Transfer Case Question

[adkinsadam1]

So in part time 4WD the right and left sides can spin seperately, but not the front and back? Or are all wheels at the exact same speed?
I am also a little concerned, because in Colorado, my main use for 4WD is for crawling over rocks. The trail is fine with no traction issues, just like a very windy dirt road. But, every now and then there are boulders which need 4WD to get over, rather frequently in fact. How can I engage part-time 4WD and go through the good-traction curvy areas and boulders without having issues? Because there is nowhere that the wheels could slip...

 

[M1911]

So in part time 4WD the right and left sides can spin seperately, but not the front and back?

The front and rear driveshafts (input to the differentials) spin at the same speed. But the outputs from the driveshafts (left and right halfshafts) can spin at different speeds. That is what a differential does.

Or are all wheels at the exact same speed?

That only happens if you have three locked differentials, front, center, and rear. Very few vehicles have three locking diffs. Mercedes G is one.

I am also a little concerned, because in Colorado, my main use for 4WD is for crawling over rocks. The trail is fine with no traction issues, just like a very windy dirt road. But, every now and then there are boulders which need 4WD to get over, rather frequently in fact. How can I engage part-time 4WD and go through the good-traction curvy areas and boulders without having issues? Because there is nowhere that the wheels could slip...

As long as you are on a dirt road, you can do that just fine with a part-time system in 4WD (high or low). The only place where a part-time system is a problem is dry pavement. Given where you are driving, a locking rear diff is a good idea.

 

[CJ3Flyr]

So in part time 4WD the right and left sides can spin seperately, but not the front and back? Or are all wheels at the exact same speed? Correct.
I am also a little concerned, because in Colorado, my main use for 4WD is for crawling over rocks. The trail is fine with no traction issues, just like a very windy dirt road. But, every now and then there are boulders which need 4WD to get over, rather frequently in fact. How can I engage part-time 4WD and go through the good-traction curvy areas and boulders without having issues? Because there is nowhere that the wheels could slip... This is the issue... The question is how much traction does the "good traction" area have? If it's more traction than a hard packed dirt road you should probably go back to 2wd. In the current 4th gen setup you'd want to unlock the center diff for that stretch of road.

All I can say is no V8, no clean diesel and this t-case thing is a "miss" on Toyota's part. I hope a mid-gen freshen up in 2-3 years addresses these issues. As it stands I'd have to go for the Limited even though I wouldn't want one in the Limited trim...
:cheers:

 

[adkinsadam1]

Wait so is it that wheels can spin faster under less-traction conditions but cannot spin slower? And if the outposts can spin at different speeds than why can't you use part time on dry pavement?

 

[JB.]

So in part time 4WD the right and left sides can spin seperately, but not the front and back? Or are all wheels at the exact same speed?

Part-time, full-time refer only to the center. Part time=locked center or no connection in center at all (2WD). Full-time=center differential. When that differential can be locked, it is the same as the part-time center connection. One 4WD system you can use some of the time, one can be used all the time -- part-time, full-time.

I am also a little concerned, because in Colorado, my main use for 4WD is for crawling over rocks. The trail is fine with no traction issues, just like a very windy dirt road. But, every now and then there are boulders which need 4WD to get over, rather frequently in fact. How can I engage part-time 4WD and go through the good-traction curvy areas and boulders without having issues? Because there is nowhere that the wheels could slip...

That's a very astute question and reveals the mild contradiction between the dire warning "NEVER lock the center diff on pavement" and the realities of wheeling. The issue is with turns and turns only. Off-road, though, even with all the wheels on solid rock, there's usually enough weight imbalance to allow more slippage than on pavement. Not always though. I come down on the side of I think a locked center is less stressful than most people seem to, but who knows. The transfer options on the FJ and 5th gen 4Runner TE would seem to indicate that Toyota engineers tend to agree. Tight, slow turns with high traction can sure be a problem, though. Not having to sweat the hard steering feedback that directly measures driveline stress like in 4th gen 4WD lo, center unlocked, sure can spoil a guy.

 

[JB.]

Wait so is it that wheels can spin faster under less-traction conditions but cannot spin slower? And if the outposts can spin at different speeds than why can't you use part time on dry pavement?

It's all about turning.

In a turn, the rear wheels trace a smaller arc than the front wheels and so must turn more slowly (average arc of the two rear wheels compared to average arc of the two front wheels). The shaft that connects them to the center must turn more slowly too (or faster for the front). A locked center means the front and rear shafts turn at the same speed so a tire must slip somewhere. The sharper and slower the turn, the more it's an issue.

 

[adkinsadam1]

But if the outposts can spin at different speeds than why can't you use part time on dry pavement?

PLEASE view this video. This is mosquito pass with a ford explorer and part-time 4WD engaged in low. The wheels are spinning at different rates! I thought this part time system did not allow the wheels to spin at different rates because if they could, then they could be used on dry pavement! That is the outposts spinning at different speeds, right? Then how come the wheels/outposts can't spin at different speeds on dry pavement!!!!!!! What is going on!?!? Thanks for everybody's help by the way.

http://web.mac.com/adkinsadam1/Site_2/Blank.html

 

[M1911]

But if the outposts can spin at different speeds than why can't you use part time on dry pavement?

PLEASE view this video. This is mosquito pass with a ford explorer and part-time 4WD engaged in low. The wheels are spinning at different rates! I thought this part time system did not allow the wheels to spin at different rates because if they could, then they could be used on dry pavement! That is the outposts spinning at different speeds, right? Then how come the wheels/outposts can't spin at different speeds on dry pavement!!!!!!! What is going on!?!? Thanks for everybody's help by the way.

http://web.mac.com/adkinsadam1/Site_2/Blank.html

Sorry, but you aren't getting it.

With a part time 4WD system, the front and rear drive shafts turn at the same speed. The front drive shaft goes from the transfer case forward to the center diff. The rear drive shaft goes from the transfer case rearwards to the rear diff.

When you are turning, the front diff traces a longer route around the corner than the rear diff. Consequently, the front driveshaft must make more turns than the rear driveshaft.

However, once you get to the front or rear diff, the diff splits the torque to the right and left halfshafts. The halfshaft goes from the diff to the wheel. The diff allows the right and left halfshaft to turn at different rates. If the rear on a 2WD car diff was locked, then you couldn't go around a corner. That does NOT mean that they can spin completely independently of each other. If they could freewheel that way, then no torque would get sent to the wheels.

There is a reason that vehicle manufacturers state that part-time 4WD systems are just that -- part-time only -- and can't be used on dry pavement.

 

[Climb14er]

PLEASE view this video. This is mosquito pass with a ford explorer and part-time 4WD engaged in low. The wheels are spinning at different rates! I thought this part time system did not allow the wheels to spin at different rates because if they could, then they could be used on dry pavement! That is the outposts spinning at different speeds, right? Then how come the wheels/outposts can't spin at different speeds on dry pavement!!!!!!! What is going on!?!? Thanks for everybody's help by the way.

Mosquito Pass can be driven in a 2WD pickup! Any combination of 4th Generation or 5th Generation 4WD or 2WD 4Runners can easily do a road like the one on Mosquito.

I've driven up the Lake Como Road to Jaws 1, one of the toughest 4 x 4 roads in Colorado in a Toyota 4x4 Pickup with a 5 speed manual tranny in Low transfer case setting. No rear locker, no center differential lock, no front locker... just good driving and a solidly built tranny and transfer case.

In my 4th Generation 4WD 4Runner, I've never locked the center differential... never have had to. The system on 4Hi and 4Lo works fine.

Most people on this forum will need the Torsen 4WD system on dry pavement rather than in tough off-road situations. Going back to the part time 4WD system is absurd when the Torsen system has been proven.

 

[adkinsadam1]

That does NOT mean that they can spin completely independently of each other. If they could freewheel that way, then no torque would get sent to the wheels.

That is it! I have had a GREAT EPIPHANY! It has clicked and I now understand. Thank you! After knowing all this, it seems the full-time 4WD is FAR more desirable than part-time, and I wonder, why would Toyota ditch that for it's trail model, which I think deserves it most. What is their thought behind it?

 

[sandcrawler]

That is it! I have had a GREAT EPIPHANY! It has clicked and I now understand. Thank you!

that's great.

After knowing all this, it seems the full-time 4WD is FAR more desirable than part-time, and I wonder, why would Toyota ditch that for it's trail model, which I think deserves it most. What is their thought behind it?

and that's why myself and at least a few others have already written to Toyota express our dissatisfaction. the TE should at least have multi-mode... wtf?

 

[fjrjim]

<So if both right side tires were on ice, but the left side tires were on pavement, you still might not be able to move.>

I've owned both systems on a Gen 2 and a Gen 3. Granted I only used the AWD on the street for ski trips to Mammoth (California) and local mountains but I never noticed much difference really as the pavement is usually at least wet if you really need AWD. AWD without a rear locker is not that great anyway.

 

[adkinsadam1]

the TE should at least have multi-mode... wtf?

I will wait until the update. When will that be, 2012, right?

 

[JB.]

...it seems the full-time 4WD is FAR more desirable than part-time, and I wonder, why would Toyota ditch that for it's trail model, which I think deserves it most. What is their thought behind it?

In difficult off-road 4WD conditions, not FAR more desirable, just nicer for tight, slow speed turn situations. In severe 4WD conditions, once you've gone beyond the Torsens torque biasing limits it can spin like an open diff which can have some negative effects compared to locked. In moderate conditions - and by moderate I mean conditions many might consider pretty gnarly - it works very well. It turns out that it's quite practical to off-road with the center unlocked, and just lock it when necessary. It's a luxury. That's why, I'd guess, it's on the Limited and not the TE. That's also why it's inclusion on every model of the 4th gen was pretty amazing.

 

[bobbarker]

I just wrote Toyota about the center diff. I hope you others that want it do the same.

"I am writing to express my disappointment in the de-contented drivetrains on the new 4Runner. The last generation 4WD models all featured a Torsen center differential, yet the new SR5 and Trail 4WD models do not. In my opinion, that is a step in the wrong direction. While CRAWL and the Multi Terrain systems are nice, they are merely piggybacked off the cruise control and ABS systems at minimal cost. I, as well as many others, feel that the Torsen differential is what separated the superior 4Runner from the other options.

My wife and I have been waiting for the new model to be released for almost a year, but I am disappointed in what is being offered, and we are not sure we are going to make the purchase unless 4WD can safely be used on dry paved roads.

Please take my letter into consideration for any mid-model updates.

it would be nice to see one of the clean diesel engine options, too.

Thanks,

"

 

[adkinsadam1]

Here's what I said:

"I am a big off-roader. I also drive on main roads a lot. That is why I have bought the 4runner, primarily for it's off-road ability and reliability. 5th generation: the Trail version seems like the perfect vehicle for me! It has higher approach angles and more off-road features/options. However, why has the full-time 4WD and locking center diff. been taken out of this model? This was my favorite feature, and above all I think the Trail edition deserves it. Why was it removed? Also, torque really came in handy when crawling over boulders. Why was the V8 replaced, and why couldn't it at least be an option? As well, I was wondering, if you guys are playing off the 4runners off-road capability, why would you make it bigger? The majority of 4WD trails are too narrow as it is, but why was it made even larger? And finally, you have falsified your ground clearance for many years. The underbody really sticks down between the front wheels on the 4th gen, and all 4th gens have less than 8" of ground clearance because of this, which is not your advertised clearance. Has the 5th gen been tucked in and made more uniform in this area? Is the ground clearance actually the minimum ground clearance? Thanks a lot for answering my questions! Please answer all of them. I look forward to hearing back from you."

 

[J.A.]

I will wait until the update. When will that be, 2012, right?

More like 2013.

 

[Martinjmpr]

That is it! I have had a GREAT EPIPHANY! It has clicked and I now understand. Thank you! After knowing all this, it seems the full-time 4WD is FAR more desirable than part-time, and I wonder, why would Toyota ditch that for it's trail model, which I think deserves it most. What is their thought behind it?

Because it's not "far more desirable."

Keep in mind that the supposedly "inferior" part-time system is exactly the same system that 4wd vehicles have been using since before WWII. Every Jeep, every Blazer, every Bronco, every Scout made before the mid-70's had a part time 4wd system (as did every Toyota FJ40, FJ45, FJ55, FJ60 and FJ62) and they worked just fine, as long as you use them within the limitations of their respective systems (full time systems were first introduced into the US market in the early 70's.)

Toyota didn't even introduce the center-diff system into their vehicles until the 1990's - the FJ80 was a full time 4wd system with a locking center diff. The 4runner got the locking center diff (with a 2wd mode that the FJ80 didn't have) in 1999. The Tacoma never got it and still doesn't have it. The FJ Cruiser doesn't have it on the automatic transmission models.

The biggest advantage of the locking center diff is not what you can do off-road, it's what you can do on-road. It allows you to run with 4 wheels turning in regular driving, which can help you in intermittently slippery situations (like driving on paved streets a couple of days after a big snowstorm, where you'll have long patches of dry pavement interspersed with corners, shadowy areas or curves that still have snow or ice on them.)

Note that the Nissan Xterra does not have (and never has had) any kind of full time 4wd system or locking center diff. Ditto for the Jeep Wrangler. And yet the Wrangler and the Xterra are among the most capable "out of the box" 4 wheelers out there.

I think the issue with the multi-mode 4wd comes up because Toyota is taking away something they used to have. If Toyota had never offered the multi-mode system in a 4runner, people wouldn't be as upset about it.

I'm trying to think if anyone's ever criticized the Tacoma for not having a multi mode 4wd system. AFAIK it's never happened - Toyota never offered multi-mode in the Tacoma, so Tacoma buyers don't "miss" it.

 

[gaberelli]

Because it's not "far more desirable."

Keep in mind that the supposedly "inferior" part-time system is exactly the same system that 4wd vehicles have been using since before WWII. Every Jeep, every Blazer, every Bronco, every Scout made before the mid-70's had a part time 4wd system (as did every Toyota FJ40, FJ45, FJ55, FJ60 and FJ62) and they worked just fine, as long as you use them within the limitations of their respective systems (full time systems were first introduced into the US market in the early 70's.)

Toyota didn't even introduce the center-diff system into their vehicles until the 1990's - the FJ80 was a full time 4wd system with a locking center diff. The 4runner got the locking center diff (with a 2wd mode that the FJ80 didn't have) in 1999. The Tacoma never got it and still doesn't have it. The FJ Cruiser doesn't have it on the automatic transmission models.

The biggest advantage of the locking center diff is not what you can do off-road, it's what you can do on-road. It allows you to run with 4 wheels turning in regular driving, which can help you in intermittently slippery situations (like driving on paved streets a couple of days after a big snowstorm, where you'll have long patches of dry pavement interspersed with corners, shadowy areas or curves that still have snow or ice on them.)

Note that the Nissan Xterra does not have (and never has had) any kind of full time 4wd system or locking center diff. Ditto for the Jeep Wrangler. And yet the Wrangler and the Xterra are among the most capable "out of the box" 4 wheelers out there.

I think the issue with the multi-mode 4wd comes up because Toyota is taking away something they used to have. If Toyota had never offered the multi-mode system in a 4runner, people wouldn't be as upset about it.

I'm trying to think if anyone's ever criticized the Tacoma for not having a multi mode 4wd system. AFAIK it's never happened - Toyota never offered multi-mode in the Tacoma, so Tacoma buyers don't "miss" it.

Count me in for one that HAS criticized the limited availability of the multi-mode 4WD system in the Toyota line. In fact, it was the only factor that led me to get a 4Runner over a Tacoma. With the playing field leveled (i.e. very few full-time options; especially one with 2wd option like the 4runner V6) I will not have loyalty to Toyota in my next purchase. It will end up being a quality and cost decision, not a unique to the market decision.

 

[Vanuatoo]

Because it's not "far more desirable."

Keep in mind that the supposedly "inferior" part-time system is exactly the same system that 4wd vehicles have been using since before WWII. Every Jeep, every Blazer, every Bronco, every Scout made before the mid-70's had a part time 4wd system (as did every Toyota FJ40, FJ45, FJ55, FJ60 and FJ62) and they worked just fine, as long as you use them within the limitations of their respective systems (full time systems were first introduced into the US market in the early 70's.)

Toyota didn't even introduce the center-diff system into their vehicles until the 1990's - the FJ80 was a full time 4wd system with a locking center diff. The 4runner got the locking center diff (with a 2wd mode that the FJ80 didn't have) in 1999. The Tacoma never got it and still doesn't have it. The FJ Cruiser doesn't have it on the automatic transmission models.

The biggest advantage of the locking center diff is not what you can do off-road, it's what you can do on-road. It allows you to run with 4 wheels turning in regular driving, which can help you in intermittently slippery situations (like driving on paved streets a couple of days after a big snowstorm, where you'll have long patches of dry pavement interspersed with corners, shadowy areas or curves that still have snow or ice on them.)

Note that the Nissan Xterra does not have (and never has had) any kind of full time 4wd system or locking center diff. Ditto for the Jeep Wrangler. And yet the Wrangler and the Xterra are among the most capable "out of the box" 4 wheelers out there.

I think the issue with the multi-mode 4wd comes up because Toyota is taking away something they used to have. If Toyota had never offered the multi-mode system in a 4runner, people wouldn't be as upset about it.

I'm trying to think if anyone's ever criticized the Tacoma for not having a multi mode 4wd system. AFAIK it's never happened - Toyota never offered multi-mode in the Tacoma, so Tacoma buyers don't "miss" it.

Well said.

I still don't understand why toyota introduced two transfer cases when they had one that worked very well in all conditions.

They now are trying to force city drivers to buy limited edition.

My opinion is that part time is only suitable for trail edition, because it's a special vehicle for special purpose and I don't think people who buy trail edition will use it mainly as a family car.

The only bright point is that toyota uses full time 4wd system in canada that borns hope that someday they will make it available for US northern states too.

Anyway Multi-Mode is the best 4wd for every situation and why the hell they discontinued it? Change just for change?

Toyota wake-up!