4 wheel drive steering

ok so the title may be mis leading but i have a question. i was told by the mechanic who looked at my jeep when i thought my steering was bad. that you can't have it in 4 wheel drive and make any form of sharp turns or else it will give feed back. if you go to your jeep and put it in 4 hi and turn sharply you should see what im talking about. what causes this and what can be done to stop it.

uhm take it out of 4 wheel drive since it shouldn't be on while on the street.

unless yo uhave a 242 case with "Full Time" 4 wheel drive.

Ill second what Wil says. Its not good to drive in 4 hi or low on dry pavement. Im surprised your mechanic doesn't know any better.

Gnat5680 said:

ok so the title may be mis leading but i have a question. i was told by the mechanic who looked at my jeep when i thought my steering was bad. that you can't have it in 4 wheel drive and make any form of sharp turns or else it will give feed back. if you go to your jeep and put it in 4 hi and turn sharply you should see what im talking about. what causes this and what can be done to stop it.

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It's called "Driveline bind".

When you make a sharp turn, the outer tires turn in a different radius than the inner tires. This is normally overcome by the differential when in 2WD, but in 4WD you have 2 axles driving, and two differntials. They fight each other because the turning radius of the front axle is not the same as the rear axle and the front and rear drive shaft want to turn at different speeds. A full time 4WD system has an additional differential or coupler in the transfer case which allows this speed difference to happen, a part time system does not and if you operate a part time 4WD system on drive pavement, at best, you get driveline bind, at worse, you break stuff.

How do you stop it? Don't use 4WD on dry pavement.

I don't even use it in the rain. Snow, or Off-Road use only. Using part time 4WD on ice is also a bad idea. Because the wheels are all essentually coupled together, if one brake locks up on ice, they all do. Locked up front wheels = no steering.

Gnat5680 said:

ok so the title may be mis leading but i have a question. i was told by the mechanic who looked at my jeep when i thought my steering was bad. that you can't have it in 4 wheel drive and make any form of sharp turns or else it will give feed back. if you go to your jeep and put it in 4 hi and turn sharply you should see what im talking about. what causes this and what can be done to stop it.

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your mechanic is either not the sharpest tool in the shed, or trying to screw you royally,

they all do it, that why 4 wheel is reserved for the dirt and not the pavement

Zuki-Ron said:

Using part time 4WD on ice is also a bad idea. Because the wheels are all essentually coupled together, if one brake locks up on ice, they all do. Locked up front wheels = no steering.

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As a fellow who lives in Ice Country, I'd disagree. With ice, the trick is to put it 4x4 and touch your brakes as little as possible and then with a light touch. Fact of the matter is that in ice, you don't have much in the way of brakes anyway. At least in 4x4 you can have the driven wheels keep the vehicle pointed in the right direction and not have your ass end pass you by (more pronounced on pick ups).

Ain't nothin' like driving on 2" thick ice that you can't even walk on.

There is more going on than the front/rear difference in speed.
The crazy feedback you get is from the front u-joints. The front differential can handle the difference in speed. In a turn, each u-joint varies in velocity, and does so out of phase --> the average speed at the pinion varies. If this is tied directly to the driveline then the forces will steer the tires wildly to compensate for this change in velocity. If you have ever removed the rear driveshaft and driven in front wheel drive with front u-joints you've experienced it.

edit: why are you guys bashing the mechanic? I admit that the first post has terrible grammar, but I read it to say that the mechanic diagnosed the steering problem as an inherent feature of 4wd.

ok sorry my fault. i made the mech. sound like he does not know anything.

he said not to use it on dry pavement.

i ment off road. i was driving in a wet grass field and put it in 4 wheel. i was a little short on the details.

Nevada City Sparky said:

As a fellow who lives in Ice Country, I'd disagree. With ice, the trick is to put it 4x4 and touch your brakes as little as possible and then with a light touch. Fact of the matter is that in ice, you don't have much in the way of brakes anyway. At least in 4x4 you can have the driven wheels keep the vehicle pointed in the right direction and not have your ass end pass you by (more pronounced on pick ups).

Ain't nothin' like driving on 2" thick ice that you can't even walk on.

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I would concur. Of course if you lock up all your wheels, you'll go out of control, but that can happen with or without 4WD. Part time 4WD tends to equalize the braking a little, and because of that it tends to resist locking one side or one end when traction conditions are uneven, as they often are. What can be a problem if you overdo it (lock all 4 wheels and crash) is a virtue if you don't. I often use part time in poor conditions even when I don't need it to keep up forward motion, precisely because of its effect on braking.

Gnat5680 said:

i ment off road. i was driving in a wet grass field and put it in 4 wheel. i was a little short on the details.

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If you have almost any traction at all you will feel some feedback through the steering wheel when you turn sharply in 4WD. There is nothing you can do about this. Obviously, in the case above, even though you were on wet grass, you had enough traction to create some driveline bind. You have only three choices:
1) Take it out of 4WD before you turn sharply.
2) Don't turn so sharply.
3) Learn to live with it.

I choose number 3, because unless the bind is really severe (in which case you shouldn't be in 4WD at all) it is not going to do any damage.