1970's cruise control on '89 W250

[Brian R]

I have installed the older type of Dodge cruise control on an '88 Ford 7. 3 diesel F250, a 1971 Baja Bug and even my '89 W250. It works great on the Bug but on the Ford (which is now gone) and now the Dodge the speed drops way off after you set the cruise. There is an adjustment on the unit to correct this but it seems to have little or no effect on the problem. The speed drops off almost 10 mph. I have tried adjusting the cable freeplay also. Does anyone know if these units do not work well using the belt driven vacuum pump as a power source? It does not really seem to me like that is the problem. The resume works well, for example, which I think is the cruise control function which requires the most vacuum power. Any thoughts?

 

[Paul Herioux]

Welcome aboard.

I'm trying to piece together a similar system for my 89. Most of my parts came from an 85 full size van. From my experience when these systems used to come into the dealership it sounds like your cable free play is excessive. If I remember correctly the spec was 3/32". I'm also kind of wondering if the high throttle effort required on the Cummins may not also be a factor. I would try running the cable as tight as possible without effecting idle. Let me know how it works out.

 

[Brian R]

As I mentioned, I have done this three times, starting from scratch. The last time I got the parts for two complete systems (one yet to be installed on my 914 project- see signature) for $54 at our local Pick 'n Pull junk yard. You probably know this but what you need is a brake light switch that accomodates cruise (older ones white and round, newer ones black and square), the transducer unit, a trans to cruise speedo cable, a cruise to speedometer speedo cable, the cable to pull the throttle, the 4 wire switch and the simple wiring harness. I have tried tightening up the free play but it does not seem to help. I am considering drilling a new hole in the plate on the injector pump that the throttle cable hooks to that is closer to the pivot so the cruise does not have to pull so far to get the same amount of throttle, if that makes sense.



It sounds like the excessively sprung pedal is common on these trucks. Maybe that's why mine has such low miles, because the guy could not stand pressing on that pedal. We did some preliminary investigation and it seems that most of the spring tension is coming from the trans kick down cable. Does that sound right? Does anyone know how to soften that pedal a bit?