2007 JKU with a 2" Procomp lift and 33's on 17's. Stock dana 30 front and 44 rear.
I'm looking at going up to 35x12.5's.

My dilemma, $$ is kinda tight. So it will be a while between purchases of both
So do i put in 4.88's first or put on 35's first?
Or be patient and wait till both are acquired and install all of them?

 

With 4.88 and 33 your rims are gonna be through the roof on the highway I had 33 on my jeep for some time with 5.13 it didn't hurt anyrhing

The Black Jeep of The Family

 

Do your rims have enough backspace for 35's? Or planning on spacers instead?

With only a 2" lift, are you planning on trimming the flares or going to flats to make room for the 35's?

What gears do you have now?

Have you verified your axles? A few early 07's came with D35 rears, and a front d44 was also an option (though I am guessing that you would notice the locker button if you had a front 44...)

If you go up to the FAQ's stuck to the top of this modified area, and scroll down to the drivetrain section, you will find a good RPM chart broken down by engine and transmission. Measure the tires and plug some numbers in to see where you'll be. (measured height, not mfg spec!!).


Which of the three options is the better choice will depend on which transmission/gears/rims/fenders/axles you have now.

 

Actually going to trim the flares this weekend.
Was told by the guy at 4wd parts that it's a 30 front and 44 rear. (we have a store here in colorado near my house)
Looking at the gear package deal from 4ws.com and they have a chart stating that 35's should have 4.88.
But thanks for the pointer. I'll go and look at the charts in faq and see what's up.

So again, would it hurt if i went gears first and then tires? or vice versa?

 

The guy at 4wp isn't going to have a clue if you are one of the lucky '07 guys with a D35 rear axle. It's a good bet that he is completely unaware that they were even offered in the first half of 07.

You didn't mention what gears you have now, or your transmission.

A generic rpm chart gives generic information. The ones in the faq's break it down by both engine and transmission type. (You realize that 3.8's and 3.6's have different gearing needs, right? And a 3.8 manual and a 3.8 auto have different gearing needs, right?)

You live in Colorado, so you are much more likely to want higher numeric gearing than someone at sea level. For a 3.8 manual, 4.88 might be a good call. For a 3.8 auto, I would look at 5.13. (I swapped from 5.13's up to 5.38's with 35's on my 3.8 4door auto). But there are about a bajillion gearing threads to look through for more opinions on it.

If you have an auto and 3.21 gears, you will not be real happy up here at altitude with 35's. If you have 4.10's and a manual, I doubt you would mind 35's until you got around to re-gearing.

Or, don't worry about any of it and just listen to the desk clerk at 4wp.

 

dude, that's great info, thanks! 3.8 auto.
it's dark now, so i won't be able to see a damn thing.

Where are you in CO? would love to pick your brain. i'll be at the Pollard show on saturday in Boulder.

 

Took a flashlight outside. Definitely a 30 up front and 44 in the rear. Housings are so damn dirty right now, I couldn't see the "tags."
I found some markings on the covers and trying to decipher them now.

front;
631-2
044-7
Rev-A

Rear
DANA
42960 1
043 7
03 20 00

 

Ok here's what i have found so far;
dana30 front (not the 35)
dana44 rear
according to below, 4.10 gearing (if stock, not sure what's in there.)
Transmission: 42RLE - Automatic Four Speed w/ Overdrive
Availability
Optional
Description
Electronic governor, electronically controlled converter clutch
Gear Ratios

1st
2.84
2nd
1.57
3rd
1.0
4th
0.69
Reverse
2.21
Axle Ratio
4.10
Overall Top Gear
2.83

 

I have learned a lot this evening. According to this, with my 3.8 auto, and having 33's, my drive should actually be better with 5.13 gearing instead of what i have currently. AND will be alright when i do upgrade to 35's.

[write-up] Jeep Wrangler JK Gearing Charts - Write-ups and Reviews - Tennessee Jeeps

 

That is the generic trans ratio chart, it is useful for the ratios for each gear in the transmission, but has no bearing on what gears are actually in your diffs. 3.21 / 3.73 / 4.10 were the available options for non-rubicons in 07. I have never bothered to look, but what I gather from other posts is that the JK does not have a tag on the axles indicating gear ratio.

The rpm charts you linked are the ones built by a member of this site, and hosted on this site. They are in the FAQ's right at the top of this modified area. Your site stole them...

At a guess, with an auto, you have 3.73's now. If you want to be sure, go to the main Jeep website, find the Contact Us area, email them your VIN # and ask for a build sheet. That will list both the gear ratio, and the specific axles, that it left the factory with. If you think a previous owner may have re-geared, lift a rear corner, mark both the tire/ground and the driveshaft/flange, then spin the tire and count the driveshaft revolutions.

The front is most likely a d30, but there is a slight possibility of a d44.
The rear is most likely a d44, but there is a slight possibility of a d35. (guess they were clearing out some over-stock inventory...)

Just mentioning the axles because it could turn out to be a very large factor in your build plans. Is it worth sinking a dime into regearing a rear d35? Doubt it, I'd find a take-off d44. And on the off chance that you have a front 44, you gain the option of 5.38 gears, which are not made for the d30 any more.

This may be helpful also.



One other thing that may be very useful when using the gear charts is OD/Off. Once you plug in the ratio and tire size to get the expected rpm, you can divide that number by .83 (the OD ratio from your trans chart) to simulate you reaching down and pressing the OD button. (forces the transmission to not use OD). This brings the freeway rpm's up to a much more usable level and keeps the tranny from constantly shifting in and out of OD.

I'm in the Springs. About the only time I'm ever up in Denver is dragging the boat out to Chattfield.