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Discussion Starter · #1 ·
From wwhat I have read, since my Jeep is a 4cyl, I should have 4.10 gears. That is fine, but what keeps mixing my up is which way I want to gear for on-food use.

3.73 or 4.88?

I keep mixing up which way for on-road compared to off road. I mostly drive on the road, and in winter will be my DD, so looking for the right size ratio. Thanks in advance.
 

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From wwhat I have read, since my Jeep is a 4cyl, I should have 4.10 gears. That is fine, but what keeps mixing my up is which way I want to gear for on-food use.

3.73 or 4.88?

I keep mixing up which way for on-road compared to off road. I mostly drive on the road, and in winter will be my DD, so looking for the right size ratio. Thanks in advance.
Im assuming "on-Road"?; lol

any way, I think you need to determine what it is you want your jeep to do, based with what you have and are willing to deal with. Are you ever planning to increase your tire size, or will you only stay stock? (what size are they now?)

Probably your biggest stumbling block will be the 4cyl; not that it wont do what you need it to do, but because of its power range its a limitation.

The 4.10 ratio is adequate for what it is, but I would not really suggest the 3.73 since it will take away from its performance and not do anything really for your MPG if that is an issue. If you are thinking (or already done) changing to taller tires than regearing to a lower ratio would be better, like 33" tires and a 4.88 would bring you back to being close to stock performance.

Ideally you want your gear ratio to match well with keeping the motor into the power band, too high and you lug the motor, too low and you are just eating fuel if you know what I mean.

So, if you answer those questions, that could help you determine what will work for you. Size of tires, and what do you realistically expect out of your jeep. As a DD I would consider just matching the gear ratio to the tallest tire I would expect to run.
 

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Discussion Starter · #3 ·
Ihave 32 inch Super Swampers on my jeep, on food was on road... lol. I was feeding my son and telling him to eat his food while typing. haha.

Yeah, I am not looking at getting to high into lift and stuff, as this jeep is kind of a beater that I didn't buy fairly new at all, and had all sorts of issues. I max out my speed on the highway at 60, if we are rolling down hill with a tailwind, and I had a tractor trailer out of no where on my ass, so thst's why i was seeing if there was anything to do with gears and top speed, or at least acceleration.

My old TJ was a 6 cyl, and I didn't have issues til I put 38" Super swampers on, but in my YJ, I am assuming the 4 cyl would cost more upgrading to a six cylinder as opposed to just upping the gear ratio....
 

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Ihave 32 inch Super Swampers on my jeep, on food was on road... lol. I was feeding my son and telling him to eat his food while typing. haha.

Yeah, I am not looking at getting to high into lift and stuff, as this jeep is kind of a beater that I didn't buy fairly new at all, and had all sorts of issues. I max out my speed on the highway at 60, if we are rolling down hill with a tailwind, and I had a tractor trailer out of no where on my ass, so thst's why i was seeing if there was anything to do with gears and top speed, or at least acceleration.

My old TJ was a 6 cyl, and I didn't have issues til I put 38" Super swampers on, but in my YJ, I am assuming the 4 cyl would cost more upgrading to a six cylinder as opposed to just upping the gear ratio....
Gotcha, so then you would want to shoot for a minimum of the 4.56 to get back to stock performance with those 32" tires; 4.88 could even get you better performance and only a little higher RPM at 60.

My calculator suggests about 2450RPM at 60 with 4.56 gears, 32" tires, and 2615RPM with 4.88. Oh, in 5th gear AX5 trans Im assuming. If its an auto or AX15 it would change.
 

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Discussion Starter · #5 ·
I guess I should have probably mentioned it was a 1991 YJ, AX-5 tranny, 4 cylinder, blah blah... lol.

I have done so much to the jeep that I forgot the basics. lol.
 

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Enjoyed you're explanation so I thought I would add on.

Have a Jeep 1990 YJ Wrangler. Has 33 x 12.5 on it. Struggles with power. Pulling small pop-up. Would the 4.88 gears make since?
 
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