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Fred Quote:

Maybe, I'm just "lucky". LOL! Anyway, I fixed the problem "my way".

Craig

2 cents; This one won't get answered conclusively, because the 10MM +- units you speak of have long been past their design life. Expecting them to perform as new for decades is quite speculative. There would have to be data from the manufacturers on how many problems where reported/year. They quickly changed the design, so I have suspected there's more to the story than crud in the system. The safety act brought dual brake systems in to decrease the probability of brake system failures. So there must have been some or we'd still have these units in our cars today.
1. I doubt that's "crystallized" PEG (DOT3) that your observing but more likely a condensation product from reaction with iron and it's oxides. It's well known chemistry at higher temperatures.
2. I haven't seen DOT5 (silicone based) being approved for use in these units, so I'd demand to see some data/approval before making changes to a safety system. Solving one problem but possibly creating another. Making casual remarks such as that could be a liability you don't want.
3. All I can say is mine ('58 Cad) is sitting on the shelf, I only had to lose brakes once, after wondering where my brake fluid had been going. Replaced with modern dual system.
4. You have to flush and replace DOT 3 systems regardless of the master cylinder in use. Easy to do at a brake job interval.
5. Storage is a separate topic.

I have been using Dot5 brake fluid since before 1992. When I replaced all my wheel cylinders and had PB unit rebuilt I flushed the system with alcohol and filled up with Dot5. I have had PB unit rebuilt since then (Ross Miller) because of one unusual occurrence - original rubber deteriorated and got down into vacuum chamber prohibiting vacuum piston from returning fully. Replaced with modern rubber.

to fish 'n jim

JUst who would "approve" DOT 5 for these units?? For sure Pres Trump won't appoint a Secretary of BTV's. NObody "approves" antifreezes for HUdsons or Firestone tires for Tuckers.

The rubber in the unit is produced tom be compatible with DOT 3 and anything that is compatible with 3 is compatible with 5.

The BTV casting is ALUMINUM, the lid which the fluid does not contact is steel and the piston is high grade steel probably with much chromium. The lid does not deteriorate, the piston sometimes does and the casting seems to stay intact. So what steel does the fluid react with.

We've had units inn cars for 20 years with silicone DOT 5 which were fine like Randy Berger.

We did a fairly rigorous limited study, you have "doubts" and speculation

to fish 'n jim

JUst who would "approve" DOT 5 for these units?? For sure Pres Trump won't appoint a Secretary of BTV's. NObody "approves" antifreezes for HUdsons or Firestone tires for Tuckers.

The rubber in the unit is produced tom be compatible with DOT 3 and anything that is compatible with 3 is compatible with 5.

The BTV casting is ALUMINUM, the lid which the fluid does not contact is steel and the piston is high grade steel probably with much chromium. The lid does not deteriorate, the piston sometimes does and the casting seems to stay intact. So what steel does the fluid react with.

We've had units inn cars for 20 years with silicone DOT 5 which were fine like Randy Berger.

We did a fairly rigorous limited study, you have "doubts" and speculation

Quote:

I'm dying to know the answer. As nobody else seems to know, please disclose the secret.

Thanks
Tom

Briefly:
There was no such thing as a power brake system PRIOR to the BTV. (now watch some chucklehead cite an obscure exception that only lasted maybe 2 years during the 1930's on some very low production car).

So somewtime about 1951 or 1952 there was sudden "demand" for power brakes.

BUT, the eng'ring departments had to come up with a way REAL FAST to shoe horn a power brake system onto cars that were simply left over designs from the 1940's. A 1940's design that was never designed to accomodate a power brake (keep in mind damned near every car built prior to 1955 had treadle type clutch and brake pedals, UNDER FLOOR mounted master cylinders, INLINE engines (not many LARGE V type engines etc etc).

SO the BTV with it's SMALL BUT LONG STROKE piston was an "11-th hour" attempt to overcome any WIDE SWEEPING major design changes. SUCH AS brake pedal redisign, major changes to allow frame clearences or relocateing other components of the car to accomodate ANY power brake unit that is at least 3 times the size of ANY standard brake unit.

The Compensator vlave was necessary to allow for the LONG STORKE SMALL BORE BTV master cylinder. And it is the COMPENSATOR VALVEE that renders the BTV a HIGH MAINTENANCE SHORT SERVICE LIFE master cylinder!!!!!

Note that the compensator valve is peculiar to ONLY the BTV master cylinder.

WHICH MEANS: That ANY master cylinder made by ANY mfg'er at ANY time or ANYWHERE in the world does NOT have a compensator valve.

Bottom line:
The BTV was a very early attempt to cobble up a power brake system at the last minute onto a "platform" automotive design left over from the late 1930's.

Thats why BTV only lasted about 10 years. Once the horse power revolution of 1955 gained steam thru the late 50's then the aautomotive platform or design of the cars became WIDER, and lower silhouette and designed for more modern automotive needs such a power steering, brakes, BIG WIDE V8's, dual exhausts, HIGHER ROAD SPEEDS etc etc.

Get the picture???

Let me put it another way:

In COMPARISON to ANY master cylinder (whether power or standard app) made by ANY company at ANY time (from about 1925 thru this very day of 2017, ANY WHERE in the WORLD) The BTV master cylinder is a short service life high maintenance master cylinder.

It is short service life and high maintenance because of the COMPENSATOR VALVE PECULIAR DESIGN!!!!!

Now that i have drawn picture of the problem, i hope i don't have to paint a Rembrandt about it.

PackardV8 said: There was no such thing as a power brake system PRIOR to the BTV. (now watch some chucklehead cite an obscure exception that only lasted maybe 2 years during the 1930's on some very low production car).

This is the only part of your discussion I'll comment on, and you may want to brush up a little on your prewar car history, call me a chucklehead if you must. Power brakes on heavy luxury cars predate the BTV by at least 20 years back to the very early 30s if not earlier. Power-boosted braking was standard equipment on Cadillac, Lincoln, Packard, Pierce-Arrow, Rolls, Duesenberg, Chrysler, Hispano, Delage, and many more heavy and high-end cars as well a MANY truck brands, even the commonplace Chevrolet trucks.

Two systems had most of the market share, the Bragg-Kliesrath system (purchased by Bendix about 1935, the same Bendix who later introduced the BTV) using a vacuum cylinder and the Stewart-Warner system, licensed from a European design, which used the rotation of the transmission output shaft as a source of mechanical leverage. The B-K system was used on both Bendix mechanical brake systems, and hydraulic systems. The Stewart-Warner system was more commonly found on European cars, the primary U.S. user was Pierce-Arrow and on their mechanical-brake cars.

ok. But again, those applications are all rather LOW production vehicles or "boutique" type vehicles.

Did any of them have a compensator valve????