Stuck twice ... Lock diff as soon as I hit dirt?

[KrazedJD]

I think I saw a thread somewhere about this but I could not find it. First is first I have a 2003 4.7 V8 4 Runner Limited.

Four weeks ago I went on the beach and dropped pressure to 15 psi. (as I always did with my 93 Pathfinder SE) Put the vehicle in 4lo without differential being locked and truck dug in. Got towed out and dropped to 10 psi. and locked the differential and no problem at all.

Two weeks ago I was driving through the sandy pine barrens of NJ and came across a trail that was heavily soaked and large standing puddles. When I crossed it the first time I had 4 Hi since most the trail was just bumpy and not soaking wet with large puddles. I crossed over this one fairly easily at about 20 mph. However, I came across the same large puddle (about 12' wide and long and about 8-10" deep) and got stuck trying to cross it at 5-10 mph. After getting stuck I noticed the drivers side of the truck started digging in, listing the drivers side into the water. After being stuck I realized that activating the differential lock actually did nothing. The drivers front wheel was spinning and the passenger rear wheel was spinning but not the others.

So I am wondering do I really have to engage the differential lock the second I know my truck is about to go off asphalt?

 

[CJ3Flyr]

I think I saw a thread somewhere about this but I could not find it. First is first I have a 2003 4.7 V8 4 Runner Limited.

Four weeks ago I went on the beach and dropped pressure to 15 psi. (as I always did with my 93 Pathfinder SE) Put the vehicle in 4lo without differential being locked and truck dug in. Got towed out and dropped to 10 psi. and locked the differential and no problem at all.

Two weeks ago I was driving through the sandy pine barrens of NJ and came across a trail that was heavily soaked and large standing puddles. When I crossed it the first time I had 4 Hi since most the trail was just bumpy and not soaking wet with large puddles. I crossed over this one fairly easily at about 20 mph. However, I came across the same large puddle (about 12' wide and long and about 8-10" deep) and got stuck trying to cross it at 5-10 mph. After getting stuck I noticed the drivers side of the truck started digging in, listing the drivers side into the water. After being stuck I realized that activating the differential lock actually did nothing. The drivers front wheel was spinning and the passenger rear wheel was spinning but not the others.

So I am wondering do I really have to engage the differential lock the second I know my truck is about to go off asphalt?

Yes, lock it. The real challenge pre-08 is no VSC defeat. The VSC/TRAC is what cuts the engine power as you're getting stuck preventing you from powering through/over to avoid being stuck. After the vehicle is stopped, say mid-puddle, there's little hope starting again without assistance.

By locking the center diff you are doing two things: 1) Locking the center, duh. 2) Placing the VSC in a defeat mode where it won't throttle back the engine to prevent wheel-slip. Power control will be your job not the computers. The ATRAC will still try to balance the power right-to-left (limited-slip like) on the front and rear axles but no throttle back.

If you want to mod with a neat little mod click on the VSC off link in my sig. It's good for V8, V6 4wd T4R 2003-2007. 2008- came witha a factory defeat switch.
:cheers:

 

[KrazedJD]

The VSC makes perfect sense, I swore that both times I got stuck it felt like someone killed the engine or hit the brakes. Thanks I will look into that, I imagine there is a button I can order or something to hit on the dash to do your mod.

I will look at it now.

 

[ncrunner]

... The ATRAC will still try to balance the power right-to-left (limited-slip like) on the front and rear axles but no throttle back....
:cheers:

I was under the impression the ATRAC AND the VSC disengages when the center diff is locked. This is good news to hear the ATRAC remains functional.

 

[Thai]

I was under the impression the ATRAC AND the VSC disengages when the center diff is locked. This is good news to hear the ATRAC remains functional.

Center diff lock = no VSC

ATRAC is always ON.

 

[offshorebear]

The traction control systems that use brakes don't work very well in sand. You need power and momentum to keep going.

I always lock the diff when I leave the pavement. I've taken my 4Runner to the beach a few times now and it does great.

 

[KrazedJD]

Yeah I found out the hard way once but apparently it took twice to make it stick lol. I will have to take pics of my gutted 4runner so I could get all the mud outta the car!

 

[offshorebear]

I imagine the Pine Barrens are pretty bad this year with all the rain we have had. Are there any easy trails left?

 

[techno]

I thought the center diff locked automatically as soon as low range is selected? Am I wrong?

 

[Thai]

I thought the center diff locked automatically as soon as low range is selected? Am I wrong?

On the newer 4runners, it is not automatic.

 

[KrazedJD]

They are not so bad, it’s just certain areas that seem to be retaining water from the high volume of rain this summer. The real problem is the damage to the trail front he standing water and trucks/tanks going through it. It has made the affected area more of a crater from the waves washing away the fine sand, leaving behind nice soft silky mud. This particular crater I have seen over the last 10 years get bigger and bigger, and sadly the bigger it gets it seems the puddle never fully dries out. I was thinking of doing a charitable cause and filling it in come fall the best I can with some shovels friends and some beer.

According to the manual the center diff does not lock on the full time 4WD model when selecting 4LO, its is a manual buttone press on my part. I am not clear about the 2WD models that have the convenience of selecting 2/4HI/4LO. How I wish I could change my V8 full time 4WD to a 2WD mode. I am sure it’s not impossible but at the same token I am sure it’s not cheap or cost effective either.

Also I wish I could change how the differential locks, I wish it would lock after you get stuck, not require a little bit of forward motion, or reverse.

 

[Thai]

Also I wish I could change how the differential locks, I wish it would lock after you get stuck, not require a little bit of forward motion, or reverse.

The center diff is mechanical with gears. So, the gears have to line up before it locks...so, this is why it is not instantaneous.

 

[techno]

On the newer 4runners, it is not automatic.

Thats interesting. It almost seems like that makes things a little more complicated yet more versatile at the same time. Maybe it has something to do with atrac operation...

Center diffs used to auto lock in low range because unlocked there were too many gears moving to fast at different rates (the cd gears rotate around four times faster the the axle diffs gears) and there was a high potential for overheating and damage. I suppose technology has caught up with that.

Incidentally, I would recommend locking the cd on anything other than hard top and good gravel roads. In my opinion, 99% of the time if you need low range then you definately need the cd locked.


In general when offroading;

2wd will get you ___________this far
4wd unlocked center will get you ________________________________________this far
4wd locked center will get you ________________________________________________________________this far
4wd fully locked f, r, c will get you ________________________________________________________________________________________________this far

 

[offshorebear]

Unlocked 4 hi is nice for bad weather. I even used unlocked 4 low to pull some stumps out. I needed to turn on pavement but needed the low range.

Its kind of annoying on the 4runner the steps it takes to get into an offroad mode. Nuetral, switch to 4 low and wait, press button to lock center diff and wait, hold button to turn off the side airbags. It only takes 10 - 15 seconds but its still a pet peeve of mine.

 

[Thai]

Its kind of annoying on the 4runner the steps it takes to get into an offroad mode. Nuetral, switch to 4 low and wait, press button to lock center diff and wait, hold button to turn off the side airbags. It only takes 10 - 15 seconds but its still a pet peeve of mine.

Better to have choices than none at all. I rather wait and get into the exact mode that i want rather than let a CPU do it for me (aka Terrain Response in Land Rovers).

 

[Thai]

Incidentally, I would recommend locking the cd on anything other than hard top and good gravel roads. In my opinion, 99% of the time if you need low range then you definately need the cd locked.

x2. When off-road, i am almost always in 4-LO (for the type of off-roading that i do) and center diff locked. Most of those times, my rear locker is also locked.

 

[KrazedJD]

Now I have a new wish, wish I could lock my front and rear diff with a button

 

[Pikeman]

You can... its called ARB or not sure on the 4th gens but can at least get an E-locker for the rear.

 

[Duhockey]

Unlocked 4 hi is nice for bad weather. I even used unlocked 4 low to pull some stumps out. I needed to turn on pavement but needed the low range.

Its kind of annoying on the 4runner the steps it takes to get into an offroad mode. Nuetral, switch to 4 low and wait, press button to lock center diff and wait, hold button to turn off the side airbags. It only takes 10 - 15 seconds but its still a pet peeve of mine.

While some of us just wish we had the problem of having a diff lock!!

 

[CJ3Flyr]

Unlocked 4 hi is nice for bad weather. I even used unlocked 4 low to pull some stumps out. I needed to turn on pavement but needed the low range.

:iagree: I use 4lo unlocked at the boat ramp, love it!