stumblyjoe

Hi everybody,
I was just reading through some 4runner threads about the selectable center diff on newer models. Bacically, I have a 4x4 Tacoma (2002 to be specific) and I would like to be able to run it with the center diff open to have all-wheel drive for street driving. Is there any way to adapt the components from a 4runner for my truck? Other options? If so, what is involved?
Thanks.

HBoss

I'm not sure I understand. You want to run on pavement w/the center diff open. But isn't it open by default normally?

L33T35T 4Runner

i think he's saying he wants to run in 4wd mode on the streets. you shouldnt do this because the open diff puts 40% to the front and 60% to the rear, which would bind the tires

somebody correct me if im wrong, i'm only a 2wd owner

Robinhood150

What he is saying is he would like to be able to run on pavement in 4wd, without risk/stress to the drivetrain. But, since the taco doesn't have a center differential this isn't possible. In a sense, it's always locked.

Joe, I think the only way you'd be able to do that is to swap the entire transmission from a 3rd or 4th gen 4runner that is equiped with a center diff. I doubt this is a simple swap and will require a computer swap and possibly some custom fabbing. You may even need the axles for sensors (I have no idea about this one, just a guess). If you want to run in 4wd on pavement then I suggest you sell the taco and get a 4runner, or an all wheel drive car.

Jason, since the taco doesn't have a center diff, the distribution is 50/50 front/rear.

Edit: Hey Joe, you live in san ramon too!

HBoss

Ahhhh, I get it now. I thought the Tacos had center diffs in the newer 3rd gens like the 4Runners did. Learn somethin' new everyday.

stumblyjoe

Yeah RobinHood explained it perfectly. Unfortunately for me, it doesn't sound like anything I'll be doing on my truck any time soon.
RobinHood, I live in San Ramon right off 680. I always meet the nicest people through truck modifying! Do you by any chance know exactly how the center diff is linked up in the 3rd and 4th gen Runners? Or does anyone have access to the relevant sections from a factory service manual? Although I guess I have to put it on my dream to-do list for now, I am interested enough in being able to run all-wheel drive while on the street to warrant more research. Thanks.

Robinhood150

Nope, sorry, I have no idea. Why do you want to run in 4wd on the street anyway? Millions of people drive in the snow everyday without it. If you're going to pursue this then look into the 3rd gens, the 4th gens are totally different. I'm not sure why I said 4th gen in the first place.

I live off of Bollinger.

Gadget

I would like to do the same thing in my 97 4Runner.

I have seen some Tacomas with the push button 4 wheel drive and have wondered if it was the same system as in the 4Runners or not.

Anyway, the mechanicals should bolt up fine since it is basically the very same truck. The issue would be with how it is controlled and you may need to obtain the control unit and its wiring harness.

If you find out more info on this please update me as I am very interested in doing the very same thing.

Gadget

www.GadgetOnline.com

stumblyjoe

I am interested enough in this project to continue my own research, but there are a few questions I have which I imagine someone here can answer.
First, does anyone have the factory service manual for a 4runner with center differential? Basically, I want to know where it fits relative to the transfer case, transmission, drive shafts...
Second, how does the center diff engage? Is it fully open, and then 50/50 or 60/40? Do you have to stop to engage/disengage or can it be done on the fly?
Last, what other vechiles offer this option? I know there is a really expensive (looks like a bread box) Mercedes that has locking center. front, and rear hubs. I think I remember someone saying that some FJs or landcruisers had similar options. Does anyone know the facts?
Thanks a lot.

2001Millrunner

my 2001 has the same option and i would much rather have a rear locker, did this even come as an option for 01-02models?

phong

Nope. 2000 was the last year for the electric locker in 4Runners.

GV27

OK, I'll correct you.

You're thinking of a regular system w/ out a differential. In this case if you somehow sent 40% front and 60% rear it would bind in the dirt too. But that doesn't really make logical/mechanical sense anyway. In a traditional 4wd system the front and rears are locked together, always turning at the same rate, always 50/50 power split - no differential action.

An AWD system w/ center diff will allow for different torque biasing, but allows the wheels to turn at there own pace so there is no binding. For example, an older Mitsubishi Eclipse AWD actualy biases torque 90% front, 10% rear until it starts to lock up. The new Subaru STi actually has a variable split center diff that the driver can control anywhere from 65% rear/35% front to 35% rear/65% front IIRC using a dial. A Jag X-type biases 60% rear/40% front.

C

stumblyjoe

Thanks GV27, that was very useful info about the center diff. Do you know if the center diff in the 4runner has a torque bias? Is that where the 60/40 number came from?

Gadget

The 3rd gens that had the option of running all wheel drive simply had an open diff in the transfer case. If one end started spinning that end got all the power just like the open diffs in the axles. You can lock the center diff to make it traditional 4x4.

The new 4th gen V8 has an all wheel drive system that uses a TORSEN torque biasing center diff. Very nice unit. You can then lock the center diff to make it true 4x4.

I would really like to get one of these 4th gen transfer cases and mate it to my 3rd gen. It is starting to get really hard to drive with that rear end sliding all over the place. If I have all wheel drive that would really be wonderful.

Gadget

www.GadgetOnline.com

stumblyjoe

That's very cool Gadget. Have you found out how those two units bolt up, respectively?

Highland Runner

Is this what you are talking about?

For 1999, 4Runner Limited models receive a new multi-mode 4WD system as standard. The new multi-mode 4WD feature is actually a full-time all-wheel-drive system with 2WD capability. The all-wheel 4WD mode may be used in normal driving conditions on all types of roads from dry, hard surface roads, such as pavement, to wet, icy or snow-covered roads. Driving with the new multi-mode's all-wheel drive system engaged provides the driver with a more controlled, sure-footed feel to the road because power is applied evenly to all four wheels thus improving traction.

To switch from 2WD to the all-wheel 4WD mode, simply reduce the vehicle's speed to less than 62 mph and push in the One-Touch "4WD" button located on the front drive control lever knob (on the transfer case the all-wheel 4WD mode is indicated as "H4"). Returning to the 2WD mode is just as easy, depress the "4WD" button once more and the vehicle is again operating in 2WD.

It seems my wifes 98 Limited has this Multi Mode even though it supposedly didn't come out till 99. The instructions on the visor read as the above 99 states about being able to drive on dry surface in 4WD etc. The center diff locks on going into 4-Low. I think you would just need the transfer case to accomplish this. Hers has some type of large vacuum/electrical solenoid on the back of the transfer case.
I would be curious if others with 98 Limiteds have this Multi Mode system. I have driven on dry roads in 4WD with no binding. BTW it was built in 6/98

Macgyver

I have added push button 4WD to my '98 4Runner 5 speed and the only difference between push button 4WD and regular J-Pattern 4WD system in '96-'98 4Runners is instead of moving the lever to move the shift fork inside the transfer case a motor on the back of the transfer case moves the shift fork. The motor operation is exactly like the e-locker, in fact I just used a junkyard diff lock ECU to control the motor. Toyota used a double syncro instead of a single syncro on the high 4WD gear for smoother operation but that's just about the only differences that I recall, when I converted to push button I added the double syncro along with my stock syncro on low 4WD which is gives me an overkill triple syncros.

I have not seen a multimode 4WD transfercase yet but that would be very cool, maybe someone with a FSM could scan some pics.