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SUVs Toyota Highlander Toyota 4WD systems explained
2400 messages, Last post on Nov 22, 2009 at 10:30 AM
You are in the Toyota Highlander Forum. Your Hosts are steve_ & tidester
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Replying to: wwest (Jun 15, 2009 7:44 am) You should only use 4wd low and/or lock the center differential when you are off road. The 4th Gen 4Runner V8 has basically the same drivetrain, but does not have the option for 2wd high. For the 2007 model there is a separate switch for un/locking the center diff'l regardless of driveline model, plain 4WD or Multi-mode That locking switch has remained the same throughout the entire run of 4th gen 4Runners, both V8 and V6. It is a pushbutton on the lower portion of the dash, to the left of the steering wheel.
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Replying to: nedzel (Jun 15, 2009 12:41 pm) |
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Replying to: nedzel (Jun 15, 2009 12:41 pm) The center differential should ONLY locked as above or in low traction, oil/water(rain) slicked, slippery roadbed, or wintertime adverse roadbed conditions. Even in these additional low traction conditions it is NOT a good idea to keep the center diff'l locked once underway, traveling at a decent speed, say above 15MPH.
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Replying to: wwest (Jun 15, 2009 3:44 pm) I would not lock it on rain-slicked roads or snow-covered roads. The 4Runner becomes quite tail-happy when you lock the center diff and there is simply no need to lock it on your typical rain-slicked or snow covered road. I've put 80,000+ miles on my 4Runner and only lock the center diff when I go off road.
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Replying to: nedzel (Jun 18, 2009 12:01 pm) Don't you have that a bit backwards....?? With the center diff'l locked the F/R torque bias is neutral, other than F/R weight bias, and it should be just as "front-happy" as rear. On the other hand with the center diff'l locked you lose all the "nanny", "watchover your shoulder" electronic aspects, ABS, VSC, etc, and maybe that's why you appear to have had a tail-happy experience. But as I said, the center diff'l should NOT remain locked once underway.
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Replying to: wwest (Jun 19, 2009 7:41 am) No, I don't. I've driven my 4Runner in the snow, with the center diff locked and with it unlocked. I've driven it with all-season tires and snow tires. I've put 80,000 miles on it. Have you driven a 4th Gen 4Runner in the snow with the center diff locked? With the center diff'l locked the F/R torque bias is neutral, other than F/R weight bias, and it should be just as "front-happy" as rear. You can argue about how it "should" or "should not" handle. I can tell you how mine does handle, because I've driven it in the snow with the diff locked. With the center diff locked, when driving in the snow, if you get heavy on the gas in a turn the rear steps out quickly. Given that the 4Runner has a lot of weight over the front wheels and far less on the rear, it is perhaps not unsurprising that with equal torque to the front and rear axles that the rear will lose traction before the front. On the other hand with the center diff'l locked you lose all the "nanny", "watchover your shoulder" electronic aspects, ABS, VSC, etc, and maybe that's why you appear to have had a tail-happy experience.. You just might want to re-read your technical manuals. You do not lose all the nanny electronics when you lock the center diff; you lose the VSC. You don't lose ABS and you don't lose the traction control. Which, in some ways, is unfortunate. There are times when I'd like to lose ABS and traction control. I learned to drive in Chicago, driving a 1969 Ford Falcon, 1970 Ford Galaxie 500 station wagon, and a 1972 Mercury Capri. When driving the Capri, in particular, my brother and I liked to hang the back out in the snow. It was very, very controllable, far easier to control than my 4Runner.
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Replying to: nedzel (Jun 19, 2009 8:48 am) Tail-happy is when you are driving STRAIGHT along and step on the gas and the rear tries to get in the lead, very common to RWD. On the other hand, in your case. diff'l locked, if you happen to be turning at the same time then inertia comes into play and the rear end will skid toward the outside of the turn while the front plows to the same "degree". So your 4Runner, with the center diff'l locked, and equal tires on all four, will have neutral "happiness", just as the Toyota design engineers intended. I'm surprised at ABS, and TC, remaining enabled since BOTH drivelines MUST turn in synchronization and that compromises the functionality of ABS and TC.
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Replying to: wwest (Jun 20, 2009 8:32 pm)
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Replying to: nedzel (Jun 21, 2009 6:51 am) How about miles upon miles on mountain passes in WA, OR, ID, and MT, more often packed snow than not. Except for those many early morning drives up the mountain in order to be the first to lay "tracks" in the freshly fallen snow. I can't imagine that the 4runner drive system and handling dynamics in various drive configurations would be that much different from my '85 Jeep nor my '92 Jeep, both Cherokee Limited's with RWD/"AWD"/4WD/4X4 modes. Maybe as much as 150,000 miles overall, and quite a few NW winters with Ski trips. The '92 is still doing duty in the "family" on a cattle and wheat ranch in north central MT. I admit I never found much, if any, use for the AWD mode, 4 wheels driven but center diff'l open, and I probably never found use for the 4-lo mode. But I did find lots of use for the 4WD (diff'l LOCKED) mode, often with rear chains installed and sometimes with all four chains. Oh, I always removed the ABS fuse during the summer.
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Replying to: wwest (Jun 19, 2009 7:41 am) You've repeated that idea, with emphasis, a few times (even branding it unsafe) so I'm curious to know your reason. I don't expect to hear anything I haven't heard, but your position seems to be even more extreme than the standard "NEVER lock on dry pavement" warning which is already over simplified, imo.
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