[tonydaytonSSCamaro396]

I am in the process of replacing the original 2 piece front disc rotors and calipers. I also replaced the hold-off valve since the lower bolt was slightly corroded. Four years ago, I installed a new master cylinder and power booster. When we started to bleed the rear, we could not get any fluid out. After trying for over an hour, we decided to try the front, and if successful, then go back to the rear.

We were able to get the front bled, but still no success on the rear. Next step is to go back and reinstall the old hold-off valve. I also thought to try disconnecting the rear brake line from the hold-off valve to see if fluid is getting through, but that is going to be a BIG mess and this is a concours car. Has anyone had a problem with a repro hold-off valve or an issue like this?

Thanks in advance.

Tony

[JohnZ]

Originally Posted by tonydaytonSSCamaro396

Next step is to go back and reinstall the old hold-off valve. I also thought to try disconnecting the rear brake line from the hold-off valve to see if fluid is getting through, but that is going to be a BIG mess and this is a concours car. Has anyone had a problem with a repro hold-off valve or an issue like this?

Thanks in advance.

Tony

The hold-off (metering) valve (the round one between the front outlet of the master cylinder and the distribution block) isn't connected to the rear brake system; it's in the front system. Are you talking about the proportioning valve down on the subframe below the driver's door?

[tonydaytonSSCamaro396]

Actually the proportioning valve in locating under the master cylinder and the hold-off valve in the one under the left side frame rail. If you look up the photo of the hold-off valve in Rick's Camaro, Classic Camaro or any other catalog, it will show the rear brake line connector is the hold-off valve.

Got any ideas?

[davidpozzi]

Originally Posted by tonydaytonSSCamaro396

Actually the proportioning valve in locating under the master cylinder and the hold-off valve in the one under the left side frame rail. If you look up the photo of the hold-off valve in Rick's Camaro, Classic Camaro or any other catalog, it will show the rear brake line connector is the hold-off valve.

Got any ideas?

Tony, Welcome to Team Camaro!

Sorry but you have it backwards, the hold off is in the front brake line, it's the round valve under the master cyl. The valve on the subframe is a proportioning valve of sorts, GM calls it a "Brake Pressure Regulator Valve".

You are new here so you probably don't know that JohnZ is a retired GM engineer who worked in the assembly plants when our cars were built. We are very lucky to have him here.
David

[tonydaytonSSCamaro396]

Then I stand corrected. It's odd that all of the car part catalogs have it backwards too.

So any ideas?

[tonydaytonSSCamaro396]

Could it be that the repro part is defective? I went back last night and tried to unscrew the bolt at the bottom but it would not budge (but it is 40 years old). Should the bolt, or I assume it is an 'adjustment screw', be able to be 'set'? I'll try to reinstall the old one back in, but it make take a few days since I'm really busy.

[tonydaytonSSCamaro396]

Well I replaced the pressure regulator with the original one and bled the brakes and everything is fine. I called the company I purchased it from and they are RMA'ing me a new one. Of course now I will have to go through the whole R&R again, and have to re-detail out everything since I'll get brake fluid on something no matter what.

Tony