Quick question on how our transfer case works

[JonathanExp]

Hopefully this is easy.
Regarding the V8, 4x4, 4-high/low, 2002 Explorer model, does the transfer case equally split power 50/50 to the front and rear regardless of slip? What I am really interested in is I would like to install a locker (trying to do a big desert crossing) in either the front (preferably) or rear and if I have only one locker in and a wheel slips on the other axle will all of my power go to the slipping wheel?
Thanks,
Jonathan

 

[Mbrooks420]

In high it should send equal power regardless of slip.

 

[camodown]

It functions no different than a traditional 4wd system power split unless you add a traction device. If you have open front diff and open rear, your power split become 50/50 front and rear in High and Low range.

The only times it would not function the same would be if you make the clutch in the case slip or in Auto mode. Auto sends pulse width modulation lockup signal to clutch to apply varying amounts of torque to front driveshaft.

And just the same as open diff on a conventional system, if opposite fron and rear wheels have 0 traction in High range, then yes, 100% of that axles' torque goes to least tractive wheel. So 100% of the 50% front goes to least front traction wheel and same for rear=probably stuck.

If you lock the rear diff with a locker or add a limited slip (especially a gear driven), then yes you can significantly change capability.

My recommendation is Torsen T2R, aggressive but work exceptionally well. I would recommend Trutrac by Eaton/Detroit but bias ratio is less and they do not machine for circlips, only c clips.

 

[JonathanExp]

Thank you both for the replies. So in 4-low, power gets split equally as well but the only difference is there is a gear reduction, right?

I was leaning towards installing an ELocker in the front. I have read a little bit about the Torsen (from the Maximum Traction Solution write up) but it seems I would not be able to maximize its benefits since I do not have a brake-base traction control system. Maybe a Torsen in the rear and an ELocker in the front???

 

[camodown]

Correct, 4high and 4low both lockup the electromagnetic clutch using 100% duty cycle. This means as long as you don't overcome the clutch plate holding capacity, 50% of torque goes to rear driveshaft and 50% to front driveshaft. From there however, with equal traction, the two fronts would see similar torque split same as rear.

Since you are pre Advancetrac, you would benefit greatly from lockers or helical gear limited slips. I would shy away from front locker as the steering tends to want to go straight when locked, moreso when steering angle increases. A rear lcoker can tend to understeer as well since both halfshafts will not differentiate rotational velocity.

A selectable locker up front though would behave better than a limited slip inslipper situations though since you could disable it. Whereas a LS up front could be more finicky.

We tested two helical LS systems in deep sand on two Ford Super Duty trucks, one single rear wheel, one dual. Both with and without trailers in 2wd. Wheelspin occured occurred partially sinking the rear axles but both wheels turned in sync. 4wd was engaged (open diff front) and they had no problem continuing forward.

Unless you forsee opposite wheels coming off the ground, the manners of a helical limited slip are much better than a locker. And while yes, the helical LS will act like an open diff if opposite wheel comes off ground, you can apply parking brake (for rear application) and it will start to transfer torque to other wheel.

 

[TechGuru]

Just install the factory LSD.

 

[JonathanExp]

Thanks again for the great info/insight. I am preparing to cross the Simpson Desert in Australia (worlds longest sand dune desert with more than 1000 dunes to cross) which is about 430 miles long. No help or cell service for days so I do not want to mess around. I have the factory LSD in the rear but it has left me hanging when trying to do some rock climbing around here. I really need the vehicle to handle sand, mud, and rocks though not really in the same trip.

 

[TechGuru]

Just buy a new Jeep Gladiator...

 

[JonathanExp]

agh. no thanks.

 

[CDW6212R]

If you drive on much soft sand etc, you will need a very good limited slip diff, in the front and the back. Without decent diffs, you will have two tires spinning and two at ground speed.

The OEM LS diff, is a low strength differential, they are weak in new/rebuilt clutches form, and bad when worn out. You need a diff, that holds each axle more strongly than a weak LS diff. So replace the LS with something like the True Trac, and there are many 8.8 units to choose from.

The front diff, that's a tougher deal. I don't know what's available for that model(2002-2005), but in the 2nd gen's there is only one choice(Torsen for the hybrid D35). That kind of differential would be the best for what you want to do(soft sand), but people can tell you it's not going to be locked hard as needed for rock climbing etc. The cost of those will be high of course, they are not going to be easy $200 each units, more like $500 each, then add the labor to install.