Re: CAUTION ON THE USE OF SILICONE BKAKE FLUID IN ESAMATIC BRAKE SYSTEMS
Posted by BH On 2007/10/26 13:57:06
Peter -
Many vehicles of that era used the TreadleVac system, including highly-popular cars like the 55-56-57 Chevy - not just Packard. If there was a genuine design problem with it, something would have been published long ago. While I doubt that anyone involved in design and production of those automobiles and their component parts (back then) ever envisioned people driving them so many decades later, those old cars were (thankfully) built to be renewable. Yet, some people may not fully understand what they're working on, and people tend to fear (or even oppose) what they don't understand.
In that regard, know that Bendix offered TWO levels of overhaul kits - minor and major = throughthe after market (as well as the aftermarket).
The minor kit contained only those parts that were required to rebuild the hydraulic section; everything you need to upgrade the T-V master cylinder to DOT5 is in that kit. That kit was reproduced decades ago and remains widely available today, and I prefer fresh rubber parts to 50+ year old NOS ones (provided they are of sufficient quality). Attached is a pic I snagged from Kanter's site (www.kanter.com/p08-bk.html), showing the contents of that (minor) overhaul kit. Notice that it includes a new compensator port valve, but NOT the fine-wire spring.
The major overhaul kit included the additional parts that were needed to overhaul both the hydraulic and vacuum sections, but I'm not sure if it included the compensator valve spring. I do have an NOS major kit somewhere (not for sale) in offsite storgae; if I can ever get time and can lay my hands on it, I will take a pic, inventory the contents, and report back here.
Now, anyone smart enough to take one of these units apart and put it back together would notice something like a pitted hydraulic plunger/piston, but it was not included in either of the kits - had to be purchased separately.
Yet, my point is that the compensator port valve spring is one of those things that is often overlooked - especially by those who do not understand its purpose and function. The 1955-56 Packard Service Manual explains the TreadleVac operation better than the "restorograph" sheet included with some overhaul kits. With a little patience, operation of that valve can be checked with the unit still in the car. The reservoir cover can usually be removed without ruining the gasket, though you might have to remove some fluid from the reservoir to see it. Also, during a rebuild, one should inspect this spring for corrosion as the spring will break in that point.
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Many vehicles of that era used the TreadleVac system, including highly-popular cars like the 55-56-57 Chevy - not just Packard. If there was a genuine design problem with it, something would have been published long ago. While I doubt that anyone involved in design and production of those automobiles and their component parts (back then) ever envisioned people driving them so many decades later, those old cars were (thankfully) built to be renewable. Yet, some people may not fully understand what they're working on, and people tend to fear (or even oppose) what they don't understand.
In that regard, know that Bendix offered TWO levels of overhaul kits - minor and major = throughthe after market (as well as the aftermarket).
The minor kit contained only those parts that were required to rebuild the hydraulic section; everything you need to upgrade the T-V master cylinder to DOT5 is in that kit. That kit was reproduced decades ago and remains widely available today, and I prefer fresh rubber parts to 50+ year old NOS ones (provided they are of sufficient quality). Attached is a pic I snagged from Kanter's site (www.kanter.com/p08-bk.html), showing the contents of that (minor) overhaul kit. Notice that it includes a new compensator port valve, but NOT the fine-wire spring.
The major overhaul kit included the additional parts that were needed to overhaul both the hydraulic and vacuum sections, but I'm not sure if it included the compensator valve spring. I do have an NOS major kit somewhere (not for sale) in offsite storgae; if I can ever get time and can lay my hands on it, I will take a pic, inventory the contents, and report back here.
Now, anyone smart enough to take one of these units apart and put it back together would notice something like a pitted hydraulic plunger/piston, but it was not included in either of the kits - had to be purchased separately.
Yet, my point is that the compensator port valve spring is one of those things that is often overlooked - especially by those who do not understand its purpose and function. The 1955-56 Packard Service Manual explains the TreadleVac operation better than the "restorograph" sheet included with some overhaul kits. With a little patience, operation of that valve can be checked with the unit still in the car. The reservoir cover can usually be removed without ruining the gasket, though you might have to remove some fluid from the reservoir to see it. Also, during a rebuild, one should inspect this spring for corrosion as the spring will break in that point.
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