Gear Upgrade

[Dennis B.]

I’m wanting to upgrade my gears to 5.38’s but my concern is how strong will they be in my 2020 JT? I don’t want the pinion to break every time I go wheeling.

 

[wayoflife]

On factory axles, I would highly recommend AGAINST anything higher than 5.13. Anything higher and the pinion will be way too small.

 

[Dennis B.]

On factory axles, I would highly recommend AGAINST anything higher than 5.13. Anything higher and the pinion will be way too small.

That’s what I was wondering. Thank you for your knowledge, I appreciate it.

 

[CalSgt]

On factory axles, I would highly recommend AGAINST anything higher than 5.13. Anything higher and the pinion will be way too small.

This for sure ^^^^

I watched a little social media clip of Mel Wade explaining pinion strength difference between different differential makes.

On a 5.38 pinion head from an advantec 44 the head was almost skinnier than the shaft.

what size tires are you planning to run?

 

[Dennis B.]

This for sure ^^^^

I watched a little social media clip of Mel Wade explaining pinion strength difference between different differential makes.

On a 5.38 pinion head from an advantec 44 the head was almost skinnier than the shaft.

what size tires are you planning to run?

37X13.50

 

[wayoflife]

37X13.50

4.88 will bring you back to stock performance. 5.13 will give you more power but you'll be driving on the high side of RPM at highway speeds. 5.38 would be way too much for 37's or at least, in my experience. They'd be more for 40.

 

[Dennis B.]

4.88 will bring you back to stock performance. 5.13 will give you more power but you'll be driving on the high side of RPM at highway speeds. 5.38 would be way too much for 37's or at least, in my experience. They'd be more for 40.

I am also wanting to pull a small camp trailer also when we go camping. I have a little single axle dump trailer and when I’m hooked to that it gets a little work out with the 4.10’s.

 

[Dennis B.]

I am also wanting to pull a small camp trailer also when we go camping. I have a little single axle dump trailer and when I’m hooked to that it gets a little work out with the 4.10’s.

I appreciate everyone’s input on my issue at hand so I’ll take all I can get. Thanks.

 

[CalSgt]

I’m wry pleased with my 4.88’s and 37’s, the only towing I do is my little adventure trailer though

 

[Dennis B.]

I’m wry pleased with my 4.88’s and 37’s, the only towing I do is my little adventure trailer though

How heavy is your trailer? If you don’t mind me asking.

 

[CalSgt]

Can’t remember…. I’d bet it’s about 2K+ Lbs without stacking any extra gear in it

 

[Dennis B.]

Can’t remember…. I’d bet it’s about 2K+ Lbs without stacking any extra gear in it



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I really appreciate your input, gives something to go off of.

 

[jwolfejt]

On factory axles, I would highly recommend AGAINST anything higher than 5.13. Anything higher and the pinion will be way too small.

This - most reputable shops around me would not even install 5.38 gears in stock axles. 5.13 would be the were they put the stop. I drove a JT with 40s on 5.13's - you will get by IIRC this shouldn't be far off what stock ratios would be.

 

[wayoflife]

I drove a JT with 40s on 5.13's - you will get by IIRC this shouldn't be far off what stock ratios would be.

With 40's? Sure, you can get by but with 5.13s, for me personally, it's far from what stock would be. 5.38 is the correct ratio for 40's and with a 3.6L, just barely or at least in my experience.

Also my experience - blowing up a rear end running 40's and 5.38s on a factory axle.

 

[jwolfejt]

With 40's? Sure, you can get by but with 5.13s, for me personally, it's far from what stock would be. 5.38 is the correct ratio for 40's and with a 3.6L, just barely or at least in my experience.

Also my experience - blowing up a rear end running 40's and 5.38s on a factory axle.

Not disagreeing with you at all. Was even recommended to stick with 4.88's for my use case. I recall watching a wayalife nitto jl experience - there was a white JL with 40s and 5.38's that had that same exact problem - although you guys were doing some pretty wild stuff lol.

 

[ScoobyCarolanNC]

I just did 4.88s on 37s and I'm wicked happy. I was on 4.10s for almost 2 years and it made a HUGE difference. Not to mention going from ~11mpg on the computer to ~15. I'm probably getting like 50-70 more miles a tank so that pretty solid!

 

[jesse3638]

I just did 4.88s on 37s and I'm wicked happy. I was on 4.10s for almost 2 years and it made a HUGE difference. Not to mention going from ~11mpg on the computer to ~15. I'm probably getting like 50-70 more miles a tank so that pretty solid!

Spoken like a true Bostonian!