I know how to lock my hubs in and move the lever to activate the differential inside. I’m not sure when I should do this and how bad it will be for the vehicle if I screw something up.
An example: I’ve locked the hubs and differential and driven on snow, now I get to wet pavement that could turn into slush occasionally. Do I leave it in 4 wheel drive? do I leave the hubs locked in but inactivate the differential?
Is it bad to drive on wet but not really slick pavement for 20 miles with 4 wheel drive activated?
This happens every day we get snow. THe back streets are slick so I need the 4wd system, but within a couple of miles I’m on major roads that may be wet, or may be dry, or may be spotty with some wet/slick spots.
I would like to either drive with just the hubs locked in or also with the differential powered up, but I don’t want to damage the system. What is best?
You can leave the hubs locked in with out any problem. Just a very little extra wear on the bearings because the axle with be turning. This is just normal wear and tear though and won’t cause any undu stress.
It really depends on how much turning you do. The more turns the worse. If it’s pretty much a straight shot, I wouldn’t really worry about it. Of course, you could just pop it out of 4x and leave the hubs locked in.
I go in and out of 4x4 every day for about 6 months out of the year. I just leave the hubs locked in. If you have a couple of snowy days where you go from good conditions to bad, just leave um locked in.
If I remember my car geekery correctly, the differential is there to stop stresses building up due to the wheels covering different distances as you drive along - i.e. the outside wheels travel farther than the inside wheels when you go round a curve. Unless they can move relative to each other or relieve the stress by slipping against the road surface, you get ‘wind-up’ stress developing which can cause damage. So basically, you should really unlock the differential unless you are driving on a straight road OR it’s a slippery surface and the vehicle is light enough to let the wheels ‘scuff’ and unload the stress. However the car won’t fall apart if you drive it a few miles with the diff locked, especially on a wet road while lightly loaded - just don’t make a habit of it.
Hubs are neither here nor there - they originally came about as a way of improving the fuel economy of 4x4s. Even in two-wheel drive mode, the wheels had to rotate all the ironmongery in the non-powered section of the drivetrain, which increased the rolling resistance. Putting in free-wheeling hubs meant the wheels could spin on their own without the front diff etc. So leaving the hubs locked might cost you a mile per gallon or so.
I think we have our terminology a little mixed up. I seriously doubt Sigene is talking about the differential between the wheels, rather locking the transfer case. So, leaving the transfer case unlocked (not in 4x) and the hubs locked would be the easiest way to go with changing driving conditions. When the road gets slick, just lock in the trasfer case and you don’t have to get out and lock in the hubs.
If the roads are clear for a while, unlock the hubs. It all depends on how often you want to get in and out and lock/unlock the hubs.
D’oh! Just to be clear, this only refers to 2-wheel drive.
4x4 mode uses more fuel anyway, and it would be pretty daft to leave the hubs unlocked in 4x4.
Unless you have full-time four wheel drive I would come out of 4-wheel on wet pavement. The question isn’t about turning it’s about tire size. Tires are never exactly the same size and so the number of front wheel rotations will be different from the number of rear wheel rotations for the same linear distance traveled. The differences between the two tires on the front and likewise on the rear is handled by the differentials on those axles. However there isn’t a differential between the front and rear axles and they will bind up quite quickly unless the road surface allows some slip between them.
Basically, if the road/surface is loose enough to allow the tires/wheels to spin a little, this means it is okay to use 4wd. When in 4wd and the tires don’t slip to grip, then you are increasing the rate at which you are wearing down drivetrain parts (I’m thinking differentials).
I don’t use 4wd on wet roads, because I can feel that the tires aren’t slipping enough on turns, and the tricky turning is more dangerous than using 2wd while driving responsibly. Emergency manuevers are almost impossible.
Use 4wd when you need it! This answers all the questions. Can’t get your truck up an icey hill = 4wd. Can’t get down granma’s dirt and gravel driveway = 4wd. Can’t get out of your street after 7" of snow = 4wd/
In the rain, 4wd has almost no value. It hinders turning and lane changes (and evasive maneuvers). Rain covered roads are not ‘loose’.
Use it when you need to. Besides wearing out parts, 4wd makes the vehicle less manueverable.
I always used 4-wheel drive to get out of difficulty. I went as far as I could in 2-wheel and then when I got into a problem I used 4-wheel to get out of it and go back to easier ground. If you go a little past where you can in 4-wheel drive it will cost a fortune to have someone come and get you out.
Of course I’m a coward.
Turning, tire-size? It’s a quibble. Never use 4-wheel drive on a surface that isn’t loose enough to allow slightly different speeds between front and rear wheels.
This deserves to be re-emphasized. Locked differential 4WD makes a vehicle less manuverable. Those folks that think that their 4WD SUV is going to be good on ice and slick pavement are not only buying a vehicle that has inherently worse stability, weight distribution, and control than a sedan, but are also (when engaging the 4WD system) degrading their traction performance. Exceptions to this include the Series 80 and newer Toyota Land Cruisers, the Land Rover Discovery and other newer models, and many of the crossover/hybrid SUVs that use a permenant four-wheel/all-wheel drive system.
All-wheel drive, like the Audi Quattro systems, the Subaru Symmetric All-Wheel Drive system, and others, are the only “four wheel drive” systems that provide a measurable advantage on slick pavement and are safe to drive at highway speeds.
On a locking-hub or “on-the-fly” 4WD system, only engage it when you need it, as Philster says; when you are dug into snow or mud, or are on loose gravel/sand, or are otherwise off-road.
I took my 4wd truck on a gravel road in the middle of the night to play around with it a little, to get the feel of what 2wd, 4HI, and 4LO were like. I figured the gravel would be loose enough that I shouldn’t cause any damage.
And you are right. I drove on a newly graveled road in Iowa a few years ago and it sort of felt like driving on ball bearings if I got to going too fast. I.e. over about 45-50 mph.
Good point. Stick a 4x and you’re going to need a bigger one to get you out. Yesterday, my Wife stuck her Grand Jeep (with brand new tires) in our driveway. I got her out with my plow truck that is chained on all 4 wheels.