Various types of 4-wheel-drive



I'm new here, and I apologize if this is a subject which has been beaten to death.

I'm a bit puzzled by the various types of 4-wheel-drive and All-wheel-drive systems, and am wondering which is best for plowing.

My limited understanding of this is that most alleged 4-wheel-drive vehicles are really 2-wheel-drive.. one in the back and one in the front. And, further, that the only way to achieve true 4-wheel-drive is to use locking differentials.

Assuming I'm correct so far, the next question would be.. do people use these for plowing? If not, wouldn't it be a great help to have double the traction?

I notice that, for cars, they say that "the best there is" is the Audi Quattro.. which has a Torsen center diff and automatic electric locking of both front and rear diffs. Is there a reason (there must be! :) that trucks don't use a similar arrangement?

What type of drive mechanism seems to be best for plowing? I realize this might start a "mine is better than yours" war, and hope that doesn't happen! But you probably get the drift of what I'm asking.

I want to get a vehicle for plowing, and hope to do this for a little extra income when I retire. Any thoughts or suggestions gratefully accepted.

Bob Trevithick

Alan Addict
Four point drive would be great for pushing, but if you were on any side slope and spun all four you would likely slip down the slope and potentially find yourself stuck in a bank. Posi rear is ok, although a little squirrely under power in 2 WD. If I was going to set up a truck for plowing only I'd probably go with an air locker in the front so I could use both wheels only when I chose to. In all truth, I've never felt at a real loss with open differentials on both ends except for the occasional time when I'm digging myself out of a "pilot error" situation.
Hi Bob - welcome to the Forum.

Don't get too hung up on what the four wheel drive magazines say about open and locking differentials. For snow plowing with a basic pickup, you can get buy with any one of the multitude of systems out there. Full time, part time, Quadra-trac etc all work. What is important is that there be some way to lock the differential in the transfer case to send equal torque to the front and rear axle when you are plowing. Transfer cases that use clutches to transfer power, I believe, are not up to the long term abuse of constantly shifting power fore and aft while plowing. Locking these types (ie. the GM AutoTrac) into 4Hi or 4Lo will give virtually no trouble.

As to the off road magazines' touting lockers etc, they are useful if you are going off road in off-camber situations, but for snow plowing, don't sweat it that you don't have one. In fact, our last truck was ordered specifically without a rear posi with its main job being plowing. It will plow inch for inch with my truck that I bought off the lot with a posi. The posi can lead to you getting stuck or body damage in a side hill situation as the rear end will shoot down hill when spinning.

Hope this helps - we are not usually so long winded here.


Senior Member
Ft. Wayne IN
You can't put a truck's massive amount of torque through a small electric locker like the Audi setup you mentioned.The weight of the truck combined with the power of the engine would shred them.2WD is engine torque routed to the rear axle and split by a device called a differential.Because it is convenient for most automobiles to turn corners,the differential allows for this by permitting the inside wheel to turn at a reduced speed (mathematically actually turn backward)and at the same time the outside wheel in the turn to increase it's speed to compensate.FWD(front wheel drive)is the same only on FWD cars.Part time 4WD simply is a vehicle with front AND rear differentials and a handy little item tucked behind the transmission called a transfer case,which is basically another power splitter or diff.The part time of Part time 4WD is a lever(or switch)allowing the driver to choose between 2 or 4WD.Full time 4WD is no driver choice in the matter.All Wheel Drive,according to your buddies at Audi,is a center differential in place of the transfer case,which is said to cadd a measure of intelligence to your drive train.4WD systems are "dumb" because the left front wheel has no idea what the right rear is up to.In All Wheel Drive systems each wheel knows what the other is doing and can compensate.The downside to AWD is one foregoes durability,and snowplowers HAVE to have dependable equipment.Part time 4WD is the way to go.You can always add traction aiding devices to your diffs later on like limited-slips or a locker,although it's hard to find a locker for a heavy pick-up.A Detroit mabey.


Wow.. I think I just found the Mother Load for information! You folks don't mess around. What a great bunch of replies... I thank you very much!

As strange as it sounds, I understand this now. It explains why, for example, my old car with a posi rear end would always slide the back end sideways at the most inopportune moments. And I'm glad to hear that I don't have to obsess over which drive system to get.

I'm sure I'll have lots of fun reading the posts here.. and may even know what I'm doing when it comes time to select a plow vehicle.

Thanks again!


Western CT
Limited Slips are the way to go over lockers if you have a choice. Most trucks can be ordered with them. They work really well for me and sometimes in lots I don't even use the 4 wheel drive. It all depends on the situation.


Senior Member
Grosse Ile, Mi.

The one thing I have notice about having an open dif. is the ability to stay on the road. Trying the push your whole axel can cause some definite crazyness. I have open diffs on my plow truck and it stays straight. I have noticed that sometimes when there is alittle snow I don't use 4 wheel drive and is saves on fuel alittle and only really affects some steering situations and when I am pushing the snow over a curb I could use the extra traction. Full time 4 wheel drive is not the system to use. I recently drove a new mountaineer into a snow bank. It is all wheel drive and it took a couple of seconds for the thing to turn the wheels with the traction. I can understand why this would not be ideal or efficeint for plowing. I don't like it really.


2000 Club Member
I have the g-80 locker in my GM truck and I love it. So what if the back end swings out from time to time, when I was younger I lived for those moments. With the sander and a yard of material I can most places with out 4x4, I took the 89 the other night with the one legger, and HAD to use 4x4 to plow the drive. SO locking diffs for me.

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