Transfer Case & Center Diff Question?

[Grimarine]

So I was reading my manual and it is unclear to me if I have a locking center diff or not. My transfer case shift knob has H2-H4-N-L4. I do not have a locking center diff switch but if I put my car into 4L does that lock it or do I not have a locking center diff? If so, I have heard that in some other toyota vehicles, they already have the locking gears they are just missing the switch or etc parts to make them lock. Sorry if this confused anyone, I am not very inclined on my transfer case knowledge.

 

[Mgyver1]

So I was reading my manual and it is unclear to me if I have a locking center diff or not. My transfer case shift knob has H2-H4-N-L4. I do not have a locking center diff switch but if I put my car into 4L does that lock it or do I not have a locking center diff? If so, I have heard that in some other toyota vehicles, they already have the locking gears they are just missing the switch or etc parts to make them lock. Sorry if this confused anyone, I am not very inclined on my transfer case knowledge.

I'm guessing yours is a standard J shift transfer case and not a multimode. If that is the case (pun IN-tended!) then your center diff is locked when you go to H4 or L4. If you have a button on the side of your transfer case shifter then you have the option of being in 4WD without the center diff locked, which I believe the correct term on this board is a selective full time 4wd.

 

[02SE]

Unlike the '99-'00 4wd Limited model 4Runners, your SR5 is just a Part-Time 4wd T-case.

This means there is no differential in your T-case. So you would want to try and limit your 4wd usage to surfaces that allow some wheel slip, to prevent excessive binding in the driveline.

 

[Grimarine]

So in my case there is not center diff? In that case would power distribution between the front and back of my car be equal just as if I did have a locking center diff?

 

[slapdappy]

Edit: I am incorrect. 4WD can exist without a center differential. The rest of it is accurate, I think. But maybe not. Maybe just ignore what i said.

your center diff DOES lock.
This is what makes it 4WD.
An open center diff is AWD.
AWD open center diff
4WD locked center diff
every vehicle that is capable of sending power to all 4 wheels has a center differential (as well as a front differential and of course a rear differential).
A rear wheel drive vehicle only has a rear differential.
also http://www.toyota-4runner.org/3rd-g...rs-3rd-gens-transfer-case-awd-multi-mode.html

 

[Grimarine]

So when I put it in H4 that means my center diff is locked? If that is correct, what makes L4 different?

 

[02SE]

your center diff DOES lock.
This is what makes it 4WD.
An open center diff is AWD.
AWD open center diff
4WD locked center diff
every vehicle that is capable of sending power to all 4 wheels has a center differential (as well as a front differential and of course a rear differential).
A rear wheel drive vehicle only has a rear differential.

He has a '99 SR5. They were Part-Time 4wd ONLY. HE DOES NOT HAVE A DIFFERENTIAL IN HIS TRANSFER CASE. So there is no confusion HE DOES NOT HAVE A CENTER DIFFERENTIAL.

No, not every vehicle that can send power to all four wheels has a center differential.

In the OP's transfer case, since there is no differential, when he shifts from 2wd to 4wd, the front and rear output of the transfer case will turn at the exact same speed under all conditions WITH NO DIFFERENTIATION WHATSOEVER.

OP, this means that your Part-Time 4wd behaves the same as a 4wd system which has a center differential which is locked. The difference being you do not have the option of unlocking a center differential, because you do not have a center differential.

 

[slapdappy]

HE DOES NOT HAVE A DIFFERENTIAL IN HIS TRANSFER CASE. HE DOES NOT HAVE A CENTER DIFFERENTIAL.

No, not every vehicle that can send power to all four wheels has a center differential.

when he shifts from 2wd to 4wd, the front and rear output of the transfer case will turn at the exact same speed under all conditions WITH NO DIFFERENTIATION WHATSOEVER.

less ignorant than I was 30 minutes ago.
what other vehicles have 4WD but no center differential? Is this rare?

 

[csp]

Most 4WD pickups and SUVs do not have a center diff.

Any fulltime 4WD vehicle (notice I didn't say AWD since that's a different thing altogether) has a center diff.

Grimarine L4 means low range, 4WD. It's a lower gear.

Anyone can google this stuff, BTW.

 

[Mgyver1]

So when I put it in H4 that means my center diff is locked? If that is correct, what makes L4 different?

L4 is low range 4 wheel drive. Your transfer case changes to a much lower gear ratio to help slowly crawl over or down something. It is for low speed only, typically you put it in L4 to get over a difficult object or section and then switch back to H4 or H2. You can also use it as an engine brake while going down a steep decline. And yes your transfer case sends the same power to the front and the back, which is why you don't want to have it engaged on the street.

 

[slapdappy]

Anyone can google this stuff, BTW.

I've googled the crap out of it many times, until I finally understood the difference between AWD and 4WD, as well as what a differential is and what 'open differential' vs 'closed or locked differential' means.
I never knew, and it would never occur to me, that any vehicle capable of selectively engaging all 4 wheels could possibly do this without a center differential. You see, as one who is not omnniscient I occasionally learn something like this because another person teaches me... during a discussion... on a forum... about 4 wheel drive trucks.
Etc.

 

[csp]

That was just a general comment slapdaddy. Not directed at you per se.

Personally if I'm curious about something my first inclination is to find an existing answer to my curiosity, thus the suggestion. I'm aware that it doesn't fit every situation.

The fact is that many find these forums and never look anywhere else.

 

[slapdappy]

Most 4WD pickups and SUVs do not have a center diff..

He has a '99 SR5. They were Part-Time 4wd ONLY. HE DOES NOT HAVE A DIFFERENTIAL IN HIS TRANSFER CASE. So there is no confusion HE DOES NOT HAVE A CENTER DIFFERENTIAL.

No, not every vehicle that can send power to all four wheels has a center differential.

In the OP's transfer case, since there is no differential, when he shifts from 2wd to 4wd, the front and rear output of the transfer case will turn at the exact same speed under all conditions WITH NO DIFFERENTIATION WHATSOEVER.

OP, this means that your Part-Time 4wd behaves the same as a 4wd system which has a center differential which is locked. The difference being you do not have the option of unlocking a center differential, because you do not have a center differential.

http://www.toyota-4runner.org/3rd-gen-t4rs/60217-does-my-4runner-have-differential-slip.html
post #6 "the 96-00's had no center diff lock."
post #8 "When put into either 4Hi or 4Lo the front and rear driveshaft are locked together by gears in the Transfer case."
post #10 "moving the t-case shifter is like the locking center diff described above. (even though there is no real center diff lock, it's just the t-case doing it's thang)"

So as a matter of mechanical truth and accuracy, I do Not have a center differential? I have gears IN the Transfer Case that accomplish the same thing? and thus is commonly referred to as a center differential? ('99 LTD, multi mode transfer case, rear e-locker).
If so, is this also true for 96-00 as asserted in post #6?

 

[slapdappy]

That was just a general comment slapdaddy. Not directed at you per se.

Personally if I'm curious about something my first inclination is to find an existing answer to my curiosity, thus the suggestion. I'm aware that it doesn't fit every situation.

The fact is that many find these forums and never look anywhere else.

If Google was Haagen-Dazs Choc Choc chip I would be morbidly obese.

 

[csp]

Only those 3rd gen 4Runners with the Multi-mode transfer case have a differential.

I think you're confusing the job of the differential be a part that allows the tcase to be locked. That's not correct. The tcase is by default locked when the shift lever is moved into 4Hi or 4Lo. The differential allows it to be open and that's what separates the multi mode function from straight up 4Hi and 4Lo.

The comment about "gears doing the same thing as a differential" isn't relevant or accurate. Every tcase has gears. Those with a differential allow the speeds to be different, front and rear. Those without a diff have both the front and rear driveshafts turning at the same speed 100% of the time when 4WD is engaged.

The post #6 you refer to is incorrect. The '96-00 that aren't multi-mode have no center diff. Obviously since there were some '96-00 which did have multi-mode, therefore that post #6 was not accurate.

 

[02SE]

So as a matter of mechanical truth and accuracy, I do Not have a center differential?

According to your signature, you have a '99 Limited model 4Runner. The '99-'00 Limited model 4Runners and all 4wd '01-'02 models have a Multi-Mode T-case. The Multi-Mode T-cases DO have a differential. Also commonly referred to on here as a center differential.

That means you can run with the T-case differential unlocked, allowing Full-Time 4WD, often erroneously referred to on here as AWD.



The OP has a '99 SR5, which is a Part-Time 4wd only T-case. His transfer case DOES NOT have a differential.

 

[amalik]

L4 is low range 4 wheel drive. Your transfer case changes to a much lower gear ratio to help slowly crawl over or down something. It is for low speed only, typically you put it in L4 to get over a difficult object or section and then switch back to H4 or H2. You can also use it as an engine brake while going down a steep decline. And yes your transfer case sends the same power to the front and the back, which is why you don't want to have it engaged on the street.

I thought you could also utilize 4L to climb up or down steep hills (either direction) in slipper, icy, or wet conditions... but I think I read something online that indicates this is wrong -- do you agree? I thought it's better because the wheels put out less torque, so the tires don't have a chance to spin as fast (I don't have any diff lockers, so I sometimes do slip in bad CO weather even with part-time 4WD on my 97 Limited).

Here's what I'm referencing:

"4-low" does not create more traction - it creates more torque at slower speeds and that can be detrimental when the ground is slippery. Slipping tires are more likely in "low" than in "high"! On snowy, icy roads "low" would be a bad choice - some really deep snow, however, puts up so much resistance that "low" is needed to push forward.

The low setting is an advantage for drivers who need to tow and maneuver a heavy trailer etc. and for drivers who at one point or another may want to negotiate difficult off-road terrain, when more torque and/or slower speed is needed.

According to your signature, you have a '99 Limited model 4Runner. The '99-'00 Limited model 4Runners and all 4wd '01-'02 models have a Multi-Mode T-case. The Multi-Mode T-cases DO have a differential. Also commonly referred to on here as a center differential.

That means you can run with the T-case differential unlocked, allowing Full-Time 4WD, often erroneously referred to on here as AWD.

The OP has a '99 SR5, which is a Part-Time 4wd only T-case. His transfer case DOES NOT have a differential.

Good explanation. I found this explanation online is really good for you as well [MENTION=94063]slapdappy[/MENTION],

All wheel drive (AWD) is almost the same thing as full time 4WD - it is a system that powers all four wheels of a vehicle at all times as well. It can be used full time on all surfaces including pavement like full time 4WD. Difference to full time 4WD is that a "4-low" setting is not available in AWD cars. Due to the lack of "low range", AWD vehicles are much less capable in off-road settings than full time 4WD vehicles, but work perfectly well on-road.

[MENTION=107811]csp[/MENTION] -- Would having front and rear lockers on a non-center diff (Like my 97) essentially be the same concept as having the ability for a locked center diff in the TC? I don't plan to get lockers, but just trying to see if I understood the concepts.

 

[Mgyver1]

I thought you could also utilize 4L to climb up or down steep hills (either direction) in slipper, icy, or wet conditions... but I think I read something online that indicates this is wrong -- do you agree? I thought it's better because the wheels put out less torque, so the tires don't have a chance to spin as fast (I don't have any diff lockers, so I sometimes do slip in bad CO weather even with part-time 4WD on my 97 Limited).

Here's what I'm referencing:





Good explanation. I found this explanation online is really good for you as well [MENTION=94063]slapdappy[/MENTION],


[MENTION=107811]csp[/MENTION] -- Would having front and rear lockers on a non-center diff (Like my 97) essentially be the same concept as having the ability for a locked center diff in the TC? I don't plan to get lockers, but just trying to see if I understood the concepts.

I would say 4L gives you more control. I guess you could use it in an icy situation but usually it's used offroad when you come up to a difficult obstacle. Stop, put it in 4L, get over/through difficult section, stop, back in to 4H or 2H. Really you can use it whenever you need to, it's totally up to the driver and how he is interpreting the terrain.

Front and rear lockers lock just that, the front and rear differentials. It has nothing to do with a center diff. If you do not have a center diff, then you can just pretend that you do have a center diff that is locked 100% of the time and can not be unlocked. An unlocked center diff only allows power to be unevenly distributed between the front and rear diffs. Just like how your front and rear diff allow power to be unevenly distributed between the driver side and passenger side wheels. Locking the front or rear diff gives extra traction as the power is now evenly distributed between left and right (just light your locked transfer case will distribute power evenly between front and back), but locking the front or rear diff should only be used in unique situations requiring their operation, kind of like L4, and typically the lockers are only used in L4. Now that is not an absolute and people with more understanding of how everything works can and do use their lockers in 4H or even 2H, but the basic/beginning usage of it would be in L4. Toyota believed this so much they wired the factory rear locker to where it would not work unless you were in L4 (unless you were driving a Taco Prerunner, but that's for another day).

 

[amalik]

Front and rear lockers lock just that, the front and rear differentials. It has nothing to do with a center diff. If you do not have a center diff, then you can just pretend that you do have a center diff that is locked 100% of the time and can not be unlocked. An unlocked center diff only allows power to be unevenly distributed between the front and rear diffs. Just like how your front and rear diff allow power to be unevenly distributed between the driver side and passenger side wheels. Locking the front or rear diff gives extra traction as the power is now evenly distributed between left and right (just light your locked transfer case will distribute power evenly between front and back), but locking the front or rear diff should only be used in unique situations requiring their operation, kind of like L4, and typically the lockers are only used in L4. Now that is not an absolute and people with more understanding of how everything works can and do use their lockers in 4H or even 2H, but the basic/beginning usage of it would be in L4. Toyota believed this so much they wired the factory rear locker to where it would not work unless you were in L4 (unless you were driving a Taco Prerunner, but that's for another day).

Ah, ok. I basically thought the point of a center diff lock was in the 'lock' mode, it would evenly distribute power to both the front and rear differentials... i.e. so each wheel has 25% power (Like you would get if you had front and rear lockers).... and in 'unlocked' mode, it would allow the 4 wheels to turn unevenly.

Guess I'm wrong.

 

[Mgyver1]

Ah, ok. I basically thought the point of a center diff lock was in the 'lock' mode, it would evenly distribute power to both the front and rear differentials... i.e. so each wheel has 25% power (Like you would get if you had front and rear lockers).... and in 'unlocked' mode, it would allow the 4 wheels to turn unevenly.

Guess I'm wrong.

well you were right in that unlocked it would allow the 4 wheels to turn unevenly, unless you had an unlocked center diff with a locked front and/or rear diff.

Locked center will give you 50% front and 50% rear. What happens after that is all up to the front or rear diff.