I have an 81 with Cruise Control and Auto Trans.
When I got it the speedo would jump around a lot until about 60 mph, then it would stay on point. The Cruise Control, when turned on and hit "SET" would accelerate the car from freeway speeds.
Yesterday , the speedo completely quit working, but now the Cruise Control works correctly.

Ideas?

Mark

 

Hi Mark, It sounds like the speedo cable between the cruise transducer and the speedometer, probably broke from age and lack of lube. The transducer is in the left fender but in back of the wheel, the cable is relativly short ( 3-4 ft. ).

 

Thanks for the info, I'll have to try to get under the dash and see what I can do. I have small hands, so I might be able to get it out. I'll have a look at a catalog and see what holds the bugger onto the Speedo.

Thanks,
Mark

 

I had the same proublem on my 79 Vette, I put new cabels on and even put a newtransducer on, but that didn't work. I found that the part that they call the bullet - this is the part that fits it to your trans that the cable screws on tothat has the gear in it, itwas worn and let the gear move and will not stay in contack with the gear in the trans. when I took the bullet out of the trans it had a very very small amount of play that I thought was not enought play to cause this to happen but when I put A new one in It fixed the proublem. Just something to try I hope it works for you.

 

Hey Mark,Buckshot is right on target.Had the same problem with my 1980, the gear in the tranny was stripped and the cable end at the transducer was stripped. Don't know if the transducer seized or just an old cable. Bought a rebuilt transducer, upper and lower cable and gear for under $150 just waiting for the lower cable due to a backorder. But very easy to do , good luck, Scott