Re: Locking brakes.

Posted by BH On 2009/1/26 18:15:50

Morgan -

The repro overhaul kit for these master cylinders, like the original from Bendix, would have everything you needed to "refresh" the hydraulic section - EXCEPT for the compensator port valve spring. However, I doubt that spring is a problem in this particular case.

I suggest you first visually verify proper movement/operation of the compensator port valve stem, as noted by HH56. If that checks out, then try his later suggestion about disconnecting the vacuum source when the problem occurs. You should be able to easily access the large supply hose for the power brake unit on the check valve located at the rear of the carburetor throttle body - originally secured by a spring wire clamp (which makes for easy removal).

While there are undercar power brake units available in the kustom aftermarket that can replace the non-power brake master cylinder that was mounted under the floorboard on 1954 and earlier Packards, you will not have sufficient clearance to use them on the V8 models. While I tip my hat to a couple of other members here who have adapted other dual-chambered units, there is no alternate power brake unit I would recommend for the V8 Packards.

Yet, don't believe all the negative hype about the Treadle-Vac. Properly serviced it works fine on each of my cars (and I went through them myself). Should you need the service of a professional rebuilder, just be sure to send it to a reputable Treadle-Vac specialist. Do NOT send it off to someone who is merely expert at rebuilding and sleeving conventional master and wheel cylinders.