So I just installed a new speedo cable all nicely lubed up with graphite powder the other day and it still is very jumpy with it's readings. It bounces up and down rather than a smooth transition. Also, it topped out at 70mph and wouldn't go any higher even though I was still accelerating. Is it possible that it's the speedometer itself as oppossed to a problem with the cable? I'm pretty sure that it is still the original unit from 1966.

 

Was it jumpy before? I dont know anything about the speedo cable but it would seem that if it worked before replacing the cable, and now it doenst work, it would be the cable.

Maybe there is a break in time? Someone else will have to chime in.

 

You're right, I should have addressed that part of it seeing as it is important. The speedometer has always been jumpy as long as I've owned the car (8 years) and it's had 3 different cables in it. But this toping out at 70 problem only happened after the new cable install. I'm real confused with that issue. I guess I could take the cable off again and reinstall it but I thought maybe I could get some advice first.