So something has been bothering me for awhile and you guys might be able to help me out.

My understanding of multimode 4wd that came standard on 01-02 4runners, is that it allows you to engage the transfer case without locking the differential. IE gaining a type of All Wheel Drive. Then later you can lock the center differential, and force the transfer case to spin both drive shafts at the same speed. This is "true" 4wheel drive mode.

I have noticed more and more people suggesting to 01-02 owners to install a e-locker in the rear. Isn't this redundant because the shafts are already turning the same speed?

Can someone clarify for me? I'm interested in seeing the possible advantages.

 

You can still spin two wheels (one front, one rear) with open differentials on the front/rear.

 

A rear locker forces both rear wheels to spin at the same rate, while the center lock just sends equal power to the front and rear axles. With the center locked and the rear axle locked, both rear wheels and at least one front will spin regardless of traction.

 

In 4wd, you can still get stuck and spin one front tire and 1 rear tire. With the center locked the 1 front will spin at the same speed as the 1 rear, but the other 2 tires will sit still. A rear (or front) locker will force both tires on 1 axle to spin together no matter what and the improvement in traction is huge.

 

open differentials send power through the path (wheel) of least resistance. locked differentials send power equally no matter what (both wheels). think of this concept but in a transfer case, where the "wheels" are actually in this case the driveshafts. normal AWDs aren't always 4wds because the transfer case is like an open differential and will send power to the path of least resistance, though in all cases if resistances are the same it will send power to both. 4wd vehicles have transfercases which lock when in 4wd and send power at equal rates to both drive shafts. this is also why it is so crucial to have matching gearing front and back or else you'll shread your drivetrain.

There is more to it as there always is but this is the basic concept. you can research tolerances in gearing and differences in hard locked or not, look up locker faq sticky for more info to get you started.

 

Thanks guys! this helps out alot. I get why everyone upgrades to rear e-lockers now!