NP 203 Shift pattern

[19gmc84]

84 GMC...not sure if its original T Case or not...but I'm pretty sure from pictures I've seen...I have a NP203 T Case...manual locking hubs. I have no clue what the shift pattern is. From what I've read ...the shift pattern is as follows and could someone confirm...

4L
2L
N
2H
4H

Straight up and down. I understand the tranny has to be in N to go from any gear into 4L or 2L and I can be in D to go from 2H to 4H.

Problem is...I'm not sure what gear the shifter is actually in...with that said...how can figure out what gear the T Case is in without damaging anything...

So questions I have...

is the pattern above look right ?

How can I figure out what gear the T Case is in w/o damaging anything...can I simply lock hubs and then put tranny in N and shift T Case from gear to gear without harming anything and once I shift T Case to whatever gear...can I then put tranny is D and see if 4WD works?

And once in N...will shifter go side to side like a stick shift does? Will I be able to tell it's in N pretty easy?

 

[firebane]

Just because you have manual hubs doesn't mean much. You would also need the part time kit installed. If you have both of those your shift pattern becomes..

CONVERTED PART TIME 4x4 NP203 W/ AFTER MARKET HUBS
This NP203 is a chain driven part time 4 wheel drive t-case
Almost all part time conversions are done in conjunction with after market manual hubs.
The shift pattern is forward 4 lo lock, 2 lo, N, 2 hi, 4 hi lock closest to seat.
In 2 hi with hubs unlocked the front drive shaft, diff and axels do not spin. This would be used for normal driving conditions.
4 hi,lo lock with hubs locked would be used for 4x4 driving conditions.

 

[19gmc84]

Thanks for replying...I've read about the conversion kit...correct me if I'm wrong...but I understand originally the NP203 to be full time 4WD and the conversion kit makes it a 2WD and the way to determine that is with the hubs free and the shift in 2H the front drive shaft should spin...mine does...so does that mean I have the conversion kit and I'm in 2H at this point?

 

[rich weyand]

Thanks for replying...I've read about the conversion kit...correct me if I'm wrong...but I understand originally the NP203 to be full time 4WD and the conversion kit makes it a 2WD and the way to determine that is with the hubs free and the shift in 2H the front drive shaft should spin...mine does...so does that mean I have the conversion kit and I'm in 2H at this point?

No, the way to tell is that with the NP203 in 2H and the hubs free, if the part-time kit is NOT installed, the front driveshaft will spin and the truck won't move -- that is, there will be no drive to the rear wheels. If the truck drives normally in 2H with the hubs free, the part-time kit is installed.

Some tips (some of this is WITH the part-time kit; should be obvious which):

You can't shift the NP203 through neutral unless the transmission is in PARK or the engine is off. Basically, if the transmission isn't in PARK or the engine off, when you shift the NP203 into neutral, the output shaft of the transmission will start spinning (even in Neutral), and you won't be able to shift out of Neutral into 2H or 2L because the shaft speeds aren't the same.

You can shift from 4H to 2H or from 4L to 2L at any time, whether on the move or not. You can shift from 2H to 4H or 2L to 4L while moving if the hubs are locked, but only when stopped when the hubs are free. Basically, in 2L or 2H, the front driveline parts are only spinning if the hubs are locked, so the speeds of the front driveline and the rear driveline are matched and you can make the shift. If the hubs are free, in 2L or 2H the front driveline is stopped, and you have to stop the vehicle to match them so you can shift.

Being a full-time transfer case, the NP203 has no oil pump to feed the rear output bearing. The chain drive to the front flings oil on the inside of the case, and a pair of oil ways on the inside of the case deliver oil to a small gravity-feed reservoir over the output bearing. Drive it around in 2H all the time with the hubs unlocked and you will run the reservoir dry and eat rear output shaft bearings, the replacement of which is annoying.

The solution to that is, when the hubs are unlocked, to shift into 4H for the first couple of miles every day, or when traveling long distances the first couple of miles after a gas fill-up or rest stop, to engage the chain and fill the reservoir. You can then shift to 2H while on the move. If the hubs are locked (I leave mine locked during the winter when there is snow on the ground), then you don't need to do this because the chain is being spun from the other end and is keeping the reservoir full.

Annoying shifter rattles can be because the handle that sticks up into the cab is not the actual shift actuator. The pretty chrome handle in the cab is bolted to the actual shift actuator under the boot. The bolts come loose, and then the thing rattles. You can tell because the shifter will have free motion without changing modes. Take the boot off and tighten them.

The transfer case shifts should be very smooth and easy. If they are not, your shifter is full of road grime and dirt. The solution is to remove the boot and hose the thing down with WD-40 or PB Blaster or Silikroil. Do that and let it sit overnight, then do it again the next day. Finally, run some oil down through the shifter to lube it. Do this all out over some gravel somewhere, or over a pan, because you will make a mess.

 

[79K10]

i had the np203 with the part time kit ... im pretty sure mine was 4L lok, 4 Low, N, 2H, 4H LOK ... I dont think there was a 2Low

 

[rich weyand]

i had the np203 with the part time kit ... im pretty sure mine was 4L lok, 4 Low, N, 2H, 4H LOK ... I dont think there was a 2Low

Yeah, there is. With the part-time kit it is, front to back, 4L-2L-N-2H-4H.

Without the part-time kit it is LO LOC - LO - N - HI - HI LOC.

 

[79K10]

damn! if id of known i had 2lo, i would have hit some mean donuts lol

 

[rich weyand]

Yeah, 2L with a 3.73:1 gives 7.46:1. Yowza. Easy way to dynamite a G60, though.

 

[BETO 54]

Sorry, Im pretty new to this. What is the difference between Lo and Lo-Loc, the
same with Hi and Hi-loc?

 

[77 K20]

The LOC position actually locks the "center differential" (transfer case).

The 203 was supposed to be a full time 4wd transfer case. If the transfer case locked the front and rear axles together then it would fight you when turning sharp as the front and rear drivelines need to turn at different speeds.

One you put it in LOC then the transfer case locks the front and rear drivelines together and if you turn sharp then you can feel the steering wheel jerk/fight you as one of the tires has to give and it will slip.

Lo just means you are in low range (1.96:1) and Hi range is the normal range for driving/highway (1:1)

 

[75gmck25]

If you have an unconverted NP203.

In the Hi or Lo positions you have all wheel drive ( AWD) or full-time 4WD. Great for winter or muddy driving. There is a differential in the transfer case that lets the front and rear axles turn at different speeds, so you can also drive on hard pavement. The downside is that you are always turning the front axle and driveshaft, so gas mileage suffers a little.

Hi-Loc or Lo-Loc - in this position the transfer case differential is locked and both axles turn at the same speed. This is equivalent to standard 4WD with most transfer cases. You should keep to relatively slippery surfaces (mud and snow) to avoid binding in the drivetrain.