What The?!

[toyrunner95]

ok guys, tech question again.
my girlfriend has a 2000 4runner. its got this funky 4wd setup, or at least funky to me. it has 2H 4H H4L and L4L i know how to operate it, there is a nice little 4H button on the shifter that moves it from 2Hi to 4Hi but the H4L means hi 4wd with the center diff locked..... center diff lock? ****** is that? its not a land rover. why is there a center diff lock? is it necessary? is it a POS?
how does it work? where is it?.... WHAT THE?!

 

[DaveInDenver]

ok guys, tech question again.
my girlfriend has a 2000 4runner. its got this funky 4wd setup, or at least funky to me. it has 2H 4H H4L and L4L i know how to operate it, there is a nice little 4H button on the shifter that moves it from 2Hi to 4Hi but the H4L means hi 4wd with the center diff locked..... center diff lock? ****** is that? its not a land rover. why is there a center diff lock? is it necessary? is it a POS?
how does it work? where is it?.... WHAT THE?!

Must be a Limited? In the 2000 model year Toyota introduced the One-Touch Hi-4 system. This is how the current 4Runner and the 80 and 100 series Land Cruisers work (sort of). In 2WD it's regular 2WD. In 4WD it's full time 4WD, so you can use it all the time, pavement even. It's got a center differential. The button on the dash locks the center diff, so H4L is regular high range 4WD and L4L is regular low range 4WD. To be honest, it's kind of nice to have full time 4WD in places that get snow. When they plow the roads, you just put it in full time and the truck worries about powering front and rear without binding on pavement. But unlike the Cruiser and V8 4Runner, having an option of true 2WD with the V6 is nice for gas mileage.

 

[dieselcruiserhead]

I think that is a pretty nice feature. Sort of like AWD that you can turn off to save fuel...

 

[Dave Bennett]

H1's have a Center Diff and they go wherever they want, seems like a solid system IMO.

 

[Tucson T4R]

My 2004 4Runner has a similar center diff. When open, it splits power about 60/40 between the rear and front axles. When locked, it splits power 50/50 between the axles and acts like any gear driven xfer case ( no diff action between front and rear axles when locked).

 

[DaveInDenver]

A Center Diff is a viscous coupling operating alot like a clutch pack in a automatic tranny, so normally when those are used there is no transfer case, you basically bought a Subaru. That's about as simple as I can put it.

I don't think it's a viscous coupling on the 3rd gen, it's a planetary geared center differential with a lock option. The 4th gen ('03+) is definitely a Torsen-type differential. Anyway, they work like a TrueTrac but with the ability to lock the diff for a guaranteed 50/50 torque split. AFAIK it's never been a viscous coupling on a full time 4WD 4Runner.

 

[taco chaser]

I don't think it's a viscous coupling on the 3rd gen, it's a planetary geared center differential with a lock option. The 4th gen ('03+) is definitely a Torsen-type differential. Anyway, they work like a TrueTrac but with the ability to lock the diff for a guaranteed 50/50 torque split. AFAIK it's never been a viscous coupling on a full time 4WD 4Runner.

That's better than the standard viscous, it still is a horrible thing to do to a 4runner and a Land Rover.

 

[Tucson T4R]

That's better than the standard viscous, it still is a horrible thing to do to a 4runner and a Land Rover.

To me it seems to be an improvement over a choice between a totaly open or locked transfer case as it was in the past. When open, you have the benefits of the Torsen torque sensing between front and rear. When you need serious traction you lock the center Torsen diff and you are mechanicaly locked front to rear as you are with a normal transfer case.

Where's the negative?

 

[DaveInDenver]

That's better than the standard viscous, it still is a horrible thing to do to a 4runner and a Land Rover.

Why? I'm not being argumentative, I prefer a part time manual case, too. I am just wondering why this is bad. I mean, the early 80 series HF2A is basically the same operation with the center diff lock button and no 2WD option. At some point they added a viscous coupling to the 80 series to eliminate the CDL button, but the HF2AV is pretty much still the same t-case. In any case, it seems like a center diff would be nice for a partially snowy road so you don't have to keep shifting into and out of 4WD. In theory, of course. ;-)

 

[taco chaser]

To me it seems to be an improvement over a choice between a totaly open or locked transfer case as it was in the past. When open, you have the benefits of the Torsen torque sensing between front and rear. When you need serious traction you lock the center Torsen diff and you are mechanicaly locked front to rear as you are with a normal transfer case.

Where's the negative?

Sorry, but the words serious traction and center diff just don't go together unless you are on the street, and there is no gear reductions after the transmission that's a huge negative and it all comes down to simplicity and strength on the trail not torque sensing this and push button that. There is no improvement mechanically at all just convienence geared toward soccer mom's going to the grocery store in the snow. It's not your fault Toyota ruined the 4runner for good. They look cool though that's all that matters it seems like these day's. I've seen stock tacoma's handle trails that a land rover discovery with a center diff had to be winch out 3 times and needed a ton of rocks stacked at every obstacle on a class 3 section of trail 4 miles long. It's still piston or solinoid operating bands grabbing planetary carriers that happen to have sun, ring, and pinion gears in them, so it's not gear on gear , it's band over planitary drum or is it something completely different ? I'll stay out of this for the sake of the guy who originally posted, it's gone off subject.

 

[Tucson T4R]

ok guys, tech question again.
my girlfriend has a 2000 4runner. its got this funky 4wd setup, or at least funky to me. it has 2H 4H H4L and L4L i know how to operate it, there is a nice little 4H button on the shifter that moves it from 2Hi to 4Hi but the H4L means hi 4wd with the center diff locked..... center diff lock? ****** is that? its not a land rover. why is there a center diff lock? is it necessary? is it a POS?
how does it work? where is it?.... WHAT THE?!

As you can see from the discussion, the subject has differing opinions. As discussed (both pros and cons) the "center lock" effects the relationship between the front and rear axles, not the axles themselves.

The high vs low range is still a gear reduction after the transmission as in manualy shifted transfer cases. It just is done with phu phu electronic solinoids.

You can still add locking differentials in the axle like an ARB Airlocker if you need locked axle type traction.

 

[DaveInDenver]

OK, I'm confused. I thought the CDL part was separate from the gear selection. So when you lock the CDL all you are doing is disengaging the limited slip option and still have essentially a regular 2-speed transfer case. In the '93-'97 80 series they have that 7-pin mod so they can get regular high/low select or viscous coupled high/low. This is nice so that they can have 4WD low and a center diff, which makes turning in 4WD easier. I know in the 4Runner you have an option of full time (limited slip FR/RR) 4WD, locked center (50/50) high range 4WD and locked center (50/50) low range 4WD.

 

[Tucson T4R]

OK, I'm confused. I thought the CDL part was separate from the gear selection. So when you lock the CDL all you are doing is disengaging the limited slip option and still have essentially a regular 2-speed transfer case. In the '93-'97 80 series they have that 7-pin mod so they can get regular high/low select or viscous coupled high/low. This is nice so that they can have 4WD low and a center diff, which makes turning in 4WD easier. I know in the 4Runner you have an option of full time (limited slip FR/RR) 4WD, locked center (50/50) high range 4WD and locked center (50/50) low range 4WD.

You have it right. The center lock is independant of what gear range you want to drive in. Open high or low and locked high or low.

 

[dieselcruiserhead]

I don't think they are really meant to be off roaded in the non diff locked mode, which is why they offer the center lock. It is excellent for things like: snow storms, rain storms, higher speed on dirt roads. Basically on road. I think it is an excellent option, again. What I hate about full time 4WD is that it cannot be turned off aka wastes fuel for when it is perfectly dry. That is the beauty of this system. Rather than think of it is as a feature, think of full time 4WD that you can turn off.

 

[Bergger]

I don't think they are really meant to be off roaded in the non diff locked mode, which is why they offer the center lock. It is excellent for things like: snow storms, rain storms, higher speed on dirt roads. Basically on road. I think it is an excellent option, again. What I hate about full time 4WD is that it cannot be turned off aka wastes fuel for when it is perfectly dry. That is the beauty of this system. Rather than think of it is as a feature, think of full time 4WD that you can turn off.

I agree 100%. It's a great feature. My wife got rid of her 02 4Runner for an 06 Xterra OR and while I love more things on the Xterra vs. the 4Runner I really miss the center diff option. And the sun roof! If Nissan would keep the rear locker, add a center diff and figure out how to put a sun roof in that funky roof line of the Xterra they'd almost have the perfect mid size SUV.