242 Transfer Case Modes
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242 Transfer Case Modes
I have read different things about this online, and I'm still confused. What is the difference between part time and full time on a 242? I know you can drive a 242 in 4WD full time all the time, unlike the 231. If you don't have a rear driveshaft installed and you put it in full time you won't move, and could damage something, but I don't know why.
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Part time with a 242 is the same as part time with a 231. Slick conditions only. Deep snow, for example. Do not use it on dry pavement. Full time with a 242 is just that. You can use it all year round no matter what. As for driving around without the rear driveshaft in full time, i do not know. Never tried.
Last edited by fb97xj1; 01-08-2017 at 12:03 AM.
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That didn't answer my question. I know what the different modes are used for, I want to know how they are different in operation. What does full time do that part time doesn't to allow use full time on the road? I know that you can't drive in full time without a rear driveshaft, because I tried before I installed the new transfer case output shaft and shims.
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To answer your question simply put the part time case mechanically connects the front and rear axles with no slippage between the two, as for the full time case there is a set of clutches connecting the front and rear axles allowing for slippage needed between the two needed to run down dry pavement. If you pull rear driveshaft on a full time case it will burn up those clutches causing damage. Think of a full time case a a limited slip differential they are very similar in how they work.
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To answer your question simply put the part time case mechanically connects the front and rear axles with no slippage between the two, as for the full time case there is a set of clutches connecting the front and rear axles allowing for slippage needed between the two needed to run down dry pavement. If you pull rear driveshaft on a full time case it will burn up those clutches causing damage. Think of a full time case a a limited slip differential they are very similar in how they work.
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To answer your question simply put the part time case mechanically connects the front and rear axles with no slippage between the two, as for the full time case there is a set of clutches connecting the front and rear axles allowing for slippage needed between the two needed to run down dry pavement. If you pull rear driveshaft on a full time case it will burn up those clutches causing damage. Think of a full time case a a limited slip differential they are very similar in how they work.
The NP242 dont have any clutches.. it has a set of planetary gears that act like an open diff when set to fulltime..
NP242 planetary gears
When in part Time the front and rear axle are locked together 50% front 50% rear.
In full time the np242 engages the planetary gears and splits the torque 48% front, 52% rear.. The planetary gears kinda act like an open diff in the T-case..
Last edited by Dumajones; 01-09-2017 at 05:15 PM.
#7
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I would expect that functionality-wise since full-time 4WD is an open diff, if one tire loses traction the Jeep will sit there and spin that one tire. AMC Eagles used a similar setup in 1986 only with as I recall the NP128 transfer case. (Other years used a viscous coupling.) I had an '86 Eagle years ago and found that as a practical matter that kind of slippage rarely happened. With the 242 you of course would be able to switch into part-time 4WD, which the Eagle lacked.
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The way i understand and i could be wrong, if you don't have a rear drive shaft installed, the entire 4W full time system acts as an open diff. between the front and rear axles. All the torque goes to the least resistance, in this case the rear Tcase output (minus the rear diff. of course).
Similar as with an open rear diff., all the torque goes to the spinning wheel.
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I would expect that functionality-wise since full-time 4WD is an open diff, if one tire loses traction the Jeep will sit there and spin that one tire. AMC Eagles used a similar setup in 1986 only with as I recall the NP128 transfer case. (Other years used a viscous coupling.) I had an '86 Eagle years ago and found that as a practical matter that kind of slippage rarely happened. With the 242 you of course would be able to switch into part-time 4WD, which the Eagle lacked.
Agreed.
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Why would you not have a rear drive shaft?
The way i understand and i could be wrong, if you don't have a rear drive shaft installed, the entire 4W full time system acts as an open diff. between the front and rear axles. All the torque goes to the least resistance, in this case the rear Tcase output (minus the rear diff. of course).
Similar as with an open rear diff., all the torque goes to the spinning wheel.
The way i understand and i could be wrong, if you don't have a rear drive shaft installed, the entire 4W full time system acts as an open diff. between the front and rear axles. All the torque goes to the least resistance, in this case the rear Tcase output (minus the rear diff. of course).
Similar as with an open rear diff., all the torque goes to the spinning wheel.
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The NP242 dont have any clutches.. it has a set of planetary gears that act like an open diff when set to fulltime..
NP242 planetary gears
When in part Time the front and rear axle are locked together 50% front 50% rear.
In full time the np242 engages the planetary gears and splits the torque 48% front, 52% rear.. The planetary gears kinda act like an open diff in the T-case..which allows the axles to go different speeds around corners without binding up and bucking.
NP242 planetary gears
When in part Time the front and rear axle are locked together 50% front 50% rear.
In full time the np242 engages the planetary gears and splits the torque 48% front, 52% rear.. The planetary gears kinda act like an open diff in the T-case..which allows the axles to go different speeds around corners without binding up and bucking.
Last edited by chilipepper; 01-09-2017 at 05:02 AM.
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and why are the numbers so important? just put in your head the power is split at the transfer case 50-50 and stop thinking about it.
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transfer case output shaft speeds are the same in Parttime. In Fulltime, there is a differential in the case to allow the output speeds to vary as needed.
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By the way, what happened to the little clickable dropdown in each person's avatar showing the year, engine, trans, etc. of their XJ? That was very handy, but I've not seen it for a few weeks.
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Last edited by IJM; 01-09-2017 at 11:53 AM.