We just re-Geared our Gladiator, very happy with our choice - Video inside with RPMs

[jeepncrowd]

FYI: I’m now running 4.88 gears with 37x12.50/R17 tires - runs great!

Ya. I knew my MPGs would take a hit, but I'm hoping to get as much as I can back.
For me to do want I want it just seems like the JT needs 37"s/38"s and 3" lift to compensate forvthe breakover and departure angles.
What MPGs are you getting at 70? And do you live in flat, small rolling hills our mountainous area?

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[No IFS]

5.13 for me. Swapping 4.10 to 4.88 is a waste and not enough for 37” and up. The tires are heavier. The factory Rubicon could’ve went with 4.56 nicely.
It’s impossible to gear to low with the 8 speed auto and any tire bigger than 35”

 

[WhatExit?]

5.13 for me. Swapping 4.10 to 4.88 is a waste and not enough for 37” and up. The tires are heavier. The factory Rubicon could’ve went with 4.56 nicely.
It’s impossible to gear to low with the 8 speed auto and any tire bigger than 35”

9 posts huh. You’re really just tossing crap out there but I’m not buying it. Give me 1fact to support that nonsense you’re spewing.

 

[No IFS]

It’s a balance. I’d be doing the lowest ratio, but I’m worried about strength , not freeway RPM with that small pinion head.

 

[WhatExit?]

It’s a balance. I’d be doing the lowest ratio, but I’m worried about strength , not freeway RPM with that small pinion head.

What Huh You’re “worried about strength”

Do tell us what you know that all the owners who are running 35’s and 37’s on stock gears don’t know

 

[RH 67]

It’s a balance. I’d be doing the lowest ratio, but I’m worried about strength , not freeway RPM with that small pinion head.

Yes, it`s a balance but going too low is as bad as having too high of gearing. With 37`s 4:88`s seem to be right in the middle.

 

[Daniel.cox8]

What gear oil do you run trying to deside

 

[Punkin Luvin]

What Huh You’re “worried about strength”

Do tell us what you know that all the owners who are running 35’s and 37’s on stock gears don’t know

The 5.13 is 41-8 teeth on the ring/pinion, the 4.89 is 44-9 teeth. The 5.13 will have an inherent advantage strength wise over the less girthy 4.89 ring/pinion. I would agree with his statement and that's what I chose 5.13 over 4.88 for my Bronco 9".

 

[RH 67]

The 5.13 is 41-8 teeth on the ring/pinion, the 4.89 is 44-9 teeth. The 5.13 will have an inherent advantage strength wise over the less girthy 4.89 ring/pinion. I would agree with his statement and that's what I chose 5.13 over 4.88 for my Bronco 9".

4:88`s are stronger than 5:13`s this has been known for quite awhile. Neither should be an issue with the amount of power the stock motor puts out.

 

[Daniel.cox8]

What gear oil is ran in the gladiator overland I'm almost done with break in for my new gears the book says m200 75w140 and m220 75w85. I got an overland

 

[Ericshere03]

9 posts huh. You’re really just tossing crap out there but I’m not buying it. Give me 1fact to support that nonsense you’re spewing.

To give my 2 cents. My Old 5.7 liter V8 Tundra with 32" street tires had 4.30 gears factory. So does the tacoma. Toyota has had as deep as 4.56 OEM gears on pickups. My 2005 Jeep LJ Rubicon was 4.10 w 30" tires and a .84 OD (not a steep OD) ... all the above are examples where OEM engineers got aggressive on gear ratios for similar vehicles. The icing here is that ALL the motors in the mentioned vehicles are low RPM dinosaurs (I Love the 4.0 BTW). Our 3.6 Pentastar is a spinner, low friction and light weight engine. Another data point, my 1980 vette's spins 3500RPM on the freeway with a stock flat tappet cam and has been doing so for 100k miles on my last car and 60k miles on my current (they didnt have an overdrive).

Bottom line Don't fear the RPM, the super low RPM gearing came about from the Oil Crisis days of the 70's. I think its better to spin our motors at 2500RPM than bog them down to 2000rpm. I'd say running at 3000rpm is a bit high, but we are literally all wrapping our minds around 100-200rpm @ 75mph.

ok, that was more like 75 cents... excuese my brain dump.

 

[Jzmattingly]

I also went with 5.13 on my JT Sport with 37's & AEV Borlah Beadlocks, but i also have the manual transmission and felt it was even more necessary to keep power in higher gears.. It was running fantastic until i started leaking oil from the rear seal. Its back at the dealership getting fixed now, then will be refreshing the diff fliuds (just hit 500 miles with the new gears) and testing offroad!

 

[Wizzard005]

I also went with 5.13 on my JT Sport with 37's & AEV Borlah Beadlocks, but i also have the manual transmission and felt it was even more necessary to keep power in higher gears.. It was running fantastic until i started leaking oil from the rear seal. Its back at the dealership getting fixed now, then will be refreshing the diff fliuds (just hit 500 miles with the new gears) and testing offroad!

we did ours in CA, but we live in AZ.. we forgot about the 500 mile thing, we had to stay a little bit longer... Gears have been great, no problems, so much more power offroad now in 4low..

 

[Texops]

What gear oil is ran in the gladiator overland I'm almost done with break in for my new gears the book says m200 75w140 and m220 75w85. I got an overland

hey what was your spline count on your overland 32 ?

 

[Alabama Mud Machine]

Yes, it`s a balance but going too low is as bad as having too high of gearing. With 37`s 4:88`s seem to be right in the middle.

If your jeep came with 4.10's and 33's from the factory, going with 4.56 and 37's puts it pretty damn close to stock power and final gearing. 4.88 is what I plan on eventually going with, to slightly over-gear for a little extra low-end and passing power. For now, my Jeep pulls the 37x13.50's with stock 4.10's just fine.

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