4.56 vs 4.88 gears

K

K9wells

New member
I have a 2012 Rubicon 2D automatic and will be running 35" MTR/kevlar tires i was told that 4.88's can send the ecu into limp mode and was told I should go with 4.56 anyone have any input?
 
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jnabird333

jnabird333

-
K9wells said:
I have a 2012 Rubicon 2D automatic and will be running 35" MTR/kevlar tires i was told that 4.88's can send the ecu into limp mode and was told I should go with 4.56 anyone have any input?
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Any gear change will likely confuse the computer if you do not correct it with a programmer. As long as you have a programmer that can adjust for it, a gear swap shouldn't be an issue.
 
cozdude

cozdude

Guy with a Red 2-Door
jnabird333 said:
Any gear change will likely confuse the computer if you do not correct it with a programmer. As long as you have a programmer that can adjust for it, a gear swap shouldn't be an issue.
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^^^this. if you have a programmer like a supercips flashcal or the aev procal to set the ECU to the proper gear ratio you will be good.

that being said i would do the 4.88's. its a great ratio for 35's and if you even want to upgrade tires to 37's you will not have to worry about being underpowered.

here are some nifty charts that Wayalife provided in the noobie section to help show where your rpm range will be depending on your transmission, tire size, and gear ratio

attachment.php
 
K

K9wells

New member
I am running the Bullydog GT but was told the ECU can still sometimes go into limp mode I only want to re gear once and being stationed overseas don't have access to a dealership if the ECU gets messed up.
 
AZDIESELPIG

AZDIESELPIG

Member
K9wells said:
I am running the Bullydog GT but was told the ECU can still sometimes go into limp mode I only want to re gear once and being stationed overseas don't have access to a dealership if the ECU gets messed up.
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I am running 5.13's on a 2013 2 door automatic. I used the FlashCal to adjust tire size and gear rato. No limp mode.

However, I had also installed a Yukon grizzly auto locker at the same time - come to find out auto lockers create havok with the tranny in the 2012 and up JK's.

Removed the Grizzly and replaced it with the Eaton "E" Locker and all my issues went away.

if you have a manual its a non issue, but the autos can only use a selectable locker in the rear. The traction control is confused by the locking and unlocking of the auto locker when turning.
 
K

K9wells

New member
Well to be on the safe side i went ahead and took northridge4x4 advice and went with the 4.56 gears trying to avoid messing up the ecu. The bullydog also allows me to put in the new gear ratio. My next hope is these italian mechanics can swap gears and not mess them up!
 
K

K9wells

New member
silversmoke said:
I am running 5.13's on a 2013 2 door automatic. I used the FlashCal to adjust tire size and gear rato. No limp mode.

However, I had also installed a Yukon grizzly auto locker at the same time - come to find out auto lockers create havok with the tranny in the 2012 and up JK's.

Removed the Grizzly and replaced it with the Eaton "E" Locker and all my issues went away.

if you have a manual its a non issue, but the autos can only use a selectable locker in the rear. The traction control is confused by the locking and unlocking of the auto locker when turning.
Click to expand...

I plan on going with the Eaton E locker once my stock lockers go.
 
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