full time 4x4 ??

[us111]

HI all,,i have a couple questions i'm sure everyone but myself can answer..lol..anyhow i have had 4wd before just never got into the working of them,,now i have a 1976 k-10,shortbed,4x4 ,camper special is what it is listed as that i am restoring so i figured it was time to learn about 4x4..as i said i have been told it is full time 4wd,,what does that mean exactly??? also the shift pattern tag on sunvisor is all faded out,,i can make out just enough to make it confusing and thought i would ask you all just exactly what all this is?? i do not know what transfer case it has but it all appear's original and is mounted to a th350 tranny...i just wanna learn before i go tearing gears out or something ...thank you all for any help you can give....(more the better)..

[LONGHAIR]

That's an NP203 transfercase and as the name "full time" implies the front axle is being driven just like the rear....all of the time. It's not quite as simple as it may sound though. The transfercase has a differential inside, much like an "open" rear-end. It allows the power to the axle with the least traction, but instead of left to right like the rear axle does, this type of transfercase shifts power from front to rear. It can how-ever be "locked" (by the shifter) so that you get power to both the front and rear at the same time.
The shifter should have 5 positions, in a straight line front to rear. They should be marked as:
Low Loc
Low
Neutral
Hi
Hi Loc

"Normal" everyday driving is in "Hi"
These shifers are known for sticking and being very hard to shift. They are not really complicated, it's just that the "works" are not sealed and mud/snow etc. will gum them up.

Most of these have been converted to "part-time" four wheel drive. It cuts down on wear of moving parts and generally improves driveabilty/ handling while improving fuel mileage at the same time. They haven't been built since about 1980 and I haven't seen an unconverted one in several years.

[Mudder]

To loosen the linkage up just spray a bunch of wd-40 down the shifter so that it runs down into the linkage. This will usually loosen things up. if taken care of they arent bad transfer cases. All the ones I have had have been converted to part time.

[us111]

thanks all..i just put the cab on and before i did checked all the linkage,tightened up etc.. is there a way to tell if it has been converted??? thanks

[Mudder]

Does it have selectors on the hubs for locking, unlocking?

[Yamaha74]

Sorry to interupt this thread but I am in the same vote. I have a 83 4x4 chevy and I was told it was all time 4x4. But the way it was explained to me was that the front axle is just spinning all the time and there is no power being put to them. There is no selectors on the hubs for locking or unlocking. It is automatic. Just put it in 4x4 from inside the truck and you are good to go. I was told that the gas mileage is going to be worse on these trucks. If there is a conversion, what do I have to do?

[us111]

on mine it does have manual locks on the hub's......


also i guess i'm confused,,if that is the shift pattern what is neutral for??

thank's for all the help,,once i get on something sometimes i ask to many questions..lol.....

[JIMs70GMC]

yamaha74, on your automatic hubs you need to shift the transfer case into 2 hi and drive backwards about 15-20' to unlock the hubs. The hubs lock when power is being transmit from the tc, not the other way around. I had these on an 85 K5 I had. You only need to install manual hubs if youwant to get out and lock the axle in and out.

[us111]

hello,,sorry to put this back to the top but still trying to find a couple answer's,,,thanks

[smokekiki]

Neutral can be used for flat towing.When You fill Your tank,or every couple hundred miles,either lock the hubs,or put the t-case in 4wd to lube it.You only need to run it like this for a few miles.Since the case has been converted,it no longer oils the rear bearing.

[LONGHAIR]

Sorry to interupt this thread but I am in the same vote. I have a 83 4x4 chevy and I was told it was all time 4x4. But the way it was explained to me was that the front axle is just spinning all the time and there is no power being put to them. There is no selectors on the hubs for locking or unlocking. It is automatic. Just put it in 4x4 from inside the truck and you are good to go. I was told that the gas mileage is going to be worse on these trucks. If there is a conversion, what do I have to do?

This is not the same thing..........You have "automatic" hubs and most likely an NP208 transfercase. This is a part-time unit. The full-time case is NP203...and they were out of use well before your '83 was built.
The driveshaft really shouldn't be turning on your truck under "normal" circumstances. However you probably will have trouble with the "automatic" hubs. They are well known for not locking when you need them to...........and sticking in the locked position when you don't. Replace them with a quality set of manual hubs and you will be far better-off.
P.S. Just in case you want to be sure of what you have........the NP208 has an aluminum case an most of them have a slip-yolk style driveshaft. The NP203 (a full-time transfercase) is a cast iron unit with an aluminum extension housing and a "bolt-in" driveshaft.