1935 Lincoln power brakes

[Matt Harwood]

One of the other things I need to solve on this Lincoln is the power brake system. As I chip away at things that keep it from running properly, a massive vacuum leak revealed itself and kept the car from running--THAT was a challenging problem to solve. It turns out that the power brake system is a major leak. The problem is, I don't really know how it works. Well, I understand the principle, but the hardware is a little confusing and sadly, there is no shop manual available for the K so I'm left to guess at just about everything.

 

There are three components to the system. Component #1 is a control head mounted on the steering column, ostensibly to control the amount of power brake force that is applied. I presume there's some kind of variable orifice inside. There's a 1/2-inch metal vacuum line from the intake manifold to this disc-shaped controller, then a second line running down under the car to Component #2. 

 

This is the adjustable control head on the steering column. The rod going 
up the column goes to a control lever on the dash. The line coming out
goes to Component #2, below. The line in from the intake manifold is
not visible, but it's on the other side of the disc.

 

Component #2 is another disc-shaped thing that seems to be firmly bolted in-line with the make brake rod from the brake pedal assembly back to the brake levers that actually pull the brakes. I initially thought the brake rod would have moved THROUGH this part, but that does not appear to be the case. The rod is attached to the pedal assembly with a fork and pin, then directly screwed into this disc. A second rod is screwed into the other side of the disc and goes back to another fork which is connected to the brake levers. I honestly don't know what this thing does. The vacuum line from the control head goes in, then a second line goes out and to the actual booster mounted farther back. This is obviously an actuator of some kind, but since it moves in-line with the rod itself, I don't see how it can open and close a valve or anything like that. How does this thing work? It doesn't even seem to have any moving parts. It does say "Bragg Kliesrath Corp. LI City NY" on it, and doing some searching, I see patents for a vacuum power brake system, but they don't say much about how the thing works, although I gather it might be some kind of check valve or a way to hold vacuum when the engine is shut off.

 

No idea what this is or how it works. As you can see, the brake rod is
screwed directly to it, not simply passing through. Pressing the brake
moves this thing along with the brake rod. The upper line (disconnected)
goes to the control head on the steering column, while the lower head goes
to the booster cylinder. The new hose is directly from the intake manifold
but it didn't change anything.

 

Component #3 is obviously the brake booster itself, which is just a can with a single arm coming out that attaches to the brake lever. It pulls in the same direction as the lever that connects to the brake pedal and provides the power assist.

 

 

Power brake booster. One line in on the other end and it pulls in line
with the brake rod to provide boost.

 

When we found the vacuum leak, I initially suspected the control head was the problem because by fiddling with the knob on the dash, I could make the car run for a few seconds. My first move was to bypass the control head and run vacuum directly to the cylinder thing underneath (Component #2). However, there was still a massive vacuum leak and it still wouldn't run, leading me to deduce that it was either this mystery device or, more likely, the booster itself. I'm going to try to find someone to rebuild all this stuff, but I'd like to at least understand what these parts do and how they work--maybe I can do it myself. I don't want to just send out the booster canister in case it's one of these other things that's broken, but without knowing how they work or what they do, I don't have much of a chance of fixing it.

Anyone worked on something like this with some ideas? Does anyone know someone who rebuilds these systems? Right now I just have a cap on the fitting at the intake manifold and the car stops just fine, but I'd like to get this system working if I can. 

 

Thanks for the help!

 

 

[Grimy]

Although I'm not familiar with the Lincoln power brake, I have some experience with the 1936-38 Pierce vacuum power brake system.  The first thing is to inspect and/or replace any and all rubber hose.  I diagnosed a friend's 1936 Pierce with a lean condition at 36-38 mph and found that the rubber hose portion of the line from intake manifold to vacuum cylinder was equipped with heater hose, which collapses under significant vacuum.  VACUUM HOSE (half-inch) cost about $4/linear foot ten years ago but was essential to the cure of both the lean condition AND the power brake issue.

[edinmass]

Matt, I don't have my brake systems book down south, you can buy them on eBay and they cover ten to fifteen years for all cars. Worth the investment for what you do. It looks like the unit on the steering box is a boost control, the second unit probably applies the vacuum to the big canister just after you start pushing on the brake pedal. Some type of valve to turn the vacuum on and off as the canister will leak in small amounts so that's there to prevent leaks. Pierce used something different from 36 to 38, as did Stutz in 32 - 33. Cadillac 16's also used a similar set up. Take a propane soldering torch and open it up full blast without lighting it, passing the propane around the fittings, hoses, connections, and components. The fuel will get sucked into the engine and you will notice a faster speed and the engine should not stall with the extra fuel being added. Works like a charm, and there is no fire or flash over danger. Works good for manifold leak checking also. I think if you plug the lines infant of the rear big booster and step on the brakes and there is no change, I would start there. Most of them have leather rawhide seals, that you get to make.......been there done that. Sometimes just putting in some neatsfoot oil in the unit and soaking it for a few days softens the seal and stoops the leak. The canister and parts are pot metal inside.....with all the joy that goes with it. So BE CAREFUL if you have to take the system apart.....they almost always break to pieces. 

[Spinneyhill]

Here is what MoToR 1947 has to say about it. I hope this is a helpful overview.

 

The Bendix external valve type was fitted to 1935 Buick, 1935-40 Big Lincoln and PA 1935-38.

[Spinneyhill]

And here is what the National Service Data says, although it only refers to 1937-40.

 

[Matt Harwood]

Excellent, that is extremely helpful! That diagram of the 1932 Hupmobile system is almost identical to what I'm running, so it at least points me in the right direction for diagnostics.

 

Thank you!

[joe_padavano]

So per the writeup in Post #4, Matt's first photo is the Regulator Valve and his second photo is the Automatic Control Valve.  The Regulator Valve allows the operator to select the amount of "power" in the power brakes (25%, 50%, 75%, or 100%).  The Automatic Control Valve is what routes vacuum to the booster when the pedal is depressed. I'm willing to bet that the nut you see on the Automatic Control Valve isn't fastening the brake rod, it's likely a packing nut holding a packing seal in place around the rod.

[John_Mereness]

Do not know if any help or not, but I have bought reproduction vacuum brake parts from Brian Joseph www.classicandexotic.com  - beautiful quality.