Alright this is a newbie question but I'm not ashamed

I was driving in some light snow the other day in 4Hi and I made a fairly tight right-hand turn (in an area not completely covered with snow) and my jeep bucked a little bit.
I am confused about why my jeep bucked like my axles were locked.

I thought that 4wd just meant that I was getting power to one of my front tires as well as one in the rear.
And that locking my axle meant that I was locking my differential, getting power to all 4 tires, and thus cannot make tight turns because one tire is covering more ground than the other.

Please contribute your 2 cents.

Thanks!

 

A conventional four-wheel drive system is going to work like that - it's not like a Subaru with full-time all-wheel drive that is smooth & seamless to drive. The conventional four-wheel drive system works best when it's got a loose surface to work on, so some slippage is allowed.

Think that was bad? Try it with a locked differential! She'll be bucking and snorting when you try to turn!

Regards, CW

 

you have u-joints at the knuckle,they allow the front wheels to turn.while in 4wd hi or low.you are sending power to the front axle.the shaft is locked.making your jeep 2wd.one front wheel getting power and one rear wheel getting power.on dry pavement and packed dirt.the wheel with traction will bind the u-joint just enough on tight turns to cause the vehicle to jurk around.this is normal on tight turns.that is why you are not supposed to use 4wd on dry roads.
the word 4 wheel drive is not a good word in my opinion.with open diff's.which most stock jeeps are,you have 1 wheel in the front and 1 wheel in the rear getting power.unless you have a locking diff. front and rear,which gives the power coming from the T-Case to both wheels on the axle front and rear.and with a fully locked front axle you can not make tight turns very well with out some kind of breakage.because the outer wheel needs to spin more than the inside wheel.

i hope this helps your newbie question.

 

Jeeps don't have a centre diff so this makes tight turns in 4wd on solid surfaces more binding also.

 

Where does this idea come from that only one wheel gets power on an open differential?
Both wheels always get equal power. Lots of cars with open differentials can leave 2 strips of rubber.

The reason the JK bucked around the turn as if the axles were locked is they were indeed locked together at the t-case.
The differentials still do their jobs between wheels on each axle, but each drive shaft wants to turn at its own speed. They can't when locked together.
In a turn, all four wheels want to turn at different speeds. With good traction, it's very difficult for them to do that. The tires slip and stick on the pavement.
The front u-joints make it worse because in a turn, each joint speeds up and slows down twice in each revolution.

 

An Open Differential, by definition, sends power down the path of least resistance. While yes, both wheels will get power, the least bound one will get most of the available power. Hence the need for Limited Slips/Lockers. The T-Case locking the driveshafts together only ensures equal power will go to the front and back. Where it goes from there is another question.

The reason your Jeep was bucking, was because while you are in a turn, all your wheels are traveling a different line, and traveling a different distance. This puts strain on your T-Case, and that bucking was the result of all that stress trying to "get out" of there. The effect magnifies ALOT with lockers.

 

That's a common misconception. Visually it appears to be correct, but that's not what is really going on.
The torque from the drive shaft is always distributed equally between the two wheels in an open differential.
If you are referring to definitions, it applies to the mechanism's ability to allow the two wheels to rotate at different(ial) speeds.

On dry pavement, both wheels propel the vehicle forward with equal torque.
Let's say one tire is on ice, and the other is on dry pavement.
If it takes only 20 ft/lbs to make the one on ice spin, the one on pavement will also get the same amount of torque: 20 ft/lbs.
However, 20 ft/lbs on the tire with traction may not be enough to move the vehicle.
That's why applying the brake to the spinning wheel helps. Applying the brake will increase the torque it takes to make the tire spin, so the other tire gets more torque, too. Apply enough brake to the spinning wheel, and the one with traction will get enough equal torque to move the vehicle.
Bottom line: in an open differential, the torque from the drive shaft is always divided equally between the two axle shafts.

 

No stupid questions. No body in here came out of the womb knowing this stuff. That's that value of these forums. Ask on brother!!!

 

Correct, but you misunderstood me. Torque is equally applied, but power is not. Which is why with an open diff, the sum of the speed of the tires, has to remain the same. For example, if one tire slows down 1mph, the other must speed up by 1. When one wheel is stopped.. The other is capable of spinning at the twice the speed that would normally be possible at a constant engine speed. The same torque is still at each wheel, but the excess power is bled off on the traction-less wheel in the form of more, and more speed.

 

To sum up both our statements:

Power is a measuer of work done.
Torque will always be split equally in an open differential.
The limited power being made goes out the spinning wheel. (There is no work being done at the other wheel.)