engine speed at 60mph
so, I figure about 517 tire revolutions per mile..... 6.83 rear end gear means at 60 mph IF you have one to one drive in high gear. then that means you spin the engine at 3,530 rpm......... or 58.85 revolutions per mile an hour.... that is a bunch for most diesel engines....... so lets see what a 5.38 rear gear will do....... at 60 mph with direct drive I have figured about 2,780rpm.... bout the upper limit and maybe even stretching it a little...
4.88 will put you at 2,500 rpm at 60 mph with a 9r20 assuming a 9r20 new is around 40" diameter and my math putting that tire at 517 revolutions per mile.
If my math is correct you are at around 2700 rpm at 45mph right now... so, if the motor can pull it on flat land with small head wind... then a 4.88 gear will give the about the same rpm at 60 mph
william
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