68 deville cruise control question

[Trace]

   I thought I had a perfectly functioning cruise control. 'Tis not the case. It engages at the right speed settings but gradually accelerates until I have to brake or turn off the unit at the switch. It seems to have no upper limit. I set her once on 40 and she 'grabbed' right there, and then slowly creeped up to 65 before I shut it off. The troubleshooting chart in the manual does not address this problem. Anyone else have their cruise control do this? .... and how was the problem fixed?

[cadillactim]

Might be dried up grease causing the centrifugal weights to stick. The weights control the points that cause the motor to run forward or backward. Appears the points are staying in the forward position. Remove the cover and with the car off, pry the weights apart with your fingers and notice the points. Is anything sticking, can the points touch either end of their travel?

Tim

[Trace]

Tim, the only time the points are not being touched by the contact arm is when the weights are in their neutral position. As soon as the weights are moved to separate them, the contact arm comes up and stays up against the upper feed. I am assuming by this that the motor will only go in one direction. I never went through and calibrated the unit because I am sure that my dad didn't mess with it. It should be as he received it. I did have the switch on the dash apart and repaired that. But when I put the cables back into the power unit, I guess doulble-checking calibrations would be in order. Any particular area to pay close attention to?

[cadillactim]

That long spring where the centrifugal weights are should have virtually no compression on with the speed dial at the lowest speed. Rotate the dial to the highest speed and the spring should be compressed a lot. Calibrate the dial to this basic setting, see what it does then.

Tim

[Trace]

Tim, .... I believe you nailed it again ! I went through the sections in the manual that may have caused the issue and adjusted those. The motor points feed (they were fine), the limit/throttle switch (about 1/8 in. high), accelerator linkage (that was off by 3/4 in.) .... all reset to specs. What the manual didn't suggest, but you did, was probably the main problem. With the control wheel set at '40', there was no compression on the spring. AAMOF, the spring had 1/4 in. play between the rod end  and the actuator. Per your advise,  I adjusted the speed selector the where the spring makes contact with the actuator at 30. The dial now maxes out right at 80 .... perfect! I just got back from a test drive. I set her at 40 and got her up to 40. There was not nearly as much resistance at the pedal as there was before so I thought it wasn't working at all. But I let off the accelerator and at 38, she gently grabbed and stayed between 38 & 39 for the whole trip. Tim, you need to do a book for these Cruise Controls also! Thanks again, my friend.

[cadillactim]

Glad you got it fixed. These cruise units are really pretty durable.

Tim

[bilhallen]

Glad you got it fixed. These cruise units are really pretty durable.

Tim

[Koolminx]

Hey guys can you walk me through on how set the initial speed so my cruise works past 69 mph?   My dial hits the end of the teeth at 69.

[Trace]

If you have the manual and read section 16 on page 15-17, you may come away confused. I did at first. If you are assuming that your Selector Dial stopping at 69 is the main issue, then honestly, all you should have to do is gently continue rotating the dial past where it stops until you get to 80. The dial has no 'teeth'. The reason it stops is because it is pushed against the mechanism that moves the Control Cable  (see Fig.15-21, pg.15-22).... which, by the way, does have gearing inside that you don't want to mess up. If the dial does not want to nudge past '69', and you start hearing plastic clicking sounds as it turns, I would stop, remove the Switch Lever Knob (section 27-a-1, pg.15-22), and try to loosen the nut a bit and freeing up the dial.
   This may not be you're only issue (I did see your other posts). But if your Cable and it's adjuster in the Speed Selector have their full range of motion, the above will solve at least the one issue.

[Koolminx]

I’m going to upload a photograph and tell you exactly why the dial stops.  Because there ARE teeth that move the rod.
I need to read that section and if it doesn’t tell me how to start the initial settings with the speed dial backed all the way up to 30 then I’ll come back and try to explain it in a different way.

Is there an inexpensive site to host photographs so I can drop an image into here?

[Trace]

Click the "Attachments" '+' below the posting section: ... the option presents itself then.

[Koolminx]

The Gear and Teeth I'm referring to are Inside the speed control unit at the dash.   The max pull on the cable regardless of dial numbers is 69 mph on the speedometer.

When the backpressure should be applying during the driving speed control setting procedure, while maintaining 50 mph, the back pressure will not occurr, but it Will occurr if I hit auto, then move the dial speed about 15 MPH faster, that's about when it kicks on, and the travel of the dial to max only produces 69 mph.

I'll call you up here in a couple hours.  Seeking a new radiator for this car now.  the Odometer hot 70K even yesterday, and that's when the radiator passenger tank started leaking...   so there's more fun in my day yet to come because nobody produces this radiator WITH the heater return hose on the tank....   sigh....

Regards,

Gary