General off-road driveability questions.. with pics!

[audiness]

Hello everyone. I am a long time lurker on this board, but I don't post too often. I am thankful for the vast wealth of knowledge and information I have gleaned from this board over the years. I own a '00 T4R Limited., and I recently took it to an ORV park, and had some fun. I don't have a lot of off-road driving experience, except for an old 80 series Landcruiser that I drove off-road a few times. The 80 series was very capable, basically you just point it where you want to go, and it went there. The 4runner feels more nimble, but also more delicate than the 80.

I was wheeling with a few other vehicles, and my 4runner got "stuck" where some other vehicles did not.:wtf: I was actually quite shocked at how easily I got "stuck". Here is a prime example of where I had trouble:

Whenever my truck got into this situation, one back wheel would spin, and the truck just would not go any further, until I turned the rear electronic diff lock on. Once the rear diff lock was on, it would climb out with ease. My main question is - if the truck is in Lo-4, which also locks the center diff, why was I stuck in this position?? I thought if the truck is in Lo-4, that also automatically locks the center differential, which would distribute power to the front and rear diffs 50/50?? Why was the truck not able to pull itself out with just the front wheels? As you can see from the pics, both front wheels had plenty of traction in this situation.

My next question is, if I did not have the rear e-locker, how could I have gotten out of this situation? Or maybe the better question is , what could be done to avoid this hangup in the first place?

Thanks for reading!!!!:hiding: and sharing your opinion. I am trying to understand the best way to drive in off-road situations.

 

[techno]

Assuming the 4wd system is not broken, one of your front wheels had to be spinning also. From the pic, we can not see the front drivers side wheel but I'd bet money that it was spinning also. The suspension seems to be in the classic 'crossed up' configuration.
Now if you are 100% certain that neither front wheel was spinning when the rear one was, then you have something wrong with the 4wd system.
Without the diff lock to help, you would need to try approaching that spot with a different line, with more right foot, with more suspension travel or more aggressive tires.

 

[theizzardking]

Hello everyone. I am a long time lurker on this board, but I don't post too often. I am thankful for the vast wealth of knowledge and information I have gleaned from this board over the years. I own a '00 T4R Limited., and I recently took it to an ORV park, and had some fun. I don't have a lot of off-road driving experience, except for an old 80 series Landcruiser that I drove off-road a few times. The 80 series was very capable, basically you just point it where you want to go, and it went there. The 4runner feels more nimble, but also more delicate than the 80.

I was wheeling with a few other vehicles, and my 4runner got "stuck" where some other vehicles did not.:wtf: I was actually quite shocked at how easily I got "stuck". Here is a prime example of where I had trouble:

Whenever my truck got into this situation, one back wheel would spin, and the truck just would not go any further, until I turned the rear electronic diff lock on. Once the rear diff lock was on, it would climb out with ease. My main question is - if the truck is in Lo-4, which also locks the center diff, why was I stuck in this position?? I thought if the truck is in Lo-4, that also automatically locks the center differential, which would distribute power to the front and rear diffs 50/50?? Why was the truck not able to pull itself out with just the front wheels? As you can see from the pics, both front wheels had plenty of traction in this situation.

My next question is, if I did not have the rear e-locker, how could I have gotten out of this situation? Or maybe the better question is , what could be done to avoid this hangup in the first place?

Thanks for reading!!!!:hiding: and sharing your opinion. I am trying to understand the best way to drive in off-road situations.

going to slow and not enough tread grip, assuming your 4wd is actually working (transfer case) you should have made it up that no issues, that ground looks like it has a thin layer of mud on top of it, you can have the most bad A 4x4 system on planet earth but if your tires are bald your not going anywhere, where the rubber meets the road as they say....in short the 2 things you care about when off-roading is traction and momentum, you need both of those to get through most off road challenges...sometimes you can get by using only one, but that usually breaks things and makes you crap your pants.

at the start of the hill pick your line/lines and keep a slow but steady speed making small adjustments on the way up, but keep the truck moving forward.

rules are different for different environments, but generally you can use those as a go by in sand,mud,a mildly rocky trails.

 

[JWaldz]

If your front end is doing all the work your 4Runner is most likely not going to go anywhere. Especially in loose dirt or gravel, no matter what kind of traction you have on your tires. In your case, not much. Your rear tire is flexed out not getting any traction and your front tire(s) could just be spinning away. People forget that on the flat roads, sure it's 4x4. In the event of flexing suspension though all the power goes to a specific wheel. This is where lockers come into play. You got stuck because your rear was flexed out (left rear not spinning and rear right no traction) and your front was only getting power to one wheel most likely. Which in that case it probably wasn't getting traction either and was not enough to pull all the weight.

You can avoid situations like this by either taking a different angle or getting more speed (when available). From the picture it looks like you had plenty of room to back away and take a different angle with maybe a little more speed.

 

[4-Ripcord]

Im guessing you forgot to lock the center diff.. which means you were just in all-wheel drive and not 4x4.

If you were in 4x4 the front would have pulled you forward from there no problem.

 

[fish0281]

Im guessing you forgot to lock the center diff.. which means you were just in all-wheel drive and not 4x4.

If you were in 4x4 the front would have pulled you forward from there no problem.

Do you still need to lock the center diff in 4-Lo? I (and I think the OP) was under the assumption that 4-Lo locks the center diff...

 

[audiness]

Do you still need to lock the center diff in 4-Lo? I (and I think the OP) was under the assumption that 4-Lo locks the center diff...

The 4Runner in this post is a 2000. In the 2000 and older T4Rs, the Center diff is automatically locked when in 4-Lo, and with the 2001+ the center diff lock switch allows you to turn the center diff lock on and off.

 

[audiness]

Assuming the 4wd system is not broken, one of your front wheels had to be spinning also. From the pic, we can not see the front drivers side wheel but I'd bet money that it was spinning also. The suspension seems to be in the classic 'crossed up' configuration.
Now if you are 100% certain that neither front wheel was spinning when the rear one was, then you have something wrong with the 4wd system.
Without the diff lock to help, you would need to try approaching that spot with a different line, with more right foot, with more suspension travel or more aggressive tires.

Perhaps there is something wrong with my 4wd, because this happened to me 6 or 7 times that day. Or maybe there is something wrong with my driving, as I was going very slow, but maybe I didn't have enough momentum. Thanks for all the replies!!:hello:

 

[Bishard]

Seems like your front end shoulda pulled you right through that. Maybe 4x4 issue. For me going fast is the best way to avoid getting stuck.

 

[audiness]

Tires are fairly new Cooper Discover's

And according to my dash lights my 4WD is engaged, and Center Diff is locked.

so.... not sure what the deal is.....

 

[emmodg]

Looks like a classic "crossed-axle" stick - well, as close as you can get to it with an IFS truck.

You'll need to know how a diff. works to know why your stuck and what to do about it. Without getting overly technical suffice it to say that a differential will always try and send "power", or more accurately torque, to the wheel with less resistance. Like water flowing downhill or electricity taking easiest path to ground. (It MUST do this when the vehicle is turning so that one wheel can spin at a different rate than the opposite wheel as each wheel is taking a different path than the other while in a turn remember.)

When one wheel encounters lower resistance than the other wheel due to loss of grip/traction the diff will continue to send more and more "power" to that wheel until the great majority of all "power" going to the particular driven axle is sent to the "slipping" or spinning wheel. You're rear passenger-side wheel is barely touching the ground so it of course has little to no resistance and thus your rear diff is going to direct more and more "power" to that wheel until the power available to the rear axle via the drive shaft has gone into your one spinning wheel. Result: You're stuck!

Now, if everything is working on your truck - ie your multi-mode case - you have one rear wheel spinning and one front wheel spinning, (looks like your driver's-side front wheel is probably the culprit as your passenger-side wheel looks a bit "stuffed" under the fender, the only wheel getting traction in an IFS system is the one with weight on it), the two spinning wheels are now "stealing" all the power necessary to move the truck! A locked center diff won't help when there isn't enough "power" available to move the truck. (Again, we're actually dealing with torque when talking about diffs. A spinning wheel doesn't have enough torque to move the truck.)

Your chosen line on that trail has compromised your suspension putting the truck in a crossed-axle configuration. Drive your suspension "flatter" to fix that situation or use brake/throttle modulation or you could use a little momentum to get through that one spot. It looks like you could have turned more passenger in the above photo making the front suspension "flatter" which would then get the rear "flatter" as well - it's hard to tell of course. I will say - once you have a wheel spinning don't just keep giving it gas! You're just sending more and more "power" to an already spinning wheel and taking that power from the good wheel! You'd be surprised how much it helps to just ease off the throttle a bit - don't dump all gas, just ease off - your no longer allowing the diff to send "power" to the slipping wheel but instead "keeping it" on the good wheel longer.

When you lock your rear diff you effectively no longer have an open differential - your rear axles are now "locked" relative to each other, both wheels now spin at the same rate no matter how much or how little traction/grip you have. The differential is now sending all power available to it from the drive shaft to both wheels equally. That's why you're able to drive out of the above situation when you use your locker.

If you really are in 4LO and you can only see ONE wheel spinning in your above situation something is wrong in that case. A part time 4WD truck should always have at least 2 wheels spinning when the transfer case is engaged. A full time 4WD truck uses a center differential, (Yep! It has THREE!), and if that center diff. isn't locked you can eventually only have one wheel spinning!

We have students getting cross-axled all the time. We have full-time trucks, part-time trucks, lockers and open diffs - they'll all succumb to a cross -axled stick!

Hope some of this explains it!

 

[audiness]

^ great explanation, thank you!

 

[rickashay]

I think knowing your vehicle goes a long way. Obviously that takes some seat time but I like to be able to anticipate how the vehicle will react in a giving circumstance and then choose my "line" accordingly. Speed is NOT always the answer, IMO being smooth and keeping your momentum moving ahead when needed, is key. I find myself using the skinny pedal less and less as an escape route, but granted sometimes it may be needed.
"Two-foot braking" is also a good technique to get the torque converter locked up in your automatic, and keep you smooth on the trail.

A question for you OP, were your tires aired down? If so, to what psi?

 

[audiness]

I think knowing your vehicle goes a long way. Obviously that takes some seat time but I like to be able to anticipate how the vehicle will react in a giving circumstance and then choose my "line" accordingly. Speed is NOT always the answer, IMO being smooth and keeping your momentum moving ahead when needed, is key. I find myself using the skinny pedal less and less as an escape route, but granted sometimes it may be needed.
"Two-foot braking" is also a good technique to get the torque converter locked up in your automatic, and keep you smooth on the trail.

A question for you OP, were your tires aired down? If so, to what psi?

I did not air down, perhaps i should have. I didn't do so because I thought I would need the extra ground clearance... as my truck is stock, with saggy springs no less.

 

[hrt4me]

Looks like a classic "crossed-axle" stick - well, as close as you can get to it with an IFS truck.

You'll need to know how a diff. works to know why you're stuck and what to do about it. Without getting overly technical suffice it to say that a differential will always try and send "power", or more accurately torque, to the wheel with less resistance. Like water flowing downhill or electricity taking easiest path to ground. (It MUST do this when the vehicle is turning so that one wheel can spin at a different rate than the opposite wheel, as each wheel is taking a different path than the other while in a turn, remember.)

When one wheel encounters lower resistance than the other wheel due to loss of grip/traction, the diff will continue to send more and more "power" to that wheel until the great majority of all "power" going to the particular driven axle is sent to the "slipping" or spinning wheel. Your rear passenger-side wheel is barely touching the ground, so it of course has little to no resistance, and thus, your rear diff is going to direct more and more "power" to that wheel until the power available to the rear axle via the drive shaft has gone into your one spinning wheel. Result: You're stuck!

Now, if everything is working on your truck - i.e. your multi-mode case - you have one rear wheel spinning and one front wheel spinning, (looks like your driver's-side front wheel is probably the culprit, as your passenger-side wheel looks a bit "stuffed" under the fender; the only wheel getting traction in an IFS system is the one with weight on it), the two spinning wheels are now "stealing" all the power necessary to move the truck! A locked center diff won't help when there isn't enough "power" available to move the truck. (Again, we're actually dealing with torque when talking about diffs. A spinning wheel doesn't have enough torque to move the truck.)

Your chosen line on that trail has compromised your suspension, putting the truck in a crossed-axle configuration. Drive your suspension "flatter" to fix that situation, or use brake/throttle modulation, or you could use a little momentum to get through that one spot. It looks like you could have turned more passenger in the above photo, making the front suspension "flatter", which would then get the rear "flatter" as well - it's hard to tell of course. I will say - once you have a wheel spinning don't just keep giving it gas! You're just sending more and more "power" to an already spinning wheel and taking that power from the good wheel! You'd be surprised how much it helps to just ease off the throttle a bit - don't dump all gas, just ease off - you're no longer allowing the diff to send "power" to the slipping wheel but instead "keeping it" on the good wheel longer.

When you lock your rear diff you effectively no longer have an open differential - your rear axles are now "locked" relative to each other, both wheels now spin at the same rate no matter how much or how little traction/grip you have. The differential is now sending all power available to it from the drive shaft to both wheels equally. That's why you're able to drive out of the above situation when you use your locker.

If you really are in 4LO and you can only see ONE wheel spinning in your above situation, something is wrong in that case. A part-time 4WD truck should always have at least 2 wheels spinning when the transfer case is engaged. A full-time 4WD truck uses a center differential, (Yep! It has THREE!), and if that center diff. isn't locked, you can eventually only have one wheel spinning!

We have students getting cross-axled all the time. We have full-time trucks, part-time trucks, lockers and open diffs - they'll all succumb to a cross -axled stick!

thanks for the good explanation and clarification, especially relating to TruTrac brake biasing like I formerly had in my Gen1 '85 4Runner with solid front axle

also, your reference to 'students'.... what and where do you teach?

 

[VA07]

To add to the questions: I know the Limited was the only one with a rear locker. Was it also the only one with the center dif lock on the 2000 model?

I have a 2000 SR5 and it doesn't even utilize the same 4wd indicator. It just uses the green indicator in the lower right corner of the dash. My question is: Does it lock the center dif in 4lo?

 

[techno]

VA07, your vehicle doesn't have a center differential. Some SR5's got the locker, it was an option.

 

[audiness]

To add to the questions: I know the Limited was the only one with a rear locker. Was it also the only one with the center dif lock on the 2000 model?

I have a 2000 SR5 and it doesn't even utilize the same 4wd indicator. It just uses the green indicator in the lower right corner of the dash. My question is: Does it lock the center dif in 4lo?

According to the sticky on this board ( if I am reading it correctly) all 99 and 00 had the center diff lock if it is a 4wd model. It comes on automatically when the truck is put into 4-lo.

 

[emmodg]

thanks for the good explanation and clarification, especially relating to TruTrac brake biasing like I formerly had in my Gen1 '85 4Runner with solid front axle

also, your reference to 'students'.... what and where do you teach?

I'm an off road driving instructor for Overland Experts.

 

[techno]

According to the sticky on this board ( if I am reading it correctly) all 99 and 00 had the center diff lock if it is a 4wd model. It comes on automatically when the truck is put into 4-lo.

That only applies to models with the multi-mode (one-touch 2-4) transfer case. That's the one that has a push button to activate 4wd on the transfer case shifter.