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Yes, I have done it---it was especially common 50s and 60s--but only happens with the ratios that don't divide out to a whole number. tooth ratios that divide out to the fartest digit will wear the most evenly?
The nine inch ford gears are the ones with the deepest offset pinions(works more like a screw than a common gear mesh) and the shape of the teeth vary more with the various ratios---some ratios that are close will have huge differances of tooth shape and will result in different parasitic drag amounts---look at the tooth counts of the various ratios and you will get an idea abouth tooth size(and shape)
example --4.0 9/36 10/40
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