VIDEO : OP ED - Are 5.13 Gears Needed with 37 Inch Tires on a JL Wrangler... and MORE

wayoflife

Administrator
Staff member
I get a lot of people asking me a ton of questions on a regular basis and rather than let them get lost somewhere in cyberspace, Cindy and I decided to start answering them on our YouTube channel and in an all new series we're calling, OP ED. Essentially, we'll be creating videos where you'll get to hear exactly what I think and get my 2¢ on all sorts of topics regarding Jeeps and all based on the questions I've been getting. In this very first episode of OP ED, I'll be taking on the question of, "do I need to re-gear my JL Wrangler with 37" tires?" As an added BONUS, you'll even get to see something special, a kind of easter egg and totally unrelated to gears or tires, if you stick around to the very end. We hope you enjoy.


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JAGS

Member
Ha ha. Creative title. I see what you did there. Gonna watch now, and look forward to future OP EDs.
 

Jeeeep

Member
good info, i'm running 4.88's in my JK and will probably do the same in the JL.

5.13's IMO still give pretty good mileage but given the PR44 runs JKU gears, are you not too concerned about the RP?

Jeep truck already in the garage! Good to be Mel :rock:
 

JTCO

Meme King
Good info about the gears. And love seeing close-ups of the sport JT. Can't wait to start building mine :wings:
 

jorgelrod

New member
good info, i'm running 4.88's in my JK and will probably do the same in the JL.

5.13's IMO still give pretty good mileage but given the PR44 runs JKU gears, are you not too concerned about the RP?

Jeep truck already in the garage! Good to be Mel :rock:

The difference in JK and JL ring gear in the Dana 44 is not that big that it would be an issue, while the pinion shaft on the JL is bigger, ring diameter is about the same.
 

Jeeeep

Member
The difference in JK and JL ring gear in the Dana 44 is not that big that it would be an issue, while the pinion shaft on the JL is bigger, ring diameter is about the same.

yep, my question was in reference to the JL PR44 since it still uses JK gears
 

DavidDJL69

Member
Thanks Cindy and Eddie for this new installment on your forum. It’s like having a conversation with you and having you answer many of the questions the rest of us would like to ask. Your comments about regearing to 5.13’s, both pros and cons, was instructive and very helpful to those of us considering a regear. Great stuff.


Sent from my iPad using JL Wrangler Jeep Forum mobile app
 

doubletapdaddy

Caught the Bug
In my VERY limited experience in running 37's with the 8-speed, I'm very happy that a re-gear is not entirely necessary. If there's anything I don't like it's the thought of dumping good money into stock axles.

Have you tried any of the other "37.xxx" calibration settings in the Tazer-JL to see if that helps downshifting without compromising speedo accuracy? I know that when I adjusted the Tazer for my 37s, the setting of "37.065" that you used in your TAZER JL How-To was not even an option for mine, or at least on the firmware that I am running.

Also, I understand that we are not discussing 4-wheel drive however I couldn't help but to think of the transfer case mod that was done when deleting the FAD on CODE1.
 

dixonk

Member
In my VERY limited experience in running 37's with the 8-speed, I'm very happy that a re-gear is not entirely necessary. If there's anything I don't like it's the thought of dumping good money into stock axles.

Have you tried any of the other "37.xxx" calibration settings in the Tazer-JL to see if that helps downshifting without compromising speedo accuracy? I know that when I adjusted the Tazer for my 37s, the setting of "37.065" that you used in your TAZER JL How-To was not even an option for mine, or at least on the firmware that I am running.

Also, I understand that we are not discussing 4-wheel drive however I couldn't help but to think of the transfer case mod that was done when deleting the FAD on CODE1.

This is an interesting concept. Right now I have mine set to true measurement of 36.xxx. It will occasionally hit 8th gear but for the most part it’s pretty much gone. Otherwise the Jeep drives fine and I have no other complaints. I’m wondering if it’s just a simple programming to get it to go into 8th past 70mph.


Sent from my iPhone using JL Wrangler Jeep Forum mobile app
 

tjeeper

New member
Eddie- Are you still happy with your choice of 5.13s for Jet Li? Everything I have been reading 4.88s do better on the highway with 37s and the 8 speed, but my installer is telling me 5.13s will allow me to be in 8th gear more often. Maybe it is the altitude, the hills or the 80mph speed limit, but I'm not understanding why he seems to think I would be better off with 5.13s. Today would you still pick 5.13s over 4.88s?
 

wayoflife

Administrator
Staff member
Eddie- Are you still happy with your choice of 5.13s for Jet Li? Everything I have been reading 4.88s do better on the highway with 37s and the 8 speed, but my installer is telling me 5.13s will allow me to be in 8th gear more often. Maybe it is the altitude, the hills or the 80mph speed limit, but I'm not understanding why he seems to think I would be better off with 5.13s. Today would you still pick 5.13s over 4.88s?
To be honest, I am way happy that we went 5.13s now than when we first had them installed. I don't know if it was the transmission that learned or me just getting used to it but over the long haul, I find that I LOVE the extra power I have and find that even MPG has gotten a bit better since making this video. If I were to do it again, there'd be no question that I'd go 5.13 with 37's.
 

Ron

New member
Sorry, late to the party, reading as much as I can while I wait for my first Jeep to be delivered.

The not downshifting below 5th issue might be this..... The speedo receives it's signal from one of the wheel speed sensors or, maybe, the output shaft. The transmission ECU uses a speed signal from the output shaft only.

The Tazer adjusts the signal to the speedo but not the trans ECU. With the 5:13 gears the driveshaft and therefore the output shaft is turning much faster and is probably telling the ECU that another downshift will over speed either the trans or the engine.

Most of my experience is with Toyotas. 3rd Gen Tacos will hit the speed limiter based on output shaft RPM if you run 5:29 gears and 33 inch or smaller tires. I'm thinking the JL might be doing something similar.
 

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