Re-gearing question: 37's with 5:13 or 4:88 gears?

[Jwardrip]

I know its been discussed a million times, but I'm concerned I might of messed up. When I went with 37's, I never see 8th gear hardly. (Currently have 4:10's) My Gladiator is in the shop now as we speak, getting 5:13's installed. I was going to go with 4:88's, but my mechanic suggested I go with 5:13's, because he said it will help with towing. Anyone have any issues with 37's and 5:13's or does anyone with 4:88's wish they would of went 5:13's?
Hoping I will be ok. Guess Ill find out this evening

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[YPCUB]

5.13s will be fine. There really is not much differnece between 4.88s and 5.13s. If you were 37s on flat roads with a bit of towing 4.88s are the choice but elevation and towing 5.13s are good. Checkout this video for more info. You wont regret 5.13s especially if you ever go taller tires again , add weight, tow etc.

 

[Jwardrip]

5.13s will be fine. There really is not much differnece between 4.88s and 5.13s. If you were 37s on flat roads with a bit of towing 4.88s are the choice but elevation and towing 5.13s are good. Checkout this video for more info. You wont regret 5.13s especially if you ever go taller tires again , add weight, tow etc.

Thank you!!

 

[Alanscott_1]

I share the same concerns, mine is currently is the shop as well getting 5.13s installed. I don’t really want to take a hit to highway mileage, but the reality is I’m on the freeway less than 10% of the time.

I originally wanted to go with 4.88s, but my shop strongly recommended 5.13s, saying they have re-geared many JT/JLs running 37s and that seems to be the sweet spot for them. I guess we shall see.

Update: Got the Jeep back today, had a 50 mile trip back home, driving through some hilly roads at 55-65mph it held 8th with no problems at all. I’ll be driving to Texas in a month or so from NJ, and up into some higher elevations in New Mexico and Colorado, will be a good highway mileage test for the jeep.

 

[tmqdoc1]

I share the same concerns, mine is currently is the shop as well getting 5.13s installed. I don’t really want to take a hit to highway mileage, but the reality is I’m on the freeway less than 10% of the time.

I originally wanted to go with 4.88s, but my shop strongly recommended 5.13s, saying they have re-geared many JT/JLs running 37s and that seems to be the sweet spot for them. I guess we shall see.

Update: Got the Jeep back today, had a 50 mile trip back home, driving through some hilly roads at 55-65mph it held 8th with no problems at all. I’ll be driving to Texas in a month or so from NJ, and up into some higher elevations in New Mexico and Colorado, will be a good highway mileage test for the jeep.

 

[tmqdoc1]

Hey how did your trip go?

 

[Minty JL]

Based on the feedback here and now my real world experience.....4.88s should be fine with 37s

I have a '23 Mojave with and AEV lift and 37x13.5s and I'm honestly content right now with the 4.10s. I was expecting it to be a total slug with the 3.6......but it's very much drivable.

I was set on 5.13s, but I think if I upgrade gears I'll go 4.88 and be perfectly happy. I do a fair amount of road trips and so far I'm not bummed with the performance. I actually think 5.13s in my opinion would be an overkill for a daily driver.

And I say this coming from a Tahoe with a built motor, cammed, 3200 stall converter and 3.73 (2wd).

 

[Wheelin98TJ]

You did not mess up, 5.13 is ideal for 37s.

 

[Panthers65]

I"m waiting on my 5.13's to be delivered.

 

[Richard79]

Vary rarely will u hear someone say they wish they went with higher gear, most ppl wish they would have went lower, I went with 4.56 on my wrangler with 35’s and wish I would have went 4.88, when u do the gladiator I will go with 5.13 with 37’s

 

[TheRealGinjaNinja]

I am finally about to pull the trigger on regearing my Mojave on 37s. I will be doing 5.38s. If you plan to run 37s I don't really understand 4.88s...it will provide some improvement but not ideal. These Jeeps were undergeared from the factory in my opinion. Between 4.88s or 5.13s...no question go with the 5.13s, they are solid choice.

To run 75mph on 37s, the 3.6 motor is gonna need around 2300-2500 rpms to maintain speed. On my stock gears I sit in 7th gear at 75mph just under 2500 rpms. It is comfortable even with my loud exhaust and would only be a huge improvement running 2500 rpms with 5.38s in 8th gear.

Don't fear the gear!

Cheers

 

[Escape.idiocracy]

I am finally about to pull the trigger on regearing my Mojave on 37s. I will be doing 5.38s. If you plan to run 37s I don't really understand 4.88s...it will provide some improvement but not ideal. These Jeeps were undergeared from the factory in my opinion. Between 4.88s or 5.13s...no question go with the 5.13s, they are solid choice.

To run 75mph on 37s, the 3.6 motor is gonna need around 2300-2500 rpms to maintain speed. On my stock gears I sit in 7th gear at 75mph just under 2500 rpms. It is comfortable even with my loud exhaust and would only be a huge improvement running 2500 rpms with 5.38s in 8th gear.

Don't fear the gear!

Cheers

5.13’s is the rout we are going! Woo!
Any concerns with pinion head for 5.38’s??
I understand the axle improvements between Jk and JL/JT are decent… seen several 5.38 pinion heads sheer and rip teeth apart… what I haven’t see. Is a JL/JT pinion next to a JK pinion (44’s)…. So maybe im assuming the similarities are close enough.

 

[Ted Striker]

I am finally about to pull the trigger on regearing my Mojave on 37s. I will be doing 5.38s. If you plan to run 37s I don't really understand 4.88s...it will provide some improvement but not ideal. These Jeeps were undergeared from the factory in my opinion. Between 4.88s or 5.13s...no question go with the 5.13s, they are solid choice.

To run 75mph on 37s, the 3.6 motor is gonna need around 2300-2500 rpms to maintain speed. On my stock gears I sit in 7th gear at 75mph just under 2500 rpms. It is comfortable even with my loud exhaust and would only be a huge improvement running 2500 rpms with 5.38s in 8th gear.

Don't fear the gear!

Cheers

Just for reference, I run 2500 in 8th gear at 75 mph with 5.13s and 37s.

 

[TheRealGinjaNinja]

Just for reference, I run 2500 in 8th gear at 75 mph with 5.13s and 37s.

Good to know actually. I was basing this off the popular regearing calculator in the forums. 2500rpm is where I would like to be in 8th.

What tire are you running?

Cheers

 

[TheRealGinjaNinja]

5.13’s is the rout we are going! Woo!
Any concerns with pinion head for 5.38’s??
I understand the axle improvements between Jk and JL/JT are decent… seen several 5.38 pinion heads sheer and rip teeth apart… what I haven’t see. Is a JL/JT pinion next to a JK pinion (44’s)…. So maybe im assuming the similarities are close enough.

Pinion strength between 5.13 and 5.38 are essentially the same. That is one argument for the 4.88s though is that they should be a little stronger, but I don't think that is much of an issue on JL/JT until you get into power adders (supercharged or V8).

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