IJM

Que?

chilipepper

That doesn't make any sense. You said the driveshafts are locked at the transfer case in part time, and then contradicted yourself when you said in part time they won't turn at the same speed. I'm confused, sorry for all the questions but I really want to understand this and nobody has been able to explain it to me.

chilipepper

I don't understand what the full time option does that open differentials don't do on the road, basically.

chilipepper

I think I get it, correct me if I'm wrong.

When you turn, the open differentials send the power to the axles with the least resistance. In part time, the driveshafts are mechanically locked together, so the power will be split 50/50 to the left front and left rear if you are turning right. The only problem is the front has a wider arc than the rear when turning right, so the transfer case in full time acts like an open differential and sends the power to the left front of the vehicle.

CCKen

1999 NP/NV 242J differential internals:



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cruiser54

It has NOTHING to do with axles and EVERYTHING to do with the transfer case.

You are getting excellent explanations. If not, I woulda piped in earlier.

chilipepper

Did you even read what I posted last? Explain to me how I'm wrong if I am but don't just say I'm wrong.

Look at my last post with the colorful picture of the car turning, and try to understand what I was saying.

Also if it has NOTHING to do with the axles, why did Dumajones and moparado bring up axles?

Cane

you clearly just don't understand the whole concept and this causes misunderstandings. i'm not saying this like it's a bad thing, but you're too much on the defensive here, people are trying to explain to you how it works and the way you reply makes it sound like you're doubting what we say. this doesn't really make people wanna help. "explain to me how i'm wrong" no, he has nothing to explain to you..

you're confused between 2 concepts here, a differential and a transfer case. i simply suggest you go watch some youtube videos about the whole thing and then try to understand again, because there's nothing more to explain here.



http://rubicon-trail.com/4WD101/difference_4WD_awd.html

chilipepper

I don't think anybody is understanding what I'm trying to say. The transfer case transfers power to the front and rear axles, you have open differentials so you can turn on pavement. WHY do you need full time if you have open differentials? The only thing I can come up with is the relationship between the front and rear axles needs something like an open differential when turning and that's where full time comes in. It's similar to an open differential because it's acting like one between the front and rear outside axles when turning. Is that correct or incorrect? If it's incorrect, how is it incorrect? Nobody can explain this to me, which makes me think nobody knows their self. I'm not stupid, I'm 18 and I helped install the new transfer case output shaft, and everything else on my Jeep. Please LOOK at the last picture I posted on the 2nd page and try to understand what I'm saying and HELP me understand like you're supposed to do on a forum instead of just saying I'm wrong.

dans98xj

If the front and rear drive shafts are locked together via the transfer case, then they essentially one piece of a rotating assembly. when you go around a turn with a front and rear drive shaft locked together the two drive shafts have to rotate at different speeds because the shafts are is two different parts of the turn making the tires chirp. If the transfer case has full time option this engages a differential causing the front and rear drive shafts to rotate at different loads there fore able to rotate at different speeds when turning.

If you drive around in a brand new Subaru STI with the Driver controlled center differential in the locked setting you have essentially created a locked transfer case like when you put your jeep in 4 hi and drive around. If you were to continue driving like that some thing would fail. This why there is the Full Time option in the 242 so you have the availability of 4wd without having to be in 4 hi.

chilipepper

Oh my god. RE READ what I said, that is exactly what I SAID. The only difference is the differentials take care of the wheels horizontally and the T case takes care of the binding caused by the different arcs on the outside front and rear VERTICALLY. Correct or incorrect?

dans98xj

if you were to remove one of the front axle shafts then you could drive around all day in 4 hi and not have a problem. This was the problem with the old Cherokees and Wranglers that had the 2 piece front axle shaft. If the vacuum was not locking the two pieces of the shaft together you would not be in 4wd. The axle with the least resistance in the front would be the uncoupled one that would be the one getting the power. Once all 4 wheels are on the ground and being pushed by the transmission though a locked transfer case and going around a turn every single one of those components has to operate at a different speed. You are incorrect in your thinking of how a transfer case works. You are looking at it from an AWD transfer case like to 249 with a viscous coupling that will change the power from the front and rear wheels wile also allowing it to slip wile in a turn. The center differential in a 242 does not operate in that way. Like an opened differential in an axle the drive shaft with the least resistance will get the power.

CCKen

That first Youtube video does a good job of describing how torque is transferred to the front and rear axle differentials. It is, however, a description of the 231 transfer case, not the 242 transfer case. The difference is that the 242 has a differential assembly incorporated that, when full time is selected, it allows the front and rear axles to turn at different speeds (see my pics of the differential internals). When the transfer case is selected to a four wheel drive mode other than full time it acts like a 231 transfer case where the front and rear axles are driven at the same speed.


The front and rear axle differentials do their jobs regardless of the transfer case selections.

chilipepper

It does change power from the front and rear wheels, not sure what you're talking about there, you contradicted yourself in that last part by the way.

chilipepper

This is what I've been saying all along. When you turn, the differential allows the outside wheel to travel faster because it has to go a farther distance than the inside wheel.

OK, but what about the relationship between front and rear, you need something to stop binding there right? When you turn to the right your left front and left rear wheels will cause the driveshafts to bind up, this is where full time allows them to slip.

Am I making myself clear now? I don't know how many times I've said this. If you go back and look at the last picture I posted, it's a very colorful picture, you might understand what I've been trying to tell you all now.