All,
My Bendix Cruise Control had these symptoms:
1) If set at or around 65mph it would hold: sometimes 2) if set above about 69 mph it would begin a rapid acceleration to 75mph+ (I always shut it off at 75) and 3) brakes weren't disengaging the cruise.
The fellow I called in Dallas who works on Bendix Cruise controls (a dying breed) told me for my symptoms I had a stuck potentiometer on my rear air cylinder and to shoot it with WD 40 thoroughly. After crawling under the coach for about 2 weeks on other issues/fact finding I found this cylinder and soaked it with WD 40. Drove to San Angelo yesterday (75 miles) and cruise began as before, but did not run away all the way to 75 ONLY about 73. Long story short: after many engagements/disengagements of the cruise control, by the time I was on the way back this PM, it now works! I set it on 70mph which it held fine, and coasted down in speed and resumed up in speed on the rocker panel. Apparently the approx 175 mile trip with the cylinder moving in and out got the WD 40 in where it needed to be and let the potentiometer get back to it's proper baseline. It took a lot of pushing the rocker on SET and RESUME to get the cylinder working to finally get it where it is apparently working as spec'd.
Leave it safe to say I be a happy camper!
If your Bendix cruise is acting erratic, try and find that air cylinder near the engine and soak it with WD-40. May fix yours also.

Good information ...think I might give mine a shot of lube just to keep things moving!

What does the air cylinder look like? Do you have a photo?

quote:

Originally posted by Keith Hopper:
What does the air cylinder look like? Do you have a photo?

No photo. I will work on getting a pic to post here. To find it look at the Injector Pump throttle linkage, and find the control cable attached to it. Follow the cable to the air cylinder. Mine is mounted starboard side on the bottom of the sheet metal where my coach batts are mounted.
I also forgot to mention the tech told me to hit all the connectors that plug in to the air cylinder with WD40 which I plan on doing soon and will report my findings after this.
Apparently the Bendix/King air driven cruise contol is a very well built system and can be brought back up to new with just some cleaning of contacts.