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Old 05-09-2015, 02:57 AM
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Gear ratio

Hey guys, pretty new to the jeeps, I know there is lots of threads on the gear ratio topic but I'm quite unsure of what I have. Build sheet says 3.73 gears, previous owner didn't do any re gearing and wasn't sure what it came with. I know the gear ratio/ rpm chart isn't the most accurate but when rolling at 70MPH im just below 2500RPM. I have 35" marked tires and even if they are 34" with squat I'm nowhere near what the chart says. When I'm home from work in about a week I will be jacking it up and chalking the driveshaft and checking but for now I look to you for advice. Again sorry about the additional gear ratio thread

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Old 05-09-2015, 03:36 AM   #2
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I bet your transmission isn't shifting into overdrive. That would account for that RPM range at that speed. What year is your Jeep?

Have you double checked the speedometer against a GPS? That may also be slightly off if the advertised tire size is programmed in the computer instead of the actual tire size.

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Old 05-09-2015, 05:11 AM
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It's a 2013 auto tranny. And I will double check on the speed when I am home. It does seem to want to stay in 4th gear usually unless i throw it in 5th.
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Old 05-09-2015, 06:15 AM   #4
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Quote:
Originally Posted by hoks4 View Post
Hey guys, pretty new to the jeeps, I know there is lots of threads on the gear ratio topic but I'm quite unsure of what I have. Build sheet says 3.73 gears, previous owner didn't do any re gearing and wasn't sure what it came with. I know the gear ratio/ rpm chart isn't the most accurate but when rolling at 70MPH im just below 2500RPM. I have 35" marked tires and even if they are 34" with squat I'm nowhere near what the chart says. When I'm home from work in about a week I will be jacking it up and chalking the driveshaft and checking but for now I look to you for advice. Again sorry about the additional gear ratio thread
If you have 3.73 I bet previous owner didn't reprogram the speedo.
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Old 05-09-2015, 09:38 AM   #5
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If you have 3.73 I bet previous owner didn't reprogram the speedo.
This would be my guess as well.
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Old 05-09-2015, 12:21 PM   #6
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If you have 3.73 I bet previous owner didn't reprogram the speedo.
I doubt it. The auto trans would shift horribly if that was the case.

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