake line... yeah i forgot that on one of them had the exact same problem as you.