203 part time questions?

[77 Shorty]

So if I bought my truck with warn lock-outs in the front how would i check to see if it has the part time conversion?  If I'm driving the front driveshaft wont turn?

[Irish_Alley]

put it in 4 unlock high or low and have the hubs unlocked. if the truck moves you have the part time kit if just the front drive shaft moves you dont.

[jdl71]

put it in 4 unlock high or low and have the hubs unlocked. if the truck moves you have the part time kit if just the front drive shaft moves you dont.

Why would the truck not move in unlock? I drive mine like that all time, it still sends power to the rear wheels.

[1979C20]

Jd, do you have a 203? If you do, then your tcase has the part time kit  unless you have automatic hubs on the front.

[jdl71]

Yes I do. No hubs. I thought they split the torque by design. Didn't know they only powered the front wheels unless it was "locked".

edit: NM, figured it out. Sends power to the "path of least resistance" unless locked. Thus, no hubs engaged, no resistance. Found a pretty good article here about the 203 from my favorite rag:

http://www.4wheeloffroad.com/howto/47538/index.html

I don't think I have the part time kit. My reasoning was it's spun the back tires before in wet/muddy grass and so I knew the back wheels were getting power when unlocked. This explains it. Easier to spin the rear wheels than power the fronts on solid ground.

[bake74]

     The transfer case only controls the front end, has nothing to do with the rear, if your transmission is in gear your rear tires will spin, for awhile chevy (and others) thought all wheel drive would be good on trucks, so the 203 turned your truck into all wheel drive.  It sucked on gas mileage, so everyone put in conversion kits so to take it from all wheel drive back to 2wd with the option of 4wd.

[Irish_Alley]

bake the t case controls front and back this is why you can put it in low and have both front and rear turning same rpm.

[jdl71]

     The transfer case only controls the front end, has nothing to do with the rear, if your transmission is in gear your rear tires will spin, for awhile chevy (and others) thought all wheel drive would be good on trucks, so the 203 turned your truck into all wheel drive.  It sucked on gas mileage, so everyone put in conversion kits so to take it from all wheel drive back to 2wd with the option of 4wd.

It has to have "something" to do with the rear since it's between the transmission and the rear driveshaft and without it you'd go nowhere.

[1979C20]

The 205 tcase plays a big role with the rear, because if you twin stick the 205 you can have rwd high and low, fwd high and low, or 4wd high and low

[bake74]

     What I meant is without shifting the transfer case in on a normal 4wd, it goes straight through to the rear wheels.  When you shift in the transfer case it "locks" in the front axle.  That is why everyone put in the part time kit in the 203 so it would not turn the front all the time.

[ehjorten]

In a full-time or AWD transfer case there is a center differential (i.e. you have 3 differentials)!  You have to have because when you turn a corner your back wheels turn a tighter circle than your front; so the front wheels have to travel a farther distance than your rear wheels.  This is also the same on the inboard vs. outboard wheels.  The outboard wheels have to travel farther and thus you have a differential between the inboard and outboard driven wheels.  You don't need a differential on the front of a 2WD (traditional RWD vehicle here guys) because those wheels are not driven and can spin at different rates from each other.

So...on a NP203 from the factory you have an open differential in the transfer-case.  The thing about an open differential is that like anyone that has been stuck in the mud with a peg-leg 2WD car knows...the tire with the least amount of traction just spins and you go no where!

Shift Pattern:
4LO Lock
4LO
Neutral
4HI
4HI Lock

If you convert a NP203 to manual locking hubs and you drive in HI or LO (non-locked position and hubs unlocked) and you do not have the conversion kit in the transfer-case you will not go anywhere!  You will only spin the front driveshaft.  This is because that center differential sees no resistance on the front axle and resistance on the rear axle.  The transfer-case conversion kit takes the center differential and locks it up with a set of partial spider gears that do not turn.

Now you have a Part-time transfer-case that has the following shift pattern:
4LO
2LO
Neutral
2HI
4HI

And...the reason why people started converting the NP203 to Part-time was not really for fuel economy.  You don't gain much at all in fuel economy with this conversion.  The real gain is front-end wear and tear.  The U-Joint half-shafts just don't work very well in a full-time situation and the angles that they are required to work just eats parts up when driving on pavement.