Gear swap causes speedometer problems

I replaced the stock 2:73 ring and pinion gear in my 1973 Chevrolet Nova with a 4:10 ring and pinion gear and now the speed indication is not accurate anymore.How can I fix this problem?Does the speedometer need to be recalibrated? Thanks in advance for your answer.

Reply to
Disruptor
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You need a new speedo drive gear.

The speedo "reads" the speed by couting RPMs at the tail end of the transmission, and assumes a specific gear ratio is going to alter that number by a certain fixed amount. You've changed the amount of that alteration, and haven't "told" the speedo about the change. Change the speedo drive gear ("Tell the speedo" about the new gearing in the rear end, and how much different the alteration of the RPM number is) and you'll get an accurate speedo again. Whoever sold you the new gear set will probably have (or at least have an idea about who does) the right speedo drive gear to match the new gear set. I'm actually a little bit surprised that one didn't come with your new gears, since they're so closely related.

Reply to
Don Bruder

Approximately 8/29/03 15:54, Disruptor uttered for posterity:

On some cars as trivial as replacing a gear in the drive with one for the correct ratio.

Reply to
Lon Stowell

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