CF_Machete
Senior Member
[MENTION=135175]jhguth[/MENTION], what he said ^^^
Distance/Time in 4WD??
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[MENTION=135175]jhguth[/MENTION], what he said ^^^
Power is split 50/50 because its locked front to rear - you're scrubbing tires when you turn in 4wd even with open front and rear diffs because you have no center diff. When you turn each tire is at a different speed, that means the speed is different both side to side and also front to rear.
I'm not sure how else to explain this. Are you familiar with the difference between full time and part time 4wd? AWD vs 4WD?
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CF_Machete
Senior Member
The only time you will scrub your tires in 4wd is in a tight turn... like in a parking lot. For road use, zero issue with scrubbing
Bilbo
New member
You've got that backwards about the Limited's center differential. When not locked, it sends more torque to the axle with greater traction (within its design limits, normally 40% to the front axle and 60% to the rear axle, but ranging from 30-53% to the front axle and 70-47% to the rear axle as traction varies).
See https://torsen.com/how-it-works/
Which does raise the opposite question - why lock the center in snow or icy conditions? Locking does create an understeer that makes your rig feel like it's riding on rails. Beyond that, it's a matter of personal preference. Some almost always lock, and others almost never lock. I don't think you'll find a single "correct" answer.
mtnbiker49
New member
Have you driven in 4x4 before?
ElZilcho
New member
In my 3rd gen I've driven empty snowy roads and 80MPH for a couple hundred miles at a time with no ill effects. It was part time 4WD and the transfer case locked the center diff. I left it locked the entire time.
The trick is to know how to drive properly for a given situation and a given drive train. For example, if you are in a 4WD vehicle (transfer case, locked center diff, 2-way LSD, or viscous coupling) and your rear end starts to slide sideways... letting off the accelerator can make it worse! The rear tires have no traction, the front tires DO and decelerating can spin the vehicle in short order. It's called lift-off over steer and it's terrifying when it happens at speed. Counter-intuitively getting on the throttle can pull you straight.
Conversely, in AWD or with a 1/1.5-way LSD on a "full-time" 4WD letting off the throttle won't make it worse, but accelerating may still pull you straight.
In FWD over steer can be corrected with acceleration.
In RWD it will inevitably be exacerbated... which is awesome! (if you're expecting it).
Locking the center diff will always "scrub," you just don't notice at low steering angles or on low traction surfaces.
Hydroplaning is a completely different scenario. Lots of people mistake any loss of traction in wet weather for hydroplaning. Regardless of drive-train, hydroplaning generally happens to the front tires because they are the leading edge and when they pass over standing water, flow is laminar and it lifts the tire off the pavement. They don't (technically) lose traction... They are (technically) no longer in contact with roadway! By the time the rear tires hit the same patch of roadway there is enough turbulence in the standing water that they can cut through to the pavement. This means they are driving you forward while your front tires are no longer holding you straight. Your going to spin very fast. This happens so fast (~0.2sec) even professional drivers can't correct for it. It's frightening and it happens without warning. (Well... not entirely! I mean come on... it's wet and you were going too fast. You know better.) There is a video of it happening to Jeremy Clarkson here:https://www.youtube.com/watch?v=RrVaKgNaUEI You can see the confusion on his face as he tries to figure out what is happening... and what is going to happen.
Don't confuse anything I said above for advice. Those are all specific examples of road conditions and specific examples of drive-trains. My advice... the first time there is a dusting of snow this year, find a big empty parking lot and drive like an a$$hole! Do donuts, power-slides, reversies, J-turns, accelerate hard and slam on the brakes. When the cops or mall security inevitably show up, address them politely and explain, "sorry sir, (or ma'am) I was just taking an opportunity to re-familiarize myself with driving my vehicle in adverse conditions. I didn't want to get caught off guard this winter." Mall security usually tells you to pack it up, and frequently the cops tell you to carry on. No one needs to know you just have a sick piece of you that just really likes wicked power-slides!:rockon:
Seriously though, if you know how to initiate a slide than you can control and correct it, and more importantly you know how to avoid it in the first place.
The trick is to know how to drive properly for a given situation and a given drive train. For example, if you are in a 4WD vehicle (transfer case, locked center diff, 2-way LSD, or viscous coupling) and your rear end starts to slide sideways... letting off the accelerator can make it worse! The rear tires have no traction, the front tires DO and decelerating can spin the vehicle in short order. It's called lift-off over steer and it's terrifying when it happens at speed. Counter-intuitively getting on the throttle can pull you straight.
Conversely, in AWD or with a 1/1.5-way LSD on a "full-time" 4WD letting off the throttle won't make it worse, but accelerating may still pull you straight.
In FWD over steer can be corrected with acceleration.
In RWD it will inevitably be exacerbated... which is awesome! (if you're expecting it).
Locking the center diff will always "scrub," you just don't notice at low steering angles or on low traction surfaces.
Hydroplaning is a completely different scenario. Lots of people mistake any loss of traction in wet weather for hydroplaning. Regardless of drive-train, hydroplaning generally happens to the front tires because they are the leading edge and when they pass over standing water, flow is laminar and it lifts the tire off the pavement. They don't (technically) lose traction... They are (technically) no longer in contact with roadway! By the time the rear tires hit the same patch of roadway there is enough turbulence in the standing water that they can cut through to the pavement. This means they are driving you forward while your front tires are no longer holding you straight. Your going to spin very fast. This happens so fast (~0.2sec) even professional drivers can't correct for it. It's frightening and it happens without warning. (Well... not entirely! I mean come on... it's wet and you were going too fast. You know better.) There is a video of it happening to Jeremy Clarkson here:https://www.youtube.com/watch?v=RrVaKgNaUEI You can see the confusion on his face as he tries to figure out what is happening... and what is going to happen.
Don't confuse anything I said above for advice. Those are all specific examples of road conditions and specific examples of drive-trains. My advice... the first time there is a dusting of snow this year, find a big empty parking lot and drive like an a$$hole! Do donuts, power-slides, reversies, J-turns, accelerate hard and slam on the brakes. When the cops or mall security inevitably show up, address them politely and explain, "sorry sir, (or ma'am) I was just taking an opportunity to re-familiarize myself with driving my vehicle in adverse conditions. I didn't want to get caught off guard this winter." Mall security usually tells you to pack it up, and frequently the cops tell you to carry on. No one needs to know you just have a sick piece of you that just really likes wicked power-slides!:rockon:
Seriously though, if you know how to initiate a slide than you can control and correct it, and more importantly you know how to avoid it in the first place.
JayceeP
New member
Thanks for the clarification. I do prefer locking when driving in snow, particularly on the highway. For whatever reason, I feel as though I have more traction.... or actually more control.... and maybe it’s actually the fact that there is still even power being sent to the slipping wheels as opposed
to the Torsen cutting back power to one of the axles. Any time I have to go up a steep slippery snowy hill that requires some acceleration I always lock and I always disable traction control completely. I do not like or want power being cut to any wheels. Your explanation now confirms my thought, I just was coming to the same conclusion but with incorrect reasoning lol.
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MTN4RNR
New member
There is no “pulling” when you are hydroplaning. If you are truly hydroplaning, there is zero traction, front or rear, because there is a layer of water between your tires and the road. 2wd or 4wd, if you’re hydroplaning you’re at the mercy of physics and no turning the steering wheel or having 4wd will change that. Only driving at a slower speed, or having “better tires” will make a difference.
CF_Machete
Senior Member
yup, used every feature my truck offers. Sounds like you don't cycle 4wd per the manual. perhaps you should.
like I said, coming out of a hydroplane or sliding situation not during
mtnbiker49
New member
You are right, I don't. It's an unreasonable distance for the majority of people, except during winter months. But go ahead, keep binding your drivetrain. I'll continue to engage 4wd periodically and when needed.
IanB
New member
That's actually EXACTLY what 4x4 is, locking the center differential so power is routed 50/50 front/rear.
CF_Machete
Senior Member
Yes your power is split to the front and rear, no your front and rear diferentials are not locked.
Yes I am perfectly familiar with how our drivetrain operates. I quoted your post that said locked front AND rear, and in the same post said front TO rear. My post clarifies that the front AND rear remain open.
tjmclaug91
New member
Thanks for this. Just got a 17 TRD Pro with 11k on the clock. I'll be sure to set a reminder in my phone to go find a new trail/Beach (Loc: SoCal) every 30 days to keep things running tip top.
Jeremy556
New member
I've left mine in 4hi for about a month at time, couple thousand miles. Also ran it in 4hi on dry pavement for 500 miles to help break in my 4.56 front differential gears. Coming up on 230k miles.
I have to laugh at the people that think running 4hi on pavement in a parking lot is going to break anything. I run lots in 4lo on slickrock with tires at 8psi, doing multipoint turns. Tires bark like crazy under many times more stress than street pressure in 4hi.
I have to laugh at the people that think running 4hi on pavement in a parking lot is going to break anything. I run lots in 4lo on slickrock with tires at 8psi, doing multipoint turns. Tires bark like crazy under many times more stress than street pressure in 4hi.
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SCMountaineer
New member
So, probably a stupid question, but reading this thread (and others) I'm scratching my head...
In any given month, I'm not going to have an opportunity to drive in snow, mud, etc. for ten miles. So should I be putting it in 4WD for my commute to the office (pavement)? The reality is, I only NEED 4WD a handful of times a year, but I certainly want to take care of this thing like I'm supposed to.
i said it locks the front and rear together, i.e. it's locked front to rear
tires scrub even though the front and rear diffs are open because there is no center diff, it's locked in the center
the center "differential" is "locked" because there isn't a center differential, 4wd means it's locked in the center which means you are scrubbing tires on a turn. 4wd is what we've been talking about, don't use 4wd in the rain. it's not that your transmission will suddenly explode, it's that you are wearing tires prematurely and also because of the tires scrubbing experiencing reduced grip.
if you have traction problems on wet roads you need new tires, not 4wd.
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Dude, no one is saying you're wrong. Let's chalk it up to a typo...the bottom line is that you said, in a singular statement, separate from your mention of locking front TO back, that the front and rear lock (no mention of together) when in 4WD. Someone who is not familiar with the way diffs, 4wd etc work may interpret that as the front and rear diff are locking diffs, which is why I clarified. I NEVER said that you were wrong in your understanding of the physics and geometry of a differential.
thanks for clarifying, i didn't see that one when i looked back- you're right that post could be misinterpreted, i my head that means the front and rear are locked but i get what you're saying now. you're wrong though about no one disagreeing though, CF_Machete is still confused about it and doesn't think tires scrub in 4WD
