[JerseyJim]

I'm a little late seeing this post. But thought that I would put my two sense in any how. You didn't indicate whether it is high or low? You also didn't indicate if the difference in speed is consistent or varies according to speed. If it is a speedo gear issue, the percentage of variation should be consistent at all speeds. That means that as your speed increases, the variation should increase. Assuming this to be the case, the next question is did the replacement speedo gear that you put in have the same number of teeth? A fairly wide variety of gears are available. Depending on whether you are faster or slower, you can typically buy gears with more or less teeth as required.

On older cars, it isn't tough to figure out which one to use. These older transmissions (with the exception of over drive transmissions) typically have a final gear ratio of one to one. Drive your car at a set speed. Let's say 60 miles per hour. Get someone to pace you with a vehicle with a known accurate speedometer. At 60 in your car, ask them what they are reading in theirs.

If they are reading 70 miles per hour, simply divide your speed into theirs. 60 into 70 will give you 1.16. Now let's assume that you have 16 teeth on your existing gear. You need to reduce the number of teeth to increase your speed reading. So divide the number of teeth on the existing gear... let's say for example that it is 15 by 1.16 and you will get 12.93. Use a 13 tooth gear and your speedometer should be almost dead on.

If they are reading 50 to your 60, here's the way it works: Divide your 60 into their 50 and you get .833. Divide 15 by .833 and you get 16.8. You would round up to 17. Again you will be very close.

Hope this helps.