Flintstone Braking system???
 

Hello,
I have an 81 with some brake issues. I have changed the master, and bled the system several times. At best I would get only a a half pedal, meaning that nothing happens until the pedal is depress at lest half way. The brakes after a few weeks go away (pedal to the floor) and the brake light comes on. I am not leaking fluid anywhere, but there is air getting into the system somewhere. I am going to pull and replace the caliper seals, but again there are no leaks that I can find anywhere. Has anyone else had this problem and more importantly solved it. Thanks.

A special hello to Smokefoot in AZ. the gentleman I purchased the car from. A fellow forum member!

Mike Fesi

Just asking......are you aware that the rear calipers have 2 bleeders, each?


EDIT......how are the brake hoses? Sometimes they break down internally and give you funky issues.

I am aware of the back caliper having two bleed screws. It only took me one extra bottle of brake fluid to realize it, so I am sure many make that mistake.

I have seen calipers not leak a drop on the floor, but still manage to leak at the piston seals and they seem to take on air too. When you bench bled, you didn't go too far in the MC with the screwdriver did you? You will damage the seals / void the warranty.
1 3/8" max insertion of the piston.

What type of the five bleeding methods did you use?
Pedal
Gravity
Motive Pressure
Vacuum
Have someone else do it method.

And the Flintstone brake system is better than the Navy brake system:
dropping anchors.

Welcome to the Corvette brake hall of shame. :willy:
I've been chasing this problem as well.

I find that using a piston centering tool in the combination valve works well. Then bleed the brakes in the proper sequence.

Have you checked your rotor runout?
If the runout is over .002 you need to correct it. You do this by way of special shims. Excessive runout can introduce air into the brake system.

What method are you using to bleed the brakes?

Craig


https://cimg3.ibsrv.net/gimg/www.cor...4c3979c61d.png

Craig,
I have used every bleeding method I know of. Finally I bought a vacuum bleeder system which works well, As for the run out I have not checked that yet. Seems like this should be a simple fix but it has not been.

Did you tilt your master cylinder forward, backward, and level when bench bleeding it? Minute bubbles can be an issue as well.

Personally I prefer the Motive bleeders.

Tap on the calipers to bring air to the surface while bleeding.

No this is not a simple fix on these cars. There are too many variables in the equation that people overlook.

What order did you use for bleeding the calipers?

As soon as a poster says "installed New Master" the odds are 9 out of 10 times there's still air in the MC. Click on my profile and check out my photo album of bench bleeding.

A few items to think about:
If you only drive your Corvette once in a while the brake pedal travel might be in spec. but seem to be lower than your used too.


https://cimg9.ibsrv.net/gimg/www.cor...3f950f9a93.jpg


https://cimg7.ibsrv.net/gimg/www.cor...4f3c3d0212.jpg

Do you have power brakes?
If so see post 2 about adjusting the booster to master cylinder gap.

https://www.corvetteforum.com/forums...l-on-78-a.html

You say the pedal goes away (pedal to the floor).
If the pedal goes away after driving so many miles then check your rotor run out.