68 GT500KR Brake Woes

[shelbydoug]

If it was me, at this point, I'd say it is just time to take the entire system apart and go through it piece by piece. It's the only way to know for sure what the issue is and what needs to be replaced.

[TOBKOB]

The centering tool was never used at the dealer level. If the brake light is on , the valve is not centered, if it's off it's centered. We used to have someone sit in the car and open a line on one side of the master cylinder and slowly push it down until the light went out, if one side did not do it, you tried the other side line. The idea was to create a low pressure and the valve would move to shut off the pressure on that side

+1

At the dealer where I worked we would depress the pedal really hard and hold it a few seconds and if that didn't work we would bleed at the master cylinder as above.

TOB

[1967 eight barrel]

An old test for "air entrapment" is to have someone pump up the brakes and hold the pedal down, then carefully remove the master cylinder cap and quickly have them release the pedal, you should see a slight rise as the fluid returns to the master cylinder. If you have a tall geyser of fluid then you have "air entrapment" in what ever side of the brake system has the air. As someone mentioned if the calipers are mounted on the wrong side, the bleeder location will not allow all of the air to be removed. If I remember correctly the bleeder should be horizontal to the ground if is correct, if it points up then it's on the wrong side. The centering tool was never used at the dealer level. If the brake light is on , the valve is not centered, if it's off it's centered. We used to have someone sit in the car and open a line on one side of the master cylinder and slowly push it down until the light went out, if one side did not do it, you tried the other side line. The idea was to create a low pressure and the valve would move to shut off the pressure on that side
Hope this helps

No, that tool wouldn't have been used "back in the day". No one cared about a little brake fluid. On a fully restored car no one is going to crack brake lines on the master or distribution valve to center it. I hopefully won't ever have to re-center my system again, but the 10.00 is worth it. It allows you to get everything out of the system and the old rule no longer applies of bleeding the furthest from the master first. However, out of habit I did it anyway.
I have also noted that once the valve has moved completely to one end or the other you'll have to push the pin back centered in the valve. I removed the master and both lines. Then I used a pick to push it back centered and locked it there with the tool. 
No more light and it stops as good as you're going to get out of factory brakes.
                                                                                -Keith