AWD Or 4WD?

Sansui

First of all I'd like to thank all of you that responded to my 4WD questions last month!!!

I bought a Toyota 4Runner SR5 Sport (V6) Monday before last. Heck of an upgrade from a '99 Cavalier!

I've read the manual and have a question or two. I'm confused a bit as to whether I have an AWD, 4WD, or both. According to the manual, in 2WD it kind of acts like a AWD (with VSC on) and in 4HI it acts like a AWD (with VSC on). With VSC off 2WD acts like a regular RWD and 4WD acts like something I guess.

As I read the manual it got to explaining about the "center locking differential" which can be turned on and off. That REALLY confused me after kind of to understanding the Vehicle Stability Control.

Does anyone have a clue what I'm confused about and can tell me what's up in something easier to understand than the manual explains it?

Am I correct in understanding that I can "on the fly" switch from 2WD to 4HI (up to 60 mph/not that I would at that speed) without stopping? BTW, I know I shouldn't do this on pavement because doing so will tear up my tires.

I know I should have asked these questions on a 4WD or a 4Runner specific forum but I can't seem to locate any.

Like my sig says, ...

Serendipity

Sansui wrote: »

First of all I'd like to thank all of you that responded to my 4WD questions last month!!!

I bought a Toyota 4Runner SR5 Sport (V6) Monday before last. Heck of an upgrade from a '99 Cavalier!

I've read the manual and have a question or two. I'm confused a bit as to whether I have an AWD, 4WD, or both. According to the manual, in 2WD it kind of acts like a AWD (with VSC on) and in 4HI it acts like a AWD (with VSC on). With VSC off 2WD acts like a regular RWD and 4WD acts like something I guess.

As I read the manual it got to explaining about the "center locking differential" which can be turned on and off. That REALLY confused me after kind of to understanding the Vehicle Stability Control.

Does anyone have a clue what I'm confused about and can tell me what's up in something easier to understand than the manual explains it?

Am I correct in understanding that I can "on the fly" switch from 2WD to 4HI (up to 60 mph/not that I would at that speed) without stopping? BTW, I know I shouldn't do this on pavement because doing so will tear up my tires.

I know I should have asked these questions on a 4WD or a 4Runner specific forum but I can't seem to locate any.

Like my sig says, ...

All I know is that part-time 4WD cannot be used on dry pavement. I think it would destroy the center differential? I might be wrong though.

Serendipity

This article is an interesting read:

http://www.4x4abc.com/4WD101/driveline-bind.html

bobman1235

appadv wrote: »

All I know is that part-time 4WD cannot be used on dry pavement. I think it would destroy the center differential? I might be wrong though.

Usually the problem with part-time 4WD (as I understand it, though I'm sure I'll be told I'm an idiot in a few minutes) is there IS no differential. A differential's job is to basically compensate for different speeds of rotation. A part-time 4WD system (like most pickups have, for example) has no differential between the front and rear wheels, so when you're in 4WD they're locked together, and when tehy spin at different speeds (which happens all the time) there is a lot of stress put on the point where they're connected. When you're on wet, slippery pavement this isn't a big deal, but on dry pavement... big deal.

Aimen RG

ur surf 4runner most probly is a part time 4 wheeler
u will drive normally in 2wd every where, just like RWD car
when u engage the 4wd, it will run all tyres, but with NO DIFFERENTIAL LOCK.
that means ur front and rear tyres can spin at different speeds.
when u turn the central diff lock ON, it locks the differential, and now ur front and rear tyres share 50 50percent power.

2WD it kind of acts like a AWD (with VSC on)

it will be running as RWD, but when ever ur SUV demands more power at the front, the VSC will provide them that power, by changing the differentials at run time.

4HI it acts like a AWD (with VSC on)

normally will be runnin as 4wd/awd, but depending on traction issues, VCS can vary power. gear range will be HIGH

With VSC off 2WD acts like a regular RWD and 4WD acts like something I guess

2wd = RWD, hence all power to rear tyres. rear tyre can share the power as they like
4wd = 4wd, all power to all wheels, they share power as they like, like if ONE tyre is off the ground, it will be most easy to spin, and hence all power will be directed to it , ie power waste. that is when u need to turn on VSC, or center diff

with center diff, u r locking the front in rear tyres together, if front left tyre is in air, not all power will be wasted, only 50%; the one which was directed towards front tyres, rear will still be spining at thr speed. hence u dont get stuck. center diff is very important in offroading, if u r stuck in mud or sand, u need all the traction that is possible and no power loose on loose wheels.

center diff is a mechanical lock, which u do to keep power on all four wheels. mostly it keeps 50-50 ratio between front n rear, but im not sure about u SUV
VSC is traction control, directing power to only those wheels which the computer thinks are in grip.

ON road, VCS will work better, OFF road, it always better to manually lock the center diff.

using center diff on pavement will tax ur tyres and u might hear screeching sound when turning, but thats normally more related to front and rear diff.
u will not break ur shaft or anything. they r not that weak.

Sansui

Aimen RG wrote: »

ur surf 4runner most probly is a part time 4 wheeler
u will drive normally in 2wd every where, just like RWD car
(etc.)
using center diff on pavement will tax ur tyres and u might hear screeching sound when turning, but thats normally more related to front and rear diff.
u will not break ur shaft or anything. they r not that weak.

Thank you! I wish you'd written that part of the manual!

jdhdiggs

You can read that? Damn, I'm getting old...

bobman1235

jdhdiggs wrote: »

You can read that? Damn, I'm getting old...

No, you just speak English.

MSALLA

It's been awhile, but I think the VSC is a viscus cupler in the transfer case. When it is engaged, it will transfer torque between the front and rear axel but let them spin at different speeds. I like old fashion part time 4-wheel drive systems. Better gas milage and there is no need for all the wheels to be powerd unless there is deep snow, mud, or other extream conditions. Keep the VSC off.

Sami

I agree with MSALLA, keep the vehicle in 2WD mode (VSC off) unless it's a system that keeps 100% of the power in the rear when there is no traction issue. Turn the VSC on when the weather is bad or you're going off road.

Aimen RG

isnt VSC vehicle stability control??

strider

Aimen RG wrote: »

isnt VSC vehicle stability control??

Yep.

What year 'Runner is it, Sansui?

ben62670

2 wheel drive in normal conditions
use the vsc in snow.
4wd is for off road(locking the center, or sometimes front or rear diff), or nasty snow, or you get stuck.

vsc will improve stability
vsc is usually an extremely high viscosity silicone fluid that allow for minor differences in front to rears tire speed. The OD of a tire can be slightly less, or more so vsc allows some give.
Anything that says locked should not be used unless the ground is totally covered in snow, and you are not reaching speeds above 40mph.

Serendipity

So was I wrong in my understanding that 4WD with the center diff locked should not be used on dry pavement?

I'm new to all this so I'm not sure if I understand everything correctly.

Sami

appadv wrote: »

So was I wrong in my understanding that 4WD with the center diff locked should not be used on dry pavement?

No, you were correct.

Sansui

Aimen RG wrote: »

isnt VSC vehicle stability control??

According to the manual it is. I plan to keep it in 2WD unless the snow we get is high enough to make driving unsafe in 2WD.

Sansui

strider wrote: »

What year 'Runner is it, Sansui?

2008. I've had it for two weeks. It has 307 miles on it. I have to tell you, it's one heck of an upgrade from the `99 Cavalier I bought new.

Sansui

ben62670 wrote: »

2 wheel drive in normal conditions
use the vsc in snow.
4wd is for off road(locking the center, or sometimes front or rear diff), or nasty snow, or you get stuck.

vsc will improve stability
vsc is usually an extremely high viscosity silicone fluid that allow for minor differences in front to rears tire speed. The OD of a tire can be slightly less, or more so vsc allows some give.
Anything that says locked should not be used unless the ground is totally covered in snow, and you are not reaching speeds above 40mph.

According to the manual I should only lock the center differential when I'm stuck and that's after I've put it into "4LO".

So if it snows a lot and I feel I have to switch out of 2WD I'm going to put it into "4HI" and go from there. It seems I can switch to "4HI" while moving but if I want/need to go "4LO" then I have to do it after I've completely stopped.

The manual "kind of" says I can switch to 4WD without coming right out and saying it.

scrapyd

4wd all the way! AWD is horse crap

wodom1

Sansui wrote: »

According to the manual I should only lock the center differential when I'm stuck and that's after I've put it into "4LO".

So if it snows a lot and I feel I have to switch out of 2WD I'm going to put it into "4HI" and go from there. It seems I can switch to "4HI" while moving but if I want/need to go "4LO" then I have to do it after I've completely stopped.

The manual "kind of" says I can switch to 4WD without coming right out and saying it.

With my '02 Durango, I can transfer in and out of 4HI at speeds up to 55mph while moving, but you shouldn't drive it past that speed. If I want to put it in 4LO, there are two options -- stop, put it in neutral, shift to 4LO and wait for it to engage (you'll be able to hear it as 4LO is noisy) or slow to 2-3 mph, shift to N, and turn it to 4LO while rolling at that speed. 25 is the max speed for me in 4LO. I never need to use 4LO. 4HI works just fine for me if I feel like I need a little more traction and power in the snow. Your transfer case should be fairly similar, but there will always be slight differences.

rskarvan

scrapyd wrote: »

4wd all the way! AWD is horse crap

Quadratrak on my Jeep Grand Cherokee is the way to go. Full time 4-wheel drive - shifting torque upon wheel spin. Shifting into 4WD manually (on a pickup) isn't nearly as good.

bobman1235

My brother's Grand Cherokee has the worst 4WD system I've ever seen.

It has the switch to turn on part-time 4WD. It will go into 4WD fine. But when you put it back in 2WD, it doesn't happen. YOu have to drive over a pot hole or a curb, at which point it will pop back into 2WD. How do we know this? IT SAYS IT IN THE MANUAL! So they made this transmission, saw that it had a MAJOR problem that required ridiculous actions, and rather than fix it they just threw it in the manual.

Yup, American Union work at its best. Garbage.

rskarvan

bobman1235 wrote: »

My brother's Grand Cherokee has the worst 4WD system I've ever seen.

It has the switch to turn on part-time 4WD. It will go into 4WD fine. But when you put it back in 2WD, it doesn't happen. YOu have to drive over a pot hole or a curb, at which point it will pop back into 2WD. How do we know this? IT SAYS IT IN THE MANUAL! So they made this transmission, saw that it had a MAJOR problem that required ridiculous actions, and rather than fix it they just threw it in the manual.

Yup, American Union work at its best. Garbage.

What you are talking about is "Select-trak". And, yes, that does suck. My Jeep Grand Cherokee has a V8 and is Full-time-4WD ALL THE TIME. There is no switch to go into 2-HI. Quadratrak is awesome. Select-trak is awful. That is why I advocate real FULL TIME 4WD SYSTEMS. If you can switch out-of 4WD, its not as good.

MSALLA

ben62670 wrote: »

2 wheel drive in normal conditions
use the vsc in snow.
4wd is for off road(locking the center, or sometimes front or rear diff), or nasty snow, or you get stuck.

vsc will improve stability
vsc is usually an extremely high viscosity silicone fluid that allow for minor differences in front to rears tire speed. The OD of a tire can be slightly less, or more so vsc allows some give.
Anything that says locked should not be used unless the ground is totally covered in snow, and you are not reaching speeds above 40mph.

Thats basically what I said. I just don't like this set up. I think it's just a waste of gas. My mothers mountaineer has this system and it eats gas. But, I do feel safer for her as she is not the best driver in bad weather.

Sansui

wodom1 wrote: »

With my '02 Durango, I can transfer in and out of 4HI at speeds up to 55mph while moving, but you shouldn't drive it past that speed. If I want to put it in 4LO, there are two options -- stop, put it in neutral, shift to 4LO and wait for it to engage (you'll be able to hear it as 4LO is noisy) or slow to 2-3 mph, shift to N, and turn it to 4LO while rolling at that speed. 25 is the max speed for me in 4LO. I never need to use 4LO. 4HI works just fine for me if I feel like I need a little more traction and power in the snow. Your transfer case should be fairly similar, but there will always be slight differences.

Well you kind of put the whole thing in a nutshell for me. Thank you!

strider

rskarvan wrote: »

That is why I advocate real FULL TIME 4WD SYSTEMS. If you can switch out-of 4WD, its not as good.

Please explain. I fail to see any advantage in being in 4WD on a dry surface.

strider

Sansui wrote: »

2008. I've had it for two weeks. It has 307 miles on it. I have to tell you, it's one heck of an upgrade from the `99 Cavalier I bought new.

Nice. One hell of an upgrade, not that Cavaliers are all that bad. Now we need some snow! Better happen soon, it's supposed to be up into the 60's by Tuesday :eek:

Gotta love Maryland weather.

jtgranby

strider wrote: »

Nice. One hell of an upgrade, not that Cavaliers are all that bad. Now we need some snow! Better happen soon, it's supposed to be up into the 60's by Tuesday :eek:

Gotta love Maryland weather.

I love it when it's 60. Boy what a bite in the **** the past couple of days. I don't understand the all time 4WD either

Jim

mrmusicman

bobman1235 wrote: »

Yup, American Union work at its best. Garbage.

WTF:rolleyes:

rskarvan

strider wrote: »

Please explain. I fail to see any advantage in being in 4WD on a dry surface.

I can't explain as well as Jeep can. My 4x4 Silverado is ok. My 4x4 Jeep Grand Cherokee with quadra-trac is absolutely fabulous.

http://www.jeep.com/en/4x4/how_systems_work/quadra_trac/

Sansui

strider wrote: »

Nice. One hell of an upgrade, not that Cavaliers are all that bad. Now we need some snow! Better happen soon, it's supposed to be up into the 60's by Tuesday :eek:

I bought my Cavalier (new) in '99. I've kept it in perfect condition and gave it to my son for X-mas. The problem with it is that if we got about 3" of snow I wouldn't be able to drive it for a day or so. Anything over 5" and I wouldn't be able to drive it for three to four days.

Gotta love Maryland weather.

Ah, yeah, right...