# 69 hold off valve



## Shadetree Racing (Apr 15, 2015)

I have a 69 GTO conv that has all drum brakes but the cylinder setup has the hold off on it.
The car hasn't run in 15 years and I don't remember how it got there, I'm assuming a service station cylinder change 25 years ago used whatever was on the shelf.
Problems with keeping it on the drums?


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## Pinion head (Jan 3, 2015)

Very odd, makes me wonder if the master cylinder is a disc/drum, and the entire master and lines have been swapped years ago. Is the metering valve the style with a big nut on one end, or no big nut(?). 

The metering valves can get rust sediment in them from many years of moisture and mild internal corrosion, I'd probably remove the metering valve, and replace it with the correct drum line, but hang on to the metering valve, in case you or a friend needs the metering valve for a concours disc brake resto., the valves can be rebuilt.


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## Shadetree Racing (Apr 15, 2015)

The valve has the big nut on it, the car could have had disc from the factory but i don't know for sure, it had a 350 and a lemans interior when i bought it so there was certainly a lot of swapping before i got the car.
the build sheet was missing from the tank when i removed it, except for a small corner piece


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## Shadetree Racing (Apr 15, 2015)

hold the phone,
i ordered the bill of sale on the car from Pontiac about 25 years ago so i dug that out and sure enough it listed the car as "Disc Brake Package"!
would that have been front disk and rear drum? that would match the master+ metering set-up i currently have.


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## Red1970GTO (Jun 25, 2011)

Yes, that option would have been front Disc and Rear Drum. The (Front) Disc set up used a different Master Cylinder than the Drum set up.


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## Pinion head (Jan 3, 2015)

The factory disc pieces can be put back on it. Caliper brackets are avail either nice used, or can buy the cheap chinese jobs. Clean drum spindles can be made into disc spindles or you hunt and hunt for nice used orig disc spindles, or buy the chinese steel repop spindles (not me). On the calipers, I used to have my nice originals gone through by Cardone in Dallas, it was cheap. Now, for customers drivers, usually order repro calipers through O'Reilly's. Your disc brake hose brackets may still be there, the drum ones are different, won't accept the disc brake hoses. On rotors, most part store rotors are made in China. If you can find some made in Mexico, will be better off. Even nice thick used ones are fine, on used I def would buy some new quality A2 A6(?) wheel bearing/races sets along with a pair of wheel bearing seals.


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