Leadfoot

My '69 S has a currently inoperable cruise control. Hopefully I can figure out how to successfully attach pictures, since that will make it obvious why it's not working.

I'm certain that it's not factory. There is no dash switch, the control is turn signal mounted, and I can't find any markings at all on the servo, which is mounted to the inner fenderwell in what seems to be the usual location. Maybe it was a dealer installed option, or it may have been a prior owner DIY setup. In any case, if it's not factory original and since it's not working anymore, I'd prefer to remove it entirely. I love cruise control, but on this car I won't miss it.

Is removing it as simple as it appears to be? I don't want to leave something behind that will cause other problems.

Leadfoot

The system seems to be self-contained and vacuum operated. There is no speedometer cable connection, and no extra vacuum diaphragm. The cable coming out of the servo is a simple push-pull cable which attaches to the throttle linkage.

Sorry for the fuzzy pics.

In the third photo, you can hopefully see the sensor coil which is installed on the #1 plug wire. I haven't traced the wire back, and until I looked more closely at it and found the printed tag on the wire, I thought it was for the HEI or a tach feed.

Greg Rogers

Dana Speedo-stat. We used to install them at Montgomery Wards back in the 80's. You still see new ones that were stashed back in the day in Dad's garage or basement (probably after getting as a present but never got installed) on ebay today. They are a good unit and I am planning to put one on my Vista. Looks like your servo is broken where the throttle pull cable comes out.

Leadfoot

One more of the sensor coil and the wire tag. Any ideas on what the purpose of this coil is?
The tag reads:
"Spark Plug Current Sensor -- Important: On gasoline engines, this device must be installed to prevent engine damage -- See Cruise Control Owner's Manual for instruction."

I'm hoping somebody will recognize this setup, and can tell me if there's something I need to look for to ensure that I remove the system completely. I haven't yet found a break switch on the brake pedal or linkage, but it seems there must be one somewhere.

Greg Rogers

I maybe wrong I don't know what that sensor on the plug wire is. The ones we installed had a magnet glued to the drive shaft and that was where you got the "speed sense" by the magnet rotating past a sensor that mounted to the floor or crossmember, etc.

Leadfoot

Thanks, Greg. I first thought of Speedo-stat, but couldn't find any markings anywhere on the servo. Yes, the plastic housing that holds the end of the cable broke loose, and my experience is that there is no good way to repair the plastic. And I really don't care for the piggy-back turn-signal mounted control, either.

Sounds as though this was definitely a 3rd or 4th-party owner-installed setup.

joe_padavano

As noted, this is an aftermarket unit. I too have seen the magnets mounted on the driveshaft for speed sensing, but I'm guessing that on this unit, the spark plug sensor is sensing RPM, which this system uses in place of a speed sensor. Certainly easier to install, if less accurate.

Leadfoot

Thanks, guys. I appreciate the info. Googling turned up a few hits that verify that this is definitely a Speedostat product, and a couple of mentions of the sensor coil being used in lieu of the driveshaft magnet and pickup. Should I expect to find a control unit somewhere (like behind the dash)? Seems like there must be more to the system than I'm seeing so far.

JohnnyBs68S

I installed one of these on my '69 Toro years ago. Purchased mine from Sears, but the servo and turn-signal mounted control looked identical. There should be a small control box, ~5" x 6" somewhere under the dash for it w/ a handful of wires coming out. The spark plug sensor is to detect a over-rev in the event of a clutch push-in on a MT car or kicking the trans into "N" on an AT car. If the unit detected a rapid increase in RPM, it would disengage the cruise control to protect the engine.

Also had a '77 Camaro LT that the previous owner had installed nearly the identical system. It was a MT, and the switch that was normally connected to the brake pedal on an AT car had some trick hardware (chain and pulley arrangement) that connected it to the clutch pedal too so that if either the brake or clutch pedal was pushed in, it would disengage the cruise control.

Interesting triva on the Toro install: Since the speed pickup is normally via a single magnet on the driveshaft, which is not accessable on the Toro, this system used 2 magnets attached to the axle shaft that went under the oil pan to the passenger side. The second magnet doubled the frequency of the pulses that made up (somewhat) for the loss of a gear ratio between the wheel speed and driveshaft speed. These things merely measured the frequency of the pulses from the mag pickups and attempted to adjust throttle to maintain that frequency (it had no idea what actual speed the vehicle was going, it just maintained whatever speed it was going at when the button was pushed).

Leadfoot

I thought I should update to give this thread closure.

I finally got around to removing the cruise control system this weekend, and it turns out that everybody who replied was right.
There were no manufacturer-identifying markings anywhere on the servo unit, which seems a little odd... but the control box was indeed tucked up behind the dash, with its own wiring harness. Once I found that, it was relatively easy to trace and remove everything. It actually seems that it was a pretty well-designed and well-engineered system as far as being self-contained and not screwing with the factory wiring harness.

There was in fact a very small magnet strapped to the driveshaft right behind the transmission u-joint, with a bracket-mounted sensor screwed to the crossmember. I was wondering earlier what the large twisted pair of wires strapped to the speedo cable was for... mystery solved.
It's nice to have all of that stuff out of the engine compartment and out from under the dash. Where I previously had more than a dozen wires going through the firewall, I now have only two.

Thanks much to all who offered help and ideas. You guys gave me exactly the info I needed to know.