[C2] Brake Bleeding
Thread Starter
Burning Brakes
Joined: May 2004
Posts: 1,249
Likes: 143
From: South MS
Brake Bleeding
I upgraded my 65 to power brakes using 67 PB parts from Zip, I think. Anyways, everything is brand new from MC to lines to calipers. I've been trying to bleed the brakes using the clear hose and bottle method but I'm not getting anywhere. I started with the passenger rear caliper and see bubbles coming out but the fluid in the MC is still at the same level. I've pumped on them for at least 30 minutes and nothing seems to be happening. Shouldn't I see the fluid lowering in the MC if it was moving down the lines, in know a stupid question? Is there something I should have done before bleeding the calipers?
Thanks for any assistance,
Dex.
Thanks for any assistance,
Dex.
Race Director
Joined: Apr 2005
Posts: 11,265
Likes: 2,131
From: Bowling Green, Kentucky
Dex:
Did you install the 1967 brake failure light block like all 67 cars have, or did you do something different??
I would start at the master cylinder with a helper and try the bleeder connectionss on the master cylinder. A correct 67 MC should have them. But if not, I would start at the closest connection to the master cylinder and see if you can get fluid to come out. Then work your way toward the rear. Same with the front system. Start closest to MC and then work toward the farthest point.
Did you bench bleed the MC?? That might be a problem, but if MC has bleeders, using them is just about the same thing.
I will often pull a vacuum on the caliper bleed connections to help get fluid flow started. I use a Mighty-Vac. But that should not be required for the job.
Larry
Did you install the 1967 brake failure light block like all 67 cars have, or did you do something different??
I would start at the master cylinder with a helper and try the bleeder connectionss on the master cylinder. A correct 67 MC should have them. But if not, I would start at the closest connection to the master cylinder and see if you can get fluid to come out. Then work your way toward the rear. Same with the front system. Start closest to MC and then work toward the farthest point.
Did you bench bleed the MC?? That might be a problem, but if MC has bleeders, using them is just about the same thing.
I will often pull a vacuum on the caliper bleed connections to help get fluid flow started. I use a Mighty-Vac. But that should not be required for the job.
Larry
Thread Starter
Burning Brakes
Joined: May 2004
Posts: 1,249
Likes: 143
From: South MS
Dex:
Did you install the 1967 brake failure light block like all 67 cars have, or did you do something different??
I would start at the master cylinder with a helper and try the bleeder connectionss on the master cylinder. A correct 67 MC should have them. But if not, I would start at the closest connection to the master cylinder and see if you can get fluid to come out. Then work your way toward the rear. Same with the front system. Start closest to MC and then work toward the farthest point.
Did you bench bleed the MC?? That might be a problem, but if MC has bleeders, using them is just about the same thing.
I will often pull a vacuum on the caliper bleed connections to help get fluid flow started. I use a Mighty-Vac. But that should not be required for the job.
Larry
Did you install the 1967 brake failure light block like all 67 cars have, or did you do something different??
I would start at the master cylinder with a helper and try the bleeder connectionss on the master cylinder. A correct 67 MC should have them. But if not, I would start at the closest connection to the master cylinder and see if you can get fluid to come out. Then work your way toward the rear. Same with the front system. Start closest to MC and then work toward the farthest point.
Did you bench bleed the MC?? That might be a problem, but if MC has bleeders, using them is just about the same thing.
I will often pull a vacuum on the caliper bleed connections to help get fluid flow started. I use a Mighty-Vac. But that should not be required for the job.
Larry
I did buy the block for the 67 setup. I didn't bench bleed the MC but will see if I can do it on the car.... When I figure it out. There's actually 2 borders on the MC and I'm trying the first house and bottle method now. I see plenty of air bubbling in the bottle but nothing coming out of the bleeder into the clear hose.
Thanks,
Dex.
Race Director
Joined: Apr 2005
Posts: 11,265
Likes: 2,131
From: Bowling Green, Kentucky
Dex:
Inside the differential pressure warning light block is a piston with o-ring seals on both ends (I believe). Piston can move in response to pressure on either side. It may be pushed over to one side and partially blocking that brake line (front or rear). It should eventually self-center when front and rear brakes finally build pressure. That is why I said to break a few connections close to MC and see if you can get flow.
Also make sure you have a little bit of free play in the MC push rods...........between brake pedal and booster and between booster and MC. The AIM gives the free play, which is around 1/16 to 1/8 inch. You must have some free play for things to work correctly inside the MC.
Larry
Inside the differential pressure warning light block is a piston with o-ring seals on both ends (I believe). Piston can move in response to pressure on either side. It may be pushed over to one side and partially blocking that brake line (front or rear). It should eventually self-center when front and rear brakes finally build pressure. That is why I said to break a few connections close to MC and see if you can get flow.
Also make sure you have a little bit of free play in the MC push rods...........between brake pedal and booster and between booster and MC. The AIM gives the free play, which is around 1/16 to 1/8 inch. You must have some free play for things to work correctly inside the MC.
Larry
Melting Slicks
Joined: Apr 2005
Posts: 2,777
Likes: 105
Get a mity vac hand vacuum pump and from each caliper, furthest one first, put clear plastic tubing from vac pump to the bleeder end. Pump the vac then crack open the bleeder m, and close the bleeder. This works without pumping the brake pedal. Watch the mc fluid level and replace the fluid as required.
This should do it for ya
I've been doing mine this way for decades.
This should do it for ya
I've been doing mine this way for decades.
Thread Starter
Burning Brakes
Joined: May 2004
Posts: 1,249
Likes: 143
From: South MS
Dex:
Inside the differential pressure warning light block is a piston with o-ring seals on both ends (I believe). Piston can move in response to pressure on either side. It may be pushed over to one side and partially blocking that brake line (front or rear). It should eventually self-center when front and rear brakes finally build pressure. That is why I said to break a few connections close to MC and see if you can get flow.
Also make sure you have a little bit of free play in the MC push rods...........between brake pedal and booster and between booster and MC. The AIM gives the free play, which is around 1/16 to 1/8 inch. You must have some free play for things to work correctly inside the MC.
Larry
Inside the differential pressure warning light block is a piston with o-ring seals on both ends (I believe). Piston can move in response to pressure on either side. It may be pushed over to one side and partially blocking that brake line (front or rear). It should eventually self-center when front and rear brakes finally build pressure. That is why I said to break a few connections close to MC and see if you can get flow.
Also make sure you have a little bit of free play in the MC push rods...........between brake pedal and booster and between booster and MC. The AIM gives the free play, which is around 1/16 to 1/8 inch. You must have some free play for things to work correctly inside the MC.
Larry
Thanks,
Dex.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Thread Starter
Burning Brakes
Joined: May 2004
Posts: 1,249
Likes: 143
From: South MS
Get a mity vac hand vacuum pump and from each caliper, furthest one first, put clear plastic tubing from vac pump to the bleeder end. Pump the vac then crack open the bleeder m, and close the bleeder. This works without pumping the brake pedal. Watch the mc fluid level and replace the fluid as required.
This should do it for ya
I've been doing mine this way for decades.
This should do it for ya
I've been doing mine this way for decades.
Thanks,
Dex.
Melting Slicks
Joined: Jul 2011
Posts: 2,064
Likes: 141
From: Bornem
I am not the absolute expert on this, but have done several bleed exercises on my 64. In any of them , step 1 was bleeding the MC. If you have not done this, that is what I would recommend to start with. Using the bleed nipples as shown in post#4 it's a straightforward process.
Thread Starter
Burning Brakes
Joined: May 2004
Posts: 1,249
Likes: 143
From: South MS
I am not the absolute expert on this, but have done several bleed exercises on my 64. In any of them , step 1 was bleeding the MC. If you have not done this, that is what I would recommend to start with. Using the bleed nipples as shown in post#4 it's a straightforward process.
Thanks,
Dex.
Thread Starter
Burning Brakes
Joined: May 2004
Posts: 1,249
Likes: 143
From: South MS
Race Director
Joined: Jul 2018
Posts: 10,560
Likes: 8,359
From: San Antonio, TX/Mahopac, NY
2024 Corvette of the Year Finalist - Modified
2024 Corvette of the Year Finalist - Unmodified
2023 C7 of the Year Winner - Modified
I have one similar, but instead of a hand pump, it clips to a tire valve stem and has a regulator you adjust to about 15 psi. Works great and you don’t need to bleed the mc first as it simply powers right through.
Instructor
Joined: Aug 2018
Posts: 207
Likes: 15
From: Glenwood springs, Colorado
Did you leave the rubber boot on the new master cylinder? it needs to be removed if you have a brake booster for power brakes. If left on it will jam up between the master and booster, limiting the movement of the pushrod. Ask me how I know this.. 
Last edited by JFP58; Jul 4, 2019 at 09:46 PM.