Re: CAUTION ON THE USE OF SILICONE BKAKE FLUID IN ESAMATIC BRAKE SYSTEMS

Posted by Gauss On 2007/10/29 23:24:17

Read with great interest everybody's comments on the Treadle-Vac. I've been rebuilding these things for myself and a couple of friends for almost 30 years. I drove my rebuilds reliably in two cars for fifteen years to and from work in Fresno and Long Beach, California, and across the country to the east coast and back, twice, as well as other trips to Fort Worth, Portland, Las Vegas, the central California coast, etc.

Many years ago I was blessed with the good fortune of locating a Bendix power brake technical binder containing extensive parts listings and procedures. I found it at "Acres of Books" in Long Beach, and paid a goodly sum for it, since "Acres of Books" charges by the inch.

Having this resource at my fingertips allows me to confirm the contents of repair kits for Bendix Power-Vac, Master-Vac, Hydro-Vac, Treadle-Vac, and numerous other Bendix products of the 1940's and 1950's.

For the group's benefit, I list here the complete contents of the four repair kits that Bendix made available for 1955-56 Packard Treadle-Vac:

Minor Repair kit:

Guard - Push Rod (boot)
Gasket - End plate (the triangular cork gasket)
"C" Washer - Compensating Valve
Seal - Compensating Valve Fitting
Poppet and Stem - Compensating Valve
Seal - Hydraulic Outlet Fitting
Cup - Residual Check Valve
Gasket - Cover, Fluid reservoir
Cup - Hydraulic Plunger
Washer - Hydraulic Plunger (fiber)
Seal - Hydraulic Plunger (leather)
Seal - Master Cylinder End (rubber)
Gasket - Flange (the large roughly square one)
Gasket - Air cleaner screw (a small rubber washer)
Gasket - Plate and tube (for the vacuum inlet fitting)

Major Repair kit:

All of the above plus:
Seal - Push rod
Seal - Tube plate
Atmospheric Poppet
Vacuum Poppet
Clips (for Vacuum poppet) Quan. 2
Gasket - Diaphragm

Don't expect a new push rod guard (boot) with kits you buy today...that is an extra-cost item (around $15).

Note also the "C" washer that retains the compensator spring was included in the minor and major repair kits, but neither contained the spring itself. Today, expect to have to re-use *both* parts from your old unit, as neither part is provided in new kits.

Piston Packing and Diaphragm kit:

Tube - Vacuum (the short curved rubber hose)
Spring - Piston Packing Expanding
Wick - Piston Packing
Packing - Piston (Leather)
Seal - Tube Plate
Diaphragm
Gasket - Diaphragm

Poppet Replacement kit:

Diaphragm - Vacuum Poppet Compensator
Atmospheric Poppet
Spring - Atmospheric Poppet
Vacuum Poppet
Clips (for Vacuum poppet) Quan. 2
Snap Ring
Gasket - Diaphragm

Notice with the Bendix kits, you really didn't get everything unless you bought all four, and even then you still didn't get that lousy compensator spring.

On DOT5 fluid, have not used it myself, but I've heard generally negative comments about using it with Treadle-Vacs. Would like to hear any positive experience from someone who has used it successfully over an extended period.

The only things I've ever had fail on my Treadle-Vac were the leather piston seal and the compensator valve and stem, and in both cases they simply began to seep a little...nothing sudden, nothing catastrophic.

BTW, the book recommends the 1956 Packard unit (P-4) as the service replacement for for 1955 early (P-2) and 1955 late (P-3) Packard Treadle-Vacs.

The identification numbers can be found stamped into the vertical end of the Treadle-Vac master cylinder.

Wish I knew more about this Craig Henderickson fellow, and what the nature of his brake failure was.

Hope this helps someone.