Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??

Posted by BH On 2009/7/24 12:48:39

Actually, the TreadleVac unit is the hydraulic and vacuum cylinders combined. What I understand, then, from your post is that your mechanic feels that the (vacuum) power assist section is working fine, but the (hydraulic) master cylinder requires repair or replacement.

The original special tools are really not essential, but when needed, they can be fabricated rather easily if one reviews the procedure in the Packard Service Manual (archived here for your viewing pleasure). I've overhauled those master cylinders in my home garage with little trouble. The outlet fitting can be a bear to get loose; as such, it is best done first, while still attached to the vacuum cylinder - as shown in the factory shop manual.

Often, the hydraulic piston has become pitted and will quickly ruin new hydraulic seals, but a new piston could be fabricated by a decent machinist out of steel or even stainlesss steeal (the latter alleviating the need for hard chrom plating).

However, the condition of the compensator port valve spring is critical - yet not included in any kit. Corrosion from even small amounts of moisture absorbed into the hydrualic system over the course of many years will take its toll on this part, too, and failure of that spring will result in a complete loss of hydraulic action.

In the absence of off-the-shelf replacements for such parts, one need look to a reputable and competent rebuilder who specializes in servicing the unique technology of the Bendix TreadleVac and has reproduced the essential parts. They will want the entire unit and go through it completely. Most people seem to favor Ed Strain, though I've not personally done business with him. A quick search on Google showed the following address and phone:

Ed Strain
6555 44th St, Unit #2006
Pinellas Park, FL 33781
800-266-1623