Pre 84 Trucks 1st gen pickups

checking gear ratio

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Old 05-18-2009, 07:38 PM
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checking gear ratio

how do you check your gear ratio. i lifted the tires up and spun the driveline which gave me 2 spins of the driveline for 1 spin of the tire but that seems insanely high. its a 1981 stock pick up
Old 05-18-2009, 07:47 PM
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http://www.4crawler.com/4x4/4R_TechI...oDetermination

Remember the factor of 2 factor assuming you have and open differential.
Old 05-18-2009, 07:51 PM
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ya i have an open diff so does then mean that my gears are 4.10 to 1 then
Old 05-18-2009, 07:53 PM
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Originally Posted by Nimyad
ya i have an open diff so does then mean that my gears are 4.10 to 1 then
Might be 3.90 or 4.10. Best way to tell is as described on the web page above. Use 10 (or 20) driveshaft revs. while counting wheel revs, then divide the ratio by 10. A lot easier to tell the difference of 30 or 41 wheel revs than 3.9 or 4.1 revs.
Old 05-18-2009, 07:59 PM
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well thats definetly a lot better then i thought i had but it still seems really fast in first gear. it has the stock 4 speed transmission and i can't find the gear ratios in it
Old 05-18-2009, 08:01 PM
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Marlin's page will probably tell you that information:
- http://www.marlincrawler.com/tech/tr...ar-ratio-chart
Old 05-18-2009, 08:13 PM
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thanks
Old 05-18-2009, 08:15 PM
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You've got 3.90s if it's an '81
Old 05-18-2009, 08:27 PM
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not always... i've seen 3.73 and 3.42 gear ratios from 1st gen pickups
Old 05-19-2009, 07:38 PM
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so im going to run 33 12.50 tires most likely with a dual t cases. should i stay at stock gears or go to 4.56s
Old 05-19-2009, 07:45 PM
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4.88's
Old 05-19-2009, 08:19 PM
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but i still want this to be my daily driver without getting terrible gas mileage. i also want to be able to go at least 60 with my stock 4 speed
Old 05-19-2009, 11:24 PM
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Originally Posted by Tofer
not always... i've seen 3.73 and 3.42 gear ratios from 1st gen pickups
In an 1981 4wd? I've only seen 3.90s in '81s
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