Wrangler 3.07 vs. 3.73 Axle

Bill, trust me on this... if you're considering which Jeep to buy, one with a 3.07 vs. one with 3.73, go for the one with the 3.73. The engine will struggle less (due to slightly higher engine rpms) and you'll be MUCH happier with the all-around performance of the 3.73 than you would with the

3.07 that no one I've ever talked to that had the 3.07 ever liked.

Jerry

Just a guess, but if stock, one would be for the 5 speed and the other for the automatic. The difference is in the tranny ratios so the auto will rev the same on the highway as the 5 speed at the same mph.

I also have done many highway runs beside the auto version and the mpg is really close to the same.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Bill D>

That figures. They don't care that 5th is only good with a tail wind as long as the mpg go down eh.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"L.W.(ßill) Hughes III" wrote:

Hi Jerry. You helped me out of ton of jeep problems as did all the people here responding to this thread. In my experience my 97 sport with 3.07 got about 20 mpg highway. My 98 sport with 3.73 (30" wheel) gets about 15 mpg. The 3.73 gears make 1st gear at a stop light almost unnecessary. You can take off easy from 2nd. You have to shift so fast into second anyhow. I recently put 31" on them and didn't notice any change in mpg. Of course the bigger tire needs the lower gears.

I'm thinking of possibly trading for a new TJ. I'm actually torn between the two gear ratios!! I don't do much off roading. The stuff I do is real mild and just for fun. I'm not really into serious upgrades and crazy rock crawling. I like the fact that I don't get stuck in snow or mud and can go pretty much anywhere I care to.

With gas prices the way they are, I'm seriously thinking of the smaller tire and 3.07s. I guess I'm not a true jeeper, but I still love all things about 'em.

On the highway with the 3.07's, I had a ton of pickup in fifth. It was great. No downshifting for passing. The jeep had a lot of punch and just seemed quicker driving. The 3.73 make my jeep feel heavy or sluggish. more downshifting even around town. I'm sure that's better for off road. Just another side to it.

Jeff, it sure reads like you're reversing how a 3.73 vs. a 3.07 would be described by anyone I know.

Jerry

Bill-

I have an '03 TJ Sport (I6 w/30" Tires) with 3.73's. I average about

19 MPG, and have done so since new. I drive the s*it outta my rig too, 48K miles in less than 2 yrs (purchased in 11/02).

I am like you and I don't do any really heavyduty off roading, but when I want to find out where that logging road goes, I can without any worries... It's my daily driver- 49 miles one way to the office (I absolutely have to be able to get there- hence, the TJ). Although I don't absolutely HAVE to start out in 1st gear, I just don't like to feather the clutch that much in 2nd... I think you'll find the 3.73's to be superior to the 3.07 for overall performance. 5th gear doesn't have a lot of "pull" (it's not gonna snap yor head back ;-)) but it holds it's own on hills pretty well.

My $0.02.

John

Maybe the tire sizes had a lot to do with it as well. But my same travel when I got my Dana 44/3.73 TJ required a lot more trips to the gas station. I love it but it's a pig.

The 3.07 had those grizzly wheels and metric tires. They weren't the real small ones, the medium sized factory tires. P29 or something, I can't remember. I calculated mostly highway MPG as almost 21 mpg! For a six banger that's good

When you switched to the 31s with your 3.73s (as I understood it you were running smaller tires on the 3.73 axles before), did you adjust your gas mileage comparison for the tire size difference? Because your speedo and therefore trip odo will be off slightly...enough to hide probably 2 or 3 mpg (depending on what your original tire size(s) were).

No Bob, I just recently got the 31's last winter. I had my '98 since winter of 97 and did these comparison of stock jeep vehicles.

3.07 w/ grizzlys vs. the 3.73 w/ 30" wheel package and Dana 44.

The 3.07 had way better mpg.

With the 30" wheel deal, the speedo was off from factory. That's how it was back in '98. If you put BFG's 31" on, it's pretty much dead on without changing a thing. Don't know how it is now.

I just put 31's on my 2004 with the 3.73 and gas mileage dropped 1 mpg. Speedo is off by a couple miles an hour, I checked it on one of those roadside radar things