Cruise Control Basics (lesson request)

[BigBrother-84]

Hi Gentlemen!

Well, I digged throughout the forum, and found multiple topics about CC. But seems that all of them are assuming that we already know everything that has to be about the subject...

This is not my case. So, pardon me if this question was already answered in the forum and if so, please just point me to the right thread.

BUT, if not, would be very kind to take me by the hand and explain me the basics of an OEM CC.

Let's say that maybe, there is a vague possibility that I would probably contemplate to eventually install an OEM CC in Big Bro:

- How would you describe the general functioning of the CC system?

- What are the required components I will have to seek for?

- Is this a difficult operation, or something a lazy mechanic can do himself?

My goal:

- Add the comfort of a CC to Big Bro's drive.

- Has to look as if was dealer installed in 1984.

Thanks for your advice!

[85lebaront2]

Cruise control was developed in the 60s if my memory serves me correctly. The idea was very simple on the early ones, they had a speedometer cable driven flyweight system like many early steam and hit and miss stationary engines used. There was a cable or mechanical link connected to the carburetor.

When the system was activated, an electromagnet connected the throttle to the reaction area of the flyweight assembly. It was set up so if the vehicle slowed down, the weights would move in and the attached linkage would open the throttle, speed up too much and it would close it.

Essentially a giant sized small engine centrifugal governor, difference being rather than tightening a spring, you just "clamped" the throttle to the governor at the desired speed. The first ones were built by Perfect Circle and the brand name was a Speedostat.

The next improvement was to use a vacuum servo to work the throttle, but still using the mechanical governor, which now controlled a vacuum and vent valve. Chrysler used these units until 1987 when they changed to an engine computer controlled system. Ford and GM used an electro-mechanical system with a processor that took a speed signal (pulse) and once engaged would try to hold it as close as possible. The processor controlled a pair of solenoid vacuum and vent valves. These were fairly good at maintaining speed, except on a long upgrade the vacuum would fall off and it would lose speed.

Ford came back to the original motor operated control in the mid 90s, a metal unit with a motor, electric clutch and micro processor reading the speed signal pulses. These are great, and were designed to bolt in place of the vacuum servo units.

Now, with "drive by wire", there is no mechanical connection to the throttle plate or plates, so the engine computer now just maintains the speed it was set at.

[BigBrother-84]

Cruise control was developed in the 60s if my memory serves me correctly. The idea was very simple on the early ones, they had a speedometer cable driven flyweight system like many early steam and hit and miss stationary engines used. There was a cable or mechanical link connected to the carburetor.

When the system was activated, an electromagnet connected the throttle to the reaction area of the flyweight assembly. It was set up so if the vehicle slowed down, the weights would move in and the attached linkage would open the throttle, speed up too much and it would close it.

Essentially a giant sized small engine centrifugal governor, difference being rather than tightening a spring, you just "clamped" the throttle to the governor at the desired speed. The first ones were built by Perfect Circle and the brand name was a Speedostat.

The next improvement was to use a vacuum servo to work the throttle, but still using the mechanical governor, which now controlled a vacuum and vent valve. Chrysler used these units until 1987 when they changed to an engine computer controlled system. Ford and GM used an electro-mechanical system with a processor that took a speed signal (pulse) and once engaged would try to hold it as close as possible. The processor controlled a pair of solenoid vacuum and vent valves. These were fairly good at maintaining speed, except on a long upgrade the vacuum would fall off and it would lose speed.

Ford came back to the original motor operated control in the mid 90s, a metal unit with a motor, electric clutch and micro processor reading the speed signal pulses. These are great, and were designed to bolt in place of the vacuum servo units.

Now, with "drive by wire", there is no mechanical connection to the throttle plate or plates, so the engine computer now just maintains the speed it was set at.

Thanks Bill.

About the "dealer installed" kit, is it possible that it wasn't on the steering wheel?

If so, this is not the project I am figuring out. I am willing to find an old OEM installation and take it out from a donner truck.

As for example, my local yard has a 1988 Econoline speed control equipped. Maybe I could take on it most of the needed parts?

[85lebaront2]

Thanks Bill.

About the "dealer installed" kit, is it possible that it wasn't on the steering wheel?

If so, this is not the project I am figuring out. I am willing to find an old OEM installation and take it out from a donner truck.

As for example, my local yard has a 1988 Econoline speed control equipped. Maybe I could take on it most of the needed parts?

Since the Ford cruise control uses the horn wiring for it's power and ground, it uses a short jumper harness that also adds a horn relay to the circuit. The horn pad is equipt with the switches which at worst case might involve a different steering wheel.

Aftermarket systems were quite popular in the 70s and 80s, after that many vehicles had it as a basic upgrade with what was generally called a "convenience package". The aftermarket will usually have a piggyback switch on the turn signal lever.

Adding a Ford factory system (which could have been a dealer installed kit) would involve a hole in the firewall (possibly there, but at least located on the firewall stamping), addition of one or two vacuum valves and a clutch switch if needed and not installed.

FWIW, the system on my Chrysler convertible is a dealer installed kit that was available in 1987. I found one NOS at a dealer in South Carolina as Chrysler provided the circuitry and program in the 1987 up ECMs. Here is what it looked like as received:

There were also 3 small parts bags for mounting hardware and vacuum fittings. If you look at the pictures of it laid out on the table, you will see several throttle cables, vacuum hose, etc. The 4 wire connection is in the 1987 up harnesses, just tied back with a dust cap over it.

[Gary Lewis]

Since the Ford cruise control uses the horn wiring for it's power and ground, it uses a short jumper harness that also adds a horn relay to the circuit. The horn pad is equipt with the switches which at worst case might involve a different steering wheel.

Aftermarket systems were quite popular in the 70s and 80s, after that many vehicles had it as a basic upgrade with what was generally called a "convenience package". The aftermarket will usually have a piggyback switch on the turn signal lever.

Adding a Ford factory system (which could have been a dealer installed kit) would involve a hole in the firewall (possibly there, but at least located on the firewall stamping), addition of one or two vacuum valves and a clutch switch if needed and not installed.

FWIW, the system on my Chrysler convertible is a dealer installed kit that was available in 1987. I found one NOS at a dealer in South Carolina as Chrysler provided the circuitry and program in the 1987 up ECMs. Here is what it looked like as received:

There were also 3 small parts bags for mounting hardware and vacuum fittings. If you look at the pictures of it laid out on the table, you will see several throttle cables, vacuum hose, etc. The 4 wire connection is in the 1987 up harnesses, just tied back with a dust cap over it.

Bill - I have a minor disagreement with what you said. I think the electronic speed/cruise control came out at least by 1990. That's because the one in Big Blue came out of Huck, the 1990 half-truck I bought to get the E4OD for Dad's truck.

Jeff - Do yourself a favor and get the later cruise control like I have. It is WAY better than the vacuum-driven unit from a Bullnose. Let me count the ways:

• Smoothness: The Bullnose unit is way too aggressive. It gives too much throttle to speed up and chops the throttle too much on a hill - only to have to open it again too much. But the later unit is far, FAR smoother. I just ran almost 2000 miles with it and it was wonderful.

• Resume: With the Bullnose unit when you hit Resume it basically floors the throttle until it gets up to speed. With the later unit it says "Hmmm, let me think about that. Ok, lets go there, but gracefully."

• Change Speeds: With the Bullnose unit if you want to speed up or slow down you hold the Set/Accel or Coast button until the speed you want is obtained and then let up - and hope you caught it where you wanted it. But bear in mind that in speeding up it basically floored the throttle, and in slowing down it basically cut the throttle. So you are changing speeds abruptly, making it hard to catch the right speed and obvious to your passengers that you are doing something.

  But with the later unit if you push Set/Accel or Coast once you go up/down by 1.00000 MPH, and you do it gracefully. Go from a 70 MPH speed limit to a 65 MPH limit and you push the Coast button 5 times and you are there. Can't tell you how many times I did that in our 525 mile drive today, almost all of which was on cruise.

The later unit uses the same spot under the hood and the same horn pad switches as the Bullnose one. And it is easy to make a couple of wiring changes to accommodate it instead of the Bullnose unit. I LOVE IT!

[BigBrother-84]

Bill - I have a minor disagreement with what you said. I think the electronic speed/cruise control came out at least by 1990. That's because the one in Big Blue came out of Huck, the 1990 half-truck I bought to get the E4OD for Dad's truck.

Jeff - Do yourself a favor and get the later cruise control like I have. It is WAY better than the vacuum-driven unit from a Bullnose. Let me count the ways:

• Smoothness: The Bullnose unit is way too aggressive. It gives too much throttle to speed up and chops the throttle too much on a hill - only to have to open it again too much. But the later unit is far, FAR smoother. I just ran almost 2000 miles with it and it was wonderful.

• Resume: With the Bullnose unit when you hit Resume it basically floors the throttle until it gets up to speed. With the later unit it says "Hmmm, let me think about that. Ok, lets go there, but gracefully."

• Change Speeds: With the Bullnose unit if you want to speed up or slow down you hold the Set/Accel or Coast button until the speed you want is obtained and then let up - and hope you caught it where you wanted it. But bear in mind that in speeding up it basically floored the throttle, and in slowing down it basically cut the throttle. So you are changing speeds abruptly, making it hard to catch the right speed and obvious to your passengers that you are doing something.

  But with the later unit if you push Set/Accel or Coast once you go up/down by 1.00000 MPH, and you do it gracefully. Go from a 70 MPH speed limit to a 65 MPH limit and you push the Coast button 5 times and you are there. Can't tell you how many times I did that in our 525 mile drive today, almost all of which was on cruise.

The later unit uses the same spot under the hood and the same horn pad switches as the Bullnose one. And it is easy to make a couple of wiring changes to accommodate it instead of the Bullnose unit. I LOVE IT!

Gary, I am willing to go to Big Blue's Transformation thread, and follow your CC journey to the "later unit" (I suppose you are meaning "electronic"?).

Where to start, somewhere here?

Oh, and don't forget that Big Brother's 351W is carbed.

Thanks!

[Gary Lewis]

Gary, I am willing to go to Big Blue's Transformation thread, and follow your CC journey to the "later unit" (I suppose you are meaning "electronic"?).

Where to start, somewhere here?

Oh, and don't forget that Big Brother's 351W is carbed.

Thanks!

That's too early, Jeff. Try here. And the wiring doesn't matter carb vs EFI as it doesn't change. The only issue is the lack of a horn relay and the extra ground wire on the later module. And yes, "later" means electronic.

[BigBrother-84]

That's too early, Jeff. Try here. And the wiring doesn't matter carb vs EFI as it doesn't change. The only issue is the lack of a horn relay and the extra ground wire on the later module. And yes, "later" means electronic.

[85lebaront2]

That's too early, Jeff. Try here. And the wiring doesn't matter carb vs EFI as it doesn't change. The only issue is the lack of a horn relay and the extra ground wire on the later module. And yes, "later" means electronic.

Gary, there is still a horn relay on the later trucks, it is just in the PDC underhood. You are correct in the fact that the resistors and switches in the horn pad are the same, the changes were all cosmetic on them.

One item we discovered is the difference between a car and truck cruise control module when you tried my Taurus spare in Big Blue.

[Gary Lewis]

Gary, there is still a horn relay on the later trucks, it is just in the PDC underhood. You are correct in the fact that the resistors and switches in the horn pad are the same, the changes were all cosmetic on them.

One item we discovered is the difference between a car and truck cruise control module when you tried my Taurus spare in Big Blue.

Yes, Bill, you are right. There still is a horn relay on the later unit and it is a Bosch-style in the PDB. But a Bosch-style won't work on the earlier vacuum unit from a Bullnose truck. Apparently the coil resistance is too small.

And yes, the car "amplifier" for the vacuum unit won't work in a truck.

I used the goodie out of the electronic cruise control on Big Blue yesterday. In 8 hours of driving there were lots of speed limit changes and I just raised and lowered the set point one MPH at a time by pushing buttons. Or coming up behind someone going slightly slower (I was rarely the one being overtaken) and a button push or two let me tail them until a convenient time to pass. The vacuum units do not do that nicely.