What we have here is a HYBRID speedometer. My customer wanted a dual register speedometer--as in a Monte Carlo--for use in his standard 1966 96 two stroke car. The trouble was that the Monte Carlo cars--either two-stroke or V4--had a transmission with a 4.88:1 final drive transmission. The '66 two-stroke had a transmission with a 5.43:1 final drive. So the MC speedometer would be WAY WRONG in both SPEED and MILEAGE recording......Hmmmmm.....
Clearly, the solution was to change the internal gearing of the MC speedometer [see first photo]. After some head-scratching, I did that gearing change, and the finished speedometer [above] reads correctly on the test bed, for a Saab with 5.43:1 gears.
Here is the flip side of the finished speedometer. I set the odometer miles to match the miles currently shown on the speedometer in the customer's car. The change-over can be done, but it is nice to prove that the change was done correctly, by running the finished speedometer on the test bed. Good stuff!
City Car Design
4 years ago