i have a '63 belvedere i drive every day. i kept breaking speedo cables so i thought it was the speedo itself that was breaking them. i cut out the back and bought a speedo from the bay. also, it turned out i needed a cable and housing. can't go back. it only went to 80 mph but that was fine. it wasn't accurate, as the rear gears and tires had the car going 70 at 75. enter a new pumpkin with 3.55-1 from 3.33-1. now it goes 62 at 80. here is my question, the needle will go all the way to almost 0 again when the pedal is pushed further. is this going to break the gears or brake off the needle or what?
Get a new gear for the end of the cable 1 or 2 teeth more than the one you have. You can also buy a gear change which connects to the trans and the cable to it. I had a 3.21 rear gear the highest available at the time and we installed a new rear end with 2.74’s. I used one of external change and my speedo is perfect. You figure by using the GPS on your phone.
The speedo won't break if you make it go too fast, the needle will eventually hit the "zero" stop and not move any further. There is no solid mechanical connection, it works with a magnetic coupling. Don't worry too much about it.
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