Viscous coupling?

I am trying to understand more about limited slip with respect to the 2004 Xterra.

My father has a 1991 Toyoto Land Cruiser, which has a viscous coupling in the transfer case. This makes it so that even when he doesn't engage his lockers, one wheel slipping on one axle will NOT prevent the other three tires from getting power.

What I am wondering is if (for example) I got only a limited slip for my rear differential, what would happen if one of my front tires was off the ground? Would my rear tires still get power and propel me forward, or would all my power get dumped into that one wheel that is off the ground?

Thanks for any info.

-Verxion

With a transfer case, the wheel in the air will get all the torque for that axle, but with two tires firmly planted in the rear you will maintain forward progression, unless one begins to slip and takes the torque away for that axle too.

I had the factory LSD in my '03 and it was worthless, I toy'd with the idea of putting in a LSD in the front, but instead traded up to the '05 OR with the factory locker and it makes things that were nearly impossible with the '03 a cakewalk in the locked up '05.

Well, the '05 isn't an option for me, so I have to look at what I can do within my '04.

Thanks for the info though.

-Verxion

I understand, but after all the mods to make me happy with my '03, I'm glad I reversed course and spent the $$$ to upgrade to the '05 instead. Good luck and hope to see you around. Your '04 is capable.

Nissan doesn't use a full time case like the Toyota you mention. No viscous coupling...it's either engaged or it's not.

You say it is either engaged or it isn't - does that mean that the transfer case is geared as opposed to using fluids for the coupling?

And is the gearing such that power is ALWAYS sent to both front and rear, or can the power end up all being sent to one or the other?

Conundrum:
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The way you described transfer cases, you made it sound like your description was of transfer cases in general, but I know I have seen four wheel drive vehicles spin a single tire and not be able to move because all power went to that one wheel. Is there something specific in my 2004 Xterra that prevents that?

Thanks,

-Verxion

That's correct. When in 4wd, it's geared together. At least one front and one rear wheel will spin at the same rate when in 4wd, assuming you have open differentials.