Ajkaz

Hi all,

I'm looking for real world feedback From Jeepers with a 3.8 6 speed manual running 35's with 4.56 or 4.88.

I'm stuck between the two gear sets and definitely need more power at the bottom end.

What rpm are you highway cruising at? What's the torque like off the line? Is the motor revving excessively at 70mph?

Any feedback is appreciated.

Jnorman831

I have 35's with 4.88 gears and a 6sp and to keep up with traffic on the freeway I'm turning at least 3000 rpm's . The 4.88's are great off-road but not the best if you have to commute

Mark Doiron

4.88 gears here. There are still times it lacks the power I need, but the six speed lets me downshift to fourth or even third when traveling on the Interstate into the wind uphill fully loaded (in the vicinity of 6800 pounds). I wouldn't want to go any lower (smaller pinion)--I recently had the rear pinion gear fail on me, and that was just driving down a paved road on the way to catch breakfast at a local restaurant. But, the gearset had about 120,000 miles on it.

My definition of fully loaded ...

Ajkaz

Thanks for the feedback guys! Maybe 4.56 would be better for my application, not a daily driver but always a 2.5 hour drive to the nearest trails. Not sure I want to run over 3k Rpms on freeway that long.

Any 4.56 users out there?

Ajkaz

Wow! When you say loaded you mean it!

Bonedoc

Personally I think 4.56s will be perfect for onroad with 35s. It will be fine for wheeling as well. Serious rock krawling will be more of a challenge but not impossible. I have 4.88s with 37s and it is perfect on road. Jeep has plenty of power, feels stronger than stock, for the highway, climbing hills, etc.
I originally was going to go with 5.13s but that would of been too low for onroad. I instead added a rubicon transfer case, gives me great gearing for onroad and the transfer case gives me the extra low for wheeling.

Canvas

Well I would suggest thinking at future upgrades. I am went with 5.13's because I am going to bump up to 37's and only wanted to rehear once. Yes my gas mileage sucks but it is worth not having to repeat again. JMHO

Cheemsaf

FWIW, I'm running 37s with 4.88s on my manual (underpowered 3.8L). If you decide to ever go to 37s, then 4.88s are a-ok. It brought back the "normal" feel.

jtphoto JK

What is your average highway speed. Taylor your gear set to that. My average highway speed is 60mph / 2100rpm which is perfect for my set up 3.8 auto 5.38 gears on true size 37s.

CMHilbert

I just had 4.88 installed on my 2011 6sp. I have Cooper "35's" which measure closer to 34.5".

You don't have to shift out of 6th on the highway except for very steap grades. Around town driving is fine, any type of downslope and you can start in second no problem. Also, doing a 1-3-5 shift works well with the new gears.


I am happy with the choice, but will probably go with slightly larger tires next time (true 35 or maybe a little larger) to help bring the rpms back down some. I am showing right around 2600 at 65. I think 4.56 would have been fine as well, and maybe sound like the better option for the driving you describe.