Need help with my straight axle explorer!!

I have a straight axle 98 explorer 4.0 ohv automatic with a manual shift bw1354. Its got 4.10 gears and 38.5 boggers on steel wheels. Problem is when rock crawling it has a rough time spinning the tires. It wont move and the tranny doesnt slip its almost like it doesnt have the power. Yesterday it got hot and the overflow started pouring out tranny fluid. My brother has a 5 speed ranger with same motor and tires and gears, spins the tires fine. I know alot of yous are running 35s and up with 4.10 gears and have no problem with spinning the tires. I need an imput on what can be wrong. Like the tranny being bad or the lines being blocked. Any help appreciated

 

[jrgaylor]

you need lower gears or a doubler

 

[RangerX]

You're KILLING your auto trans.
I don't think most people running 35s are running 4.10s.
Your brother's Ranger weighs 1000lbs less than your Explorer, by the way.

 

[tenny]

if your "overflow is pouring out tranny fluid" you have a problem.

 

[colintrax]

38" boggers with 4:10s... yeah you need lower. 4:88 or lower.
Remember explorers did come stock with 4:10 gears and a 29" tall tire. Taller tires make your overall gear ratio taller. IE move farther every rotation.

 

[Rick]

I would run 5:13s or lower. I'm running them with 36s and could even go lower still.

BTW, even with the lower ratios your not going to have the power to spin the tires at will as you would with a V8. The 4.0 is excellent for crawling, but it's terrible for hill climbing, dunes, or anywhere that wheel speed is really needed.

 

[OffTrac]

Pictures required for correct diagnosis.

 

[98explorerkid]

Ive been pricing a 4.3.1 atlas

 

[colintrax]

If this rig hits the roads I'd suggest lower axle gearing first.

 

[98explorerkid]

And as the tranny gets hotter the tires dont want to move more