Time to regear the JK 4.56 vs 4.88

[MuleShoer]

The JKU is equiped with ARB bumpers, winch, hardtop, full rack, and 33 in tires ( actually they are 285-70X17" so not quite 33")
I drive 80 miles / day on the interstate, things were ok unitil I added the rack, now th JK can't get out of its own way.
Since a diesel conversation has not materialized so I am going the regear route.
This is an automatic with 4.10 gearing. on a one for one basis 4.56 gearing would bring back operating rpm to stock , roughly 2150rpm @ 70mph
My concern is not many people use 4.56 gears instead they go with 4.88's
WHY?
Also I plan on towing a Conqueror Compact out to Chaco canyon in June so the mileage performance is a big concern on a 3000 mile trip

Thoughts

 

[leman]

if your gonna be towing i would go ahead with the 4.88, but thats just me.

im running 35"s with the 3.72 gears and had a rack on there for awhile. when i regear im going to 5.13s

 

[ROKTAXI]

I've been running 4.88's for about 3 years now. Although it's not my DD, it still behaves well on the highway (fuel mileage). I'm running 33's, auto trans. RPM's are about 2300 @ ~65 mph. I rarely do 70.

I don't think you'll get much, if any, negative input from those that have changed to 4.88's.

 

[MuleShoer]

I've been running 4.88's for about 3 years now. Although it's not my DD, it still behaves well on the highway (fuel mileage). I'm running 33's, auto trans. RPM's are about 2300 @ ~65 mph. I rarely do 70.

I don't think you'll get much, if any, negative input from those that have changed to 4.88's.

Things were OK until the kicked the interstate speed to 70 now I have trucks climbing up my spare tire

What kinda of fuel mileage you getting?

 

[ROKTAXI]

What kinda of fuel mileage you getting?

+ / - 16mpg

130K

 

[ssmathis]

I had a similar setup and went with 5.13 gears but I live at over 6000 feet. I was running 2800 rpm's at 75 out here in Colorado.

Scott

 

[Hilldweller]

I have 4.56 gears, 285/75-16 tires, an automatic, and tow a Conqueror Compact. If I could do it again, I'd have 4.88s.

I live in a hilly area and the gears are fine (after using the Superchips Flashpaq) until I hitch up the trailer; then it dogs-down on the hills something awful.

Fuel economy? Forget it. 15-18 without the trailer; 14-ish with the trailer.
We pulled it from N. Georgia to S. Arizona on our longest trip; about 11,000 miles of towing it so far.

I have a 2-door that had the second softest springs. Added bumpers & winch ---- that made it sag and wallow. Switched the springs to the stiffest OE, donated from an Unlimited/tow package. Then added a Teraflex 2.5" puck lift with shocks on top of that.
It rides much better than stock.

Do yourself a favor and add another trans cooler before you tow.

 

[Scott Brady]

Go as low as you dare. I would go 5.13s with that motor. We have 4.88 in the OVJK and it is adequate.

 

[Hilldweller]

Go as low as you dare. I would go 5.13s with that motor. We have 4.88 in the OVJK and it is adequate.

Don't you have 35s on it now though?

 

[Scott Brady]

It does have 35s.

I would love it to have 5.13s

I had 5.29s in the Tacoma with 34s and it was juuuuuust right

 

[Hilldweller]

It does have 35s.

I would love it to have 5.13s

I had 5.29s in the Tacoma with 34s and it was juuuuuust right

Dude, drive one with 35s and 5.38s; you'll really like that.

 

[alosix]

I went through a similar dilema with my TJ when it was running 4.10s and 35s. It badly needed more gear.

After doing the math on both, 4.56 just didn't seem to be enough of a change to warrant the work. Ended p with 4.88s. Jeep much happier. I know, diff engine, diff Jeep. But, if you're unhappy with 4.10, I don't think 4.56 is enough of a change to make it better.

Jason

 

[MuleShoer]

no longer 4.56 now 4.88 vs 5.13

I have 4.56 gears, 285/75-16 tires, an automatic, and tow a Conqueror Compact. If I could do it again, I'd have 4.88s.



I went with OME springs and the improvement was great. roger the trans cooler..Oh and Conqueror used to be Chips.

All the comments/ suggestions, both here and on the JK site have been..4.88 or 5.13... going to 5.13's makes me very nervous
My concerns are when I am in some serious mountains and I come out of OD, ouch. I have a couple weeks before I drop the cash but today I am thinking 4.88's now.

Hope to come down for the Eastern EXPO if they settle on a date, I leave for Chaco June 10th

 

[alosix]

My concerns are when I am in some serious mountains and I come out of OD, ouch. I have a couple weeks before I drop the cash but today I am thinking 4.88's now.

If you're in serious mountains you probably don't want to be going up it trying to do the speed limit with trailer in tow most of the time. Looks like the Hemi JKs can do it, but if you're going up something with 4.88s or 5.13s that is too much for OD you'll prob be crawling up it anyway trying not to cook it

The only question to ask yourself at this point is are there bigger tires in your future. If they are, 5.13s might be the ticket.

 

[MuleShoer]

IfThe only question to ask yourself at this point is are there bigger tires in your future. If they are, 5.13s might be the ticket.

today no but in two years when I replace them I just might go up to 34's (315/70X17) but thats a long way off so I will worry about it then

4.88's are planned once my lockers show up

Thanks