4 high 4 low operation
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Iowa4Runner
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noserider said:
The output of your 5 speed transmission is sent through a transfer case. The transfer case has two sets of gears, one for high and one for low. Low gears mean a larger gear reduction - it takes more revolutions of the engine to make one revolution at the wheels. Low means you get more torque (but less speed) at the wheels.
Low range is good for high pulling force applications like pulling a heavy boat up a steep ramp. It's also good for low speed driving over rugged terrain. Sometimes you don't need a lot of "power" (torque), but you want better control in super low speed driving situations, that's where low range is nice. I have no use for low range in snow or ice.
The center differential locker is good for lower speed situations where traction is poor and wheelspin is a problem. If you're stuck in the snow or mud, lock the center diff. Locking the center diff. helps to send torque to the wheels that have the most traction. Locking the center diff. also shuts off the traction control feature, allowing more wheelspin which can sometimes help you get unstuck. TRAC (traction control) automatically reduces the throttle position if wheelspin is detected. This can help you from spinning off into a ditch. If you're driving down an icy or snow-packed road, it'd be a good idea to unlock the center diff.
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Colemanfu
New member
I'll take a shot at this one with the KISS theory.
4hi when going over 35 in poor traction conditions
4lo when going under 35 in poor traction conditons
I would suggest a test of each so you have some experience when you need it. Get it off the pavement and play around a bit. I 1st used the hill decent system on my parents drive way in VA. Not much need for it in flat FL.
Hope this helps.
Here is an example of when to use 4low. this was my 3rda and final run up the hill. Once all the grass stuff got chruned up it was pure greese. Slid into the tree and had to cut it down to get out. Stuck the limbs under the rig for more traction. Running boards came off the next weekend. A good reason to carry recovery gear.
4hi when going over 35 in poor traction conditions
4lo when going under 35 in poor traction conditons
I would suggest a test of each so you have some experience when you need it. Get it off the pavement and play around a bit. I 1st used the hill decent system on my parents drive way in VA. Not much need for it in flat FL.
Hope this helps.
Here is an example of when to use 4low. this was my 3rda and final run up the hill. Once all the grass stuff got chruned up it was pure greese. Slid into the tree and had to cut it down to get out. Stuck the limbs under the rig for more traction. Running boards came off the next weekend. A good reason to carry recovery gear.
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Guys
Thanks for the info. It makes sense. This is my first 4 wd so I'm starting from scratch on the mechanics. Would you ever want to be in 4 wheel high with the center diff locked? When you lock the center differential how does this send more torque to the wheels that have the most traction? I guess I dont understand the gearing when you lock the center differential.
thanks
Thanks for the info. It makes sense. This is my first 4 wd so I'm starting from scratch on the mechanics. Would you ever want to be in 4 wheel high with the center diff locked? When you lock the center differential how does this send more torque to the wheels that have the most traction? I guess I dont understand the gearing when you lock the center differential.
thanks
Do you have some images?Iowa4Runner
New member
noserider said:
Driving through deep snow on an unplowed road might be a time when you'd use high range and center diff lock.
To understand how a locker helps, you have to be familiar with the basics of how a differential works. With an open differential the amount of torque sent through each shaft is equal. If one shaft is driving a wheel with no traction, no torque is delivered to that wheel. This means that no torque is delivered to the other wheel, even if there is grip. A locking differential allows torque to be sent to the wheel with grip.
In a nutshell the output shafts of an open differential get equal torque but can turn at different speeds. The output shafts of a locked differential turn at the same speed, but can get different amounts torque.
Your 4Runner has 3 differentials, a front, center, and a rear. Only the center has a locking feature. The front and rear don't have a locker but the control system can apply the brakes independently to emulate a locker.
By the way you can drive on pavement in 4 low if you want to, just be easy with the throttle. I've done it several times and to my knowledge Toyota doesn't advise against it.
