70NPORT
Old Man with a Hat
Anyone in PA/NJ/DE area have this done? If so where at?? I'm looking to do the same.
Speedometer Calibration
- Thread starter 70NPORT
- Start date
I'm interested to know too. I've noticed that my NY'er at 50 mph on my speedometer and the GPS says I'm going 57 mph. The faster I go the more of an increase in the difference from speedo to GPS speed. Nothing modified on the car and appears to have the original speedo gear. 47,000 miles on the speedo.
BillGrissom
Active Member
The reading will be affected by the tire diameter. You can get different plastic gears for the end at the tranny, but not easy to find today. In my 65 Newport, after a speedo rebuild I adjusted it to read correct at 60 mph, which is the region I really care about. There is a little adjustment tab you can slide on the needle assembly to change the zero offset. I was able to push it with a little screwdriver with the cluster in. I recall I had to lower down the steering column each time, but that is easy (2 bolts). My cluster has the speedo that wraps around the column in a 180 deg arc, and yours is surely different. To measure true speed, hold the car steady at 60.0 mph and time between mileage markers on the interstate and adjust until you measure exactly 60 sec (1 mile/min).
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