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Toyota Sequoia, Toyota Highlander, Toyota 4Runner, Toyota Land Cruiser, Toyota RAV4, Toyota Tacoma, Truck, SUV
#1975 of 2493 4Runner Rear and Center Differentials ?
Jun 30, 2006 (7:55 pm)
I have read the "Toyota 4WD Systems explained" thread in the Toyota 4Runner forum, but I am still a little confused about the differentials in the 4Runner and the RAV4.
Here are my 4Runner questions...
Does the 2006 / 2007 V8 4Runner have a Torsen rear differential, or a Viscous Coupling Limited Slip unit in the rear differential, or does the rear differential simply rely on the Traction Control system to accomplish slippery surface wheelspin control on the rear axle ???
When the 2006 / 2007 V8 4Runner Torsen center differential is locked by the dashboard switch, is the Traction Control system disabled ???
Does the Traction Control system wear out the brake pads / warp rotors at lower mileage than a vehicle without traction control ???
How capable is the 2006 / 2007 4Runner V8 on ice and in snow ??? I have family members that often need emergent medical care. I have to be able to get to care providers regardless of weather.
There was something mentioned about wanting to disable the traction control for situations like pulling onto a highway in the rain to avoid having it slow you down suddenly and put you at risk of getting rear-ended. Is this accomplished by a switch or pulling a fuse or some other modification ???
Thanks in advance for any info.
#1976 of 2493 Re: 4Runner Rear and Center Differentials ? [ccarofknowldge]
Jul 01, 2006 (7:41 pm)
The rear has an open differential, which relies on traction control to limit wheel spin.
When the center differential is locked the traction control system is still active.
No. When a wheel is slipping, it doesn't take much force to brake it. My brother is pretty hard on is 04 4Runner,with 30,000 miles brakes have 75% pad left.
Very capable. If you get really bad winters, put snow tires on in the winter and it will be unstoppable.
I think this mainly happens on the V6 when in 2WD. It is very hard to slip a wheel in 4WD.
#1977 of 2493 Re: 4Runner Rear and Center Differentials ? [2toyotas]
Jul 03, 2006 (7:48 pm)
Thank you for your very detailed reply. It is very much appreciated.
Another 3 questions, if you can answer:
When the 4 Lo Range is activated does that automatically lock the center differential ???
Does the Traction Control function on the front wheels also ???
Does the Sport Model suspension hop around when driven on less than smooth highways ???
#1978 of 2493 Re: 4Runner Rear and Center Differentials ? [ccarofknowldge]
Jul 04, 2006 (6:22 am)
Note that locking the center diff turns off spin control. As previously noted, it does not turn off traction control. On road, even in moderate snow, there's no need to lock the center diff. Lock the center diff in extreme conditions. I doubt you will ever find such conditions on the road.
It performs well in snow, but realize that the controlling factor in snow is your tires. The 4WD system will allow you to accelerate quite well in snow. But it doesn't improve braking and turning performance. The OEM Dunlops absolutely sucked in the snow -- acceleration was fine but braking and turning were completely horrible. I purchased a set of dedicated snow tires. I've driven through 1 1/2 feet of snow without a problem.
Traction control functions on the front wheels as well.
Concerning the ride quality, I strongly suggest that you take one on an extended test drive. The 4Runner is a truck. It drives pretty well, for a truck. It handles pretty well, for a truck. It rides pretty well, for a truck. But there is no mistaking it for anything other than a body-on-frame truck with a live rear axle. My 2003 4Runner does have a mild hobby-horsing motion on rough pavement. You can certainly feel that heavy rear axle moving around. It is not a sedan, minivan, or car-based SUV. It's big and heavy with a high center of gravity. It's cornering limits are low and when you reach them it will understeer mightily.
I've never had a problem with the spin control kicking in prematurely on rain-slick pavement. The 4WD system provides plenty of traction in such situations. I do feel the spin control is a bit over-eager in snow. In those situations, the spin control can cut in a bit too quickly, shutting down the throttle. You can turn lock the center diff (thus defeating the spin control) in the snow, but then the truck gets a bit tail happy. These days, I only lock the center diff when I'm offroad. The true answer to this issue is to get snow tires. Once you do that, you'll have all the traction you'll ever need in the snow.
#1979 of 2493 Re: 4Runner Rear and Center Differentials ? [nedzel]
Jul 04, 2006 (9:25 am)
I am confused again. If traction control and spin control are different, what does each one do?
I was not asking about the ability to prevent vehicle understeer, oversteer, and turnover. Instead I was asking about the ability to send power to wheels that have grip to pavement or tractionable snow or tractionable ice.
Once I can get going, I usually can drive cautionsly enough with a good set of tires to stay in reasonable control. If I cannot get going at all I'm in big trouble.
I know the importance of good tires. I do appreciate very much what you folks are saying about this. I have had some really bad all season tires that I threw away practically new at great replacement cost, but I felt my life and the lives of my passengers, (and everyones property too) was worth it.
I have had to use center differential lock and lo range on some of my older full-time 4wd suv's to get off of ice. That's why I'd like to know if 4 Lo automatically locks the center diff and if locking the center diff disables the limited slip system on the rear (whatever it's called), and if the limited slip effect works on the front diff / wheels too.
I've used limited slip clutch pack rear diffs and they stink on ice and snow. Vehicle fishtails dangerously.
I've used viscous limited slip on rears and centers operating in conjunction with standard open diffs and they worked great for me. Always got me going and no fishtailing.
I've used computerized electromechanical center diff systems in the center and they worked well, though not as well as viscous limited slip on top of standard diff.
I've never used torsen diffs at all, but they have a good rep.
I've never had computerized brake control limited slip (whatever Toyota calls it). I came here to get info.
I appreciate all the help you folks are giving me.
Looking to buy a new 4Runner V8 Sport Edition.
Have driven truck / suv's before. Know they ride hard. Just wondering what degree of punishment Sport Edition will doll out.
#1980 of 2493 Re: 4Runner Rear and Center Differentials ? [ccarofknowldge]
Jul 04, 2006 (9:00 pm)
I think when Nedzel says spin control he means VSC Vehicle Stability Control,which corrects oversteer and understeer around turns primarily. When you lock the Center Differential VSC turns off. Traction Control never turns off, and it works on all 4 wheels independently all the time. When the center diff is unlocked the torsen splits power front to back,normally 40% front and 60% rear. It can send up to 71% to the rear, and 53% to the front. Traction control send power side to side on the front and rear axle by braking the slipping wheel. When you lock the center diff both axles get 50% and traction control still does its job.
When in low range the torsen still works, or you can manually lock the center diff. Traction control does the same thing in low range.
The Sport uses XREAS suspension which I have on my Limited as an option. It links the front right shock to the left rear, and the left front shock to the right rear. It works great, and in my opinion makes the 4Runner one of the smoothest body on frame SUVs on the road.
As for traction on ice and snow, it will plow through anything, and start on ice with no problem. If you drive cautiously you will be fine stopping, but it will slip on hard stops. Snow tires change that, I put Blizzaks on my 4Runner, and the slipping stopped. It will stop on a dime on snow and ice. An All Terrain tire like Bridgestone AT Revo will do a pretty good job too.
In my opinion you will not be dissapointed with this truck!!
#1981 of 2493 Re: 4Runner Rear and Center Differentials ? [2toyotas]
Jul 05, 2006 (9:45 pm)
Thank you very much. Now I understand clearly.
Is there any kickback in the steering wheel when the brakes clamp down on a tractionless spinning tire on the front axle ???
"No kickback" in steering was supposed to be one of the advantages of using either a viscous limited slip with standard differential on the front axle of 4wd's or a torsen type differential on the front axle of 4wd's. Clutch pack diffs tried on the front axles supposedly snapped the steering wheel hard when they locked for those who dared to try it.
How does the Toyota traction control system behave as felt through the steering wheel when a front wheel gets locked down ???
#1982 of 2493 Re: 4Runner Rear and Center Differentials ? [ccarofknowldge]
Jul 06, 2006 (1:47 pm)
The Toyota traction control system, as with most others, always brakes both front wheels even though only one may be slipping. And keep in mind that this isn't "full" braking ability by any means, moderate, on and off braking much like ABS "feel" and sound but with reverse duty cycle, more off that on.
#1983 of 2493 Re: 4Runner Rear and Center Differentials ? [wwest]
Jul 06, 2006 (8:46 pm)
Wwest you are dead wrong. The Toyota system has a 4 Channel ABS system, it brakes all 4 wheels independently. If one front wheel is slipping it brakes just that wheel, and the open differential sends power to the other wheel. Where do you get your information?
#1984 of 2493 Re: 4Runner Rear and Center Differentials ? [2toyotas]
Jul 06, 2006 (9:33 pm)
Having 4 channel ABS capability doesn't mean the traction control firmware is (or should be) set up to bust knuckles or yank the stearing wheel from an unexpecting, inexperienced, driver's (John Q. Public) hands.
Besides which doesn't the 4runner allocate engine torque 30/70 F/R in AWD (non-locked center diff'l) mode? That would make it unusual, rare, for a front wheel to break traction first.