Hey guys, new here. I have a direction I think I want to go but hopefully you guys can help fill in the holes. I have a 96 XJ, 4.0 5spd. i plan to do a 6.5" IRO lift and run 33x12.50r15s with it. i will be swapping the rear for a ford 8.8 with disc brakes. I have plans to put lockers in both axles.

Now on to the unknowns: What are you guys doing with the Dana 30 up front? just beefing it up with better axles? But my biggest question has to be the correct gearing. The truck will still be driven onroad so i don't want retardedly bad fuel burn, ok more so i don't wanna be killin 4k rpm doin 65mph. That would just annoy the crap outa me. So I was thinking 3,73's but i see a lot of you guys run 4.10 and up. How do i decide what the correct gear ratio is for 33's? Thanks!

 

My buddy has 4.10's on 33's and is happy with it. I would go to 4.56's that way if I want to go up to 35's or something later, the gears are already there.

 

You go to this website and use the calculator.

http://www.grimmjeeper.com/gears.html


Also, I'd suggest finding a smaller lift for 33s.

 

4.56 is the way to go for 33s, however being a 5sp 4.10s would likely keep you at about stock rpms at highway speeds.

 

I'm at about 3k at 65-70mph with 33s and 4.56 gears. Its perfect for DD and rocks

 

You can find 8.8's with 4.10's,disc's & a limited slip in them.
Then, look for a HP 30 from a 4 banger (4.10) & put them both in.

Cost= $300 +/-

 

Thanks guys, i guess now all I have to do is figure out which Transmission and transfer case i have. I think i have the AX15 but not sure yet

 

The 5 speed that shipped with the 4.0 in 96 is the AX-15. Transfer case is probably the NP231, I've never heard of a 242 on a manual before. Shift pattern is 2H 4H N 4L

 

Thanks, that's what I thought but I wanted to verify. It definatly is the AX-15. And everywhere i have looked says it should have the NP231 but i have been unable to positivly identify it by markings on the case itself.

 

It's on this tag, but if the shift pattern is as was posted above then its a NP231 for sure anyway.

 

Yes it's the same shift patter. Thanks for the great info!

 

I have 4.10s on mine with 33s, and am happy with highway driving. In 4th I do 70 at about 3000rpm. In 5th 65mph is about as slow as i like to go, it starts to bog a bit, about 2000 rpm.

I'm happy enough with 4.10s but would prefer 4.56, even on the highway. As it is now, 3000rpm in 5th would be almost 100mph. A speed I will never drive a lifted jeep. With 4.56s 3000rpm in 5th would only be 88mph. 75mph would be a comfortable 2500rpm.

3.73 would be too tall in my opinion, you would be bogging in 5th gear at any US legal speed. 75mph would be about 2000 rpm. And 3000 rpm would get you almost 110mph.

So to sum up, 4.10s are fine with 33s, but 4.56s are better. 4.10s are a little tall for 35s if you ever plan to step up tire size. 4.10s are much easier to find in the JY. 4.88s would still be quite drivable as long as long highway drives were not your norm.

 

Oh, as a side note, to get 4000rpm at 65mph you would need something like 8.3:1 axles.

 

On an automatic with 33s, you want 4.56s

On a manual with 33s, you want 4.10s

That'll be a different story if you ever plan to go taller tires.

 

Yeah i was playing with that calculator and it looked like the 4.10 setup would be slightly better than stock with 33's. I think that's as big as i want to go on the XJ. Personally, i think 35's look to big with a 6.5" lift. Again, just my opinion, but I think the 33's look better and will get me where i want to go just as well as 35's.