Putting in 4WD when already stuck

[spud72]

I don't feel like experimenting myself, so I thought someone here may have already run across this.

I know when putting the V6 into 4WD, there is a slight lag before it engages. In my experience, it could be 2 seconds or 10, really depends.

But, I was wondering the other day: What would happen if you were just plodding along on a trail that seemed to be in decent condition, only to get stuck.

Can you engage 4H from 2H without moving forward? Would your might 4x4 be stuck in it's muddy tomb since the front end would not be moving for the drive train to "synch up?"

Like I said, just wondering if anyone has come across this. Of course, you'd probably normally just leave it in 4H if your trailing around and this shouldn't happen in the first place.

 

[Even Steven]

If you are completely stopped and try to put your 4Runner into 4wd, it may or may not engage, depending upon the alignment of the splines. If they are lined up, then it should engage without any problem. If they are not lined up, you may have to move a few inches in either direction before 4wd engages.

I guess it is possible to have difficulty engaging 4wd if you are completely stuck and cannot move at all, but I have not experienced that problem ever.

Keep in mind that you can drive in 4wd in any conditions (even dry roads) for any length of time, thanks to the center differential on the 4Runner. If you think you may be driving in conditions that can get you stuck, put it in 4wd and leave there.

I typically put my 4Runner in 4wd throughout the entire winter season. I only switch back to 2wd when the snow is gone. This does no harm at all----the V8 4Runner is always in 4wd without having the option of running in 2wd.

 

[nated05]

Good question, Ive often wondered this as well.

 

[boston_kevin]

I do exactly the same thing Even Steven. My 4Runner goes into 4wd in November and goes back into 2wd in May with occasional switching on dry days in the winter to make sure everything stays lubed and ready to go.

When I decide to venture off road, I engage 4wd at the start of the trail, not in the middle.

 

[Loggie1]

I thought if you were in 4H you must keep you speed in check...I think below 80mph...right?

 

[boston_kevin]

When you put it in 4WD you can go any speed you want to (being safe). You cannot engage or disengage 4WD above 58 MPH. Once you are engaged, it is just like the system on the V8.

 

[spud72]

Keep in mind that you can drive in 4wd in any conditions (even dry roads) for any length of time, thanks to the center differential on the 4Runner. If you think you may be driving in conditions that can get you stuck, put it in 4wd and leave there.

Oh, of course!

I was just wondering about one of those "what if?" scenarios.

Thanks for the reply.

 

[techno]

If you are stuck and in 2wd, I dont think there will be a problem shifting into 4wd. If you try to drive after shifting, you will have wheels, axles and driveline components moving (even thought the car is not), so I think everything should 'lock' into place.
The only potential issues maybe with the auto-hubs if one front wheel is not spinning...
In winter when it has snowed, I will often need to engage 4wd after having tried 2wd just to get moving in my driveway, and I have never had any problem doing that.
I find that when off road 90% of the time when I get stuck moving forward, I can usually reverse to try the obatacle again. If I am silly enough to have not engaged 4wd by then, I reckon I deserve to walk home!!

 

[TheBlueWave]

Just remember that if you have wheels spinning at different speeds, even slowly, you can bind up the chain inside the transfer case and incur a spendy repair bill. Either put it in 4wd anytime you "might" need it, or just call a tow truck. Ain't worth risking a bound up transfer case.

 

[spud72]

Just remember that if you have wheels spinning at different speeds, even slowly,

How would you get them going different speeds with the 4WD engaged?

(short of using different sized tires, or something bizarre like that)

And if 4WD isn't engaged, how would it damage the TCase?

 

[TheBlueWave]

How would you get them going different speeds with the 4WD engaged?

(short of using different sized tires, or something bizarre like that)

And if 4WD isn't engaged, how would it damage the TCase?

If Atrac is kicking in and slowing down tires that are slipping, transfering power from one wheel to the other can cause wheels on the same axle to spin at different speeds (someone correct me if I'm wrong). There is a thread on this forum where a member describes trying to engage 4wd while on a slippery surface. He heard an awful clunk and then had to stop. Turns out the chain in the t-case was bound up. It was repaired, but what a scare!
If you were stuck in mud and flipped the switch, then tried to move the wheels, this might happen.

 

[Colemanfu]

Best bet it so put it in 4wd before you get stuck. I found that out the hard way with my old Ranger. Now if I even think there is a chance of getting stuck I kick it into 4wd. Now thats for getting stuck - I do wait to see if I need it or can do with out for some challanges. Like can you climb this in 2wd - If not then.......

Don't wait till you down to the frame rails in mud to put it into 4wd.

Hope this helps. Also good to know how to do it before you need it. Had a pisser of a time getting to 4wd low last week. Just don't need it that much. I think the sequence was Neutral , foot on break then switchkind of deal?

 

[techno]

Either put it in 4wd anytime you "might" need it, or just call a tow truck. Ain't worth risking a bound up transfer case.

WTF? You're not seriously suggesting that you would rather call a tow truck ($$$) than engage 4wd are you?

 

[juneau92]

With my V8 I don't have to worry about this stuff. :runaway:

 

[TheBlueWave]

WTF? You're not seriously suggesting that you would rather call a tow truck ($$$) than engage 4wd are you?

No no no. But if I were already stuck and my hubs weren't aligned, I would call a tow truck and here's why:
If the hubs aren't aligned, you won't get 4wd no matter what you do unless you can get some wheel movement from the front wheels. So lets pretend your stuck in something where the back wheels can "rock" you back and forth a bit, but not get you out. I would call a tower because if you have problems spinning the back wheels (like above) the same speed, and the fronts are moving, the hubs may align at the wrong time and bound up your t-case. If this happens, your t-case will be severely damaged requiring repair or replacement. These senarios are unlikely, but just be smart and make sure 4wd is engaged before-hand if you might need it. Then you call the tower if you really get stuck, meaning 4lo won't get you out. :upset:

 

[racedirt1]

I pulled my camper into a campsite and the 4runner got stuck before I could unhitch (nothing like camping in the rain). Tried to put into 4wd but it wouldn't, tried rocking it a few times with no luck (4wd light was just blinking). I didn't want to unhitch, attempt to go into 4wd the hook it back up and get it situated. I turned the vehicle off and got out to look, jumped back in and turned it on and it was in 4wd. Strange that that would happen but I am glad it did, after engaged in 4wd it pulled right out of the mud and I was good to go.

 

[techno]

The auto locking hub system that Toyota uses (1990 on) is called ADD, Automatic Disconnecting Differential. It uses a sleeve that moves over the drivers side half shaft only, either connecting or disconnecting the axel to the diff. There is nothing on the passenger side shaft.
When in driving in 2wd, the drivers side wheel, hub and half shaft rotate but they are not joined to the diff. The passenger side wheel, hub and shaft rotate and the spider gears in the diff rotate, but the diff carrier does not turn since there is no 'force from the drivers side acting on the diff to prevent 'differential action'. Hence, the front diff does not turn the prop shaft (and neither is the transfer case).
So the only time the ADD sleeve will not slide over the half shafts to engage 4wd is when the drivers side front wheel will not turn at all, like if it is jammed up against rocks or has most of the vehicle weight on it, AND the vehicle can not move forward or backward at all, AND the half shaft splines are not aligned. A very uncommon situation to be in.
Now, when you move the transfer case shifter into 4hi, the front prop shaft is now engaged in the transfer case. As soon as a small amount of engine power is applied, the shaft will turn, the diff carrier will turn, and power will be directed to the path of least resistance which will be the small drivers side inner half shaft, and this gives the ADD sleeve the chance to align and slide into position. Only when the sleeve is in position and the transfer case lever is in the 4hi position will the 4wd light on the dash illuminate.
The only chance of significantly loading up or binding the transfer case will be if you are reving the crap out of the engine before the ADD sleeve has engaged in the situation I described above. A rare occurance and damage will be a result of bad driving technique, not mechanical limitations.

 

[TheBlueWave]

Good info, thanks for setting me straight.:bash:

 

[boston_kevin]

This system on the 4Runner is a fantastic system for 4WD. Running it on dry pavement without any damage has allowed me to plan well in advance of any issues I may encounter when off-roading. The only time I was stuck in 2WD, I shifted to 4HI, waited, then shifted to N then back to D and everything worked fine (my front tires were plowed in by the snowplow going around my parked vehicle.

 

[Baba Booey]

The auto locking hub system that Toyota uses (1990 on) is called ADD, Automatic Disconnecting Differential. It uses a sleeve that moves over the drivers side half shaft only, either connecting or disconnecting the axel to the diff. There is nothing on the passenger side shaft.
When in driving in 2wd, the drivers side wheel, hub and half shaft rotate but they are not joined to the diff. The passenger side wheel, hub and shaft rotate and the spider gears in the diff rotate, but the diff carrier does not turn since there is no 'force from the drivers side acting on the diff to prevent 'differential action'. Hence, the front diff does not turn the prop shaft (and neither is the transfer case).
So the only time the ADD sleeve will not slide over the half shafts to engage 4wd is when the drivers side front wheel will not turn at all, like if it is jammed up against rocks or has most of the vehicle weight on it, AND the vehicle can not move forward or backward at all, AND the half shaft splines are not aligned. A very uncommon situation to be in.
Now, when you move the transfer case shifter into 4hi, the front prop shaft is now engaged in the transfer case. As soon as a small amount of engine power is applied, the shaft will turn, the diff carrier will turn, and power will be directed to the path of least resistance which will be the small drivers side inner half shaft, and this gives the ADD sleeve the chance to align and slide into position. Only when the sleeve is in position and the transfer case lever is in the 4hi position will the 4wd light on the dash illuminate.
The only chance of significantly loading up or binding the transfer case will be if you are reving the crap out of the engine before the ADD sleeve has engaged in the situation I described above. A rare occurance and damage will be a result of bad driving technique, not mechanical limitations.

I am not doubting anything you have said, but why does the 4WD often seem to take such a long period of time to engage in what I consider to be ideal conditions?

I try to plan ahead and engage the 4WD before I get into any trouble. I make certain that I am on a long stretch of straight road, traveling well under 60 mph, no curves or turns, no wheel spin, etc., and yet sometimes the 4WD light will continue to blink for what seems like an eternity before the 4WD locks up. Other times, it takes much less time.

I've tried letting off the accelerator, braking, applying more throttle, keeping the throttle constant, and so forth, and it just seems like you never know when it's going to take a while to engage or engage quickly.