Transfer Case 101 for a newbie

[TJ1978]

I am green to this style vehicle’ mainly lowered C10’s in the past.

My truck has an np203 with manual locking hubs with 3/4 ton axles. From what I gather the np203 was full-time 4wd.

Did having full time 4wd need the manual locking hubs?

Secondly, how can I tell if my transfer case has the conversion kit installed to make it part time?

Thirdly, from browsing I see the shift pattern in the transfer case changes slightly with the np203. if true I already have a screen shot from this site on how pattern changes.

Lastly, I am bit skittish in shifting gears in the transfer case. Is there an ideal MPH to drive, or gear on the column to be in to engage the other gears in the np203 transfer case?

I hope this makes sense? I browsed around here and youtube but didnt find too much coherent info. Or its my lack of knowledge that is preventing me from understanding? Lol

 

[diesel4me]

The NP-203 is indeed a full time t-case,and factory the trucks they came in had no locking hubs,instead they used a "drive slug" gear that basically locked the axles all the time,just like having a hub in the "lock" position..

I do not know if there is an easy way to tell if it has a part time kit installed by looking at it,since the parts are inside the tail housing..but if it did have one,then the truck should have had locking hubs put on at the same time,so the axle shafts & u-joints and differential gears wouldn't be spinning,driven by the front tires..

Others here may have a better way to tell if it has the part time kit or not..

The "LOC" position on the t-case is only for off road or slick road conditions,that locks out the third differential in the tail housing so both drive shafts get full power--in the "HI" position for street driving,whichever shaft has the least resistance will spin,this allows the front & rear tires to rotate at different speeds without binding up--the part time kit replaces that diff,so you can select part or full time at will..

 

[76k5blazerr]

Put the transfer case in “hi” which is the regular street driving position, make sure hubs are unlocked. With the truck in park you should be able to grab the front driveshaft and spin it freely if it has a part time kit. Or simply attempt to drive forward. If it will not move, it doesn’t have a part time kit. Always shift the transfer case with the transmission in neutral, standing still. Shift pattern on 203 from the seat forward is High lock, High, N, Low, low lock. Or 4hi, 2hi, N, 2lo, 4lo if you have a PT kit.

 

[jimmyleetn]

If you have hubs then someone installed the kit I would imagine. We tried just installing the hubs to my 79' years ago and it absolutely would not go into gear without the kit. The kit involved a new tail housing back then. Mine was Warn and it to this day it leaks like crazy. Not sure if they even still make it. All that to say this, if you have hubs, most likely you have the kit unless I'm missing something. Someone may jump on here on correct me but I'll never forget putting lockouts on mine and then it wouldn't go down the road LOL.

 

[TJ1978]

Put the transfer case in “hi” which is the regular street driving position, make sure hubs are unlocked. With the truck in park you should be able to grab the front driveshaft and spin it freely if it has a part time kit. Or simply attempt to drive forward. If it will not move, it doesn’t have a part time kit. Always shift the transfer case with the transmission in neutral, standing still. Shift pattern on 203 from the seat forward is High lock, High, N, Low, low lock. Or 4hi, 2hi, N, 2lo, 4lo if you have a PT kit.

Ok, my shifter is all the way forward, pointing towards the fire wall. I can spin by hand the front drive shaft. Hubs are free

For everyday driving what gear or where should my transfer gear shift stick be?

When I bought the truck, transcase shifter was pointing all the way forward towards the firewall, and since I didnt have the knowledge I have just left it.
Thanks

 

[76k5blazerr]

Ok, my shifter is all the way forward, pointing towards the fire wall. I can spin by hand the front drive shaft. Hubs are free

For everyday driving what gear or where should my transfer gear shift stick be?

When I bought the truck, transcase shifter was pointing all the way forward towards the firewall, and since I didnt have the knowledge I have just left it.
Thanks

Are you sure you have a 203? What you are describing would be the correct position for 2hi on an np208. If it is a 203, than you are in low lock (4lo). I find it hard to believe you could drive around with it in 4lo and not know that something was off, because the truck would sound super wound up any faster than about 25mph. The 203 should be in high for normal driving which is the second notch forward of the seat, see the shift pattern in my earlier post.

 

[76k5blazerr]

If you have hubs then someone installed the kit I would imagine. We tried just installing the hubs to my 79' years ago and it absolutely would not go into gear without the kit. The kit involved a new tail housing back then. Mine was Warn and it to this day it leaks like crazy. Not sure if they even still make it. All that to say this, if you have hubs, most likely you have the kit unless I'm missing something. Someone may jump on here on correct me but I'll never forget putting lockouts on mine and then it wouldn't go down the road LOL.

You can install just hubs but when they are unlocked you must drive in one of the “lock” positions, either high or low.

 

[TJ1978]

A few pics. To clear up what I am working with. By the way, these wheels make it damn near impossible to get a socket on the nuts.. And yes the Speedo has some sort of block in there. And impossible to remove. I have to weld a nut to it, to try removal or bigger channel locks.

View attachment 318885

 

[TJ1978]

Are you sure you have a 203? What you are describing would be the correct position for 2hi on an np208. If it is a 203, than you are in low lock (4lo). I find it hard to believe you could drive around with it in 4lo and not know that something was off, because the truck would sound super wound up any faster than about 25mph. The 203 should be in high for normal driving which is the second notch forward of the seat, see the shift pattern in my earlier post.

posted a few pics, so we’re all on the same page. Maybe Im not all the way forward in the transfer case and one gear behind. Maybe Im in Lo not Lo-loc

 

[76k5blazerr]

posted a few pics, so we’re all on the same page. Maybe Im not all the way forward in the transfer case and one gear behind. Maybe Im in Lo not Lo-loc

If you were in Lo and not low lock than yes you would've been able to spin the front driveshaft. Pull the t case shifter all the way back to the seats as far as it will go and then push it forward one position and you will be in normal driving position, hi.

 

[TJ1978]

If you were in Lo and not low lock than yes you would've been able to spin the front driveshaft. Pull the t case shifter all the way back to the seats as far as it will go and then push it forward one position and you will be in normal driving position, hi.

So I am correct it’s an NP203 with the conversion?
I will shift the transfer case as you state.

Again, As you said, only shift the transfer case while in Nuetral? I need to be stopped and in neutral or can you coast?

 

[76k5blazerr]

So I am correct it’s an NP203 with the conversion?
I will shift the transfer case as you state.

Again, As you said, only shift the transfer case while in Nuetral? I need to be stopped and in neutral or can you coast?

Sounds like it, yes. And I always shift my transfer cases in neutral even if they are supposedly "shift on the fly".

 

[TJ1978]

Sounds like it, yes. And I always shift my transfer cases in neutral even if they are supposedly "shift on the fly".

When I start with the shifter all the way towards me and shift towards firewall, It doesnt feel like 5 positions. I wish I could post a video

One reason among many Im confused is that Tcase os all the way forward. It’s been like that since I bought and it runs fine. But as you said it should run weird above 25mph and it doesnt.

Shift pattern after full to part time conversion i found on this site, assuming its correct.
4x4 Low
2x4 low
Neutral
2x4 High (Normal Street use)
4x4 High

I do not feel this many gears engaging as I shift from firewall to rear or rear to firewall.

Starting with shifter all the towards the rear or driver seat.
I feel 4x4 high, one click going forward to what I assume is 2x4(street use), then one more and I cant shift any further towards the firewall.

I just dont feel a Neutral, 2x4 or 4x4 low.

 

[6872xtc]

You definitely have a 203.

You can get taller (longer) lug nuts that will hang out and be easier to get a socket on. Those look like Weld Racing typhoons.

I am not understanding what you mean about a block in it. Maybe it has the tip of an old cable stuck in it?

And the shifter for the 203 can get dirty, greasy and junk in the mechanism that actuates the front drive lock. This could make it difficult to get the lock positions and throw you off as far as the position count. Maybe check the linkage on the passenger side of the transfer case and see if the one of the rods is missing or unhooked. There has to be some reason that you aren't feeling a difference in how the truck drives in the "low" position and you aren't feeling the proper number of stick positions.

 

[TJ1978]

You definitely have a 203.

You can get taller (longer) lug nuts that will hang out and be easier to get a socket on. Those look like Weld Racing typhoons.

I am not understanding what you mean about a block in it. Maybe it has the tip of an old cable stuck in it?

And the shifter for the 203 can get dirty, greasy and junk in the mechanism that actuates the front drive lock. This could make it difficult to get the lock positions and throw you off as far as the position count. Maybe check the linkage on the passenger side of the transfer case and see if the one of the rods is missing or unhooked. There has to be some reason that you aren't feeling a difference in how the truck drives in the "low" position and you aren't feeling the proper number of stick positions.

Ill dig in tomorrow and take pics.

Speedo cable input is blocked off , zoom in and you’ll see. If not Ill snap a closer picture.

Thansk for all the help. I do appreciate it.

I had my son get in and shift and it cant go any further forward or backward. So either the gear engagement is more faint than I can feel, it is engaging and I just dont feel or hear it. Or Im an idiot who should have stuck with C10’s hahahahahahahahah

 

[6872xtc]

I wasn't remembering exactly what the speedometer output looked like, been a few days since I looked at mine.
It should unscrew out of the tail housing by the wrench hex right there.

Your shifter looks pretty clean, so unless there is something inside it in the mechanism for the front output arm, it should work.
The arm of the shifter that is more forward, is the one for the front output. The switch there is for the light in the dash. That arm should go forward for either lock position, even when the range selector arm goes backwards. You will probably have to rock the front driveshaft to get it to lock in.

My memory may be wrong, but it looks like it is in high range in that picture. The outer lever on the transfer case is pulled forward, correct? It should go towards the rear of the truck for low range. Is that lever NOT moving?

Remember to have the transmission in neutral and the tires blocked when you have your son try to shift it. It's surprising how little pressure it takes to keep it from shifting.

And you are welcome for the help, we all like to hang out on here and help others.

And lots of us have a C10, mine is a '72 and so is the one that @76k5blazerr has!

 

[HankScorpio]

Do you have a body lift? One of my old trucks had issues shifting the np203 all the way because the shifter was hitting the body due to the body lift. A quick trim with some tin snips and a little hammering solved it. Pull the boot and try shifting to see if it is hitting the body.

 

[rksjd8420]

Those look like Weld Racing typhoons.

They are Weld Scorpio.

 

[TJ1978]

Do you have a body lift? One of my old trucks had issues shifting the np203 all the way because the shifter was hitting the body due to the body lift. A quick trim with some tin snips and a little hammering solved it. Pull the boot and try shifting to see if it is hitting the body.

Will do this tomorrow. Body lift I dont think so.

 

[TJ1978]

They are Weld Scorpio.

They are 3 are the same but the driver side has it where it’s difficult to get to the lug nuts. Seem slightly different