Gear ratios
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Trailering
Joined: Jul 2002
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From: Roseville, CA
Gear ratios
I just bought a 68 F100 4x4, and while turning my driveshafts I found that my rear gears are 4.10's or 4.11's, but my front shaft turns twice to one tire revolution, which would put my front gears at somewhere around 2.0. But this doesn't add up because the four wheel drive works fine and doesn't bind up at all. Could my transfer case be making up for the lost gearing somehow? I'm not sure what transfer case it has but it's an "in and out" case and it's really small. Any help would be much appreciated. Thanks
New User
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Gear ratios
Front gears are usually very close in ratio as the rear.
4.10 rear
4.09 front
[font color=red]Dennis
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4.10 rear
4.09 front
[font color=red]Dennis
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Senior User
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Gear ratios
For an open differential, with one wheel off the ground, the ratio of wheel turns to shaft turns is 1/2 the actual gear ratio. For example my rear end is a 3.0. If I jack up one side and spin the wheel, the drive shaft will turn 1.5 times for every revolution of the wheel. It's the construction of the open differential that causes this.
If you turn the wheel only one or even a few revs, you'll never tell exactly what your ratio is. To see if it's a 4.09, 4.10 or 4.11, spin the wheel two hundred times. The shaft will turn over either 409, 410 or 411 times. 100 wheel turns would result in 204.5, 205 or 205.5 shaft turns, 50 wheel turns would give 102.25, 102.5 or 102.75 shaft turns, etc.
Dan Blackwell
If you turn the wheel only one or even a few revs, you'll never tell exactly what your ratio is. To see if it's a 4.09, 4.10 or 4.11, spin the wheel two hundred times. The shaft will turn over either 409, 410 or 411 times. 100 wheel turns would result in 204.5, 205 or 205.5 shaft turns, 50 wheel turns would give 102.25, 102.5 or 102.75 shaft turns, etc.
Dan Blackwell
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Gear ratios
>50 wheel turns would give 102.25, 102.5 or 102.75 shaft
>turns, etc.
>
Mr. Math just had a better idea. Turn the wheel 41 times. The shaft should turn EXACTLY 20 times if it's a 4.10, a little less than 41 times for a 4.09 or a little more than 41 times if it's a 4.11.
Dan Blackwell
>turns, etc.
>
Mr. Math just had a better idea. Turn the wheel 41 times. The shaft should turn EXACTLY 20 times if it's a 4.10, a little less than 41 times for a 4.09 or a little more than 41 times if it's a 4.11.
Dan Blackwell
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Gear ratios
>a little less than 41 times for a 4.09 or a little more than
>41 times if it's a 4.11.
>
WRONG!
The drive shaft will turn a little MORE than 41 times if if it's a 4.09 and a little LESS than 41 times if it's a 4.11. My apologies for the confusion. Stinkin' numbers.
Dan Blackwell
>41 times if it's a 4.11.
>
WRONG!
The drive shaft will turn a little MORE than 41 times if if it's a 4.09 and a little LESS than 41 times if it's a 4.11. My apologies for the confusion. Stinkin' numbers.
Dan Blackwell
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Gear ratios
Why not pull the diff cover off and count the teeth on the gears.
Then you wouldn't lose count at 35 tire turns and have to start over.
[font color=red]Dennis
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[font color=blue]78 F-150 429CJ,Silver,Explorer Pkg.
64 1/2 Mustang Pre-World's Fair Car #8092
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Then you wouldn't lose count at 35 tire turns and have to start over.
[font color=red]Dennis
FTE Adminstration
[/font]
http://www.clubfte.com/users/mil1ion/canada_flag_animated.gif
[link:www.clubfte.com/users/mil1ion/Mil1ion.html|My Website,"North Of The 49th"]
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http://www.clubfte.com/users/mil1ion/Minimorleytruck.JPG
[font color=blue]78 F-150 429CJ,Silver,Explorer Pkg.
64 1/2 Mustang Pre-World's Fair Car #8092
68-Mustang 289 2v-Sunlit Gold
[/font]
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