Gear ratio for 37s? Front locker only?

[bleda2002]

Never driven in Michigan, but if you've never driven in Texas, some of the regular highways are 80mph, and running 80 you get stuck behind all the semis. When I drive through there, I set the cruise between 85-90 just to keep up with regular traffic, and you'll still get run over by a 1 ton dually hauling a cattle or horse trailer.

At 85 with 5.13s and 37s you are up around 2800 rpm and close to the second stage of the oil pump.

At 85-90 you're going to be running high rpms anyways unless you are going down hill as even stock it won't hold 8th in 90 much less on 37s and a lift.

If you routinely drive 85-90 down hill like one of our members I could see 5.13s being too much but everywhere else you are talking like 100 rpms differences in 8th at 90 according to this calculator by Spicer. https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

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[Josh00333]

How much did that all run you? The regear and adding the locker?

E-locker was 1400, Gear set for the front and rear was 1k, Install was 650 each. I did the wiring for the locker. So $3700+tax.

 

[JT1]

At 85-90 you're going to be running high rpms anyways unless you are going down hill as even stock it won't hold 8th in 90 much less on 37s and a lift.

If you routinely drive 85-90 down hill like one of our members I could see 5.13s being too much but everywhere else you are talking like 100 rpms differences in 8th at 90 according to this calculator by Spicer. https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

unless you are REALLY aero dirty, these 3.6s make enough HP to run at those speeds at 2500 rpm
I know that mine stock at 85 wasn't turning 2500...

 

[bleda2002]

unless you are REALLY aero dirty, these 3.6s make enough HP to run at those speeds at 2500 rpm
I know that mine stock at 85 wasn't turning 2500...

8th gear, stock tire size of 32.8 on 4.10s you are running 89 mph at 2500 rpm. More likely you are in 7th or even 6th at that speed of there is any kind of head wind or even the slightest incline so you'll be running even higher.

32.8/4.10 = 35/4.56 = 37/4.88 so 5.13 is literally just 1 step farther

 

[JT1]

8th gear, stock tire size of 32.8 on 4.10s you are running 89 mph at 2500 rpm. More likely you are in 7th or even 6th at that speed of there is any kind of head wind or even the slightest incline so you'll be running even higher.

32.8/4.10 = 35/4.56 = 37/4.88 so 5.13 is literally just 1 step farther

Mine is a manual and wasn't 4.10s. I wasn't running that rpm. OP has a max tow, so 4.10s, but tiny tires originally.

And my point is, you don't want to set the cruise on the highway for 4 hours straight running 90 and being into the second stage of the oil pump.

 

[tom.mary.glad]

Mine is a manual and wasn't 4.10s. I wasn't running that rpm. OP has a max tow, so 4.10s, but tiny tires originally.

And my point is, you don't want to set the cruise on the highway for 4 hours straight running 90 and being into the second stage of the oil pump.

What rpm does second stage kick in?

 

[JT1]

What rpm does second stage kick in?

Mine kicks on at an indicated 2900 on the tach. So right at 86mph with my setup.

6spd, 5.13s and 37s.

 

[bleda2002]

Mine is a manual and wasn't 4.10s. I wasn't running that rpm. OP has a max tow, so 4.10s, but tiny tires originally.

And my point is, you don't want to set the cruise on the highway for 4 hours straight running 90 and being into the second stage of the oil pump.

Manual actually runs higher RPM's, the 6th gear is only .72 instead of .67 like 8th.

Calculator says a sport running 6th gear is at 2450 at 85 and 2550 at 90 on stock sport tires (31.5) and 3.73s. With a manual maybe 4.88 makes more sense again especially with the extra deep first gear the manual has. Manual and 4.88s is running higher RPM's everywhere than the auto and 5.13's so i think the real caveat here is that experience with the manual doesnt translate to the auto and vice versa

 

[AstroZombie]

I'm on 37s, and regeared to 4.88s. It's OK. It was slow stock, it's slow now, and it would be slow with 5.13s. I easily could've done lockers as I did my regear myself, but decided against it. I have the LSD in the rear, and with the traction control, I have never left a trail wishing I had lockers.

Which is ironic bc on my 2017 JKUR I used lockers all the time. The 2013 2 door before it? Never needed lockers then. Each vehicle has been on the same extreme rock trails in SoCal. I can't explain it but that's what it is.

where are these trails in SoCal?

 

[AstroZombie]

if a train leaves the station geared at 4.88, traveling 80 miles per how how long will it take it to travel 160 mile? Will it get there faster if it has 5.13 gears?

 

[tom.mary.glad]

Yes, you have a real limited slip so personally I'd just go front locker and leave the rear as a limited slip

Follow up question: does regearing affect the factory limited slip differential operation? Or is that a separate part of the differential?

 

[bleda2002]

Follow up question: does regearing affect the factory limited slip differential operation? Or is that a separate part of the differential?

Seperate

 

[Ali689]

2023 gas. I went with 5.13's with 37's and am very happy. I run OX lockers front and rear

 

[guntrust]

So, I'm going to regear for 37s. 3.6L, auto, Sport.

I don't wheel much yet, but who knows when last kiddo goes off to college...

First, what gear ratio do you recommend? 4.88 or 5.13? I'm in TX = flat. I don't drive aggressively. I don't tow and don't plan to.

Second, is a front locker only a good idea? I figure since the rear has limited slip or BLD or whatever Jeep calls it, maybe I can save some money and only add front??

Thanks!

I have 37's with a manual 3.6 and so cannot speak authoritatively on auto but i can say that since regearing to 5:13 i have ceased lusting for hemi conversion and/or corvette as second vehicle. Totally different driving experience, love it! And i think i actually get slightly better fuel economy than when i had 33's. Can actually use 6th gear now.

 

[Bonanza]

where are these trails in SoCal?

What are you in the mood for? Closest to you, and also a Jeep badge Trail, in Pinyon Canyon with the squeeze. The easier trails you'll find will be in Anza Borrego national Park, including truckhaven. Next up is the Big Bear trails: Dishpan, Holcomb Creek, Gold Mountain, John bull, Mottino Wash, etc. The big boy stuff is going to be Johnson Valley, home of King of the Hammers. There the easier trails are Big Johnson and Claw Hammer, stepping up to the real hammers trails. While a gladiator did finish KOH once, it wasn't pretty.

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