Since this is a fairly fresh thread, I thought I would jump in with a question to all you speedo gurus.
The car in question is a 72 Duster, 3 speed manual. We will pull the current speedo gear this weekend and figure out what is in it. I understand the tire diameter and gear ratio calculations to get the proper gear, I believe ours is pretty close when using the automatic radar signs around town.
My questions are (this may sound odd):
1. Is the gear for the 3 speed a short shaft or long shaft type? (I'll know when I pull it but thought I would ask).
2. If I want to throw my speedometer off by say 20 mph, so it reads 40 mph when I'm actually doing 60 mph, do I go up or down in tooth count?