My old OEM cruise control never worked very well. It is vacuum driven and uses the speedometer cable to sense vehicle speed.

Mine never held speed well and surged a lot on hills. On top of that, the primary cable from the trans to the cruise module broke once already. The second cable runs from the cruise to the speedometer itself and is showing signs of failure (the speedo needle is bouncing pretty badly)

Looking around for aftermarket cruise units, there aren't many choices. I decided to go with a Dakota Digital cruise control. They are all electric (no vacuum hoses) and are adjustable for sensitivity (gain) and response rate. I'm hoping to get better speed control and eliminate the need for the jerky old cables.

Dakota sells several models.

The ones for the newer cars do not need a speed sensor, they just have a single "VSS" wire to pick up the signal from the car's computer.

The ones for the older rigs with cable speedometers come with an adapter which installs in line with the cable. The adapter has an internal rev sensor and a cable to connect to the cruise module. This is the model I'm using, with the adapter attached to the trans. I won't be using the rest of the cable any more.

The cruise unit itself is the same, just gets its speed signal from a different source.

Since the cables are no longer needed for cruise, and the speedometer varies by over 5 mph, I decided to replace the speedometer with a GPS type which needs no cable. (See posting on Speedhut gauges)

The unit comes with a control module, wiring harnesses, speed sensor and transmission adapter, and a switch/turn signal stalk.



I'll start hooking these up tomorrow.

I don't use cruise control; thinking about hurtling an 8-ton RV down the road if I were to lose consciousness makes me avoid it. But then, it may be OK for someone with a copilot...

Yeah, cruise control can be dangerous! It's really tempting just to walk back, make a sandwich, grab a beer.... oops who's driving this thing?

I only use the cruise for a break for my right foot now and then. 86Barth doesn't have enough power to run cruise all the time in hills, etc. The new cruise may cope better, we'll see.

Today I installed the main module on the left forward side of the doghouse. To the right of the yellow electrical plug, the rubber plug covers the DIP switches used for changing the settings.



The throttle cable was easy, the old cruise cable was attached along side the normal cable... I just hooked in the new one in its' place.



I got the transmission speed sensor installed. Usually the speedometer cable connects to the sensor but I won't be using the cable so I will cover the end.



When I get the turn signal stalk/switch installed I just have a few more connections to make!

I can not run without the cruise control. I could not wait to replace that vacuum junk. My adaption works well although I have not found a way to alter the gain. A little sluggish for this weight vehicle/torque but will hold speed +/- 1 MPH even over small grades. I like the tap up/down 1 MPH/tap feature.

If I could get the throttle position sensor calibrated right so it would shift down quicker, it would be much better

I have some spare parts now. I thought the cruise was made by ARA but it is labelled ACME! (It makes me think of the road runner and Wiley Coyote.)



I haven't removed the other cable that goes to the speedometer, maybe later. I think there is some kind of module somewhere but I haven't found it yet.

Does anyone else have this model? Anybody want the parts? It was "working" when I removed it.

Ran back from Florida to Michigan. Cruise worked well the first time I set it. Holds the set speed really well compared to the old vacuum unit. The speed varies only about plus/minus 1 mph on the flats.

The old 454 still can't pull big hills without slowing a bit but it is way better than the old one. The rate of the throttle action is much smoother, the old one you could feel it let off at the top of the hill and it hammered the throttle on the way up. The new one is much smoother, you don't feel it surging. You can bump the set button or resume to go up or down in 1 mph increments.

If you have LED tail lights you will have to wire in a simple relay into the brake circuit. The system looks for a ground path through the brake light bulbs and the LEDs do not allow it. (The instructions show how to install the relay.)

Overall, this was very satisfactory. Installation was straightforward, operation is much improved and the system allows for some adjustment if needed. (I left the sensitivity and gain at the low settings, lighter vehicles might benefit from more sensitivity and quicker response.)

I saw Doorman with his Class C at the GTG. It looked like he had a similar old unit so I gave him the old parts for spares.

I know this is an old thread, hope you don't mind that I resurrect it. I am beginning the process of fixing/upgrading the cruise in my 24 footer (1978). I was considering the Dakota digital unit, so I'm glad to have found this thread. However, there is a replacement ARA unit available for quite cheap that I might prefer to give a try.

My only hesitation here, and I can see it was the same situation for the unit that you took off of your coach, is that the thread size for the trans and speedo cables are totally different. The speedo one is quite significantly larger. This does not appear to be the case with the new ARA unit, and would prevent me from threading on the speed cable. I'd really not want to lose my speedometer, so I am not sure how to proceed.

Are these threads pretty standard sizes? Might I find a speed cable with a smaller thread that is compatible with my cluster? Any insight or ideas would be great. Thanks

Update: after getting my unit removed, the larger diameter cable stud is actually just a coupler that can be removed, revealing a smaller stud of the same size as the other. So, it appears the ARA replica linked above would work just fine. Would just need to fabricate a mounting bracket, some good info on that here.

I have some thinking to do. I don't love the idea of vacuum actuated cruise control, and it does sound like you had a much better experience with the DD unit. I found one on eBay for $300 new as well.

Since I do like my analog speedometer, I would need to keep the vacuum unit around to avoid having to run a single, longer, cable from the transmission all the way up to the cluster.

I did find out that the lower speedo cable for an '86-'87 Monte Carlo is actually a female to male kind, that looks like it would couple right up the existing P30 chassis lower cable (I was on the internet for way too long today to have stumbled across that bit of wisdom on a vette forum). You can see evidence of that here. I'd much rather couple the cables together in this manner and not have to keep this big chunky vacuum unit in there, it would free up a lot of space, so I may order one. The only issue is it does look quite short.

Another option is to just remove the 180 degree gear ratio portion of the current unit, and build some kind of custom housing/top and mounting bracket to hold it together. I did take it apart and it looks like it would be possible. I'll try to post some pictures later if I go down that route.

You have several choices!

I was not a great fan of the vacuum driven units. When my Regal was on cruise, the engine was running with advanced throttle. When the cruise called for more throttle, there was little vacuum left with the throttle open that far.

The Dakota digital unit was good for my purposes.

There are a couple of electronic cruise controls available, that use either the drive shaft or the distributor tachometer wire to supply the speed signal. I just installed one in my 71 Barth with a 350 engine. The actual power to move the throttle linkage is vacuum.

I am using the distributor tachometer wire although in the instructions it says the drive shaft option is best for a motorhome, but I thought it looked a bit hokey. So far it works very well, except the adaptor for attachment to the throttle is long and the actual travel of the vacuum motor is inadequate to reach speeds over 60 mph. I am going to modify that adaptor with a hole closer to the carburetor throttle shaft center line allowing the existing vacuum motor travel to open it more.

Ebay offers several manufacturer options.

As Steve indicates the vacuum developed when the Rochester 4 barrels are open is probably inadequate to run the throttle, so I am not going to have that much travel in the cruise system. This of course will limit the acceleration. I think there is a cutout device in the system that disengages the cruise when the vacuum is inadequate. The installation manual states, installing a vacuum reservoir canister will help with this problem I have one but have not put it in yet.