242 Transfer Case Modes
01-10-2017, 10:24 AM
#31
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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.
No, the transfer case differential has nothing to do with the functions of the axle differentials.
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.
Regroup and get a grip on what the function of the axle differentials do compared to what the 242 transfer case differential does in full time.
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.
No, the transfer case differential has nothing to do with the functions of the axle differentials.
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.
Regroup and get a grip on what the function of the axle differentials do compared to what the 242 transfer case differential does in full time.
Move along folks nothing else to see here.
01-10-2017, 10:34 AM
#34
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Why do you need full time to drive on the road when you have open differentials so nothing will bind up? SIMPLE QUESTION. CAN ANYBODY ANSWER IT?
Last edited by chilipepper; 01-10-2017 at 11:09 AM.
01-10-2017, 10:44 AM
#35
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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.
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?
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.
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.
Now, as you correctly pointed out, there's also the fact that in a turn, the rear wheels follow a shorter path than the front wheels, as you can see from the diagram you posted. What this means is that the front driveshaft rotates faster than the rear driveshaft in a turn, regardless of the fact that you have open differentials on each axle, so you'd need some sort of ability to allow this to happen in the transfer case, as part-time 4WD locks both driveshafts together for maximum off-road traction. The 242 has a system that allows power to be applied to both driveshafts while also allowing them to turn at different speeds. It also can lock them together like the 231. Remember, even with open diffs on each axle, the average speed of the front wheels (bigger arc) as greater than the rears (smaller arc), hence, the different speeds of each driveshaft.
Part of the confusion comes from terminology. For example, in a proper 4WD vehicle like our XJs, the front and rear driveshafts are driven by a transfer case. In an AWD vehicle, as are very common today, there's a center differential instead of a transfer case. However, the mechanics of the center diff are not the same as the traditional front and rear diffs on each axle. Perhaps that terminology was causing some additional confusion.
Finally, the terms "part-time" and "full-time" are confusing in that they refer to how 4WD should be used, not what happening mechanically. Full-time 4WD can be used all the time since the transfer case can handle the front and rear axles turning at different speeds in that mode by using a system of planetary gears as posted above. Part-time 4WD can only be used during certain conditions (slippery/loose surfaces) since the driveshafts are locked together and can't turn at different speeds. Hence the "part-time" use designation. The wheels just slide on the loose-slippery surfaces to handle the difference in ground speed versus fixed wheel speed.
Make sense?
Last edited by IJM; 01-10-2017 at 10:52 AM.
01-10-2017, 10:50 AM
#36
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Yes, that's correct, though your terminology isn't technically correct. See more below on that.
Correct.
I think the confusion by several posters in this thread is coming from the fact that in a turn, all 4 wheels (assuming there's no slippage) are turning at different speeds. One the same axle, the differential (either front or rear, same principle at work) allows the outside wheels to turn faster than the inside wheels. This concept is pretty simple and easily understood.
Now, as you correctly pointed out, there's also the fact that in a turn, the rear wheels follow a shorter path than the front wheels, as you can see from the diagram you posted. What this means is that the front driveshaft rotates faster than the rear driveshaft in a turn, so you'd need some sort of ability to allow this to happen in the transfer case, as part-time 4WD locks both driveshafts together for maximum off-road traction. The 242 has a system that allows power to be applied to both driveshafts while also allowing them to turn at different speeds. It also can lock them together like the 231.
Part of the confusion comes from terminology. For example, in a proper 4WD vehicle like our XJ, the front and rear driveshafts are driven by a transfer case. In an AWD vehicle, as are very common today, there's a center differential instead of a transfer case. However, the mechanics of the center diff are not the same as the traditional front and rear diffs on each axle. Perhaps that terminology was causing some additional confusion.
Finally, the terms "part-time" and "full-time" are confusing in that the refer to how 4WD should be used, not what happening mechanically. Full-time 4WD can be used all the time since the transfer case can handle the front and rear axles turning at different speeds. Part-time 4WD can only be used during certain conditions (slippery surfaces) since the driveshafts are locked together and can't turn at different speeds. Hence the "part-time" use designation. The wheels just slide on the loose-slippery surfaces to handle the difference in ground speed versus fixed wheel speed.
Make sense?
Correct.
I think the confusion by several posters in this thread is coming from the fact that in a turn, all 4 wheels (assuming there's no slippage) are turning at different speeds. One the same axle, the differential (either front or rear, same principle at work) allows the outside wheels to turn faster than the inside wheels. This concept is pretty simple and easily understood.
Now, as you correctly pointed out, there's also the fact that in a turn, the rear wheels follow a shorter path than the front wheels, as you can see from the diagram you posted. What this means is that the front driveshaft rotates faster than the rear driveshaft in a turn, so you'd need some sort of ability to allow this to happen in the transfer case, as part-time 4WD locks both driveshafts together for maximum off-road traction. The 242 has a system that allows power to be applied to both driveshafts while also allowing them to turn at different speeds. It also can lock them together like the 231.
Part of the confusion comes from terminology. For example, in a proper 4WD vehicle like our XJ, the front and rear driveshafts are driven by a transfer case. In an AWD vehicle, as are very common today, there's a center differential instead of a transfer case. However, the mechanics of the center diff are not the same as the traditional front and rear diffs on each axle. Perhaps that terminology was causing some additional confusion.
Finally, the terms "part-time" and "full-time" are confusing in that the refer to how 4WD should be used, not what happening mechanically. Full-time 4WD can be used all the time since the transfer case can handle the front and rear axles turning at different speeds. Part-time 4WD can only be used during certain conditions (slippery surfaces) since the driveshafts are locked together and can't turn at different speeds. Hence the "part-time" use designation. The wheels just slide on the loose-slippery surfaces to handle the difference in ground speed versus fixed wheel speed.
Make sense?
https://en.wikipedia.org/wiki/Transfer_case
Look under the functions section on that link for some more reasons for full time.
Last edited by chilipepper; 01-10-2017 at 10:54 AM.
01-10-2017, 10:54 AM
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Thank you, that's what I've been trying to say the whole time. I started reading a bunch of different articles and came up with some more reasons for full time also, because every body else kept saying I was wrong.
https://en.wikipedia.org/wiki/Transfer_case
Look under the functions section on that link.
https://en.wikipedia.org/wiki/Transfer_case
Look under the functions section on that link.
01-10-2017, 11:00 AM
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Ok, I was confused at first as well. So Ill break this down as best I can.
Your front differential allows your front wheels to turn at different speeds from each other. This prevents binding in the front axle when turning.
Your rear differential allows your rear wheels to turn at different speeds from each other. This prevents binding of the rear axle.
Your transfer case when in 4HI FULL TIME allows your front and rear drive shafts to turn at different speeds from each other. This prevents binding of the drive shafts.
Your transfer case when in 4HI locks your drive shafts together with no reduction.
Your transfer case when in 4LO locks your drive shafts together with a gear reduction for more torque.
Its simple. Hope that helps. Though its the same as has been said
Your front differential allows your front wheels to turn at different speeds from each other. This prevents binding in the front axle when turning.
Your rear differential allows your rear wheels to turn at different speeds from each other. This prevents binding of the rear axle.
Your transfer case when in 4HI FULL TIME allows your front and rear drive shafts to turn at different speeds from each other. This prevents binding of the drive shafts.
Your transfer case when in 4HI locks your drive shafts together with no reduction.
Your transfer case when in 4LO locks your drive shafts together with a gear reduction for more torque.
Its simple. Hope that helps. Though its the same as has been said
01-10-2017, 11:03 AM
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While we're on the subject of transfer cases, I should point out that you should never shift out of park if your transfer case is in neutral unless you know what you're doing. I almost learned this the hard way the other day. Here is a good link that everybody should read, it could save you some trouble.
http://www.wranglerforum.com/f274/da...ral-59443.html
http://www.wranglerforum.com/f274/da...ral-59443.html
01-10-2017, 11:20 AM
#40
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Ok, I was confused at first as well. So Ill break this down as best I can.
Your front differential allows your front wheels to turn at different speeds from each other. This prevents binding in the front axle when turning.
Your rear differential allows your rear wheels to turn at different speeds from each other. This prevents binding of the rear axle.
Your transfer case when in 4HI FULL TIME (NP242 only) allows your front and rear drive shafts to turn at different speeds from each other. This prevents binding of the drive shafts.
Your transfer case when in 4HI (NP231) or 4HI PART TIME (NP242) locks your drive shafts together with no reduction.
Your transfer case when in 4LO (both NP231 and NP242) locks your drive shafts together with a gear reduction for more torque.
Your transfer case when in 2HI (both NP231 and NP242) completely disconnects the front driveshaft.
Its simple. Hope that helps. Though its the same as has been said
Your front differential allows your front wheels to turn at different speeds from each other. This prevents binding in the front axle when turning.
Your rear differential allows your rear wheels to turn at different speeds from each other. This prevents binding of the rear axle.
Your transfer case when in 4HI FULL TIME (NP242 only) allows your front and rear drive shafts to turn at different speeds from each other. This prevents binding of the drive shafts.
Your transfer case when in 4HI (NP231) or 4HI PART TIME (NP242) locks your drive shafts together with no reduction.
Your transfer case when in 4LO (both NP231 and NP242) locks your drive shafts together with a gear reduction for more torque.
Your transfer case when in 2HI (both NP231 and NP242) completely disconnects the front driveshaft.
Its simple. Hope that helps. Though its the same as has been said
01-10-2017, 11:32 AM
#41
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What real value does the full time option have if all the power goes to the wheels with the least resistance? If one wheel slips, all the power goes to it and you're stuck.
01-10-2017, 11:32 AM
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01-10-2017, 11:39 AM
#43
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My XJ has the 231, but my understanding it that it's intended for on-road use, particularly in conditions where you have varying levels of grip (rain, spotty snow cover, icy spots, etc.) where you might have too much grip at times to keep the tires from slipping a little to compensate for the locked driveshafts. Personally, I have never had an issue with driving mine in those conditions, but I have a rear auto-locker, so I can get more grip in 2HI.
01-10-2017, 11:44 AM
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My XJ has the 231, but my understanding it that it's intended for on-road use, particularly in conditions where you have varying levels of grip (rain, spotty snow cover, icy spots, etc.) where you might have too much grip at times to keep the tires from slipping a little to compensate for the locked driveshafts. Personally, I have never had an issue with driving mine in those conditions, but I have a rear auto-locker, so I can get more grip in 2HI.
01-10-2017, 04:06 PM
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