I am new hear and to 4 x 4 99 4runner limited and there is a button for "differential lock". When and why would i use this. please don't laugh, just want to be prepared.

shaun

 

ok, first off, nice job getting a runner with an RR lock, you made out good on that. The differentials of 99% of cars are normally open, meaning the wheels on eaither side of the axle can spin at whichever rate they feel like. This is awesome for normal on road driving when making turns and such. Howveer offroad, and in harsh weather, it allows one wheel to spin(the one with the least resistance). while the other wheel just its and does nothing(the wheel that wouldhave the traction). As you can see, this does not work so hot. By locking the axle, with the RR lock button, it gives a true 50/50 power split between the wheels, allowing one wheel to run only if the other one does, and at the same rate. This is very helpful if you get stuck, of are trying to power through, mud, snow, sand, or if one wheel is in the air. In short, it basically is a traction aid. I wouldnt use it on road, but some people do run locked differentials full time. This question has been covered before, since you are new, you should probably search before asking, there is an incredible amount of info here. Dont get too offended if a few guys chew you otu for not searching, I still get it too, but welcome to the board!

 

You may want to consider checking out the search function or listing the question in the newbie section (for future reference). The advice Jason just gave you in his last couple sentences is invaluable.

 

hupp nailed it but forgot one thing. always lock the diff when you decide to do doughnuts. the rear slides out so nicely with it on.