Regear for better interstate driving?

[Iowajeeptj]

Hello everyone,

I have a 2000 Tj Sahara 4.0 with a Dana 44 rear axle 3.73 gear ratio. NV3550 manual transmission. Dana 30 up front. Current tire size in 30". I've spent a lot of time getting the little things on this Jeep sorted out and I'm to the point I want to make it a little more comfortable driving to work on the interstate (70 MPH). Honestly, it doesn't like going that speed. Do I need to think about getting some more power or would regearing help me out? If so, what ratio would be recommended? On a side note, I do plan on eventually doing a modest 2 inch lift and maybe 32's in the future but I wanted to get everything sorted first. Any thoughts?

 

[Jerry Bransford]

4.10 would provide a nice boost for 30's but go with 4.56 if you go with 32's which will likely end up as 33's.

 

[1o1proof]

I went with 4.1 and really wish I had 4.56.

 

[machoheadgames]

Figure out what tire size you guaranteed want to run, and then pick your gears. If there’s a chance you’ll go 32’s, there’s a good chance you’d go to 33’s. If any chance of 33’s, I’d go straight to 4.88. 32’s I’d go with 4.56. 33’s would still be good with 4.56 but 4.88 is better, so you may as well figure it out now before you make the wrong gear decision.

 

[Iowajeeptj]

Figure out what tire size you guaranteed want to run, and then pick your gears. If there’s a chance you’ll go 32’s, there’s a good chance you’d go to 33’s. If any chance of 33’s, I’d go straight to 4.88. 32’s I’d go with 4.56. 33’s would still be good with 4.56 but 4.88 is better, so you may as well figure it out now before you make the wrong gear decision.

So 4.88 with the 33's I'll inevitably end up going with thanks for the advice guys!

 

[Rubicon88]

4.10's and 32" is the absolute max...
4.56 gearing will be much better...

The above said ....
My question to you though is this...when you say it doesn't like going 70 mph...define that a bit.

You've got 3.73's now and a 30" tire...70 mph shouldn't be a problem.

I'm just trying to figure out your realistic expectations here

 

[freedom_in_4low]

based on my understanding of what Iowa looks like, I think 4.56 would be fine for 33's. If you end up wheeling a lot in higher elevation or have to pull miles at a time of 7+% grades to get over a mountain pass, that might call for 4.88.

 

[Iowajeeptj]

4.10's and 32" is the absolute max...
4.56 gearing will be much better...

The above said ....
My question to you though is this...when you say it doesn't like going 70 mph...define that a bit.

You've got 3.73's now and a 30" tire...70 mph shouldn't be a problem.

I'm just trying to figure out your realistic expectations here

Just feels like my RPM's are getting pretty high by the time I get to 70+. I'd have to go for a drive tk tell you exactly how high

 

[machoheadgames]

Just feels like my RPM's are getting pretty high by the time I get to 70+. I'd have to go for a drive tk tell you exactly how high

A regear is going to make that higher. Get used to it. 2800-3000 cruise rpm at 70-75 is pretty damn good.

 

[Iowajeeptj]

based on my understanding of what Iowa looks like, I think 4.56 would be fine for 33's. If you end up wheeling a lot in higher elevation or have to pull miles at a time of 7+% grades to get over a mountain pass, that might call for 4.88.

It'll spend 95% of its life on very flat ground. Whenever we go to the mountains it'll be in the 2014 unlimited my wife drives

 

[freedom_in_4low]

It'll spend 95% of its life on very flat ground. Whenever we go to the mountains it'll be in the 2014 unlimited my wife drives

you'll find a couple of philosophies around gearing selection here. The more popular one seems to be "more is better". I'm in what's probably a less popular camp, which is "enough is enough" - or said less concisely - once you have enough, there's not really anything to gain by having more, and in fact risk causing other problems, like difficult-to-solve driveline vibration issues.

 

[Rubicon88]

Just feels like my RPM's are getting pretty high by the time I get to 70+. I'd have to go for a drive tk tell you exactly how high

Ok...exactly why I wanted to know...

If you feel your rpms are getting up there lower gears will make them higher.
That said bigger tires will lower the rpm and suck the power out...

Now I can tell you this you need to have no fear about those rpms. That straight six will hold just fine. I promise you.