Packard Forum Index » Post-War (1946-54)

I have replace all the lines, wheel cylinders, and master cylinder on my 1954 Clipper. Did the old treadle vac have a built in residual valve on the master cylinder? How to I tell if the new master cylinder has one? Do I need one?

The treadle vac had a residual check valve. MOst manual master cyls have them also but without knowing the exact master cyl you have used there is no way of knowing if it has a check valve. Also if it was built iwth a check vsalve there is no way of knowing if it is still in there.

I hate to be so wishy washy about this, but as it is critical safety item I would you be putting you at risk if I said yes.

The residual check valve keeps a small amount of pressure in the system (7 lbs???) so that moisture does not get into the system via the whl cyl cups

Thanks, I will check with the specs on the master cylinder.

The Napa master cylinder has a check valve.

The Raybestos MC308, which is the replacement for original Wagner F3081 has a residual valve. This is the one I have in my '54 with manual brakes. Napa has them, but there is a guy on eBay that sells them cheaper.

Thanks Kevin, I bought the one on ebay with the same number, that is why I was asking. It was about $35.00 cheaper. It appeared to match up with the NAPA one, but I needed to check it out.

I'm 99% sure it is the same one as the Napa one. The one in my car is from eBay, so I know that one will drop in place and was an exact match to the OEM one that my Packard came with.