Need some re-gearing education / advice.

1

'18 WIllysW

Member
Hello.
I have an 18 JK 2-dr Willys that's been upgraded with 3.5" Metalcloak lift, 35s, bumpers, fenders, and more.

I'm still running an unmodified d30 up front and an modified read d44 (added artec truss, LCAs, spring perches, and rear track bar mount).

I'd like to get a Dana Ultimate 44, but that's likely far in the future as I save up the cash for it. In addition to the d44, I'd like to goto 37s (after the d44).

With that in mind, I'm thinking about re-gearing to tide me over until I can save up for the front d44.

I've looked at gear charts, etc, but I'm having difficulty understanding what I'm looking at and reading.

It looks like 4.56 is the "green" (acceptable) gear ratio for 35-39s.
Whereas 4.88 is "blue" (performance) gear ratio for 33-37s.

As someone that has never re-geared, I'm not sure what this translates to in real life. I realize higher the ratio number, the better my acceleration will be with the heavier tires. I also vaguely get the idea that the higher the number, the lower my top speed will be (not a big issue as long as I can hit 80-85 on the interstate).

What I don't understand is the difference between "acceptable" and "performance." Acceptable says it's good for daily driving, which I do. But performance says it's "fair" daily driving. I suppose I don't understand how higher acceleration translates to worse daily driving... unless the top speed becomes a factor.

Another question I have is "does weight matter?" I have a moderate weight build. I'm in a 2-door, my front bumper is aluminum with a winch, whereas the rear is steel. I have a single steel skid plate over the oil pan / transmission. I've removed the back seat and pack fairly light. Do these charts take weight into consideration? Is it necessary to think that way?

I appreciate all the advice / experience you can offer.
 
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Also meant to add, I'd like to (if possible) find a good gear ratio that would cover me between the 35s for the immediate future, and would still work in the rear axle when / if I get the d44 and 37s.
 
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I'm not a 100%, but I do know there is a limit to what gear size you can run in the 30, I believe 4:88 is the max. I ran 4:88s and 37s and it would search for gears a lot on long inclines but other than that it was fine. If you are thinking of upgrading to a UD44, I would definitely go with the 4:88s now, so you don't have to regear again once you get the new front.
 
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4.88 would be a good compromise and cover you for both 35s and 37s. I know a few people running 4.88 ratio on 37s that are happy with it. 5.13 would offer better performance on 37s if you wheel hard, especially if you don't have the Rubicon's 4:1 transfer case ratio.
 
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I would not upgrade gears before moving to the D44 in front, it is expensive to regear and you do not want to have to do it twice in the front. I put a prorock 44 in before I regeared. I have a '17 JKU with '37s and 4.88 gears works just fine for me, both wheeling and highway driving.
 
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wjtstudios said:
I'm not a 100%, but I do know there is a limit to what gear size you can run in the 30, I believe 4:88 is the max. I ran 4:88s and 37s and it would search for gears a lot on long inclines but other than that it was fine. If you are thinking of upgrading to a UD44, I would definitely go with the 4:88s now, so you don't have to regear again once you get the new front.
Click to expand...
There isn’t. You can run 5.38’s. It’s about as good as fucking your sister but you can.
 
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To answer the OP's question about freeway speed. You are correct the higher the number the lower the ratio. That translates into higher RPM to achieve the same speed. So yes you'll be able to run 80-85 with your RPM's higher. This not only will affect the fuel mileage but causes your drive lines to spin faster. This may identify a driveline vibration which was not noticed and the lower RPM.
 
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