Yes another C3 brske issue...
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Yes another C3 brske issue...
I have spent 2 days reading every c3 brake brake post on CF and google. With engine off I can build pressure after 2 pumps and pedal is hard. With engine running i can push pedal to the floor easily, ni firmness at all, and it return up when released. I can pull vacuum hose off booster and can hear the woosh of air.
I have replaced:
the booster twice
the master 3 times, two stock, now with Wilwood. Used push rod tool to measure correct length for adjustable push rod.
Calibers Wilwood 6R and 4R
Braided lines
added vacuum canister
I have bench bled the master, and bled the calibers using gravity, power bleeder, and old 2 person method. There is no air coming out of caliber bleed screws at all.
I have been fighting this for 5 years. Any ideas?
Thanks
I have replaced:
the booster twice
the master 3 times, two stock, now with Wilwood. Used push rod tool to measure correct length for adjustable push rod.
Calibers Wilwood 6R and 4R
Braided lines
added vacuum canister
I have bench bled the master, and bled the calibers using gravity, power bleeder, and old 2 person method. There is no air coming out of caliber bleed screws at all.
I have been fighting this for 5 years. Any ideas?
Thanks
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,508
From: Virginia
To bleed the rear Wilwood calipers, are you removing them from the brackets?
Have you checked that your brake combination valve is centered? The "Brake" light may be off for a number of reasons, so check continuity at the switch.
Perhaps try a Phoenix reverse bleeder? Do a search, first.
Have you checked that your brake combination valve is centered? The "Brake" light may be off for a number of reasons, so check continuity at the switch.
Perhaps try a Phoenix reverse bleeder? Do a search, first.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
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
Race Director
Joined: May 2006
Posts: 18,737
Likes: 2,583
Don't remove the master at this point. Jack up the rear of the car so that the rear of the master is higher than the front. Slowly depress the brake pedal. Any air should come out the holes in the bottom of the reservoirs. Assume you are doing RR, LR, RF, LF.
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,508
From: Virginia
I don't have Wilwood rear calipers, but I've heard that they are position dependent during bleeding, and may need to be removed from the caliper brackets for best results. If you search the Forum, you should find some posts about it.
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
if you don’t have a proportioning valve, I would install one. Not sure of any benefits one would gain from removing it.
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Yeah it does. I have the same Wilwoods & SS hoses with generic/stock rest of the Manual Brakes system. works like a dream since I installed them.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Car is on a lift so it was easier to pop off the master and bench it again at an angle.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
I got a little more air out bench bleeding at an angle. So after another power bleed it doesn't go to the floor. The pedal (not the arm the pedal is attached to) is about 2" off the floor. I would say the first 75% of the stroke is effortless then you can feel it start to firm up.
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Hmmm..... it should be better than that.
How old is your dot-4? Are you certain it has not absorbed bunch of moisture? If you are NOT sure then I would just replace it with DOT-3......
Is your pressure bleeding setup totally tight? Let's see a picture of your pressure bleed setup?
How old is your dot-4? Are you certain it has not absorbed bunch of moisture? If you are NOT sure then I would just replace it with DOT-3......
Is your pressure bleeding setup totally tight? Let's see a picture of your pressure bleed setup?
I got a little more air out bench bleeding at an angle. So after another power bleed it doesn't go to the floor. The pedal (not the arm the pedal is attached to) is about 2" off the floor. I would say the first 75% of the stroke is effortless then you can feel it start to firm up.
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Hmmm..... it should be better than that.
How old is your dot-4? Are you certain it has not absorbed bunch of moisture? If you are NOT sure then I would just replace it with DOT-3......
Is your pressure bleeding setup totally tight? Let's see a picture of your pressure bleed setup?
How old is your dot-4? Are you certain it has not absorbed bunch of moisture? If you are NOT sure then I would just replace it with DOT-3......
Is your pressure bleeding setup totally tight? Let's see a picture of your pressure bleed setup?
THe motive cover doesn't fit the Wilwood so I made one from a spare Wilwood cover. It uses the Wilwood rubber seal and holds 20psi steady.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,508
From: Virginia
Can you take a picture of what is there? If you have continuity between the connector post on the switch, and "ground" of the proportioning valve*, the valve needs to be centered, and may be your entire problem.
*Yes, I know it's not really a proportioning valve, but it's the name everyone seems to understand. But pictures are even better!
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Uh...
Can you take a picture of what is there? If you have continuity between the connector post on the switch, and "ground" of the proportioning valve*, the valve needs to be centered, and may be your entire problem.
*Yes, I know it's not really a proportioning valve, but it's the name everyone seems to understand. But pictures are even better!
Can you take a picture of what is there? If you have continuity between the connector post on the switch, and "ground" of the proportioning valve*, the valve needs to be centered, and may be your entire problem.
*Yes, I know it's not really a proportioning valve, but it's the name everyone seems to understand. But pictures are even better!