What Milford is saying is that regearing for tire size is the right way to go, going slightly deeper is ok...but trying to make up for weight and lack of aerodynamics by spinning the engine to the moon on the highway, and trying to fool us into thinking that you're suddenly pulling wheelies and getting better fuel mileage than stock is a bit hard to swallow. I know he's tired and frustrated with the same thing I am here...the constant preaching to run tons of gearing with little tires.
I have never had a properly running 4.0 HO/AW4 accelerate from a stop better with too much gearing vs. not enough. That's because the 4.0 is not a quick or high revving engine, and gearing it so that it needs to rev quickly and high to row through the gears (in stock form) does not aid in acceleration for this particular engine. I've had plenty of them, and I've regeared hundreds for paying customers.
I've also had plenty of Samurai's...guess which one has given me the best acceleration and fuel mileage? Yup, the one with factory gearing and an engine upgrade on 31's (that's the same tire increase as going from stock to 32-33" on an XJ). All the ones I geared to the moon accelerated better than stock geared ones with bigger tires(but not better than this current one), but just screamed at 65 with my foot on the floor...huh, I thought gearing as deep as possible was the wonder cure, and would supply me with tons of new found "power"?
Guess what I did to get better acceleration and better fuel mileage out of my Dodge/Cummins? Added a power tuner and increased tire size to 35" to slow the rpm's on the highway...but based on the advice here, I should have geared it to 4.88 and just let it scream:nosmile:
Guess what I did to drop my fuel mileage in my '01 XJ from 18+ to barely 14...added 33's and geared to 4.56. Now it doesn't accelerate any better (but it sure makes more noise and shifts quicker), revs way higher than I want it to on the highway (4.10's would have made me much happier, but I had these) making the fuel mileage suck, the driveline sing and vibe, and it still downshifts if I'm too aggressive with the right foot trying to accelerate (wonder where my magic "more power" went), yet the engine ends up revving too high when it does downshift to actually do anything productive.
A good mix of regearing the diffs for tire size for the road, regearing the transfer case for off road, and adding some power is the "right way" to go...but to each their own. I totally get gearing super deep for a rig that is a toy...for wheeling...not a DD that sees lots of road/highway time though.
There is a happy medium, and gearing super deep doesn't make up for the need for more power efficiency from the engine.