I'm sure this is a rehash of an earlier discussion, but please humor me. I had a '98 Limited with the rear locking diff. When I put engaged the diff lock and had it in 4LO there were three wheels turning and that truck would go through anything. Now I have a '06 Limited with the locking center diff. When this is engaged with 4LO, there are only two wheels turning - one in the front and one in the back. Why did Toyota change to the center locking diff? The rear locking diff was a beast and to me this is a downgrade. I would much rather have 3 tires spinning compared to 2 when going down an especially nasty trail. What is the general consenus on this?

The center locking diff is to ensure that the front and rear driveshafts are getting power equally. Otherwise, the center "differential" acts as it should and will let the front and rear spin at different speeds. This is so you can drive your runner on the road in 4WD without 'binding' between the front and rear.

The newer runners do not have the rear locker option unfortunately.

The older runners had a transfer case for 4x4 which distrbutes power front to rear evenly - not really a differential.

And your right - the 3rd gen runners with the locker were damn capable off-road.

I don't know what the consensus is, but the fact is that a rear plus center lock is more capable than center only. The presence of traction control collapses that difference quite a bit, though. As it turns out, the rear factory lockers for FJs have proven to be a bit weak, so anyone really wanting to put a rear locker to use in a 4th gen is probably better off getting an arb rear locker. So, yeah, I'd like to have a rear locker too, but I'm not sure I'd want the one that would have gone into the 4th gens and is, presumably, in the Trail edition now.

As already stated, the center diff lock ensure that power is split equally between the front and rear. But to say that you'll only have power to two wheels (one front/one rear) isn't really correct. The front/rear diffs are open diffs, but they have ATRAC to transfer power from side to side. So in theory, the system will split power equally front and rear (with the center diff locked) and the ATRAC will distribute power from one side to the other,depending upon which wheels have traction. It's really a very capable system, especially when you understand how it works and learn to drive it accordingly.

A 3rd gen with the rear diff lock is good also because power is split between the two rear wheels and you'll always have at leat one front wheel with power going to it. Unfortunately, the 3rd gen has no way for the front wheels to transfer power from side to side if it doesn't have ATRAC. Did any of the later 3rd gens come equipped with ATRAC, or is it only on the 4th gens?

That's an interesting point, EH007. I just purchased this '06 and have not had the chance to test out this 4wd system on nasty trails. But I will say that I like knowing that 3 wheels will be turning no matter what (as in the locking rear diff and 4LO), rather than depending on electronics to distribute power where the computer deems necessary (as in the locking center diff and 4LO). Just my first take on the system in the '06. Any other takes on the capabilities/shortcomings of the rear vs. center locking diff comparison?

JB,

The rear diff locker problem on FJ has apparently been fixed. It was apparently due to a bad batch...a BIG batch! However, I would still not put on big ass tires nor abuse it off-road.

EH007,

ATRAC was available on 2001-2002 3rd gen 4runners. 4th gen 4runners came out in 2003.

mtw290,

A center differential is a good thing. A center differential like the one in the 4runner (Torsen T-3) allows the 4runner to run 4wd on dry pavement (aka on-road use, not just off-road). Your old 1998 4runner could not be in 4wd on dry land. Your '98 system was called, "part-time 4wd" system. So, your '06 4runner allows you to use 4wd for on-road use (when it rains, snows, or on dry land).

As noted above, from 2001 and up till now, 4runners have ATRAC plus center diff lock. Center diff lock allows for equal distribution of power front and rear while off-roading (similar to when you put your 1998 in 4wd mode).

ATRAC is traction control that allows for shifting of power back and forth between tires on the SAME axle, despending on which has more traction. ATRAC is equal to having limited-slip differential on your front AND rear axles. It is an effective system for the most part.

Is your 2006 4runner as effective off-road as your 1998 4runner with rear locker? Under most conditions, it should be just as good...with less headache because you don't have to always remember to turn OFF your rear locker during off-roading. Now, if you do a lot of rockcrawling or blasting through mud/sand dunes, then your 1998 4runner may hold an advantage...but it is not nearly as much as you imagine. Go out and play with your new 4runner and then come back and tell us!

The nice thing to remember is that you can always upgrade your 2006 4runner with a rear locker (ARB for instance). That would be the ultimate upgrade IMHO because it gives you a center diff locker PLUS a rear locker PLUS ATRAC controlling your front axle. And, under the grand scheme of things, this upgrade is fairly economical. Can you say the same thing about your 1998?? ATRAC is something that cannot be retrofitted into older 4runners.

BTW, ATRAC works in 4-lo and 4-hi. Your 1998 locker only worked in 4-lo (unless you modified it).

Hope this helps.

Having both ATRAC and the rear diff lock would be awesome but I'd rather have the rear locker/no ATRAC than the ATRAC and no locker if I had a choice but if I ever get a 4th gen it will be the TE.

Yeah, but if you have ATRAC, then you'll also have a center diff lock, not "no" lock.

But yes, the Trail Edition is definitely the best of both worlds by far with center diff lock, rear diff lock, and ATRAC all around. That's awesome and more in line with the Land Rover's most capable 4wd system. It would be cool to have front/center/rear lockers on a 4Runner, but I doubt we'll ever see that happen.

Well, i would argue that the '09 4runner TE is even better than the best 4wd system from LR. Those LR that do come with rear locker also have IRS (independent rear suspension). The LR that comes with solid axles do NOT have locker option from factory at all! Although LR's ETC (4-wheel traction control) system is arguably better than 4runner's standard ATRAC system, it is not as good as 2009 4runner TE's (or FJ Cruiser) A-TRAC system. ETC is similar to 4runner's standard ATRAC system in that it is made for all-season capability, with a slight more emphasis for off-roading. TE's A-TRAC system is purely an off-road tool and thus, is more aggressive than any of LR's ETC systems.