Re: 1954 Pacific disc brake conversion kit / the residual pressure valve must be removed

Posted by HH56 On 2020/8/26 11:30:03

Some GM cars (Cad, Chevy, Buick maybe) and I believe some Mercedes models did use the Bendix Treadlevac (BTV for short). The other mfgs did for the most part mount theirs differently than Packard so as to have a better pedal ratio. Eventually GM licensed rights to more or less copy the BTV and produced their version as a Moraine unit. The two operate similarly but as I understand it the Moraine version had some issues, one big one being that if a seal failed, the way ports and seals were positioned vacuum could easily suck all the fluid out of the master rather quickly.

From reports of small amounts of fluid found in the vacuum side of the Packard version, their BTVs apparently had that issue to some extent but not like the Moraine. Many of the Packard issues can be traced to a gasket and the flat reservoir cover Packard used which was OK on the first version BTVs but the same cover carried over to the later versions and blocked off a relief port on those. That blocked port caused any hydraulic seal leak to force fluid into the vacuum side or a vacuum seal leak to pull fluid rather than have an open path into the reservoir area so it could move fluid back or pull air instead of fluid. That has been noted and corrected on rebuilt units by most of our Packard vendors but unknown how widespread it might be in other rebuilds.

I do not know which GM models used Bendix and which Moraine but the unit you picture is a bit different from what Packard used. I can't say if it is the BTV or the Moraine. The vacuum input is different as is the reservoir cover and vent and there appears to be a bleed screw on the master that is not present on the BTV. If it is a BTV that one might work although there would be two check valves in the vacuum line which could cause a conflict. You might compare price with Max or Kanter for an authentic Packard rebuilt or ensure what you get from somewhere else is at least a second version poppet valve type Bendix unit as Packard used from 53-6.