Gear swap

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coolhand75
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Joined: Sat Mar 25, 2017 11:21 pm

Gear swap

Post by coolhand75 »

Hello friends
I’m in need of your advice my 75 j10 has a broken ring and pinion in the rear. It currently is 3:54. I’m thinking of changing it out to 4:11 I know if I do this I will have to change the front too. I also know it will reduce my top speed on the highways. I could run 3:73. This is not a daily driver. Please what are your thoughts. ImageImageImage


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Stuka
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Re: Gear swap

Post by Stuka »

First, I would go through and use the gear calculator at http://grimmjeeper.com/gears.html

It was created by a member here and is MUCH more precise as you put in your actual transmission and transfercase. Also, for tires size, you need to enter the rolling diameter. For a 33" tire, this is typically around 31.9" or so. Sometimes less if you are by chance running a tire that is smaller than some others, like a BFG. And since we do not have lock up converters, your cruising RPM will be higher than the calculator states.

But, back to your gear choice. 4.10's are a pretty good match for 33's with no OD. I have 4.56's with 33's and they are a bit steep. FWY time is not an option for very long.
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Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

will e
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Re: Gear swap

Post by will e »

I agree on using grimmjeeper's site. It will give you a lot of info about crawl speed and such too. Plus it can do a side by side comparison.
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dodgerammit
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Re: Gear swap

Post by dodgerammit »

Stuka wrote:First, I would go through and use the gear calculator at http://grimmjeeper.com/gears.html

It was created by a member here and is MUCH more precise as you put in your actual transmission and transfercase. Also, for tires size, you need to enter the rolling diameter. For a 33" tire, this is typically around 31.9" or so. Sometimes less if you are by chance running a tire that is smaller than some others, like a BFG. And since we do not have lock up converters, your cruising RPM will be higher than the calculator states.
Love this site! I can compare side by side!
84 Grand Waggy-Radio Flyer (Garnet Red/3M Ebony Metallic woodgrain, with honey interior) AMC 360 :cry: 2004 4.8LS/Advance Adapter/727/242 D44/AMC20 Serehill tailgate and headlight harnesses :fsj: Ongoing thread-viewtopic.php?t=11897

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