Auto Transmission - 2WD Low vs 4WD Low?

[farmerjon]

Wow, so many responses in just 24 hours! First chance to actually sit down and reply so here goes. Thank you everyone!

I read a post about this a few weeks ago so someone point out if I am wrong and I can delete this post.

As I understand it the 2 and L on the shifter will prevent the transmission from shifting higher than that gear, only first and second when on 2, only first on L. Putting it into 4lo actually changes the gear ratio but doesn't affect what gear it will shift up to. I don't think it would have a double advantage. I haven't tried but I wouldn't want to go fast enough in 4lo to get past second so I think leaving it in drive is more than enough.
That is just how I understood the post I read so I hope I explained that correctly

So the gist of it is that if I'm in 2nd, the transmission will still shift automatically between 1 and 2? I can't force it to stay in 2, like I could in a true manual?

I didn't realize there was an entirely separate transfer case for 4WD, I thought it was just a different part of the same system a way to kick in the front wheels, and the rear wheels would just keep doing their thing...

4 low is great for creeping downhill. I keep trans lever on L, figuring if I need 4 low I don't want or need the trans to shift into 2nd or 3rd. I always have OD off when wheeling.
4 hi with trans lever on L is also good for downhill.
Engine braking, my friend. Engine braking.

Where in The Rugged Rockies?

Combined with [MENTION=91423]Asaspades93[/MENTION] 's answer, I'm starting to have my own thinking answered here - I would leave it in L so that while in 4LO, it doesn't upshift, as that would be hard on the SEPARATE/BOTH transfer cases, so it is a bit of a dual "protection" or control thing...

Can you explain the benefits of O/D off, especially when wheeling? I know that keeps me in gear longer, but why is that beneficial?

As for where in the Rugged Rockies, I've grown up in the shadow of Yellowstone NP, so up in the Northern WY/Southern MT range... Ever been up that way?

Not sure what you're asking, but if I'm understanding your post then [MENTION=94063]slapdappy[/MENTION] is right. You still need to force the tranny into lower gears to get the engine compression you want to slow you down if you are in low range or high range (for the transfer case).

From my experience the transmission will go into 3rd gear (not into 4th/OD) with the transfer case in low range, but you can still do 20+ mph easily which is why for going downhill you need to drop it into 2nd or 1st gear with the shifter just like for normal engine braking in high range.

So, very similar to what [MENTION=94063]slapdappy[/MENTION] said, the shifting of the auto shifter to L helps force the 4LO to an even lower engine compression? So I was thinking along the right lines with a "double advantage" with having both cases in Low?

When you switch the 4WD shifter into 4LO you are actually disengaging from the gears in the transfer case to 2nd set of transfer case gears.

Your transmission still has the same gears 1, 2, 3, O (although O is probably disabled) and you will feel them shift as you drive in 4LO the same as HI.

My strong advice ... always stop the 4Runner completely, put it in N then shift from 4LO -> 4HI or 4HI -> 4LO.

So contrary to the previous replies, shifting the auto shifter into L would have no effect if I am already in 4LO? I'm just driving in a separate transfer case?

Does that mean that the prior replies are wrong and that the two transfer cases have nothing to do with each other?
A

And yes, anytime I enter 4LO, I always stop, put in N, and then shift to 4LO. I'm comfortable going from D to 4HI on the fly, but I always stop for 4LO.

Let's back up - what do you mean 2wd low, Jon? Unless you've done some expensive modding, you can't put your truck in 2wd low range. You've got 2wd high range (only the two rear wheels are powered, no gear reduction), 4wd high range (where all four wheels are powered, no gear reduction), or 4wd low range (where all four wheels are powered and the transfer case reduction gears are engaged).

The guys above are correct that when you move the transmission selector to L that the truck will hold in first gear no matter how fast you're going, but I suspect that you're confusing the L on the gear selector with low range in the transfer case, which are two completely different things.

Kid: I suspect you're right, in that I'm confusing the two "lows"... No expensive modding, just a stock '98... So regardless of Low on the auto shifter, it won't affect whatever is going on in the 4WD transfer case if I am in 4LO?

^^ This

"Low" on your transmission has a gear ratio of 2.804:1
When you shift into 4Hi your transfer case has a ratio of 1:1 so it takes your transmission gearing and multiplies it by 1.
When you shift into 4Lo your transfer case has a ratio of 2.566:1 now it takes your transmission gearing and multiplies it by 2.566.

Thanks for the numbers! Quite interesting to see how that works... Seems like a lot more gearing compression going on in 4Lo!

I've not tried it, but I always wondered if you put the TC into Lo, but didn't hit the 4WD button, if it would put you into Lo even though the front isn't engaged...? Make sense? A buddy back in the day with his 79 Chevy used to keep the hubs unlocked and put it in Lo and run around town to hear his loud pipes.

I don't have a 4WD button, so your theory I'm not sure how to process, because your system would pick 4HI or LO automatically, I'm assuming?

OP,
The "L" on the transmisison gear selector just means first gear in the transmission and it will not automatically upshift into other gears as you drive. This is true regardless of what position the transfer case shifter is in.
The L on the transfer case means low range, or an additional set of lower gears, regardless of where the transmission gear selector is located.

You need to understand that the transfer case is a separate additional gearbox with its own sets of gears to select from. It also is what sends power to the front axle. In 2wd you are still in high range, so the gear reduction isn't as great.

First 4wd I take it?

Starting to get confused as to what exactly people mean by the transfer case shifter - I'm assuming that is the 4WD shifter knob? The other control arm is the auto shifter, from P-R-D-2-1... Right?

Based on your answer, I was just starting to see that the transfer case is a separate gearbox... Thank you for that clarification especially!

Yes, still quite young, first 4x4, have driven it plenty off road, but seeking to understand how it works in detail. Thanks!

[MENTION=81047]farmerjon[/MENTION]

I was playing with 4L on the transfer case a while back and moved the transmission shifter into L which gave me some serious engine braking for rolling downhill. Is this what you did? and are you looking to find out what the mechanics are? If so, me too...

With regard to shifting into 4L without engaging the 4WD button on the shifter first...IME with my 2002, the front differential will automatically engage when shifting into 4L whether you want it to or not. The middle transfer case will not engage unless you activate it whether or not you are in 4HI or 4L

I figure your system with the 4WD button is different than mine, you probably have more "computerized" stuff going on, so am not sure how all that works... but yes, I had the 4Lo on, and the transmission shifter in L... that was serious engine braking.

I also don't have, on my 1998, a middle transfer case, so I think I only have front and rear?

Farmerjon, just to paint a picture to conceptualize from, here's how the engine braking power lines up in each tranmission gear from most to least in the 4th gen. 3rd gen is no doubt a little different, but you get the point.

Low range
High range


1
2
3 - 1 Same
4
2
5 - Not available
3
4
5

Not quite sure how to read this yet, still learning all this stuff... How do the low and high ranges overlap?

Thank you all to replied, for the patience and various explanations! I always like learning more about how things work!

 

[snivilous]

[MENTION=81047]farmerjon[/MENTION]

Wow, that's a lot of responses. I didn't read through them all but I feel like some were a little off so this is things simplified (I don't mean to insult your/anyone's intelligence).

You have the engine going to the tranny, then the tranny going to the transfer case, then the transfer case going to the differentials. When you are trying to use engine braking, you obviously aren't giving the engine extra gas to accelerate so the engine for all practical purposes is constant (as are the differential gear ratios). This leaves you with the transmission and transfer case to modify the gearing/torque multipliers. The shifter (D/OD Off/2/L) for the transmission forces the tranny to be at or below what the shifter is selected at, so for example if it's at "2" it can be in 2nd gear or 1st gear, but won't shift over 2nd gear. So ultimately, when you "downshift" and slide the shifter back the tranny will go to the highest gear it can be at since it will be trying to keep the rpms low (a la be at the highest gear).

With this in mind, you can then combine gearing ratios of the transfer case and transmission. So when the transfer case is in high range you have the 1:1 ratio then multiplied by say 1st gear (L on the tranny shifter) for one engine braking ratio. Likewise, you can shift the transfer case into low range and now have a 2.28:1 ratio multiplied by 1st gear (obviously that's 2.28x lower gearing). OR you could be in transfer case low range of 2.28:1 and 2nd gear which is a higher ratio than the previous.

The point I'm trying to make is, you have two gear ratios that multiply together and you can control both of them. Combine them both into their lowest setting (1st gear/Low on the tranny and Low range transfer case) and it's insane engine braking--or you can bump one or the other so the engine braking isn't as extreme. Hopefully that makes sense and maybe helps a bit...

EDIT: So for the record, 4WD vs 2WD shouldn't matter. If it's loose ground 4WD will obviously help because you are getting engine braking to all 4 tires vs just 2 but for the sake of argument if you have total traction it shouldn't matter. The only thing that should matter is the transmissions selected ratio and the transfer cases selected ratio.

 

[farmerjon]

[MENTION=81047]farmerjon[/MENTION]

Wow, that's a lot of responses. I didn't read through them all but I feel like some were a little off so this is things simplified (I don't mean to insult your/anyone's intelligence).

You have the engine going to the tranny, then the tranny going to the transfer case, then the transfer case going to the differentials. When you are trying to use engine braking, you obviously aren't giving the engine extra gas to accelerate so the engine for all practical purposes is constant (as are the differential gear ratios). This leaves you with the transmission and transfer case to modify the gearing/torque multipliers. The shifter (D/OD Off/2/L) for the transmission forces the tranny to be at or below what the shifter is selected at, so for example if it's at "2" it can be in 2nd gear or 1st gear, but won't shift over 2nd gear. So ultimately, when you "downshift" and slide the shifter back the tranny will go to the highest gear it can be at since it will be trying to keep the rpms low (a la be at the highest gear).

With this in mind, you can then combine gearing ratios of the transfer case and transmission. So when the transfer case is in high range you have the 1:1 ratio then multiplied by say 1st gear (L on the tranny shifter) for one engine braking ratio. Likewise, you can shift the transfer case into low range and now have a 2.28:1 ratio multiplied by 1st gear (obviously that's 2.28x lower gearing). OR you could be in transfer case low range of 2.28:1 and 2nd gear which is a higher ratio than the previous.

The point I'm trying to make is, you have two gear ratios that multiply together and you can control both of them. Combine them both into their lowest setting (1st gear/Low on the tranny and Low range transfer case) and it's insane engine braking--or you can bump one or the other so the engine braking isn't as extreme. Hopefully that makes sense and maybe helps a bit...

EDIT: So for the record, 4WD vs 2WD shouldn't matter. If it's loose ground 4WD will obviously help because you are getting engine braking to all 4 tires vs just 2 but for the sake of argument if you have total traction it shouldn't matter. The only thing that should matter is the transmissions selected ratio and the transfer cases selected ratio.

This helps a lot, [MENTION=92884]snivilous[/MENTION]! I'm seeing your point about the 4 vs 2 WD, that it shouldn't matter. To clarify- the 2 and 4 wheel drives are separate transfer cases - which each have their own gear ratios, so depending on what combination of transmission selection and transfer case selection, I can choose what kind of engine braking (among other things) happens?

Things are starting to really click in place! :smash:op2:

 

[D Farms]

so ive also wondered this, if i stop, put it in neutral, and shift my transfercase into 4lo, the green 4 tires blink like its trying the engage the front 2 wheels. I suspect you can some how trick the add to not turn on in the front, and lock the center diff, then you have 2wd lo.

 

[JB.]

Low range
High range

1
2
3 - 1 Same
4
2
5 - Not available
3
4
5

Not quite sure how to read this... How do the low and high ranges overlap?

The gear combinations in 3rd low and 1st high create the same overall gear ratio. The engine speed is the same in each for a given vehicle speed.

4th low provides less engine braking (or more speed) than 1st high. If 5th low were available, it would be the same situation vs 2nd high.

Not sure how the 3rd gen is but there is no doubt a similar overlap. Someone must have the gear ratios. Not necessary, though, if you have a tachometer. Get in a clear parking lot and take note of the engine and vehicle speed in whatever gear you want to test.

 

[snivilous]

[MENTION=81047]farmerjon[/MENTION]

To clarify- the 2 and 4 wheel drives are separate transfer cases - which each have their own gear ratios, so depending on what combination of transmission selection and transfer case selection, I can choose what kind of engine braking (among other things) happens?

Things are starting to really click in place! :smash:op2:

In regards to the part in bold, you have a single transfer case that controls 2WD and 4WD. The transfer case when shifted from 2WD to 4WD will then put power to the front driveshaft and front differential. You can then shift into 4Lo (transfer case in low range, 2.28:1 ratio) which then gives you the big gearing reduction. 2WD is always high range (1:1 ratio), as is 4Hi too. One way you can think of it is the only difference between 2WD and 4WD is the front wheels are spun in 4WD, and the gearing reduction is a function of the transfer case in Low Range or High Range--so the gearing isn't a function of 2/4WD but of what gearing range is selected--however, it just happens that you can only have the transfer case in Low Range with it also in 4WD...

so ive also wondered this, if i stop, put it in neutral, and shift my transfercase into 4lo, the green 4 tires blink like its trying the engage the front 2 wheels. I suspect you can some how trick the add to not turn on in the front, and lock the center diff, then you have 2wd lo.

[MENTION=81047]farmerjon[/MENTION] has a 98 so he doesn't have the multimode transfer case, so he is forced to have Low Range in 4WD. With the multimode cases like you have (D Farms), you can do electrical mods to prevent the computer turning 4WD on but allowing Low Range to engage (because Low/High Range are mechanically engaged, versus 2/4WD being electronically engaged). 4Ripcord has a write up on the electrical mod needed to allow 2Lo.

Hope this helps!

 

[D Farms]

cool ill have to take a look at that cause i dont think it would even need any switches, i would just have to engage 4wd when i want it, instead of it engaging when i shift into lo.

 

[KidVermicious]

Kid: I suspect you're right, in that I'm confusing the two "lows"... No expensive modding, just a stock '98... So regardless of Low on the auto shifter, it won't affect whatever is going on in the 4WD transfer case if I am in 4LO?

Think of your transfer case as a manual transmission with two gears (for our purposes, ignore that it also splits power to the front shaft). One of those gears is a 1:1 ratio that is transparent to your drivetrain, the other is (I think?) 2.56:1. Your automatic transmission and your transfer case are independant of each other in the sense that what goes on in one does not affect what goes on in the other. When you manually select a gear in the transmission it doesn't matter if you're in 2hi, 4hi, or 4lo, the transmission will not upshift past that gear. At the same time, when you select 4lo in the transfer case it doesn't matter what gear you're in at the transmission, whatever it is WILL get reduced further by a factor of 2:56 (or whatever) to 1. So for ultimate gear reduction when descending or crawling, you're correct to force the transmission to stay in 1st gear and shift the transfer case to 4lo (even if you don't necessarily need 4wd at the time).

Does that make sense, or did I muddy things up more?

 

[tre9er]

A bit of info we learned as an aside in this thread is that you CAN get to a 2-lo state with multi-mode transfer case (the single shifter with just 4L, N, and H positions, with the 4WD button on the side of shifter knob) just via Andymod 2.0, which fools the computer into thinking you're already in 4WD and thus won't engage the front diff.

Also that if you're using Trac Off (Andymod 2.0), you must engage it AFTER you throw it into 4WD, or else you can't engage the front.

Lastly that you can't get OUT OF 4WD until you re-enable Trac (key off, key on).

Andymod 2.0 doesn't allow the engagement/disengagement of the front diff until Trac is returned to ON.

 

[D Farms]

OK cool so I already have that set up haha.

 

[JamesDean91]

For people who are confused about 2wd low you can do it for free if you have the electric case (push button 4wd) there is a connecter you unplug and tape off, thus giving you the ability to sift the lever into 4lo but only be in 2lo until you hit the 4wd button. I did it to mine awhile ago and use it constantly offroad.
I have done this mod to a 97 runner, my 98, a neighbors Canadian model 98, a 00 Tacoma, and a 01 runner.

Also if you have a traditional j shift case you can buy a twin sick setup for it much like you can with older gear drive cases.

 

[BrianSD_42]

So contrary to the previous replies, shifting the auto shifter into L would have no effect if I am already in 4LO? I'm just driving in a separate transfer case?

If you are already in 4LO and have an auto, assuming you are in D/3 on the transmission shifter then moving it to 1 will only lock the transmission in the lowest gear -> 1. It doesn't change your transfer case again. It is like my original comment. Your transfer case and transmission are separate entities albeit connected.

That is how I understand it but I'm not an expert.

 

[GhostRing]

For people who are confused about 2wd low you can do it for free if you have the electric case (push button 4wd) there is a connecter you unplug and tape off, thus giving you the ability to sift the lever into 4lo but only be in 2lo until you hit the 4wd button. I did it to mine awhile ago and use it constantly offroad.

I would like a better detailed version of this mod.
Closest thing to swapping manual hubs that I'm willing to deal with.

 

[JamesDean91]

I would like a better detailed version of this mod.
Closest thing to swapping manual hubs that I'm willing to deal with.

The fiancé has my truck right now so i can't go crawl under and look but i think there was a write up awhile ago on it. I'll see if i can't find it, should be the blue connecter on the driver side of your transfer case if memory servers me right.


Found it http://www.nwtoys.com/content/124-two-low-modification.html

 

[tre9er]

For people who are confused about 2wd low you can do it for free if you have the electric case (push button 4wd)

Yeah, if you do the Andymod 2.0 (a switch inserted on one single wire going into the 4WD computer) you can accomplish this, as I said. Of course you'll be disabling VSC/Trac, too.

 

[JamesDean91]

Yeah, if you do the Andymod 2.0 (a switch inserted on one single wire going into the 4WD computer) you can accomplish this, as I said. Of course you'll be disabling VSC/Trac, too.

I have selective reading and only read the first page lol, however you can't do the Andy mod on 00? And older? Or 99 I forget the year.

 

[tre9er]

I think it's 99 and newer. With the AWD type elctronic 4WD button

 

[JamesDean91]

I think it's 99 and newer. With the AWD type elctronic 4WD button

Well I have done the mod to a 01 before as it has the same shift pattern as my 98 a friends 99 is a j shift pattern for awd so it is a all mechanical case. If you have not done the Andy mod (and idk why you would not of) then you can still get 2 lo by unplugging the plug.

 

[andyv760]

"H" position on shifter

I apologize if my question is steering away from the OP's question. My question is, I have a 2001 SR5, auto, 4wd and I wanted to know if my 4wd shifter should always be in "H" for day to day driving? Thank you, much is appreciated. Again, I apologize for highjacking this thread....I've searched everywhere with negative results.

 

[Frey]

I apologize if my question is steering away from the OP's question. My question is, I have a 2001 SR5, auto, 4wd and I wanted to know if my 4wd shifter should always be in "H" for day to day driving? Thank you, much is appreciated. Again, I apologize for highjacking this thread....I've searched everywhere with negative results.

andyv760, you should take the time to read the info in this well-written thread by brian2sun. It has the answer to your question and much more.

http://www.toyota-4runner.org/3rd-g...rs-3rd-gens-transfer-case-awd-multi-mode.html