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Forum Rules (Click Here) -> Ontario Rodders -> Tech -> speedometer question
Post Info TOPIC: speedometer question
classsic


OTTAWA, ONT

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speedometer question
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My 1981 chev truck speedo is in miles per hour and when I'm driving 50 MPH the speedo shows 75 MPH. That's 50 per cent increase!  This does not concern me because I'm sure someone changed the rear end previously and I can calculate the kilometers per hour speed from the tach. My question is will the mileage on the odometer be out by an equal amount? Thanks Doug



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Lightspeed Mike


BELLEVILLE, ONT

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Yes


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classsic


OTTAWA, ONT

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Thanks again.......



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poncho62


ADMINISTRATOR

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Since 50 mph is 80 kph. it reads very close to kilometers....I would just use the speedo as a kilometer one.

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jarvis1


COBBLE HILL, BC

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Was the truck built in USA?
We went metric in 1978.

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classsic


OTTAWA, ONT

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Yes the truck is American...bought it from a fellow in Trenton area who brings vehicles over the border about 10 years ago.  My concern is not the speed when traveling but the overall mileage on the truck. I'm guessing it must be over by 50 percent also.



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wuga


PRINCE EDWARD COUNTY, ONT

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users.erols.com/srweiss/calcrgr.htm

Follow this link. Enter your tire diameter and the RPM at 60MPH. This will give you the gear ratio you are currently running. Now enter 2/3 the RPM and that should give you the gear ratio that would give you the proper speed. See if these ratios make sense. Get ahold of Geoff and see if he ever changed the rear end in that truck.

Warren

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supernash


WEST PERTH, ONT

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I remember when metric came in and we could install some convertor thingy at the tailstock.

You sure could bury that speedo fast ! Just a thought cause it's an easy fix to remove.

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