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Many of the 1930's power brake systems were MECHANICAL brakes, NOT hydraulic. No?? So there is no comparison to hydraulic type systems whether power or standard.

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


When you are in a hole, quit digging.

The Olds V8 started in 1949 with a very similar minor redesign in '57 running to '64 with the 57 being a wider body. Treadle vac continued to be used in 57/58 in wider body. Surely the wider body was no surprise to Olds engineers but it took 2 years for the BTV to be replaced.

Cadillac OHV V8 debuted in 49 in narrow body, Wider body started in 57, BTV continued to 58.

Lincoln had BTV in 54 in narrow body, super duper wide body started in 58, BTV continued to 1960

I believe all but 56 Caddy had firewall mounted BTV, plenty of room.

Anybody ever speak to any former Bendix engineers to confirm the theory?? I'm sure some are still around.

Theories are just that, theories. Is there any actual research showing that compensator valves leak, if not perhaps sasquatch is causing BTV failure.

We sell many many more manual brake master cylinders and kits that BTV, what does that prove???

Unfortunately, the Pres of Bendix during those years has passed away. I met hem and spoke to him about his years of ownership of our 1930 Packard Speedster

Packard V8 WROTE

"
"The Compensator valve was necessary to allow for the LONG STROKE SMALL BORE BTV master cylinder."

Really??. The GM designed/manufactured Delco-Moraine unit debuted in about 1956 and was used in all GM divisions alternately with the BTV. It was almost the identical length/width/height as the BTV AND IT WAS ALSO A LONG STROKE SMALL BORE UNIT. It was not designed "in a rush", it came out 4 years after the BTV. It had a LONG STROKE SMALL DIAMETER but it did not have a compensator valve. THE COMPENSATOR VALVE WAS THEREFORE NOT A NECESSARY
DESIGN ELEMENT.

The look-alike Delco unit was discontinued after about 2 years in 1958. DOES THIS PROVE THAT IT WAS A POOR DESIGN????? Or just time moving on. Three speed transmissions, vent windows........poor designs....

I'm going on vacation to Loch Ness.

Hey, Fred. What does the "DOT" in DOT 5 stand for?
Luv, Fish'n Jim.

in case you want to know;
https://en.wikipedia.org/wiki/Brake_fluid

I appreciate the effort here. It was interesting.
Actually, I like the idea of non-hygroscopic DOT 5 for these but have some concerns as noted. But to me it's a dying issue, never intended, and not conforming to today's standards.
But I don't think a forum such as this is the place to decide or publicly advocate brake fluid use based on a couple photos of problem units. If someone puts it in there's of unknown condition and has problems, they'll say "Fred told us", and A. Shyster, their lawyer, will be paying you, not me, a visit. That's what I see. I don't take that type liability.
I'm glad someone had the jump on this and has 20+ years of practice. But you need to do some periodic tear down assessments of the components, prove compatibility BEFORE use. That little piece of deteriorated rubber can be life or death in an emergency.
I've stated my observations and conclusions and stand by my professional assessment.
When I see technical errors or inaccuracies I call them as I see them. If you don't like it, well don't like it, but don't attack the source especially if you not aware.

In England it would be the M.O.T.

(o[]o)

I have a 55 Cadillac and a 57 Lincoln.....in addition to my 55 Caribbean.
The Cadillac has a master cylinder mounted under the floor- similar to Packard pedal arrangement- but a Hydro- Vac unit that mounts to the radiator support on the passenger side of the radiator.
The Lincoln has a conventional firewall mounted master cylinder and a Tredle- Vac unit that mounts to the firewall adjacent to the master cylinder with a vacuum tank under the driver side fender similar to the Packard .
The conversion of the Lincoln to a dual master cylinder with integrated power brake unit has been done by many users. It is a straight forward switch to a later model power brake unit from a drum brake full size FOMOCO unit.
I have had no problem with the Lincoln except brake overheating with long grades....and one failed wheel cylinder.
THe Cadillac functioned well for for over 20 years but I did a complete brake replacement around 3 years ago when the power brakes ceased working. The Hydro- Vac unit was professionally rebuilt by a highly recommended shop in California. And the lines, wheel cylinders, brake shoes and master cylinder were replaced at the same time.
The system worked well, but two years ago I had driven the car around 7 miles and parked. When I returned to the car the pedal went to the floor and to have the car hauled to the repair shop. There were no broken lines or failed cylinders, but the master cylinder was empty. After the fluid was replaced and the system bled, the brakes were fine....for around 5 miles.
The Hydro vac has a ball check valve that is no longer produced and despite cleaning and bench testing it did not function and sucked the brake fluid into the engine until the system failed.
The rebuilder was able to secure a new Hydro vac unit from the manufacturer to replace the original. It was slightly larger but fit the original location and solved the problem.
My original two BTV units were rebuild by Tucson Packard and never worked.....hard pedal and no stop. I had another unit rebuilt by Max Merritt ( I think they use an outside contractor) and it has worked well for the limited driving I have been able to do since the car was completed.
I think the Kanter's evaluation is probably correct. The units need to be rebuilt by someone who know how to do the work and the rod should be replace with stainless.....and the system checked regularly after storage.
These are all primitive systems and the cores are over 60 years old.
Anyone expecting handling , braking or reliability of a new car is probably delusional......but it would be nice to have the things give a warning before leaving you without brakes.

"The Lincoln has a conventional firewall mounted master cylinder and a Tredle- Vac unit that mounts to the firewall adjacent to the master cylinder with a vacuum tank under the driver side fender similar to the Packard".

We've owned a TreadleVac equipped 55 Lincoln, the BTV is an integral master cylinder/vacuum booster unit. It is all 1 piece when installed. You describe a separate master cylinder and an adjacent master cylinder. The input to a BTV is mechanical pedal pressure, the output is high pressure brake fluid. You step on the pedal and high pressure fluid applies the brakes.

So what function would an adjacent non-power master cylinder perform. There would have to be 2 pedals and the output from the 2 units joined.

I think your description is inaccurate.

Fred - you are right. Just a bad description of the Lincoln unit. The master cylinder and BTV are one unit mounted on the firewall....with a separate vacuum tank under the fender. The reason for the comment is that because the unit is firewall mounted, it is possible to install a newer dual master cylinder unit and power brake unit without having to move the air vent and play with a new pedal configuration to install a later model unit.
As I understand it, the 1-1 pedal ratio on the 55 Packard coupled with the limited space where the factory BTV is located has required the various configurations shown in various posts.
I would really like to have a dual master cylinder for the limited protection afforded by that arrangement . I would also like to have power brakes to deal with the weight of the Caribbean.
I guess my question really is whether installing a dual master cylinder under the floorboards for that purpose could be boosted with a new hydrovac system like we use on the Cadillac which could be remotely mounted.
I made inquiry about the Electro- Vac units that were suggested in some posts, but never got a satisfactory answer as to whether anyone had been happy with the conversion. I believe Howard raised questions as to whether such a system would provide needed braking if the engine stalled due to the pedal ratio issue.
It would seem that the Cadillac system functions well enough and it is all new parts....and might keep the pedal in its original position.
Any commments or hints will be welcomed..
Sorry for any confusion.
RJR

Understood, my recall of our '55 Lincoln goes back to 1958 when it was out father's everyday car. There is a scary BTV story with it also but not the usual kind. The mechanic at our gas station topped it up with motor oil!!??!! and while going down a long incline with my father driving the brakes and almost my heart failed.

MY terminology: The BTV and all modern PB systems are DIRECT sysyems, pedal effort is directly applied to then master cyl portion. Cadillac, Studebaker etc Hydrovac/MasterVac etc are RELAY systems, pedal effort is converted into unboosted hydraulic pressure which is relayed to a vacuum powered booster unit.

In order have a RELAY style dual system in a Packard you would need a dual mater cylinder most likely under the floor where the 35-56 manual master cylinders are located. Simplest way is to use the pedal/linkage from a 51-56 manual brake Packard but those don't grow on trees anymore. A modern "hot rod" underfloor unit may be the answer.
Any manual master cyl needs a "lever " linkage to increase pedal effort. ( More thinking needed ??) Then you have 2 high pressure outlets , one for front, one for rear. Then you need TWO RELAY type booster units like the Hydrovac. Gettin' a bit crowded under the hood, might have to scrap that supercharger idea.

At Kanter Auto Products we're never asleep, stay tuned.