I was told by the previous owner that my 4runner SR5 has a Rear Differential Lock. Is there any way I can find out this by my self? Also, is it possible to install lock diff on the front wheels as an optional factory add on? I'm new into this offroading world and as you can see I don't have much knowledge about it? Is it possible for anyone to give me a brief introduction to locking differentials and gear ratios?

Thanks,

JJ

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If you have the rear diff lock there will be a button to the left of your steering wheel that says RR DIFF LOCK, it is just a small button, I beleive it lights up orange. Push that button in 4lo under 5 mph and your two rear tires will be locked at the axle, meaning each will receive 50% of the power to the rear all the time. When open if one side come off the ground it has less resistance and therefore receives all the power, so you will be stuck if one rear and one front are in the air. With the locked rear your other tire will pull you off the rock and you'll keep moving, same theory in front. Toyota never put a front locker on 3rd gens, so if you want one you need aftermarket, but with the IFS and 7.5" ring gear some run into problems on real tough terrain w/ locked fronts, you could get a true trac or something though. Your gear ratio is probably 3.90 or 4.10, 4.10 or 4.30 if you're locked. With gearing the higher the number the lower the ratio, the lowest offered in 3rd gens was 4.56, but those may have only been in 4 cylinders, the V6 low option was probably the 4.30. With 4.10 every time your driveshaft spins 4.10 times your wheels will turn once, so the lower the ratio the more revs the motor has to turn to maintain speed, so your RPM's will be higher with a lower ratio. People gear down to compensate for large tires and put the RPMs back to stock.

Front is independant suspension with no axle so no locker.

Thanks pat161, very interesting info. It appears my previous owner was trying to fool me or better said, lying, cause I don't have that button. That said, is there an option for installing an OEM Rear Diff?

Thanks again,

JJ

There's a few members that did junkyard swaps over on yotatech and there might even be a write up.

Well you can try to find a wrecked truck with the locker and swap it into yours, you will probably need to wire it up, though the line might be there, I'm not sure on that. The axle housing are slightly different on the models with the locker as they have the little electric motor to engage the locker, you can put the locker in an unlocked rear but it requires modification to the housing itself, search for more info on that. There are easier options, such as a Tru Trac or other non selectable locker, they are cheaper and easier to install, you could also look at an ARB air locker, though that would probably be the most expensive route.

If you go OEM you can look for Tacomas from 95.5 - 04 or 4Runners from 96-00, the locker is the same on all of them, just remember if you swap the whole third make sure your gear ratio is correct, you may have 3.90, so if you get a locked diff with 4.10 or 4.30 your diffs will be mismatched.

Check out this thread from the 'Off Roading' section on this forum
http://www.toyota-4runner.org/showth...s=&threadid=52
It describes differentials and lockers.