1969 Camaro Z28 brake proportioning valves

[wisemanz28]

I'm having brake issues in the 69. I have a super hard brake pedal. I thought it was a power booster problem but this weekend I started to look at the front rubber brake lines. I took off both sides and they are ok, checked the steel lines and they look great, no blockage. I went to bleed the whole system starting at the back and initially I had a small amount of fluid coming through both sides. I went to the front and they bled fine. I thought the porportioning valve on the frame rail was bad so I took off the line before the valve to see if it was plugged and it is fine. Now with that line off I apply the brakes and there is no fluid at all coming from that disconnected line. I haven't checked the other metering valve under the master cylinder. Is there someone that sells rebuild kit for these porportioning valves or is there something else I'm missing?

[GMAD_Van Nuys]

I believe you need to reset your brake proportioning valve and can follow the procedure below:

https://www.speedwaymotors.com/the-toolbox/brake-proportioning-valve-reset-symptoms-bleeders-adjustment/134183?srsltid=AfmBOoqrD3S5V8Sf40iceRtk3rkoKzG_eIgxzjUVJDV7E-8cmT8rvChs

As for having an issue with brake pedal effort, I would check your brake vacuum hose and the check valve which goes into the brake booster.

[David K]

I would  think the rear brake rubber line could be the culprit.

[wisemanz28]

I checked the brake pressure differential valve and it didn't need reset but I ended up rebuilding that valve and also rebuilt my proportioning valve under the driver's side frame rail, the only valve I didn't touch was the metering valve
 I took off the master cylinder and bench bled it. With everything reinstalled I still have no fluid at the rear brakes. I took off the line just before the proportioning valve under the car and no fluid. I'm not sure what could be wrong, any tips or advice would be greatly appreciated

[David K]

Have you checked the metering block under the master cylinder with the rear line disconnected?

[wisemanz28]

David are you talking about the brake pressure differential valve that's under the master cylinder? I did take the rear line off of that and no fluid came out, and then I took the front line off and fluid came out of that one. I'm wondering if it might be a master cylinder issue.I haven't touched the metering valve yet.

[David K]

Well, call me forgetful for not using the correct terms for these parts. Let's try this.

https://camaros.org/brakevalve.shtml

[Stingr69]

There is a kit for the metering valve with the big nut on the front.  I rebuilt mine.  Sorry about the link pointing to the wrong kit but you can go there and click around to find the right kit.
https://www.musclecarresearch.com/gm-1233464-rebuild

[x66 714]

There is a kit for the metering valve with the big nut on the front.  I rebuilt mine.  Sorry about the link pointing to the wrong kit but you can go there and click around to find the right kit.
https://www.musclecarresearch.com/gm-1233464-rebuild

Unless Muscle Car Research changed their design, don't buy it from them. Many have failed....Joe

[David K]

Well, if no fluid came out of it after taking off the steel line, id be willing to bet thats your issue.

[x66 714]

Send it to Mike Gibbons. He has some new kits that are working....Joe

[GMAD_Van Nuys]

Seems you had a similar brake issue back in 2012.  How did you resolve the problem?

https://www.camaros.org/forum/index.php?topic=9424.msg67919#msg67919

[wisemanz28]

I did eventually get fluid to the rear wheel cylinder, wow can't believe that was 14 years ago. This time around I found the rear rubber hose is plugged.

[Kelley W King]

I had a similar problem on my 69 SS. A hard pedal for brakes that worked ok until you really tried to stop quickly . Most all parts were new by a previous onwner. The booster held vacuum and the valve worked although I replaced it. I bled everything the old way (pedal pumping) but finally I replaced the booster and cured it all. It was a repop by the way.

[David K]

Well, I get to be right every once in a while-reply #2. The hose typically fails internally and just blocks off all fluid flow. Is all good?