Toyota 4WD systems explained

farfegnugen · August 2002

That's completely incorrect. There is an "ESP off" switch which turns off the torque reduction feature altogether. Unlike Toyota's system, the torque reduction isn't so sensitive. There is no need for any locking differentials in the ML since the traction control takes care of everything. The added benefit of this is that low range can be used for towing on dry surfaces, for example. Very beneficial for towing up hills.

MB's special low range ABS feature has been on all MLs since 1997, and it works only when you're off-roading at low speeds. Nissan/Toyota have some sort of ABS sensor which is supposed to read the road surface, however, it's not the same thing as it doesn't allow the front wheels to lock up.

Heh, who do you think Toyota copied the system off of? Just as Lexus claims to have invented dual threshold airbags in their commericals :-p

pschreck · August 2002

I don't know, but a physician I know swears that MB steals all their breakthroughs from BMW.

Also, on the Toyota, the locking diffs are in addition to the traction system. So you can use 4WD Low while towing on dry sufaces on the Toyota too.

tidester · August 2002

...the maximum traction point of a tire is when it is revolving at 15% slower than it would be if it were freely rolling over the surface.

I'm not sure I understand that. If the tire isn't revolving at exactly the free rolling speed, then it would have to be slipping or skidding. Perhaps you could clarify.

tidester
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wwest · August 2002

farfegnugen:

You should have included the next paragraph in your quote.

Okay, in same instances ABS is good, and in some instances no-so-good. The insurance company statistics are indicating a slightly higher injury accident rate with ABS than without. They're still trying to figure out why. The most current best guess is that people with lot's of non-ABS life's experience have learned to lay into the brakes until the very last minute and then release the brakes for last minute manuvering.

What they get with ABS is longer stopping distances during which they could steer to avoid an object, or avoid leaving the roadbed on a curve (into which they entered too HOT).

Just what good is ABS if it modulates the brakes so I still have steering capability but I sit there like a dummy, frozen with panic, and hold the steering wheel rigid?

Do you realize that the RATE at which a fully braked tire slows can be used to determine the coefficient of traction of that wheel with the roadbed?

In any case something is clearly wrong, maybe in the driver's head, but until we figure out just what it is and apply a fix maybe it would be better to sacrifice the need for directional control until there is some indication of need.

What the world needs is a huge fleet of driving simulators to teach people how to properly react when they encounter a real emergency, and in the process we could maybe learn from the huge mass of people with life's experience how they react and thus maybe learn why ABS is not fullfilling it's expectations.

We could even put a simulator in every dealer shop and they could use it to teach people what to expect and how to properly "react" to that vibratory brake pedal (push harder!).

wwest · August 2002

This one is where the shear idiocy of ABS designers stands out so grandly. I'm driving along on a snowy and icy mountain pass roadbed at night, with my right tires on the graveled shoulder of the road and the left tires are on pavement covered with black ice. Suddenly I see an Elk just standing in the roadbed.

Without ABS I can apply the brakes fully, well knowing (I'm 62) I will need to quickly respond to the expected yawing motion, and I end up stopping a few feet away from the elk, who now proceeds to jog merrily away into the woods.

True story.

With ABS in order to prevent that "yawing" the engineers have designed it so I get no better braking HP applied to the high-traction side than the low traction side. Pity the poor elk, pity my poor Porsche.

intmed99 · August 2002

The Mercedes M-class does indeed have a "ESP OFF" feature. HOWEVER, even with pressing this, the engine-cut-feature is STILL on!! That is why, in ALL tests to date by various magazines, the ML has FAILED MISERABLY (!!!) in off-roading terrain. Yes, it has a traction control system (LIKE THE 4RUNNER). It does NOT NOT NOT have a center differential lock like the 4Runner, which helps in tough off-roading terrain (see my comments above). If you turn ON the center diff LOCk in the 4Runner, there is NO engine power reduction! Right there, the 4Runner system is already superior to ML's. But, read on....

In addition, the ML's 4wd system is NOT very sensitive to wheel spin. Therefore, you actually have A LOT of wheelspin BEFORE the ML system becomes active (that is, brake the spinning wheel). This is OK in snow...however, in off-roading, if the system waits THAT LONG, you will have lost momentum already! This is bad! You are stuck! The Land Rover Discovery system is very good at this. Toyota's system is somewhere in between Discovery's fast-acting system and ML's SLOW-acting 4wd system.

farfegnugen, in the 4runner, you can have HIGH or LOW on DRY land too! ML's system was a good idea when it first came out; however, the newer systems (Land Rover and Toyota) are better and with more features (aka center diff lock).

I can go on and on about how the ML is really a POS in general. Cheap interior materials (yes, even worst than 4Runner). Thin-sounding doors. NO wheel articulation. Sure, it has LOW range, but it has NO FREAKING SKIDPLATES! That is helpful! It is low to the ground, with not very good aproach and departure angles.

In conclusion, it is a good & fast minivan. Unfortunately, BMW X5 kills it in every performance tests! If i were to buy a fast wagon, the X5 would be it. Who wants to buy a Mercedes ML??? The G500 is another story...i respect that ancient thing!

idahodoug · August 2002

Tidester,

I'll shed some light on that. A tire is nearly always "sliding" relative to the ground. When you're cornering, the tires are sliding a bit. When you're accelerating, the tires are rotating a bit faster than the ground is passing under them. And when you're braking the same is true.

I don't know if the figure is 15%, though it would certainly vary by tire design, pressure, surface and dowforce. This may be a rough average number but it's in the range of what I'm familiar with. The max braking is provided when you are at what is called "incipient lockup" for the tire. In this range, it is slipping a bit but not locked up - which would reduce the braking force as noted above.

A variety of things are happening in this zone. The contact patch has elongated in the direction of travel, the rubber is heating rapidly, the tread blocks flex to their max and a variety of other factors beyond this list contribute to max braking. On a graph the free rolling tire contributes negligible braking force, a gently braked tire increases it, the max is at incipient lockup and then the braking force tails off rapidly when the tire is locked.

IdahoDoug

tidester · August 2002

Thanks for trying to explain it to me! I appreciate it.

I'm still not sure I understand it, however, at least not the 15% figure you and farfegnugen mention. I wonder if you aren't thinking of "torsion" rather than speed. Let me try to explain.

Imagine drawing a straight chalk line from the center hub of the tire to a point on the rim of the tire along a radius. Now, as you're moving along with the vehicle, you can visualize the motion of the line. When you decelerate (or accelerate), that line will be distorted when the end of the line is nearest the road surface. This is because the counter-torque from the road stretches the rubber.

As end of the line approaches the surface, it's speed will be decreased briefly during braking due to azimuthal compression of the rubber. But, after it has passed the vertical (on it's way back up) it's speed will be increased as the rubber decompresses azimuthally. The average speed should still be the same as the speed of the car - decelerating or not!

Also, the point of contact should be moving with zero speed relative to the road! If it's not, then the tire is slipping and the coefficient of friction drops drastically from its static or rolling value. Then you're in a full-blown skid!

Does that make sense?

tidester
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idahodoug · August 2002

You made me dust off my "Fundamentals Of Vehicle Dynamics" book to confirm the 15% figure. According to this book the figure is actually between 15 and 20% tire slippage to generate maximum braking force, so it's even higher.

Here's what goes on in the contact patch of a braking tire. A tread block touches down at the front of the contact patch, then travels rearward through the contact patch, finally leaving out the rear as it rolls back up and away from the street. When it first touches down, it has very little downforce on it so it cannot generate much friction or braking force. When it firmly touches down it generates braking force by deflecting the rubber. This is key. The flex of the tread block means the ground is passing under it faster than it is rolling. Otherwise there can be no deflected rubber, and thus no braking force. Throughout the center of the contact patch, the tread block is fully flexed. As the contact patch arrives at the rear of the contact patch, the downforce on it reduces as it starts to roll upward and away from the pavement. This is the area where most slippage occurs - the rear of the contact patch where flexed rubber rebounds by slipping against the road. It happens here simply because as you reduce the downforce on the tread block, at some point the tread block will no longer have enough downforce on it to hold its flex and it will slip. And that's precisely what happens at the rear of the contact patch.

So, your line on the tire is a perfect illustration. As the line touches down at the front of the contact patch, it begins to distort into a curve to indicate the tread is moving slower than the sidewalls. As the line gets to the back of the contact patch, it will suddenly straighten as the tread briefly accelerates faster than the ground under it to regain its orientation versus the sidewalls. As it does so, it slips against the ground and of course wears off some rubber as a result.

For those of you still reading, the reason lockup generates less friction is that this zone of slippage starts to extend further and further forward in the contact patch as the tread's speed versus the ground gets further and further apart (tire obviously slower). Meaning that progressively more and more of the contact patch as a percent of it's area is slipping until you finally arrive at the 100% slippage of a locked tire.

Hope this helps a bit.

IdahoDoug

tidester · August 2002

Idahodoug,

I get it now! I think I was on the right track and you've added some missing pieces for me.

The part I hadn't considered is that the frictional force is proportinal to the normal reaction force on the tire/road and since the normal reaction force on the tire from the road goes from zero to a maximum and back to zero again near the contact patch there is the possibility of slippage!

Thanks for dusting off your FoVD!

tidester
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aaddven · August 2002

Has anyone installed a K&N replacement air filter or a K&N FIPK on their 4Runner? If so, are you happy with it? Pros / cons? Any noticeable increase in horsepower or throttle response? I installed the FIPK but thought it made the engine way too loud upon acceleration; objectionably loud

stever · August 2002

Try the Toyota 4Runner discussion.

Steve

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idahodoug · August 2002

Ah, glad I could be of assistance. Few outside the world of engineering realize that car tires are almost always slipping. When you turn, the front tires may be 15 degrees from center, but their actual path is only 12 degrees. When you are driving on the freeway, the tires may turn several times in a mile, and we covered the braking above. This is why tires wear, actually.

The gentleman above who decried ABS systems has a good point that they will not provide the shortest braking distance. At 62, he is near his peak in terms of driving skills and experience and I have no doubt he could outbrake an ABS system under most conditions. ABS is actually aimed at the average Joe, and functions to prevent a lot of spins when Joe panics and stomps the brake like 90% of drivers would.

One of the challenges of ABS design vis a vis tires is to maximize the amount of time the tire is in the 15%-20% zone. Given that different tire designs have different stretch, tread block squirm and other variables, it is tough to accomplish. To maximize ABS effectiveness, your best bet would be to purchase the original tires that came on your car when new as it was the tire used to fine tune the ABS system's cycle rate. This is always a tradeoff, however as you may not like the stock tire for one reason or another. But sticking close to its design and using the same size are good ideas. That's why a lot of folks who put larger tires on their SUVs may find the ABS system performance has been altered a bit. Usually this discovery is made precisely at the moment you don't want a surprise.

IdahoDoug

wwest · August 2002

But I was talking about "stomping" the brakes, or at least applying them hard enough that the brakes would lock the wheel from turning once they could.

You can believe whatever you want, but for me the only reason, ever, to release the brakes in a panic situation is to allow some directional control. I have no complaints about ABS, it works fine if I happen to need directional control along with, or instead of, shorter stopping distances.

idahodoug · August 2002

Releasing the brakes for directional control is the right choice when needed. Clearly you've learned from the driver's seat what the physics of a contact patch is regarding braking.

In a nutshell, a contact patch will provide X amount of traction in any direction you choose, and it can be split into two different directions when needed. If you use 90% of the contact patch's traction for braking, you only have 10% left for turning. Briefly letting off the brakes to the point where you're only using 10% for braking allows you to use the other 90% for avoidance maneuvering. That's an important emergency skill to have and probably explains your lack of faith in ABS. It's a band-aid for the generally clueless US driver.

Research has also shown that we often don't apply the brakes hard enough in emergencies, either. Thus, a rise in the number of models with 'brake-assist' type functions, which sense a panic stop and bring the car to full max braking. Starting with Mercedes a few years back, this can now be found throughout the entire market. We'll have to wait and see how the results come out.

IdahoDoug

wwest · August 2002

also why I think FWD and/or AWD with a definite FWD torque bias is a BIG mistake. It works fine, very fine, right up until the moment of truth, the instant you discover you need some of that front contact patch reserved for directional control, not engine leading or lagging torque.

idahodoug · August 2002

I wouldn't go so far as calling it a big mistake, but for an enthusiast driver or someone interested in wringing the vehicle's max potential out, FWD would not be the ticket. Under the situation you describe - understeer on slippery surfaces - most people would prefer understeering off the road at a shallow angle and striking something with the front end in front of you. This is the max survivable vehicle attitude into a collision and the likely one with FWD. The RWD behavior under the same condition with the same driver skill level (assumed to represent the average US driver) would likely be oversteer and either going off the road sideways (high rollover potential) or a spin into whatever the vehicle impacts.

Granted, this was one scenario of many, but my point is that FWD is benign and safe on slippery stuff while RWD is a bit more difficult to handle. Again, all assuming the average Joe - not someone wanting to motor. Fortunately, there are still RWD vehicles around for the enthusiasts. For a while there it looked like everything was going FWD (shiver).

Personally, I've owned some 20 cars over the years and only 2 were FWD - the last of which was 16 years ago. I do not like FWD either, obviously, and live in a northern climate where it would be a good idea for most. FWD has way too many tradeoffs for me.

wwest · August 2002

What would be the most common reaction, within the public at large, the instant a driver realizes the car is out-of-whack. I firmly believe that in the vast majority of cases it would be "throttle lift".

In a FWD car, or AWD with front torque bias (RX, HL, etc.) you just applied engine braking to the front contact patch, which was very likely already over-loaded. Unless you happen to be in a FWD Cadillac which has an over-running clutch.

Lifting the throttle in a RWD will have the instant effect of "pulling" the car back into the proper line of travel. A much more benign affect.

idahodoug · August 2002

At the limit handling in a RWD car may cause a spin in a classic response called 'drop throttle oversteer'. The cause is simply rear contact patches that get a jolt of engine braking force at the same moment weight is transferred off them due to the vehicle's forward weight shift in moving from accelerating to braking attitude. On slick stuff, this is even more easy to do. In fact if you're a Porsche fan (your above post) it is worth noting that the Porsche 911 was one of the most notorious high performance vehicles for this behavior ever built. To this day, the 911 must use larger rear tires to counter that tendancy - a consequence of its rear engine/rear weight bias.

On a FWD car, dropping the throttle causes more weight on the front contact patches while the braking effect occurs, minimizing the tendancy for the car to break loose. The result is usually more understeer, causing the line to widen slightly. On slick stuff it will widen more but the car is still heading off into the woods front first - preferable to sideways or backward.

So, throttle lift mid corner on slippery stuff favors the FWD by far when it comes to the average driver. I disagree with your contention RWD will "pull" the rear back into line on a slippery surface. I've had considerable track time to back up this basic principle of vehicle dynamics, including use of artificial ice skidpads.

Regards,
IdahoDoug

wwest · August 2002

about one time in the winter in MT when I inadvertantly turned down a very steep street that was covered with ice. I ended up using the parking brake to keep the car aligned with the roadbed. Thank god it was a rear brake implementation.

stever · August 2002

that I should weigh in about my 20 years in Anchorage (the first two w/ a Bug and a RWD wagon) and my definitely average (at best) driving skills.

But I won't - but I think IdahoDoug has pretty much nailed me :-)

Steve
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sandman18 · August 2002

We are looking for an SUV and are concerned that the Highlanders AWD will give us trouble in sand. We go to the Outer Banks and the only way to get to the house is to drive on the beach. We borrowed a Tahoe last year and it was fine in 4WD Low (it almost got stuck in 4WD high). Any insight would be appreciated!

stever · August 2002

We can't seem to keep the SUV for Beach Sand discussion going without it auto-archiving, but I've unfrozen it, so you may want to look in there too.

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sandman18 · August 2002

Thanks! I read every post on the SUV for Beach Sand board. Not sure what to belive or do. What I didn't mention was that we already have an Outback but were concerned that we needed a "real" SVU to get around in sand. From the board I got the impression that just getting a bigger AWD (like Highlander or Pilot) wouldn't be an improvement.

I just hate the Explorer, Jeep, 4Runner, etc. that we test drove.

What's a guy to do?

wwest · August 2002

Neither the HL nor its Lexus counterpart, the RX are REAL SUVs. They use three OPEN diff'ls, with a very WEAK VC across the center diff'l. As long as all wheels are on firm footing you will get even torque distribution all around.

But the instant any wheel, or wheels, lose traction....GAME OVER !!!

The "instant" torque distribution on encountering a low traction surface will be about 90/10 front to rear. The best we could measure on a 4 wheel dyno was 75/25 F/R and that was with artificially created circumstances which you will never encounter in real life.

For true AWD look at the BMW X5, the ML320, or even the Chrysler T&C minivan. The T&C starts out like the HL & RX, 90/10 F/R torque distribution, but it is equipped with a VC that can really, quickly, buckle down and get the job done.

idahodoug · August 2002

So, were you able to get through the sand with your Subaru? If so, the Highlander would have similar capabilities.

One consideration that may or may not be practical would be to lower your tire pressures for that section of the journey. I say this because it would seem more cost effective to buy what you want to drive on the 99.999% of applications not comprised of sand. Then adapt the vehicle to the sand during the half mile or whatever distance it is.

Lowering your tire pressures to 15psi will perhaps triple a vehicle's traction in sand. It would simply be a minor inconvenience to carry a portable air pump, or air up in some other fashion when you left the house/sand portion. In sand, it's all about contact patch surface area and even a 2wd vehicle will comport itself quite well at these pressures.

Regards,

IdahoDoug

cmack4 · September 2002

I have a 2002 Bravada and it does a great job in the sand. Other AWD systems should work OK as well, but whatever system you would buy, I would highly recommend a rear locker!

A lot of 4wheelers make the common mistake of using 4Lo in sand, and I would highly advise against it! Sure it can bail you out of deep sand conditions, but more often than not, it was the 4Lo (added torque) that dug the hole in the first place! 4Lo, if you have it, should be your last resort in sand.

Air down your tires to between 15-18psi (20 if it's a lot of mixed on/off road) and stay out of ruts and you should be fine. I know my Bravada even did a nice job on dunes, so long as the breaking points didn't interfere with my clearance.

navigator3740 · October 2002

I'm in the market to replace my Navigator. Frankly, the only thing out there that interests me other than a new Nav would be the Sequoia, largely because of the Toyota reputation, and finally, it's "almost" big enough to contend. But, then I read the posts here, and this letter from Car & Driver Reader page, quote:

"Officious" is too mild a word for the Toyota Sequoia's vehicle skid control system. Toyota may have uniquely designed the first system that is dangerous on dry pavement. In all-wheel-drive, where the VSC can be turned off only at low speeds, usual Midwest bumps such as train tracks tell the system to throttle back the accelerator. Ever change lanes with no power? And in rear-wheel drive, where the system always remains active, slight road irregularities continually activiate Big Brother, especially at low speeds. Ever turn right on red when a slight dip in the road kills the throttle as you try to power up and merge into the traffic flow? Cars backing up behind you with flashing headlights and blaring horns is a common experience in a Sequoia. It's a nightmare. John W. Riggs, St. Louis, Mo.

Response from C &

"It's the traction control chopping your p[ower, not the VSC, and we didn't experience the problem as often as you did. Ed.

Car & Driver didn't experience it "as often"? That should make me feel better?

I am hearing such horror stories about this truck, I am amazed at how human Toyota has become. Anybody else have personal experience with this phenomenon?

cliffy1 · October 2002

I can get the traction control system to cut power if I want. The early ones has a bit more sensitive system as the newer ones but if you try hard enough, you can get the RPMs to drop. This is a good thing to happen of you are on ice. You want it to happen. If you are concerned about it happening, simply do what I have suggested about 30 times in this and the Sequoia topic and leave the thing in the 4WD mode.

intmed99 · October 2002

This "problem" is prevalent in ALL systems, from BMW to Mercedes to Toyota. It is the nature of the beast! There is no perfect system yet. I read once about a BMW X5 crashing on the side of the road because it's stability system startled the driver! Geez!

You just have to KNOW that you have a stability/traction system. Don't be a fool and slam on the gas pedal to merge in traffic! You should not do that with a 4500 lbs SUV!

The Navigator, if equipped with stability control, will have the same "trait". I think you can order a Navigator withOUT this system...i am not sure.

For me, i have a '02 4Runner. I have not experienced the stability system at all during normal driving (in rain too). Only during off-roading that the system comes on.

navigator3740 · October 2002

Not very helpful, but thanks for caring. I only see knocks like this on the Tahoe (not a big surprise) and the Sequoia. Learning to just live with it isn't exactly what I was looking for. Just the fact that it has its own thread should tell me something I guess...

intmed99 · October 2002

I believe the reason for this thread is to explain the 4wd system of the 4Runner, Land Cruiser, and Sequoia. It has nothing to do with the "problem" of stability control.

As you may know, the 4wd system of the Sequoia and 4Runner is pretty diverse...2wd, 4wd HI, 4wd LO, 4wd HI with center diff lock, and 4wd LO with center diff lock. Personally, i love this variety in my 4Runner! Not many other SUVs offer this variety! (in fact, can't think of one right now.)

I don't think the Tahoe has a traction system similar to Sequoia, nor does it offer stability control.

Like i said, all stability system will have this "problem." Ford just put the stability system on the '03 Navigator...basically, it is still in it's infancy! It may be worst than the other systems!!

tedplano · October 2002

What kind of situations might require me to lock the center differential in my landcruiser?

intmed99 · October 2002

Anytime that you are off-roading in uneven terrain or slippery conditions, you should lock the center differential. If you don't, VSC will kick in and DEPOWER you when you need power the most! It is a bit too late to lock the center diff when you are ALREADY stuck.

Another benefit is that locking the center diff allows for a TRUE 50/50 power split between front and rear axles. Basically, there is no guessing by the computer where to send power...it is always 50/50. You will only need it in severe off-roading conditions. For example, when you have only ONE (or two wheels on ONE axle) wheel traction. In this situation, it is more efficient for the traction control system because 50% of power is direct at both axles no matter what. Seriously, i have never encountered such a condition. However, my center diff is almost always lock when off-roading (due to reasons in the first paragraph).

Other than that, my center diff remains UNlock during daily driving.

ray_c · October 2002

Hi,

I'm planing on getting a 03 4Runner and would like to know the different between the full time 4wd and the part time 4wd in the new 03 4runner. And Can the part time 4wd be turn on at all time, even on dry flat surface?

Thanks,

Ray

eric4wd · October 2002

So how do I lock the center differential on my Sequoia Ltd when in 4HI? Can it be done and is it the same procedure as when in 4LO.. i.e. transmission shifted to "L"? I just didn't happen to read my owner's manual thoroughly yet.. nor did I give it a try and experience that torquey engine..

intmed99 · October 2002

I don't think Sequoia can lock the center diff in 4-HI.

intmed99 · October 2002

Part-time 4wd modes in 4Runner: 2wd, 4wd HI, 4wd LO. You can use 4wd on ANY surface (e.g. dry land)

Full-time 4wd modes in 4Runner: 4wd Hi and 4wd LO.

nippononly · October 2002

and current Sequoia can only lock center diff in 4LO.

Only difference between 4WD systems controls in new Runner V-6 and V-8 is that on the V-6 it can be switched to 2WD if you want.

intmed99 · October 2002

Are you sure that the '03 4runner can ONLY lock the center diff in 4-LO??? That kinda suck! Many times i want VSC to be off in 4-HI.

Oh well, i guess it is still plenty capable.

ray_c · October 2002

So there is no different between the two in function wise. It justs that the V-8 (full time 4WD) has it on all the time and wont allow you to switch it off. I wonder why they do that?

intmed99 · October 2002

Yes, both do the same function, except that the "part-time" system will save you $$$$ with the 2wd mode.

The V8-option carries the 5-speed auto tranny, which is seen in Lexus and Toyota Land cruiser. Therefore, all 4Runners with the V8 option will have the same powertrain as the LC and Lexus. This saves money for Toyota.

cliffy1 · October 2002

There is actually one other difference and that is that the V8 models have a torsen center differential. This keeps some power available both front and back, while the 2002 is an "open" differential that will route all power front or rear. Both will get power where it is needed but the torsen works better in more extreme situations.

With either, you can lock the center in any 4WD mode.

intmed99 · October 2002

In the '02, when i put it in 4wd (center UNlock), is it 50/50 split?? What happens when slippage occurs?? Does it send power to the axle with traction??

Thanks.

intmed99 · October 2002

You will have the center diff lock anyway...thus, both '02 and '03 system will be equal then.

cliffy1 · October 2002

Yes, in the 2002 in 4WD with center unlocked, you have a true 50/50 power split IF traction is equal at all wheels.

cliffy1 · October 2002

With the new torsen center, the chances of needing to lock the center are not as great. Your worst case is 29/71 (front to rear with front slipping) or 53/47 with the rear slipping. This is without locking the center where you have a true 50/50.

foghorn48 · October 2002

Anyone know/understand the '03 Runner's 4wd system enough to say if there is any side to side traction control? Does the torsen diff accomplish this even a little? If this has been addressed, please let me know where I can find it and forgive me for not keeping up.

intmed99 · October 2002

Toyota's ATRAC (active traction control system) manages the side-to-side traction. Torsen only manages the front-to-rear transfer of torque. The 4Runner/TLC/etc. can perform ONE-WHEEL TRACTION.

Answer to your question: yes.

intmed99 · October 2002

This is from FOURWHEELER magazine (an off-roading magazine):

http://www.fourwheeler.com/editorial/article.jsp?viewtype=text&id=20998

I think they really like it!

Toyota 4WD systems explained

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