brake bleeding
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
Likes: 929
From: Tn
2024 C8 of the Year Finalist - Modified
brake bleeding
while doing a brake job i had my LF line go bad, i let it sit over night and the reservoir went empty. i bled the brakes and used 3 bottles of fluid, the pedal was firm after the bleeding with the car off
today i started the car and the pedal is feeling soft, any advice would be appreciated
today i started the car and the pedal is feeling soft, any advice would be appreciated
Le Mans Master
Joined: Feb 2009
Posts: 5,169
Likes: 199
From: Your Sister's Bedroom
while doing a brake job i had my LF line go bad, i let it sit over night and the reservoir went empty. i bled the brakes and used 3 bottles of fluid, the pedal was firm after the bleeding with the car off
today i started the car and the pedal is feeling soft, any advice would be appreciated
today i started the car and the pedal is feeling soft, any advice would be appreciated
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
Likes: 929
From: Tn
2024 C8 of the Year Finalist - Modified
Le Mans Master
Joined: Dec 2004
Posts: 5,491
Likes: 806
From: West coast CA
while doing a brake job i had my LF line go bad, i let it sit over night and the reservoir went empty. i bled the brakes and used 3 bottles of fluid, the pedal was firm after the bleeding with the car off
today i started the car and the pedal is feeling soft, any advice would be appreciated
today i started the car and the pedal is feeling soft, any advice would be appreciated
Anyway, it's very common to have to bleed it again after replacing that much fluid. You'll have an even easier time if you wait until the next morning to let tiny air bubbles rise into the reservoir.
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
Likes: 929
From: Tn
2024 C8 of the Year Finalist - Modified
I'm not sure how much I should bleed the system, I did the LR caliper until I got new fluid coming through, and did the other calipers until I was see.g new fluid.
should I pass entire reservoir of fluid through each caliper?
Could I bleed with the motor on so that the master cylinder and booster are being used?
How could air enter the ABS? Is them any way to get the air out without using a techII?
should I pass entire reservoir of fluid through each caliper?
Could I bleed with the motor on so that the master cylinder and booster are being used?
How could air enter the ABS? Is them any way to get the air out without using a techII?
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Le Mans Master
Joined: Dec 2004
Posts: 5,491
Likes: 806
From: West coast CA
If your pedal is functional but merely spongy, you're doing okay. Just wait a little bit and bleed it again.
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
Likes: 929
From: Tn
2024 C8 of the Year Finalist - Modified
That's plenty.No.No. The booster just makes the pedal easier to push, which is hardly necessary with a bleed valve open.It's probably fine. There's a thimble of fluid captive in the ABS unit between electronically-actuated valves which are normally closed. This gets mentioned all the time because people want to replace that fluid, too, when doing brake jobs. It'll get mixed in with the rest of the system soon enough.
If your pedal is functional but merely spongy, you're doing okay. Just wait a little bit and bleed it again.
If your pedal is functional but merely spongy, you're doing okay. Just wait a little bit and bleed it again.
Le Mans Master
Joined: Feb 2009
Posts: 5,169
Likes: 199
From: Your Sister's Bedroom
Im not a fan of the vaccum bleeders, ive had them in the past. The motive products pressure bleeder works awesome though. If you were in the milwaukee area id let you use mine.
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
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From: Tn
2024 C8 of the Year Finalist - Modified
Le Mans Master
Joined: Feb 2009
Posts: 5,169
Likes: 199
From: Your Sister's Bedroom
the pressure tank screws onto the master resevoir and you build pressure in the system, i usually put about 15psi into it. Then you just crack open the bleed valve and it forces the fluid through the system. In theroy it does the same thing as conventional bleeding but moves fluild much faster and makes it a one man job. Ive read somewhere that it also opens the abs valves above 13psi so it flushes through all the fluid. Unsure if that is actually true though.
Melting Slicks
Joined: Mar 2008
Posts: 2,835
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From: Avon Park FLORIDA
St. Jude Donor '08-'09-'10
the pressure tank screws onto the master resevoir and you build pressure in the system, i usually put about 15psi into it. Then you just crack open the bleed valve and it forces the fluid through the system. In theroy it does the same thing as conventional bleeding but moves fluild much faster and makes it a one man job. Ive read somewhere that it also opens the abs valves above 13psi so it flushes through all the fluid. Unsure if that is actually true though.
they are great!!I got one and I love it
I started on RR then LF, LR then RF per Tech's instructions, drove it a couple of days and did it again and got a great pedal
Tech Contributor
Joined: Oct 1999
Posts: 41,032
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From: Charlotte, NC (formerly Endicott, NY)
This is the warning that is in the Service Manual brake bleeding procedure:
Important: If it is determined that air was induced into the system upstream of the ABS modulator prior to servicing, the Antilock Brake System Automated Bleed Procedure must be performed.
Bill
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
Likes: 929
From: Tn
2024 C8 of the Year Finalist - Modified
the pressure tank screws onto the master resevoir and you build pressure in the system, i usually put about 15psi into it. Then you just crack open the bleed valve and it forces the fluid through the system. In theroy it does the same thing as conventional bleeding but moves fluild much faster and makes it a one man job. Ive read somewhere that it also opens the abs valves above 13psi so it flushes through all the fluid. Unsure if that is actually true though.
Le Mans Master
Joined: Feb 2009
Posts: 5,169
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From: Your Sister's Bedroom
Race Director
Joined: Jan 2005
Posts: 10,924
Likes: 853
From: Daytona Beach FL
What did you do? Did you remove the calipers from the car - i.e. disconnect them from the hoses that connect them to the brake lines???
If so, and you got them mixed up, that could be your problem.
The soft pedal you describe after multiple bleedings sounds like the problem many have had after removing and reinstalling the calipers. I've read here on the Forum a number of times that people have had issues getting a firm pedal after getting calipers powdercoated or rebuilt, and it's because they put them on the wrong side of the car.
If the calipers are put on the wrong side of the car and the bleed valves are on the bottom of the caliper you'll never get the pedal firm.
The bleed valves must be on the top of the calipers.
Bob
If so, and you got them mixed up, that could be your problem.
The soft pedal you describe after multiple bleedings sounds like the problem many have had after removing and reinstalling the calipers. I've read here on the Forum a number of times that people have had issues getting a firm pedal after getting calipers powdercoated or rebuilt, and it's because they put them on the wrong side of the car.
If the calipers are put on the wrong side of the car and the bleed valves are on the bottom of the caliper you'll never get the pedal firm.
The bleed valves must be on the top of the calipers.
Bob
Thread Starter
Speedy
Joined: Mar 2007
Posts: 6,105
Likes: 929
From: Tn
2024 C8 of the Year Finalist - Modified
update
just finished bleeding with a friend with the conventional method, since the fluid is new i just recycled what was coming out of the calipers, we bleed out about 1/3 of the reservoir at each caliper and it made a huge difference, the pedal still has about 1 inch of hang. ill be purchasing a power bleeder to make the job faster and to this one more time after driving the car a bit
heres what i upgraded to:
xyz big brake kit
14'' 2 piece slotted rotors all around
6 piston fixed calipers up front with steel pistons
4 piston fixed calipers rear with steel pistons
1 piece ferro carbon pads all around
stainless steel lines
custom cooling ducts up front
heres what i upgraded to:
xyz big brake kit
14'' 2 piece slotted rotors all around
6 piston fixed calipers up front with steel pistons
4 piston fixed calipers rear with steel pistons
1 piece ferro carbon pads all around
stainless steel lines
custom cooling ducts up front
Race Director
Joined: Jan 2005
Posts: 10,924
Likes: 853
From: Daytona Beach FL
Excellent!!! Sounds like you'll have a great system!!!
I use a Motive Power Bleeder with a GM cap adapter like others have mentioned.
It's designed to put fluid into the bottle, but I think many/most of us just use it as a pressure source. You could probably build your own out of a pump-up bug-spray or fertilizer-spray tank, a pressure gauge, a length of tubing, and cap that will fit the brake m/c.
Bob
I use a Motive Power Bleeder with a GM cap adapter like others have mentioned.
It's designed to put fluid into the bottle, but I think many/most of us just use it as a pressure source. You could probably build your own out of a pump-up bug-spray or fertilizer-spray tank, a pressure gauge, a length of tubing, and cap that will fit the brake m/c.
Bob
Last edited by BEZ06; Feb 25, 2011 at 10:19 AM.