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speedometer gear???

4008 Views 7 Replies 6 Participants Last post by  Ram, 
jimbo
speedometer gear or whatever it is called that you can change to correct the speedometer after getting different gears. anyway would the dealer have what i need to get my speedometer accurate after going from 235/75/15 tires and 3.55 gears to 33inch tires with 4.56 gears???

thanks for any help
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D
Here's the fomula that you requested
first you need to figure the driveshaft rpm at 60
speed x gear ratio x 336 / tire diameter
60 x 4.56 x 336 / 33 = 2786 ( or about )
take that number and devide it by 75
2786 / 75 = 37 tooth gear needed
each tooth on the speedometer gear is equal to about 3 mph.
speedometers cost about $12 at the dealership.
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