Which is better, Part time or Full time?

[Clint Dixon]

Are you sure Norm?

You're missing a huge benefit of the Select Trac (NP242). The Part Time mode is a 50/50 split between front and rear (it may actually be 49/51) to the ONE drive wheel on each axle (unless you have lockers).
Full Time is a "slip sensing mode" which sends traction to the axle, front or rear, which needs it. It is a perfect system for wet, slick, snow and or icy roads where the Part Time mode might break an axle component.
When you are in an off-road situation you can simply shift into Part Time for the old style 50/50 split.
Anytime you get tired of that NP242 you can ship it to me....= )
The only internal difference between the "Command Trac" Part Time case (NP241) and the "Select Trac" (NP242) is the extra cluster which makes the NP242 slightly weaker because of the additional moving parts. It's a great system for folks in the real world who spend 80% of their time on pavement, it also saves fuel when off-road.

However, I would think that the main point of this thread is to compare preferences between the group of NP200, NP201 and NP 205 vs. the NP 203, 208 and later cases found in the age of CAD and electric switches. I like the fact that Jeep has forsaken those labor saving gimmicks and gives us a real lever attached to real gears.

We have Command-Trac in our 98 Jeep Cherokee and Select-Trac in our 99 Grand Cherokee. I always understood that a torque sensing or "slip sensing" feature was never built into the Select-Trac transfer case. I thought that was a unique feature of the Quadra-Trac, or Quadra-Drive, or whatever Jeep is calling it now. Maybe they changed Select-Trac after '99?

Our Select-trac in the '99 is OK as far as intermittent wet and dry roads go, but when there gets to be a few snow patches mixed in, I get real nervous until I pull her down into "part time". I have broken a front tire loose and that, and only that, wheel has spun. It is kind of unnerving for me to know that any one of the four tires can spin at any time that particular tire has less traction than the other three. The scary part is not knowing which one it will be - one of the rears, left front, right front. It can cause some interesting handling characteristics when a front tire breaks loose unexpectedly and then suddenly gains traction again.

Now the 1980 Eagle wagon that Dad had, there was the machine. 4-wheel drive ALL the time with a viscous coupling. Way ahead of its time. And it had a real high stance. Kind of what the pimped out cars of today are trying to imitate.

[MoparNorm]

As far as I know the Select Trac has always been that way, that's why it is not as positive as the Part Time feature which locks the case at 50/50.
The Quadra Trac, Quadra Trac II and now Quadra Drive have a more sophisticated system than the "slippage sensing" system of the collar gear and chain in the Select Trac. The main differences in the Quadra Drive and Quadra Trac II are the viscous coupling, or silicon disc's in lieu of gears or chain which, when coupled with the electronics, send not only traction to either axle but to any individual wheel. The transfer case is in a sense a "third locker".
I think that Eagle had the Quadra Trac, or 229 case, same as the Grand Wagoner had for a year or two in 1987.

I went to buy an Eagle in 1981, but it was side by side in the show room with a FSJ wide axle Cherokee Laredo, both had the same motor, same fuel economy, same price tag but the Cherokee was so much bigger and full of shinny do dads, I loved that truck! We sold it after the girls were born, too hard to get the CA required infant car seats into the back with only 2 doors.....= (

[waynebo]

part time by a mile,,better gas mileage and less wear on t-case and front axle and front drive shaft,,tires too..also no annoying steering wheel kick back when turning,,and fun to shoot rooster tail on old dirt roads,,can't do that with full time..if the weather is bad lock in the hubs and use 4x4 as needed,,,who want 6-9 mpg with fulltime,,thats what i get with my m880,,sucks,,,wayne p.s= going to make it part time

[wsm41bn]

hmmm thats bad for an 880 i was getting 10 before i converted to a manual

[AdventurerSport]

part time by a mile,,better gas mileage and less wear on t-case and front axle and front drive shaft,,tires too..also no annoying steering wheel kick back when turning,,and fun to shoot rooster tail on old dirt roads,,can't do that with full time..if the weather is bad lock in the hubs and use 4x4 as needed,,,who want 6-9 mpg with fulltime,,thats what i get with my m880,,sucks,,,wayne p.s= going to make it part time

Hmmm...A) if you're worried about fuel mileage, why are you driving a HD 3/4 ton truck? :P B) try a tune up before you swap to parttime, it will net you more MPGs...:P

My fulltime 4wd daily driver gets 14mpg, with a stock 318-2V and automatic...:)

Wear on t-case and front axle? Please, all my fulltime trucks are so old and beat up that it really wouldn't matter at this point anyway...I've never had to rebuild a front axle or t-case yet...and I farm with fulltime 4wd trucks, pull more daily than most of you will ever see in total...:)

p.s. when you swap to parttime, what's it gonna gain? 1mpg, maybe 2, if that? The parts swap will cost you more than gas...:)

JS

[MoparNorm]

Hi JS,
I wondered when you'd chime in here! = )
How goes the battle?

[AdventurerSport]

the battle rages on...:)

All is well, how are you? :)

The battle rages on...:)

JS

[MoparNorm]

Good, thanks!
Went playing in the mountains for 2 weeks, now I'm 4 weeks behind...how does that happen??? ha!ha!

[AdventurerSport]

Never fails...if I stop for 1 day it tends to cost me about 1 week...:(

Lots to do, and lots and lots of corn growing out there that will need to be harvasted and hauled in October! :)

JS

[hpproron]

Clearing my mistake!

Just to keep my conscience clear and my mouth honest....I have to correct an error I stated in this forum!

I THOUGHT I had a NP 205 transfer case....but I actually got off my bum and crawled under the truck, rubbed off the grease from the ID plate and confirmed that I have a 203 in there......

WHHHHHHAAAAAAAAAAA! :(

Oh well, can't win them all!!!!

(I have to laugh at myself for being a fatal optimist!)

[MoparNorm]

Well,
That means you might have to change your vote...ha! ha!
...And you'll make JS happy...he loves those t-cases...
...And you can guess why the driveline was missing....= )

[MoparNorm]

We have Command-Trac in our 98 Jeep Cherokee and Select-Trac in our 99 Grand Cherokee. I always understood that a torque sensing or "slip sensing" feature was never built into the Select-Trac transfer case. I thought that was a unique feature of the Quadra-Trac, or Quadra-Drive, or whatever Jeep is calling it now. Maybe they changed Select-Trac after '99?

Our Select-trac in the '99 is OK as far as intermittent wet and dry roads go, but when there gets to be a few snow patches mixed in, I get real nervous until I pull her down into "part time". I have broken a front tire loose and that, and only that, wheel has spun. It is kind of unnerving for me to know that any one of the four tires can spin at any time that particular tire has less traction than the other three. The scary part is not knowing which one it will be - one of the rears, left front, right front. It can cause some interesting handling characteristics when a front tire breaks loose unexpectedly and then suddenly gains traction again.

Now the 1980 Eagle wagon that Dad had, there was the machine. 4-wheel drive ALL the time with a viscous coupling. Way ahead of its time. And it had a real high stance. Kind of what the pimped out cars of today are trying to imitate.

I just came across this, while searching for another topic, and thought it might interest you.

"Available on the Jeep Liberty Limited 4x4 is the all-new Selec-TracŪ II full-time, active on-demand system that anticipates and prevents wheel slip before it occurs. The system is ideal for a range of road settings including dry pavement conditions not typically suited for conventional part-time four-wheel-drive systems typically seen on competitors"

I also re-read your post and realized that the wheel slip condition you described can occur in Part Time, in any vehicle that does not have a traction control device in the differential...

[KRB64]

So, with only two choices (full vs part) aren't we lumping different beasts into unfair catagories?

My '51 B3 with lock outs is very "similar" basically to my '93 W250 CTD. But my '76 M880 with a 203 full time HI is not the same as either other truck in 4 HI right? Or is it? The only Xfer I've taken apart was in my '64 CJ-3B so I don't know EXACTLY how the 203 full time case works. But is this logic right?

The B3 hubs stay locked except for the rare time it goes to town. The M880 spends most of its life under 20mph in fields and farm roads and only have had to lock it into LO 3 times so far. The '93 with the lead head front and empty or near empty rear always "suprises" me when I hit a spot and expect to walk through only to have to get out and lock them in. I remember to "pre-lock" when its snowy or muddy but not when its marginal stuff.

Thats stuff said, I love driving all three and but especially like the option of picking which because they each have their virtues.

If I could squish them altogether I'd have a Cummins powered club cab B3 with full time 4X4...

[AdventurerSport]

Well, with the possible exception of Selec-Trac Jeeps, 4x4s are either part or fulltime.

With Selec-Trac, you get to choose, I had this feature on a '04 Liberty, and it worked very well. With Selec-Trac, you choose either 2wd, Part-Time 4wd (locked in), or Full-Time 4wd (power on demand, allows differential action while turning, so no binding). In 2Hi, there is no power put to the front axle at all, it's just there, much like any parttime 4wd, except no lockout hubs, so the driveshaft turns with the wheels. In parttime 4wd, it's locked in, with the front and rear driveshafts turning at the same speed, all the time, which can cause a bind in a turn or on dry pavement. In fulltime mode, it puts power to the front and rear, albeit at different speeds, so as to maintain positive traction at all four corners without binding, even in a turn. In low traction conditions, such as sand, snow or ice, it may be preferrable to lock in the 4wd. Just like NP203 equipped trucks. :)

NP203 has no "2wd" mode, only Hi, Lo, and Loc...in Hi, everything works normally, but the differential acts constantly, putting power to the front and rear but not at the same speed, allowing turning without binding. Same goes for dry pavement. Lo works exactly the same way, albeit with a 2:1 gear reduction. In either Hi or Lo, you can pull into "LOC" mode, and this eliminates the differential action in the t-case. Just like parttime 4wds, you now have two driveshafts locked together, turning at the same speed. This mode is used only in low traction situations like snow, mud, sand, ice, etc.

This is where the real advantages of fulltime come in...no hubs to lock or unlock, ever. You don't have to stop or backup or anything like that to "engage" 4wd. No vacuum hoses for 4wd. You can go from Hi to Hi-Loc or Lo to Lo-Loc on the fly. And, the reverse.

Also, with NP203 fulltime 4wd, you have the advantage of using Hi OR Lo without LOC...I use this feature frequently. I can pull heavy wagons on pavement in LO without having to use LOC and still have excellent traction. Most Part-time 4wds only offer Low range in a Lock position, which doesn't work well at all on pavement...:) And, if you just put your truck in Low, and leave the lockouts dis-engaged, you're only pulling ever off the rear tires and that is problematic as well (wheel spin, low traction).

Make sense? :)

JS

[MoparNorm]

"If I could squish them altogether I'd have a Cummins powered club cab B3 with full time 4X4..."

Actually there is a transfer case that "squishes" the part time/full time all together. it's the NP242.
Your B3 uses a NP200 that has only Part Time, the NP203 is a primitive (not a derogatory term JS!) Full Time system that cannot 'sense' wheel slippage or regulate power to the wheel that has traction. In fact, if you remove a driveline, a NP203 equipped vehicle will not move unless shifted into loc, manually.
The NP242 has both a part time (locked transfer case) mode, to be used only on low traction surfaces, that sends 51% of the power to the front axle and 49% of the power to the rear axle, AND a full time mode that can be used on any surface. The full time mode also allows any combination of power transfer to either the front or rear axle, depending upon need, to minimize wheel slippage.

I am curious as to why the '93 has hubs, isn't that truck equipped with a CAD (Central Axle Disconnect)? That eliminates the hubs? Are the hubs aftermarket installed?
The CAD makes hubs redundant and negates the purpose and features of the CAD and only saves a minimal amount of wear on the non CAD side of the axle.