93 YJ rear end

I ran 31" on 3.07 for quite a while. Worked alright, just used 5th gear a little less often.

-Dan

jaco wrote:

I am running 33's on 3.31's and it is doable. You just need to forget about 5th or overdrive. It still works, but the gas mileage will suck because the engine lugs.

Mike

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

jaco wrote:

Most manual trans 4.0L YJs came with 3.07s. The only exceptions were those with Trac-Lok limited slips, which were 3.55s. Automatic 4.0Ls were 3.73s.

You can run 31s with 3.07 gears, but you'll feel a loss of torque and will use rarely use 5th gear. Also, 31s will rub unless you install a mild lift of some sort.

Automatic - no 5th. Gas mileage! I'm running reformulated gas here in Milwaukee and am lucky if I get 14 mpg's the way it is, will higher gears offer better gas mileage? thanks jaco

I do want to add a locker of some type - this is a daily driver (90%) but when I go off-road I would prefer having the confidence of a tight rear end.

I've spoke with 2 shops and they both are recommending higher gears and posi-trac for about $2,000 - does this sound reasonable?

thanks jaco

It depends. For my money I wouldn't spend a nickel on a Dana 35 rear end. Money is much better spent on a salvaged TJ D44, which you can easily adapt by cutting off the spring buckets & trailing arm tabs & installing spring pads for the YJs leaf springs. Add gears & a locker and you're rear end hassles are over up to 35" tires.

If you must keep the D35, look into one of the Super 35 kits. These have Detroit Lockers which can be a handful if you're planning it to be primarily a street vehicle.

I have very limited knowledge of rear ends,,,,, So you're saying that the 35 even geared up may not be sufficient,,, is the difference between a 35 and 44 axle diameter?

So what you're trying to tell me Bill is that I REALLY should upgrade to the

Most of those fools deserved to blow things up... I sure didn't see many 31's in those photos either. LOL!

Your 35 should do just fine with the stock gears unless you plan on some insane off roading.....

Just my $0.02,

Mike

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

jaco wrote:

Nope, only my CJ came with a 44, I/we have abused the crap out of the poor old Cherokee with it's 35 to the point of blowing tires off the rim on high torque sand pit wall climbs. I only tear apart engine mounts on the CJ doing the same ones.

Mike

"L.W.(ßill) Hughes III" wrote:

Now that's what I wanna hear,,,, I really won't be doing anything severe, no giant rocks, mostly mud and forest type stuff -

Should I gear up the rear (and front) for better gas mileage with the 31's?

thanks jaco

No, you have what is or used to be called 'highway gears' designed for the best gas mileage. We used to call gears in the 400's 1/4 mile gears. Good for fast pickup at the expense of mileage.

You have a torque converter for low rpm crawling power so gearing down isn't really going to help you there.

You will see the 'perceived' mileage drop with larger tires, but that has to do with the diameter change. I 'dropped' about 4 mpg when I went

33's over 31's but if I take the diameter difference into play, I get almost exactly the same 'real' mileage which mine now is actually. I have checked my speedometer with a good GPS and it is set up right now so I am getting a 'real' 23 US mpg and my CJ7 goes like a scalded cat.

And I sure can think of better ways to blow a grand than changing gears....

Mike

jaco wrote: