Another "trouble breeding brakes" thread.
Thread Starter
Drifting
Joined: Dec 2017
Posts: 1,663
Likes: 417
From: Central Texas
Another "trouble breeding brakes" thread.
Have a '70 C3, the old Delco calipers developed a leak so I upgraded with Delco's with SS inserts and o-ring seals from Lone Star.
Got all four installed with no issue but now am having trouble getting any kind of pedal pressure. We were able to get a small amount of fluid through to the back calipers but nothing to either front. I dont have any type of power bleeder, not sure if that will help?
My buddy is insisting its the Brake Proportioning Valve, said he had same issue with his old Chevy truck.
https://www.topflightautomotive.com/...ing-valve-new/
Any brake bleeding experts out there? TIA.
Got all four installed with no issue but now am having trouble getting any kind of pedal pressure. We were able to get a small amount of fluid through to the back calipers but nothing to either front. I dont have any type of power bleeder, not sure if that will help?
My buddy is insisting its the Brake Proportioning Valve, said he had same issue with his old Chevy truck.
https://www.topflightautomotive.com/...ing-valve-new/
Any brake bleeding experts out there? TIA.
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
1. Replace your rubber lines--- and as long as you're doing it buy the Stainless Steel braided puppies.
2. Get, or make, a Pressure Bleeder.
Write back after you do that.
2. Get, or make, a Pressure Bleeder.
Write back after you do that.
Have a '70 C3, the old Delco calipers developed a leak so I upgraded with Delco's with SS inserts and o-ring seals from Lone Star.
Got all four installed with no issue but now am having trouble getting any kind of pedal pressure. We were able to get a small amount of fluid through to the back calipers but nothing to either front. I dont have any type of power bleeder, not sure if that will help?
My buddy is insisting its the Brake Proportioning Valve, said he had same issue with his old Chevy truck.
https://www.topflightautomotive.com/...ing-valve-new/
Any brake bleeding experts out there? TIA.
Got all four installed with no issue but now am having trouble getting any kind of pedal pressure. We were able to get a small amount of fluid through to the back calipers but nothing to either front. I dont have any type of power bleeder, not sure if that will help?
My buddy is insisting its the Brake Proportioning Valve, said he had same issue with his old Chevy truck.
https://www.topflightautomotive.com/...ing-valve-new/
Any brake bleeding experts out there? TIA.
Thread Starter
Drifting
Joined: Dec 2017
Posts: 1,663
Likes: 417
From: Central Texas
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
The last thing you did was rebuild the calipers. Last thing done is the first place to investigate.
I don't believe a '70 has a Proportioning Valve. It has a bias valve or distribution block?
At this point, you are not 100% sure your master is building up pressure either. You need to isolate the MC from the system to see if it is functioning.
You need two test lines. NAPA has one foot long, ready made steel lines. You will need to know the MCs front & rear brake line port diameter & TPI.
Then figure a way to block off the end of the test lines. Easiest is to just roll & pinch off. (You will be exerting 400 lbs of pressure on those test lines)
Remove the brake lines from the MC. Install your test lines. You should be able to stand on the brake pedal all day long. If the pedal moves, there's the problem.
If it holds, look elsewhere.
I don't believe a '70 has a Proportioning Valve. It has a bias valve or distribution block?
At this point, you are not 100% sure your master is building up pressure either. You need to isolate the MC from the system to see if it is functioning.
You need two test lines. NAPA has one foot long, ready made steel lines. You will need to know the MCs front & rear brake line port diameter & TPI.
Then figure a way to block off the end of the test lines. Easiest is to just roll & pinch off. (You will be exerting 400 lbs of pressure on those test lines)
Remove the brake lines from the MC. Install your test lines. You should be able to stand on the brake pedal all day long. If the pedal moves, there's the problem.
If it holds, look elsewhere.
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,510
From: Virginia
PM one of the moderators and ask them to change the title to "Another pressure bleeder thread".
Also, if you don't remember the last time you replaced the brake hoses, or you have owned the car less than 10 years, they are due for replacement.
Also, if you don't remember the last time you replaced the brake hoses, or you have owned the car less than 10 years, they are due for replacement.
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,137
Likes: 4,248
From: US-PNW
I don't believe a '70 has a Proportioning Valve. It has a bias valve or distribution block?
At this point, you are not 100% sure your master is building up pressure either. You need to isolate the MC from the system to see if it is functioning.
You need two test lines.
At this point, you are not 100% sure your master is building up pressure either. You need to isolate the MC from the system to see if it is functioning.
You need two test lines.
After that, it may be that the distribution block (the thing folks misidentify as a proportioning valve) is clogged. Disconnect the driver's side rubber hose from the short steel line at the frame and blow air (by mouth is fine) through the forward line of the master cylinder that was disconnected to bleed the MC above. If you can't do this, then remove the block and clean it and the line from the master.
Alternative to using brake fluid, you can flush the system with denatured alcohol, which flows well and can act like a solvent. I don't think I'd run the DNA through the calipers though - it could be difficult to ensure most is removed prior to putting brake fluid back in.
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Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Don't discount this advice. I once changed brake pads on my pickup and could not get them to work for ages. They worked before the pad change. It turned out to be the rubber hoses..... I was amazed. I suspect it has something to do with them being ancient and when emptied of fluid swell internally..... and then cannot be gotten to expand properly again. I also ignored a friend who told me to change the hoses because I could not believe that it would happen like that.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
Put reman calipers on mine but the brakes were always kinda soft anyway. Then one day noticed one of the new calipers had a very small leak at one of the pistons and now I got decent breaks LOL
Meh anything is better than my 4 drum 68 Camaro was.
Also couple of my calipers came with those RC car body type locks, don't use them. Almost lost the pad retaining pin on my front caliper.
Meh anything is better than my 4 drum 68 Camaro was.
Also couple of my calipers came with those RC car body type locks, don't use them. Almost lost the pad retaining pin on my front caliper.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Fill the reservoir.
Crack the front brake line at the res.......does fluid leak out?
If so go down and crack the line at the proportioning valve......does fluid leak out?
If so go to the brake line at the left front wheel and crack it at the proportioning valve......does fluid leak out?
If so go to the brake hose at the wheel cylinder.......
Do the same for the right side.......
If the master is bench bled and full of fluid.....you can crack the bleeder and fluid will gravity feed out........this is true for any brake system on any car......as long as the master is high than the calipers.
Contrary to popular belief.....a Brake system is supposed to be wide open from the MC to the caliper/wheel cylinder.....and if you have trouble......there is an obstruction.
I have gravity bled about 20 C2/C3 Vette's over the years and they all respond the same way......
If your buddy feels the proportioning valve is blocked then confirm it.......
Motive pressure bleeders work great but are unnecessary.....if the system is installed and setup as GM intended.
Jebby
Crack the front brake line at the res.......does fluid leak out?
If so go down and crack the line at the proportioning valve......does fluid leak out?
If so go to the brake line at the left front wheel and crack it at the proportioning valve......does fluid leak out?
If so go to the brake hose at the wheel cylinder.......
Do the same for the right side.......
If the master is bench bled and full of fluid.....you can crack the bleeder and fluid will gravity feed out........this is true for any brake system on any car......as long as the master is high than the calipers.
Contrary to popular belief.....a Brake system is supposed to be wide open from the MC to the caliper/wheel cylinder.....and if you have trouble......there is an obstruction.
I have gravity bled about 20 C2/C3 Vette's over the years and they all respond the same way......
If your buddy feels the proportioning valve is blocked then confirm it.......
Motive pressure bleeders work great but are unnecessary.....if the system is installed and setup as GM intended.
Jebby
Drifting
Joined: Jul 2022
Posts: 1,359
Likes: 822
From: Wisconsin
2024 C3 of the Year Finalist- Modified
2023 C3 of the Year Finalist - Modified
2022 C3 of the Year Finalist - Modified
The trouble with breeding brakes is a lot like breeding pandas. The best advice I can give you is to introduce them from a distance, slowly move them closer, if all goes well leave confined in a small space (I'd use a box) and give them some time and privacy....
Le Mans Master
Joined: May 2008
Posts: 9,063
Likes: 2,736
2022 C3 of the Year Finalist - Modified
Never had problem bleeding brakes in my Corvette. Gravity bleed all calipers, followed by Mityvac vacuum at each caliper in sequence…solid pedal…done. Never understand the problem.
Intermediate
Joined: Feb 2021
Posts: 36
Likes: 4
the master has to be bleed first. then crack all top bleeders open and grab a cold one wait about an hour checking and topping off the MC as required, once a steady stream of fluid is coming out of the bleeders close them. after they are all closed grab a clear jar and put a hose on the bleeder and stick the hose in the jar and fill it first about half way...make sure the hose and jar are not gonna move around and the hose will stay submerged. slowly pump the pedal about 5 to 10 times. then close it up and repeat on all four corners. this is a reverse power bleeder and the best way to do it by yourself