Re gearing

[grimmjeeper]

The 3.6 can handle a little more gear better. Shorter (higher number) gears let the 3.6 rev higher and that's where it performs better to a point.

For 35s, I wouldn't hesitate to run 4.88 gears, especially with the double overdrive in the automatic.

On the other hand, the automatic has such a wide gear spread that it's good at covering up "less than optimal" axle gear/tire size combos.

Given the intended use for the Jeep, I would spend money on 4.56 or 4.88 gears. Maybe lean towards 4.56. But I would also entertain swapping in Rubicon axles with 4.10s.

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[Ratbert]

True story i got the 3.6 I have 8 speed auto kinda having a hard time staying in 8th with the 33 inch tires as soon I step on the gas jeep wants 7th gear back

There was a recent thread where someone was whining that their Jeep wouldn't stay in 8th when stepping on the gas, but that's working exactly as intended. Yes, it'll be more prevalent when you go to larger tires, but still, that's working exactly as intended. Whether that's a sufficient reason to spend money on a regear (and associated impacts on fuel consumption) is up to you. The increase in performance might be a sufficient justification though.

 

[Coreyb516]

There was a recent thread where someone was whining that their Jeep wouldn't stay in 8th when stepping on the gas, but that's working exactly as intended. Yes, it'll be more prevalent when you go to larger tires, but still, that's working exactly as intended. Whether that's a sufficient reason to spend money on a regear (and associated impacts on fuel consumption) is up to you. The increase in performance might be a sufficient justification though.

No, it has a hard time getting into eighth. Yes obviously when you step on the gas, the car desires power and it’ll take you out of overdrive that I understand. I probably should’ve elaborated a little bit more but because of the additions I’ve made, including bigger tires and steel bumper. The Jeep just is very sluggish and that’s the main reason for the re gear

 

[C.Sco]

No, it has a hard time getting into eighth. Yes obviously when you step on the gas, the car desires power and it’ll take you out of overdrive that I understand. I probably should’ve elaborated a little bit more but because of the additions I’ve made, including bigger tires and steel bumper. The Jeep just is very sluggish and that’s the main reason for the re gear

I wouldn't stress that much about it not grabbing 8th gear.

If it's mostly just MPG you're worried about, keep in mind that it'll take a very, very long time for that extra 1-2 mpg to break even with your $2500 regearing cost.

That being said, if you do want to regear then I'd probably shoot for 4.88 myself, given your engine and tire specs. Might be a little higher than you need, but it lets you grow into 37's someday if you wish

 

[grimmjeeper]

No, it has a hard time getting into eighth. Yes obviously when you step on the gas, the car desires power and it’ll take you out of overdrive that I understand. I probably should’ve elaborated a little bit more but because of the additions I’ve made, including bigger tires and steel bumper. The Jeep just is very sluggish and that’s the main reason for the re gear

Did you tell the computer about the tire size change? That affects shift points in the automatic. If not, a tazer or similar device to reprogram the tire size may make a difference.

 

[JINO]

Any way you can attend a large jeep meet and politely ask (assuming they have 4.56 on 33s) for a quick test drive?

Wish I could, but not many have my 3.0 engine.
I'm on 3.73 factory, but want to feel the 4.56 or even 4.10 on 38s. I hit 8th fine, but some have said you feel like you gain power with 4.56 on 38s with the diesel.

 

[Coreyb516]

Did you tell the computer about the tire size change? That affects shift points in the automatic. If not, a tazer or similar device to reprogram the tire size may make a difference.

I did that for sure

 

[Notgeowild]

I have 4.88's on mine with 35's. I personally think for 35's it's overkill. Ordered the Jeep with going up to 37's in mind. with my 37's I think the 4.88's is perfect.

If you dont plan on going up more than a 35" tire, me personally I would just stay with 4.56's. I have driven a few XR's w/ the 4.56 from dallas to Houston, and again this is my experience, it drives better.

 

[Coreyb516]

I have 4.88's on mine with 35's. I personally think for 35's it's overkill. Ordered the Jeep with going up to 37's in mind. with my 37's I think the 4.88's is perfect.

If you dont plan on going up more than a 35" tire, me personally I would just stay with 4.56's. I have driven a few XR's w/ the 4.56 from dallas to Houston, and again this is my experience, it drives better.

What engine transmission do you have??

 

[Coreyb516]

Again thank you everyone for advice and input it’s appreciated !!!!

 

[dstevens]

I think people are looking at the wrong end of the range of gears. Even massively over-geared like a 3.45 with larger tires the drive train manages fairly well. You may never see 8th but it really doesn't make the much difference to fuel consumption or driving.
Where the correct final ratio does make a big difference is in the lower gears. Pulling out into traffic is night and day with even a single step up in (numeric) ratio. eg 4.10 to 4.56 makes a noticeable change in acceleration in the lower gears. Something like the 3.45 with 33s feels like you are hauling a boat behind you the whole time.

 

[Notgeowild]

What engine transmission do you have??

I have the 3.6.

I have driven a 2.0L with 4.56 and 4.88's. Probably did drive better just didn't like the sound.

One of my managers had 4.88's on his 4XE and 37's and that thing drove like it was on 33's! of course when it wasn't broken. lol

 

[Bill_BCNtoNY]

OP - I have a Sahara with the 3.6, Auto, 33s, and regeared to 4.56. Personally it feels like too much and I’ll be going to 35s soon.

as @grimmjeeper said, I was torn between doing a rubi axle swap vs the re-gear, but I wanted truetracs so the axle swap felt wasteful… not sure I got that one right yet

 

[Terry R]

I also have a 3.6 Sport S on 35s. The only time I see 8th gear is driving on a straight stretch of highway between 45-55 mph. Interstate is 7th or lower above 70 mph. I’ve asked the same question on this forum. Many suggest Rubi take offs because of the stronger axles, but they are significantly more expensive than just regearing ($4-5k just for the axles, not including installation).

 

[XtremeRetard]

Dont undergear it!

456 with 35 is BARE minimum IMO. 488 like others have recommended.
37s you want 513 and 40 538. Even then 538 sucks. Mine hardly if ever sees 7th and 8th with 40s.

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