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How to estimate gear ratio?
#1003763
05/31/11 03:18 PM
05/31/11 03:18 PM
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Joined: Jan 2010
Posts: 456 Santa Barbara, CA
HitIt
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 456
Santa Barbara, CA
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Hi there, I'm just trying to estimate the gear ratio in my car so I can start getting together a little deeper gears and suregrip.
When I turn the drive shaft 1.25 times, the axle rotates 1 time. Any way of knowing the gear ratio of this based on those numbers? This is an open 8.75 diff... seems like it could be between a 2.73 or 3.23 when I drive it.
Thanks!
very clever dinner. appetizing food fit neatly into interesting round pie.
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Re: How to estimate gear ratio?
[Re: buildanother]
#1003765
05/31/11 03:25 PM
05/31/11 03:25 PM
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Joined: Jan 2010
Posts: 456 Santa Barbara, CA
HitIt
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mopar
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OP
mopar
Joined: Jan 2010
Posts: 456
Santa Barbara, CA
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thanks buildanother, that's kinda what made me think they could be 2.73s.
will my measurements be off if I didn't prevent the other side from spinning backwards while I counted the one side?
very clever dinner. appetizing food fit neatly into interesting round pie.
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Re: How to estimate gear ratio?
[Re: stumpy]
#1003767
05/31/11 03:43 PM
05/31/11 03:43 PM
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Joined: Jan 2010
Posts: 456 Santa Barbara, CA
HitIt
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mopar
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OP
mopar
Joined: Jan 2010
Posts: 456
Santa Barbara, CA
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Got it, thanks. I will try again.
very clever dinner. appetizing food fit neatly into interesting round pie.
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Re: How to estimate gear ratio?
[Re: scratchnfotraction]
#1003769
05/31/11 04:10 PM
05/31/11 04:10 PM
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Joined: Jan 2010
Posts: 456 Santa Barbara, CA
HitIt
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mopar
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OP
mopar
Joined: Jan 2010
Posts: 456
Santa Barbara, CA
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thanks scratchinfortraction, that is exactly the info I was needing - 2.75 for 2.73 etc.
It's an 8 3/4 so I don't want to pull it apart just for a look. I just want to know about what gears are in it so I can decide on 3.55's or 3.91s.
Gonna try it again today. Thanks!
very clever dinner. appetizing food fit neatly into interesting round pie.
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Re: How to estimate gear ratio?
[Re: HitIt]
#1003770
05/31/11 04:44 PM
05/31/11 04:44 PM
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Joined: May 2003
Posts: 15,487 Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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if it turned 1.25 turns on the yoke to make 1 full turn of the axle it would be a 1.something gear ratio I have only saw a 2.76 as the highest gear ratio with all mine dont think they make a 1.?? gear I like 3.55 as the lowest gear for street duty and 3.91 for track duty 3.23 are a little better for mpgs over the 3.55
Last edited by scratchnfotraction; 05/31/11 04:57 PM.
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Re: How to estimate gear ratio?
[Re: HitIt]
#1003771
05/31/11 06:04 PM
05/31/11 06:04 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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1 wheel on the ground. 1 wheel just off the ground. neutral of course. make a mark on the tire at 5 o'clock & turn tire a bit to 6 o'clock to take the backlash out of it. turn tire 2 revolutions (back to 6 o'clock twice) as you count d shaft revolutions. That'll b your exact ratio (ie 3&1/4 turns is 3.23 as Scratch said)
live every 24 hour block of time like it's your last day on earth
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