Lefty

After reading Woodbert's post on the locking center diff on the new Runners, I thought it would be a useful topic !

Personally, I think it's essentially a useless feature without having either a front or rear locker, also (which you can't get - yet). Locking the center diff will split the power/torque 50/50 between the front and rear axles and disable the skid control. This is all well and good until one wheel looses traction on both axles. Say this shouldn't happen ? When was the last time you put a side of your truck in a slippery, muddy rut when out wheeling ? It happens all too much for me...

With that said, the normal full-time 4 wheel drive with skid control on should work better ! Power/torque is split 40/60 and if traction is lost, the nanny, err, skid control, kicks in to stop the spinning IN ADDITION TO the power being sent to the non-slipping axle. Using the above scenario, the nanny would allow some power to make it to the non-slipping wheels to hopefully keep momentum going and get you out of the mess.

With that said, this is all theory. I haven't gotten stuck in my new Runner and hope I never do. But considering that the locking center diff function is intended for true 4-wheeling needs, it appears that it's benefits are in contrast to what actually may happen.

Waddya think, guys ? I want to believe that I actually got something useful with this feature (other than the need to get lockers for the truck) !

Steve

Darren

What's the question?

rimpainter.com

Hey another AZ Wheeler! Good to see. Welcome.

Yeah, what is the question?

Lefty

I guess the point I was making was: What's the use of having the center locking differential ? It appears that having the Runner in normal 4-high is better when out wheeling.

Thanks for the warm welcome !

Steve

Darren

It's so you can run in AWD when unlocked.

Robinhood150

To elaborate a little more on Darren's post, it's so that you have the option to unlock the center diff so that you can drive on the pavement in 4wd without damage to the drivetrain.

Lefty

Darren and Robinhood,

Thanks for the reply. But now the tougher question - when would I WANT to lock the center diff ?

Locking it doesn't give me any benefit since wheel slippage is not controlled by skid control. A slipping wheel on both axles will end up in a stuck. Remember, this is a locking CENTER diff, not a locking axle diff (or as another member pointed out, a "true locker").

Steve

HBoss

Guys, I think his question is the reverse of your answer. I think he's saying traction control works so well, that why bother locking the center differential when you offroad, because locking the center diff would put it in part-time 4WD and turn OFF the traction control. I think he was asking that and I think you guys were answering "why the center diff?" or "why unlock the center diff?"

Lefty, I think traction control will do more for you than locking the center diff too. On one of the recent excursions, I heard a stock Jeep Liberty w/traction control (& 3 studded tires) did better up some low-traction hills than a lot of the other part-time 4WD wheelers out there.

I'd personally count on the traction control to give me grip & forget about the center diff locker. Now if they offered a rear locker, hello! But then again, traction control is so good these days, it's almost like cheating.

Al

rpeAMP

It's useful for driving in the rain. Without the center diff locked, the wheels will bind when making sharp turns in 4WD. With the center diff locked, the wheels can turn at different speeds yet at the same time still be in 4WD.

HBoss

It's backwards.. "With the center diff locked, the wheels will bind when making sharp turns in 4WD. Without the center diff locked, the wheels can turn at different speeds yet at the same time still be in 4WD"

Darren

I don't know exactly what he was saying originally as I got lost. Sorry Lefty! Though we did answer why having a center differential can be an advantage.

I can only speak for the 2001-2002 system in that if you wheeled without the center locked, the wheels are always slipping and the TRAC is engaged much more of the time. Locking it=better traction, and more smooth going. I would imagine 2003's are the same in this regard.

To be honest, I'm still not sure if that answers anything, so I'll shut up now.

Robinhood150

Ah, I see now. Well, like I said in the other thread, traction control is relatively new so not very many people have too much experience with it (actually, in the other tread I said torsen diff is new, but it's the same idea). People are just going to have to test it out and see.

I believe jeff the marmot on ODW made some good observations on the advantages of traction control while off roading. I think he said he was impressed with it, but I don't know what 4wd settings were used.

Having said that, I think I've read somebody say it's a disadvantage when tires are in the air because the engine gets retarded and the computer goes crazy trying to control the excessive slippage. I don't think the engineers designed the traction control for rockcrawling.

Darren

I believe jeff the marmot on ODW made some good observations on the advantages of traction control while off roading.

That was actually my other neighbor, Mike Brown (Aurora Sandman) who has a 2001. When he first got his and for his first few outings, he wheeled with it unlocked because that's what the dealership folks told him to do. To be somewhat fair to the dealers though, it was a new system at that time and when you only get .5% of the population that does some wheeling, nobody probably knew how the system would react. After Mike locked it, he noticed a very significant difference and substantial trails have been driven since.

The other thing about it like you mentioned, Robinhood, is that when the center is unlocked, the VSC is still enabled. With that being the case and as much slippage as there is off-road as I mentioned above with it unlocked, no engine power to pull the grade is not a good thing.

Lefty

HBoss got it right ! Now, why couldn't I say that ?:pat:

There IS a basis behind this thread. While out wheeling last weekend, I encountered the situation I initially described. Rutted road, ruts filled with all kinds of gooey mud, but the tops were dried mud. Surveying the situation, I was left with the question of "should I lock the diff and start bogging, leave the diff unlocked an play in the mud, or be safe and stay high and dry ?" Since I couldn't do the latter, I simply left the diff unlocked and started playing. Wouldn't you know, I pulled right on through - no slipping, no wildly spinning wheels, just waded on through. I was absolutely amazed !

Now reading Robinhood's reply, that also makes sense. I can see where lifting wheels in some good off-roading might make the truck loose it's marbles. Dang, looks like I'll need to get some lockers !

Steve

Woodbert

It sounds to me like we need to get these 03 rigs out and experiment in various conditions with different 4WD modes and find which 4WD combinations work best in what conditions.

I drove briefly last weekend on a beach in just HI 4WD, CDL unlocked, and had no difficulties at all.

I'll try and get out in some sand this weekend .

Good Times

as far as my 03 4runner goes i've used every combination now.

when in severe incline/decline, you def want the vsc off... that stuff gets in the way and just does stupid things... only way to turn off vsc is via locking center.

in any other condition i'd 'say keeping it unlocked is best. best way to think about is this:

do you want vsc on? if yes then don't lock. if no, then lock the center

well that's how I think about.... hehe

nhslax27

so far i have seen that the traction control, when doing muddy (slippery hill) or going through mud where you cant help but slide, has actually made it harder to get through then it needed to be. I think when the sensor or sensed that tires were spinning more then usual (but not stuck and still slowly moving forward), it slowed the spinning and made weird noises in the front of my 4runner. If it would have allowed me to keep the tires spinning i should have easily made it through. The same goes if a tire is off the ground. What i have done is turn off tract control and VSC (idk if that is a bad idea or not but idk if VSC helps off road or not). It stops the problem. I havent really given locking the center diff. much use so dont have advice there.

nhslax27

Idk about you but at least in the 08s you can turn off tract control and then after press it AGAIN and hold it for a few seconds and VSC turns off without locking center diff.

pkt1213

iTrader: (1)

Is the transfer case on the manual trannies and the later auto trannies with the selectable locker the same? I would like to be able to add the AWD feature to my 98 SR5.

cackalak han

Most people don't know how to use TRAC to help them in these situations. Not as good as lockers, but understanding how they work is useful. Here is a tutorial for 03+, but still relative to 01-02 4Runners.

http://www.toyota120.com/forum/showthread.php?t=25

There is already a similar mod for 01-02's. Andy Mod. But you can't turn it (VSC/TRAC/ABS) back on unless you restart.

Hope you have some major fabbing skills, and/or lots of money. And why would you want to add AWD? Maybe it's useful for dry pavement, but other than that, I don't see the need?

Also noticed this is an oooooold thread.