I just got a '69 Roadrunner and the speedo bounces quite a bit, but the worse part is that it reads about double your actual speed. Drive down the street at about 35-40 miles per hour and it will bounce between 65 - 80.

I'm sure the bouncing could be the cable being bound up, dry or has a bad end but I don't understand how it can read double actual speed. I don't know what speedo gear it has in but it can't be that, no gear will make it off that much. Tires are 215/70-15's.

I assume it's the speedometer head but I was hoping that I didn't have to replace it.