I remember reading somewhere that In Line Tube had reproduced the disc brake hold off valve for the rear drum brakes a while ago and they had issues with the parts inside the valve. Does anyone know if they corrected the issue with them or do they still have issues? The one on my car is not allowing fluid through and out to the rear brakes.

That would be a proportioning valve for rear brakes on the 69 Bendix disc. The hold off or (metering valve) was for the 70 and up Front Disc brake KH setup. Still using a proportioning valve for the rear drums. 69 Bendix had no special valve for the front disc.

I have the inline proportioning valve on my 70 B body for many years no issues.

Have you checked to see if the differential pressure valve (piston) in the tee is centered?

Hi John,

I have not but I would also imagine that if the piston was off in the distribution block was off centered that the dash light for BRAKES would be lit and is not. Yes, the bulb works. lol

So I think the bottom line is the question is about a proportioning valve.
Yes At low pressures (up to 500 psi) Fluid should flow freely in and out.
There is a company making rebuild kits for some proportioning valves - I have not noticed whether that includes the bendix


http://www.imperialclub.com/Repair/Lit/Master/233/index.htm

Did Mopar use a residual valve in the OEM 1969 B body disc brake master cylinders? I know they did on all the drum brake cars on both ports but not on the disc brake cars in the 1970 and later cars
It is installed behind the brass seat in the master cylinders where the brake lines install in, it is a small rubber flapper valve with a spring in it. I use a #8 flat head sheet metal screw to remove them by inserting the screw a turn or two into the seat and then pull it out with a set of pliers and then remove the valve going to the disc brakes and reinstall the seat and tighten the brake line up tight enough to reseal and reseat the seat
Remove the one to the disc brakes only, not to the drum brakes

No mopar disc brake car used residual valve for the disc. Only drums. So a real Disc MC would have residual valve for rear drum, and non for Front Disc. Bendix or KH set up. I am not sure when they stopped residual valves with the rear piston cylinder change. I though 71 or later.