All Wheel Drive = Full Time 4WD?

[LibertyFever]

Okay I know this is kind of a a nubie question but I've been thinking about this for a while now.

The NV242 transfer case offers the selection of 4WD Full Time and 4WD Part Time. I imagine the 4WD Lo is Part Time. It my understanding that the NV242 transfer case has some type of clutch mechanism to allow some slippage when the wheels begin slipping.

My question is this, can the 4WD Full Time be considered AWD? Also when do you NV242 owners use your 4WD Full Time?

 

[kjpilot]

There are many variants of AWD, & Full-time 4wd is one of them. When to use it? Any time you want. I usually use it throughout the winter time when patches of ice are on the street. If it's a heavy snow & the roads are covered then I go part-time high.

 

[HoosierJeeper]

I'm pretty sure that NV242 is Selec Trac. 4wd part time is equivalent to your 4hi. For full- time 4wd, it has a center diff. I usually don't consider it all wheel drive, because it doessn't redistribute torque. In Florida, we only use full time in hurricanes and heavy rains in the summer. In the winter, there is not a use for itsad2.gif. 4lo is not the usual part time mode, but is locked, and torque is sent through another set of gears. Hope I clarified for you.

 

[bugnout]

I use Full Time 4wd pretty much from November until the snow melts. It makes the KJ much more stable with a little pulling from the front. I think its one of the best features of my KJ.

THe difference between part time and full time is that full time mode has differential action between the front and rear drive shafts. part time 4wd drives the shafts at a predetermined constant rate (I think its something like 53% rear-47% front. but don't hold me to that)

 

[Marlon_JB2]

I use Full Time 4wd pretty much from November until the snow melts. It makes the KJ much more stable with a little pulling from the front. I think its one of the best features of my KJ.

THe difference between part time and full time is that full time mode has differential action between the front and rear drive shafts. part time 4wd drives the shafts at a predetermined constant rate (I think its something like 53% rear-47% front. but don't hold me to that)

Part Time: 50% Front, 50% Rear
Full Time: 48% Front, 52% Rear

 

[tjkj2002]

Full time = front/rear driveshafts can turn at different speeds,torque is sent to the path of least resistance just like a open diff.

Part time = front/rear driveshafts locked together and turn at the same speed causing major binding on dry/hard surfaces(including wet pavement),50/50 split in torque.

Low range = same as part time but you get the added gear reduction of 2.72:1,still 50/50 torque split.

 

[blue_kjR417]

Well AWD is literally all 4 wheels pulling at once correct? And Full Time 4WD is one wheel on each axle pulling not all 4 unless it slips then if you have a locker in the back, the back two pull but still just one in the front unless you have a front locker too right? So Full time is kinda circumstantial to all 4 pulling constantly while AWD is all 4 pulling at once now matter what.

 

[tjkj2002]

Well AWD is literally all 4 wheels pulling at once correct? And Full Time 4WD is one wheel on each axle pulling not all 4 unless it slips then if you have a locker in the back, the back two pull but still just one in the front unless you have a front locker too right? So Full time is kinda circumstantial to all 4 pulling constantly while AWD is all 4 pulling at once now matter what.

Nope.

AWD is a full time 4wd vehicle that has no low range or option of putting in 2wd only.Subaru's use a active AWD system that sends power where it is needed.Ford Escapes/Honda CRV AWD systems(also called automatic 4wd) are basically a FWD system and when wheel slip is detected(via ABS sensors) it sends power to the rear axle.There are many versions of a AWD system and the KJ does not have any of them.

In the KJ when in fulltime 4wd you are sending torque to the F/R axles at a variable ratio depending on if your turning or not.You are not powering all 4 wheels unless you have a locker F/R.To have "true" 4wd you need to be in part time 4wd or 4low and have F/R rear lockers.

Now the KJ's 242 t-case is a step child t-case,there are vehicles that have full time 4wd and can not disengage 4wd but still have part time and 4low,H1's are a example of those types of full time only vehicles.Older Chevy pickups also had a full time 4wd vehilces.These types of vehicles use a specific t-case that is very strong and are in 4wd all the time but also have what is called "hi lock" which is the same as part time 4wd and "4low lock" which locks the center diff in the t-case but no option of 2wd and must not be confused with crap systems like that found on CRV's and such.

 

[JeepJeepster]

The 242 does not have a clutch. It just has an open differential which lets the torque go where it pleases, whether is be the front or rear diff.

The KK has some kinda crap with a clutch, and no part time option, just 4low.

 

[Dave]

The 242 does not have a clutch. It just has an open differential which lets the torque go where it pleases, whether is be the front or rear diff.

The KK has some kinda crap with a clutch, and no part time option, just 4low.

Yup, and the new KK selec-trac II t-case is electronic. No manual shifter like on the KJ 242 t-case. I believe the 07 KJ is the last of the 242 t-cases used on the XJ and KJ and also used on some of the ZJ and WJ Jeeps.

I like the 242 t-case but that is just personal preference I guess. We get a lot of snow/ice here and during the winter I leave it in full-time most of the time. Road conditions will alternate between drifting snow and dry pavement and I just leave the t-case in full- time since you can run it on any surface.

Dave

 

[kjpilot]

I like the 242 t-case but that is just personal preference I guess. We get a lot of snow/ice here and during the winter I leave it in full-time most of the time. Road conditions will alternate between drifting snow and dry pavement and I just leave the t-case in full- time since you can run it on any surface.

Dave

X2

 

[CHUD]

Nope.

AWD is a full time 4wd vehicle that has no low range or option of putting in 2wd only.Subaru's use a active AWD system that sends power where it is needed.Ford Escapes/Honda CRV AWD systems(also called automatic 4wd) are basically a FWD system and when wheel slip is detected(via ABS sensors) it sends power to the rear axle.There are many versions of a AWD system and the KJ does not have any of them.

The Quadradrive system - NV247 mated to vari-lock diffs - is more of a true 4 wheel drive system as power can be routed front to back or side to side.

 

[tjkj2002]

The Quadradrive system - NV247 mated to vari-lock diffs - is more of a true 4 wheel drive system as power can be routed front to back or side to side.

Only the QDII can do that,QDI used a viscus clutch.

 

[CHUD]

Only the QDII can do that,QDI used a viscus clutch.

The QDI definitely xfers power side to side. Both front & rear vari-lok axles have gerotors that work similarly to the gerotor in the xfer case.

"In Quadra-Drive, the NV247 transfer case is mated to front and rear axles containing Jeep's Vari-Lok differentials. Vari-Lok differentials also use a gerotor to transfer torque.". The gerotor pump incorporated in a Vari-Lok differential is conceptually the same as that used in the Quadra-Trac II transfer case. Its operation is virtually transparent to the driver.

Power transfer in a Vari-Lok differential is proportional to wheel speed difference rather than torque difference as is typically the case in mechanical limited-slip systems. Because conventional limited-slip differentials are initially pre-loaded to assure torque transfer, normal use tends to cause wear that reduces the ability of the differential to transfer torque over time. By design, the Vari-Lok differential is virtually wear free.

Compared to systems with a viscous coupling, which also sense speed, Vari-Lok differentials respond more quickly and smoothly to wheel slip. Response of the gerotor pump can be precisely tuned to driving conditions, enabling the use of this advanced system in the front axle as well as the rear."


The QDII (NV245) is also side to side but uses ELSD in the f/r axles in lieu of gerotors. It is the QuadraTrac system that does not xfer side to side as it only employs the NV247 without the vari-lok axles.

You can actually feel when the power goes side to side on the Quadradrive I.

 

[JeepJeepster]

Only the QDII can do that,QDI used a viscus clutch

Youre thinking of the Quadra-Trac I(NP249 case, in the ZJ). Later on in 1996 they called it the NV249 which meant it was locked in 4low.

QDI and QTII(NV247 in the WJ) use something called a gerotor coupling which is similar to a viscus clutch. A gerotor coupling uses oil pressure to apply pressure on a set of clutches. This tcase will put 100% of the torque on the rear wheels till the front starts to spin. Then it will start putting torque on the front axle. It cannot put more torque on the front axle than the rear.
[SIZE=-1]
The QDII and QTII in the WK use the NV245 case which has electronic Clutches in it. QDII also offers the Electronic Limited slip axles. QDII may of also been available on the WJ but Im not 100% sure.

Think I got all that right. [/SIZE][SIZE=-1]
[/SIZE]

 

[tjkj2002]

Youre thinking of the Quadra-Trac I(NP249 case, in the ZJ). Later on in 1996 they called it the NV249 which meant it was locked in 4low.

QDI and QTII(NV247 in the WJ) use something called a [SIZE=-1] gerotor coupling which is similar to a viscus clutch. A gerotor coupling uses oil pressure to apply pressure on a set of clutches. This tcase will put 100% of the torque on the rear wheels till the front starts to spin. Then it will start putting torque on the front axle. It cannot put more torque on the front axle than the rear.

The QDII and QTII in the WK use the NV245 case which has electronic Clutches in it. QDII also offers the Electronic Limited slip axles. QDII may of also been available on the WJ but Im not 100% sure.

Think I got all that right.
[/SIZE]

Yep sorry I ment QTI,been a long day.

 

[icarl]

I just wanted to add that if you want to understand how the 4x4 system works you need to understand how a differential works since there is one in each axle and one in your transfer case if you have 4FT.