TJ Gear Question

My dad is thinking about regearing his '03 TJ Rubi - auto with the 4.0 Straight 6. He has about a 6" lift and 35s. I know most folks that regear a JK go with 5.13 and those that went with 4.88 wish they would have gone with 5.13. My dad is thinking about 4.56 or 4.88. Anyone have any advice about which gears to run with the 4.0 and TJ drivetrain? The gear selection needs to consider that it's his DD and he sometimes may pull a small utility trailer.

Thanks!

I plan on going 4.88s when the time comes and run 35s.

I have 4.88s and run 35s in my 2004 Rubicon 4.0 Auto. I've never pulled a trailer, but don't think I'd have any trouble pulling a small utility trailer like a 4x6 or even a small boat.

FYI, my speedo shows 10% slower than I'm actually going.

Does he wheel it? We're probably splitting hairs here but he might get slightly better fuel economy with the 4.56. The 4.88's would definitely be better for off roading/crawling. I don't think he'd have any power issues with the 4.56 or the 4.88 and pulling a small trailer.

I've got a manual '02 TJ with the 4.0 and I've got 4.56 front and rear w/ 35" tires and wish I had taller gears for 4lo crawling.

If I had to vote, I'd say get the 4.88.

Thanks for the replies. He's also looking at adding chromoly shafts and locking hubs, any advice/recommendations on those? (He's been talking about it with his local shop in LA too.)

Also, on Rubicons, is the front axle a true Dana 44? I think I've heard that the differential is a 44 but the axle is a 30? Not sure if that is TJ specific or if it's like that on the JK as well??

Thanks!

liftd & lowrd wrote:

Does he wheel it? We're probably splitting hairs here but he might get slightly better fuel economy with the 4.56. The 4.88's would definitely be better for off roading/crawling. I don't think he'd have any power issues with the 4.56 or the 4.88 and pulling a small trailer.

I've got a manual '02 TJ with the 4.0 and I've got 4.56 front and rear w/ 35" tires and wish I had taller gears for 4lo crawling.

If I had to vote, I'd say get the 4.88.

It looks like you posted while I was typing my previous response. Yes he wheels it, not all the time though - a couple times a year. He's driven it up to a few of the Camp Jeep events. One day we will make a trip to CO. I think 4.88s sound like the good choice, that will give him room if he wants to move up to 37s too.

Thanks again folks.

Gear for the road. The 4:1 low range in the Rubi case will handle the crawling stuff for him (gear your axles for the road and your transfer case for the rocks).

He can take it up to 5.13 with the 44's, and with the 42RLE he may well want to. It's got a DEEP overdrive, and it's a common complaint that 42RLE drivers with the 4.0 have to use the OD OFF switch to make a 3-speed most of the time. The 5.13 should help that as well as giving you the advantage of lower initial gears.

You're probably best off asking on Jeep Forum in the TJ section, as there are tons of people who have experience with all different ratios and can offer their input accordingly. With my 6-speed manual the "correct" ratio (put it back to factory) with 35's is 4.56, but for the 5-speed manual it'd be 4.88. It all just depends...