I have a 73 Corvette Stingray that I bought from a private seller back in May 2019.. I've been doing some work to it on my own since I picked it up.. I replaced the brake lines from the master cylinder to each caliper, put BIlstien Shocks on it, installed brand new calipers and a few other things..

One recent issue after completing the brakes, i noticed the pedal takes full pressure to stop.. a red light appears on the dash in the speedometer area "Brakes" in red... yet the car comes to a stop no problem and my rear tail lights are not lighting up..

Ideas/suggestions?

 

Red light in the dash is due to low brake pressure on either the front or rear brakes. Which since you replaced the brake lines you have air in the system. Could be at the MC or at 1 of the calipers. This means you need to bleed the brakes. What method did you bleed the MC and the calipers ?

 

If you allowed the Master to run dry, it will be very difficult to get the last bubble out of the MC. This is why a "bench bleed" is needed unless, you have a Motive Pressure Bleeder.

Click on my profile, photo albums, check out brake bleeding.

 

My process was to keep the Master Cylinder filled with fluid the entire time even before I replaced the main lines. I know the brake booster and MC was working before I changed the brake lines-- so I didn't want to disturb what was working well.

Before I removed the 2 lines off the master cylinder, I had the bench bleed kit from Summit Racing ready to attach to the master cylinder to keep brake fluid in it. This kit I used, included 2 hoses, 2 male threaded fittings and guides to hold the tubing into each opening at the top of the MC. I removed 1 line at at time and added the bench bleed tube to the ports on the side of the master cylinder. I then put the bench bleed lines back into the master cylinder (which I kept filled with Brake Fluid)...

Once I did that, then I removed all the old brake lines. I replaced the old lines with new Stainless Steel lines purchased through Ecklers Corvette. Prior to connecting the lines to the rear connections and front proportioning valve, I tested the fit 2x per fitting to make the fittings fit well with the new lines. I've watched several youtube videos and heard many consumers working on Corvettes experiencing several issue working with Stainless Steel lines, that I took note and was pre-cautious (as much as I could). I replaced both rear connections but re-used the old proportioning valve that came with the car (I just cleaned it with brake fluid real good as the external was dirty- no damage).

I "bench bleed" the MC on the car (using the brake pedal to prime it, using full pumps on brake pedal, slow strokes watching bubbles) as is with the lines pulling the brake fluid through it again, until I saw all air bubbles diminished. Once that was the case, I connected the new lines from the front proportioning valve (1 at at time) back to the MC( a little brake fluid drained out ) but I kept an eye on it to make sure it stayed at least 1/2 full per side.. I bled each caliper fully, using the gravity method, beginning with the Right Rear, and moving to the left rear, then to the front right and ending with the front left. Each caliper was treated independently. Once I got the air out of the caliper (not seeing any bubbles), I ran roughly 8 oz of brake fluid through each caliper, using this gravity method I researched on Youtube. The brakes grab but it takes a full pedal to apply the brakes...

Any idea where I went wrong?

 

Lurking to learn. Good luck op.

 

That would be correct..

 

I want to mention one thing first. That, when someone removes the break-bleeding kit from the MC and attaches the brake lines, you have introduced a bubble. Even if its just a split second to attach the lines, there is still an air pocket / air space there. But it looks like you worked the bubbles out through the system. Or did you?

Second, keep your foot away from the brake pedal to bleed the system. I know that's how to do it with every vehicle on the road. One person on the pedal, one person at the caliper with a wrench. Its just a bad method on C3s. You will trip the Proportioning Valve and dash lite every time. (To reset the Prop Valve, often a quick jab on the pedal will center the piston). Using the "pedal method" is more trouble than its worth.

Sounds like the MC is good, calipers good, Prop Valve good. No mention of the rubber hoses. Sometimes they will fail on the inside with no indication showing on the outside. The fact that you used SS lines maybe an issue here. Its difficult to get a great flare & seal on that stuff.

I think I found your issue after reading your post a third time. Your issue is a "long stroke" brake pedal. You stated you pumped the brakes with a bleeder kit installed.
Because the kit does not allow pressure to build up, you likely over extended the piston inside the MC. When that happens the piston (ring) "O" ring seal can roll-over in its bore and snag itself on the return stroke. That's why it is imperative to never allow the MC piston to travel more than 1 3/8 inches. This is all shown in my photo album. The piston seals maybe damaged and not holding 100% pressure exiting the MC ports. Its been said that the brake system has over 400 lbs of pressure in its lines.
Yours does not. Hence the long pedal stroke.

 

That method has worked very well for the 31 years I've owned my '76. For me, it's the easiest way to bleed the brakes and the cheapest. All 4's still lock up on demand.

 

To resdoggie & HeadsU.P.--
I appreciate the feedback.. I really do.
What I want to make sure is--- Do I try to gravity bleed the system again? Or-- do I need to pull MC and Brake Booster apart to fix the seal-- if that is what is damaged? My only thought was that if you use the Brake Pedal to brake, I assumed that the brake pedal wouldn't exceed the max depth-- otherwise that would happen when braking in any car at any age... right? I'm just trying to rule out my wrong, so that I don't repeat history.. LOL.... I do know that I used full brake pedal strokes, but they were at slow, little pressure.. to keep the brake fluid from spilling out of MC .

Your last point, you pointed out a method that has always worked for you--- What method is that?

In addition, I used all Stainless Steel lines.. even Stainless Steel Flex lines from caliper to hard lines. I didn't skimp on cost. I have no leaks as I checked each fitting after loading the system with brake fluid-- I see no leaks and hear no sounds coming from any fittings..

 

I guess if it were me, I would try the gravity bleed method, its cheap, slow, works. You do not have a Motive Pressure bleeder nor a vacuum pump. So, try the gravity method. Its slow enough to do 2-4 bleeder screws at a time. Such as the rear four. Then the front two.

If you are not happy with the results, then you should run a MC test which involves the purchase of some hardware.

 

Thanks for the reply-- I was hoping that was the case---
I will try the re-bleed option probably by this weekend. I was more worried that I damaged the brake booster or something more involved.

Thanks again!

 

Sometimes bleeding backwards works. Stick a screwdriver between pad and rotor. Pry on pad to force pistons back into tbleeder. Or remove caliper and use a c clamp. That pushes fluid back from calipers thru prop valve and into master. Right after disconnecting lines at valve or master this avoids you having to push the air bubbles the length of the brake system to get air out of the bleeders.

 

ANY time you disconnect ANY line, you have re-introduced air right back into the system again. Its just that simple.
Then you're back to square one.

 

Here is how I bleed the system after the brake lines or calipers have been opened. All you need is 1 simple DIY Tool.
C-Channel or something similar fitted with some air line fittings. Air compressor and a air line fitting to block one half of the brake system.




Now the procedure I use is to first bleed the MC "while on the car" and the brake lines connected.
See this https://www.corvetteforum.com/forums...-cylinder.html

Once you are happy the MC has no air proceed to "pressure bleed" each caliper. I usually do the longest to the shortest brake line.
First push in the brake pads to push the caliper pistons into the caliper and secure. Then apply ~ 15-20 psi at the MC. Use a clear tubing connected
to the bleed screw, and bleed until you see no air bubbles. If all the fluid is new collect the discarded fluid in a clean container to re-fill the MC.
Once the line is clear (leave the pressure at the MC) then remove the clamps from the brake pads to allow the caliper pistons to push out.
Then try to rotate the rotor. With 20 PSI at the MC it will be very difficult to rotate the rotor. If it moves easily you have a problem with the brake line hose from the caliper
to the brake line.

 

Providing an update-- I re-bleed all four calipers and got it!! No more red light and the pedal feels perfect-- Like a Brand New Car. HAHAHAAA thanks for everyone's input here. It helped immensely, allowing me to never give up!! Now, I just need to "adjust" parking brake. I had a minor hiccup when I replaced the cable.... the spring behind the caliper jumped over the guide and wasn't applying the parking brake evenly.. so it felt tight.. but once I fixed the spring-- it loosened the tension on the parking brake... Does anyone know the proper direction to "adjust" the parking brake through the rotor (there is a little hole/window in rotor to access the "gear") any ideas? I don't recall if its up or down, that makes it tighter? I also heard, going in reverse its supposed to "auto" adjust, but I don't believe that helped at all...

 

I don't know if C3s have the automatic drum brake adjuster. But the old cars of the 50s - 70s certainly did have that feature. I believe the adjuster is called a star-wheel on the rear drum set-up and when moving in reverse, it did tighten the shoes one notch. But it was not from daily reversing but more like jabbing the brake pedal a few times quickly and hard, forced the star wheel to click one notch tighter.

 

All C-3s had four wheel disc brakes. The only drum system in the C-3 is the parking brake. The parking brake is adjusted through the front of the rotor. If adjusted correctly, it will have no effect on the disc system. Jerry

 

Please share how you bled the brakes and what you think you did Differently ?

i just completed a rebuilt master cylinder that was leaking between booster and mc.
i have read all the bleeding reviews for the vette and tried most. My experience is
- tried gravity, jacked up front too...WAY to slow, and slight sucking on hose moves easily then back to very slow one or both rear. No way for me, fronts similiar.
- mity vac system for me SUCKS..if the vacuum works then the bleed screw lets in air never knowing if bubbles are from system or screw as they never stop.
- bench bled my rebuilt nos ebay oem special with lucky cardone remfg original cap, seemed to work, note agree with others you will introduce air in lines and full bleed required.
- 2 man method 13yo , wife, anyone can coordinate push release..this method is my default for speed and seeing when the bubbles hit vs clear.
- run at least a quart to bleed all four
- yes will trigger proportioning valve but a stab when done fixes.
- i am sure the pressure method and up / derek method would work but I don’t do enough to warrant...plus something else will need to be fixed!