4WD dos/don'ts/cans/can'ts

[jag7720]

I seem to be using 4WD more and in trying to understand my 4WD system I have a few questions...


1. Is the front axle on a M1009 a limited slip, locker or open diff?
2. If the hubs are locked can I drive in 2WD just as if the hubs were unlocked? Will anything bind?
3. If the hubs are locked can I shift into 4WD while in motion?
4 . If #3 is yes, what is the max speed at which I can shift into 4WD?
5. Can I shift from 4WD to 2WD while in motion?
6. If #5 is yes what is the max speed at which I can shift into 2WD?
7. What, if any, is the max speed at which I can drive in 4WD? i.e. is there a speed at which 4WD should not exceed?

Thanks

 

[papercu]

Except for number 1 all those answers are in your TM 9-2320-289-10 and you can download a free copy from this site. It is seachable by keywords and is full of all kinds of other info. Wayne

 

[DeuceNewb]

well here's what i'll say.
1. probably just open
2 yes, and no, its fine
3 yes, as long as you are under like 40 or something. Just don't have the rear wheels spinning. Best bet is to just let off of throttle, shift, then you can get back into throttle.
4 i think 40sih,
5 yes, all the shifting while moving though must me to 4hi, not low. low you can be moving, but it must be in N and less than 5mph
6 shift to 2 whenever, same as shifting to 4 though, not while spinning, and is better if you temp let off throttle while shifting
7 in 4high, probably 50, 55. Thats what i've done in my truck. In 4low, i wouldn't go over
20-25

also, when your hubs are unlocked, you can throw it into low rage for 2 wheel drive low whenever you need some extra torque to the ground. Probably not as useful for an auto, but when you got a stick it is pretty nice at times

 

[hobie237]

1. Open in stock configuration.
2. Yes. No.
3. Yes. Shifting into 4wd with the hubs unlocked (or with an open, with even one hub unlocked) would be pointless.
4. I've heard anything from 25 to 55. Really, though, if I'm going more than about 15mph, I likely don't have much use to shift into 4WD, and my 2-4 shifts are generally in the 0-5mph range, so I have no reason to care.
5. Yes.
6. No idea. I'd imagine it's the same speed as going from 2 to 4, which I still have no reason to care about, since my shifts are still in the 0-5mph range.
7. 4H shouldn't matter since it's 1:1, you should be able to drive just as fast as you can in 2WD. That said, conditions/terrain would likely limit you to WELL below whatever speed you shouldn't exceed. In 4L the generally accepted speed to not exceed is around 35mph for almost any vehicle, but if you need to be in 4L, you'll likely be limited to WAY below that anyway. Personally I think the answers to this question are irrelevant, since if you need 4WD, it implies you're in rougher terrain that will keep your speed down. If terrain permits 55mph+ cruising, you don't need 4WD.

 

[HardCorps79]

Pretty much verbatim from the TM (and your driver's side sun visor if it's stock):
1. Front axle is open
2. You may drive in 2H with the hubs locked, however you may experience a decrease in fuel efficiency and steering response (there's no power driving the front axle, but it's still locked in)
3. If the hubs are locked, you may shift between 4H and 2H at any speed, however it is recommended to let off the throttle and it is preferable to shift at a stop to decrease wear.
4. The TM does not indicate a max speed; it says "at any speed", however doing so may increase wear on your vehicle.
5. See #3. However you must stop the vehicle and place the transmission in P or N before shifting to and from 4L.
6. See #3
7. Do not use 4WD on dry pavement as it will increase wear on the tires and engine components. Max recommended speed in 4H is 55mph. Do not operate the vehicle over 35mph when in 4L.

 

[AJMBLAZER]

Everyone's pretty well covered it. My only contribution is that on #7 it sorta depends on vehicles, their designs, their own particular conditions, and the terrain. My Tracker's only supposed to go like 35mph in 4x4 according to the manual but I've had it up to 55mph. You sorta feel a bit more road vibes than you normally would but otherwise it's completely fine.


Just like to say I'm glad to see so many folks answering #2 in the positive that you can drive in 2wd with the hubs locked in. Always suprises me how many folks say that's a no-no. Makes me wonder who these folks are driving around in the snow and crap all winter and then stopping, getting out, and locking their hubs in and then reversing the process when they're done using 4x4. No one I know for sure!

 

[Braunchitis]

I was told (from several sources) that it's a good idea to lock your hubs at least once a month, whether you are using 4WD or not, in order to keep the parts lubed.

 

[DMgunn]

Couple additional things - seems like many older 4x4s, regardless of manufacturer, don't always disengage from 4WD immediately after shifting. If you are moving forward with even the slightest load on the drivetrain, the t-case will generally remain engaged until you let off and coast - if you want to be positive, put it in reverse. You don't have to actually back up, just the slack in the drivetrain will allow it to "un-bind" itself and go back to 2wd. Nothing to worry about, but I usually do that at a stop sign when there is a long stretch of dry pavement ahead. Better safe than broke.

Also, if you plan to run around with the hubs engaged all winter, just make sure all the u-joints are in good condition and greased, and that the gear lube is full. As HardCorp79 said, everything in the front axle (and the driveshaft) will be turning, even in 2wd.

 

[Dabba]

tis true ^