06/28/2024
1967 Lincoln Continental Cruise Control
I'm working on a repair project for a 1967 Lincoln Continental with su***de doors.
An awesome car and highly sought after. They were made famous in the movie, The Matrix.
I self developed the ability to repair a number of complex systems, especially of vintage automobiles.
The owner sent me the cruise control to repair.
These projects are challenging, intriguing, and thought provoking. Because I don't have that car, I cannot test the system “fully”. So I have to come up with enough understanding and testing to feel confident, that after working the unit thoroughly on the bench, it will or should work properly when installed in the car.
Then after much work, fixing, and testing, I get to a point where I struggle with how much testing is enough? And the economic law of diminishing returns comes to mind.
I recently successfully repaired two systems similar to this but the application was a sought after International Scout 4x4 of the same general era.
The original inventor of cruise control was a blind engineer, Ralph Teeter, who didn't like the unsteady driving of his limo driver. So he invented automated cruise control back in the 1950's. His company, Perfect Circle, went on to be the sole supplier of cruise control systems to all car manufacturers worldwide for decades.
The owner of the 67 Lincoln sent me a cruise control system to fix. Upon my first examination, it was badly corroded and broken inside, beyond repair. So I suggested we find another. He found the original from that car and had the guy in possession ship it to me. It was in better shape but wasn't working.
When I repair systems like this I don't look for “the problem”, the one broken function. I learned that complex systems have complex problems, often a number of them. They all contribute to the unwanted symptoms or outright failure. People are like this as well, by the way and people tend to look for the one thing. It's a mistake to think this way, IMHO.
What I do instead is work on fundamentals and examine every working concept that I can get my head and hands around. It's very time consuming which tests my focus, attention span, intelligence, skills, knowledge, and ability to stay at the bench for the time required. It's particularly difficult for me now as I have a recent injury and the pain prevents spending long time periods sitting at a bench working.
My mind is somewhat unique, as I think each person is unique. I have a great gift and ability to figure things out but I often cannot remember details of what it was I figured out! That is usually the case if I don't do it frequently enough and if time passes in between. So I find myself exploring and figuring a lot that I already did, again. It kind of hones those skills I guess. I surely need to take better lab notes!
I do have a love for the engineering that went into these vintage systems. In fact that's the pull for me, I am fascinated by it. How the heck can these things work? The engineers didn't have the modern capabilities such as micro chips and modern sensors, computers, etc. They had to work with what they had. They are wondrous machines! Something out of W***y Wonka's factory of imagination!
I'll try to give a brief overview of the workings for those who haven't already run away from TMW (Too Many Words).
The basic speed “governor” is a spinning set of weights. It's the moving and mechanical part of this strange and complex gadget. This concept was used for over 100 years. It was likely invented as the spinning balls to control steam engines. That's where the expression, “balls to the wall” comes from. They are called a “flyball governor”. The more the balls more towards the wall, the faster it goes! They also used spinning weights to adjust the timing automatically in Internal Combustion Engines that were Normally Aspirated, before fuel injection. It was called “mechanical advance”, which was a misnomer actually they were automatic timing re**rd to prevents pinging, but that's another story. These governors leveraged the fact that as the speed increases the force to move the balls or weights outwards increases. This moves them out and a lever moves a control item on a shaft. The counter for speed setting can come in many forms, but often a spring that is pre tensioned by a control in the cockpit by the driver to set “speed”.
They way that the engineering handles setting a speed is ingenuous. They have a solenoid that pulls down arms which hold the variable vacuum arm at the speed set point as determined by the spinning weights. As the weights go in and out, minute adjustments to the vent correspond to minute adjustments in vacuum. The variable vacuum is delivered to a vacuum servo or motor or basically a bag that shrinks and fills. At one end of the bag is a chain or arm that connects to the carburetor throttle control. This adjusts the car's speed.
What I have to do in the repair is go through each function, one at a time, ensure it is working properly on the bench as best I possibly can.
There are two solenoids in most of these. In one fancy type they add a third. I have to check each one for proper operations under electrical power. Then I have to check the corresponding outcome. In many cases it has some control over vacuum.
Typically these fail due to breakdown in the vacuum gasket materials. I have to fix and test the integrity of all the vacuum paths.
They also have a weakness in one of the solenoids. They manufactured them in the late sixties with a foam “spring”. That foam breaks down over time and with temperature. I have to custom build a metal spring substitute.
Often goes bad are any switches. In these units they use a low speed electrical switch. They prevent the unit from operations until the car reaches a minimum speed, often 30 mph. The copper contacts often corrode over time and with humidity. If the corrosion limits the current capacity, they unit will not function.
I have to check the spinning weights governor. Often the input gear “breaks loose” or something like that. I have to repair any such issue I find.
And when I fix and test everything that I can. I can simulate operations to a point. I can apply source vacuum, spin the input to emulate car speed, and observe vacuum output modulation, once the minimal speed requirement is met.
