Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend> 203 transfer case questions
User Name
lost password?   |   register now

Thread: 203 transfer case questions Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Additional Options
Miscellaneous Options

Topic Review (Newest First)
04-04-2006 07:54 PM
Blazin72 Ok, I remember you mentioning it's a 203 now. If you havent found out already, NP203 is a full time 4wd transfer case. In factory form the shift pattern is HI-LOC, HI, N, LO, LO-LOC. The case has an internal differential much like you would find in a front or rear axle. In hi or lo the differential acts normally, having the ability to put power to any of the tires the same way an open differential in a front or rear axle works. It is possible to be in low range without the differential in the t-case being locked.

In order to lock the front driveshaft from spinning the shifter needs to be in the hi-loc or low-loc position.

If the front axle still has an open differential it is still possible to spin the front driveshaft if only one hub is locked in. The shaft will just spin the other axle. When you locked the second hub how far did you try to spin the driveshaft? The hubs should hold the driveshaft but it might take a small amount of revolution to engage the hubs. --I'm not totally sure though as I've never tried to lock the hubs and turn the driveshaft by hand. I've always just locked it in 4.-- If it does, it should take less than a turn.

If the transfer case has been converted to part time 4wd then the shift pattern will be 4HI, 2HI, N, 2LO, 4LO. If this has been done you need to run it in 4wd every once in a while to make sure everything gets lubed properly.

You should read this: New Process 203 A friend of mine had a GMC pickup with a NP203 that had this done. It talks about the proper lube to be used in the t-case, problems you might run into and converting it to part time. Good piece of information.
04-04-2006 07:22 PM
jesse01 well i found the tag on the transfer case the other day and it's stamped right on the tag "203" then it has the serial #'s and such

the new noice is like a loud metal clicking noise (if that makes any sense) it kinda sounds like the front driveshaft is jumping teeth inside the yoke but i checked it out today and it's fine. i'm thinking it might be in the front output shaft in the transfer case maybe.

the rear drivshaft has a slip yoke and it has manual locking hubs, but i don't think something is right about the whole set-up b/c i was under the truck droping the front driveshaft and the tranfer case was in some gear and i reach around the tire and locked the hub so i could break the bolts free and the freaking thing turned it would't stay still so i reached around the other tire and locked the other hub too thinking maybe i might have to lock em both to keep the axle from spinning so i could break them flippng bolts free and it still spun, i ended up crawling out from under truck and putting it in what i know is 4L to keep the driveshaft from spinning so i could break them bolts loose

does that make sense to you?

04-04-2006 06:40 PM
Blazin72 If you've got a digital camera you should take several pictures of the transfer case and post them. Somebody can identify what it is for you and should be able to tell you exactly what shift pattern it has.

As far as noise goes, the 205 is a gear driven unit and might make some gear whine when it's in 4wd. If thats what it turns out you have.

Does the rear driveshaft use a slip yoke or does the u-joint bolt to the yoke on the transfer case?

Also, does your Blazer have automatic locking hubs or manual hubs?
04-04-2006 05:14 PM
jesse01 ok i'm offically lost now!

today i pulled out the driveshaft to check it out b/c of this new noise it's making and it checked o.k. so i put it back in and took it for a test drive and i started in what i know is 4low cause thats what gear it usaully makes the noise in and it still did it so i put in what i thaught was 2wd and the front driveshaft spins, but it didn't spin the other day but then again the other day i was just movinmg it around in the driveway as for today i was going down the road. think that might make a difference some how???

04-04-2006 02:38 PM
BBCMudbogger 205 has no 2lo and also has shift rods hooked straight to the shifter, not linkage rods like a 203
04-04-2006 11:21 AM
M&M CUSTOM Sound as if the part time kit has been installed.
04-03-2006 04:00 PM
jesse01 THIS JUST IN

today after work me and my bossman tinkered around with it cause i wanted to show him the new noise it was making. so anyway i went to put it in 4 low to show him and i guess i put it in 2 high by accident and the front driveshaft no longer spins so maybe i had it in 4 high before, but that wouldn't explain why i could turn the driveshaft by hand before. i dunno

so this is what i came to conclude starting all the way forward is 4 low, 2 high, neutral, then 4 high all the way back. and as for it being a 203, i guess it has to be since i found the tag on it with the model and serial number. it says 203 stamped right on the tag

but this thread {i think} has alot of good useful information i'll still use. thanx everyone

later, J
04-03-2006 05:40 AM
Originally Posted by jesse01
when it's in 2h the front driveshaft shouldn't spin......right?

see the other day i had it all the way back or close to it (it's hard to tell w/o the cover) and moved it around and the front driveshaft still spun as i was driving so i crawled under it and was able to spin the driveshaft by hand. so that means it was in 2h right? b/c when i push that little lever all the forward i can't spin the front driveshaft by hand no more so that means in locked in, but i thaught when it was in 2h the front driveshaft shouldn't spin

or maybe i'm just a retard since i'm new at this 4x4 stuff either way i love it

203 is full-time with an open or locking differential in the transfer case that os open in 4H or 4L and locked during 4H Lock and 4L Lock. That means in 4H and 4L, your front driveshaft turns (full-time 4wD), but the open diff. in the transfer case will stop the truck if even one tire on the vehicle loses traction (this assumes no posi trac or lockers exist). In 4H Lock or 4L Lock, it is like a 'normal' 4wD and broth driveshafts are locked together. This is from a 1978 Suburban I had anyway. The positions I remember are starting forward: 4H Lock, 4H, Neutral (power take-off position), 4L, 4L lock.
04-03-2006 05:29 AM
M&M CUSTOM Thanks Twistedwrench, I don't know if you yourself can add this discussion to the Knowledge Base, but when you link to the source of that information see if you can, if not I will.
04-02-2006 03:49 PM
Originally Posted by M&M CUSTOM
VERY good information, but I believe that post just might be in violation of our copy/paste policy? or am I wrong?

I read the policy, did an edit and removed it. if I can find the site where I once got it from I will post a link. Sorry
04-02-2006 12:43 PM
the 205 will have a cast tail except when it comes divorced.
Any of the 205s I've seen (including mine) have been all cast iron with the exception of the yoke housings and the lower cover. Those are aluminum.
04-02-2006 10:50 AM
M&M CUSTOM VERY good information, but I believe that post just might be in violation of our copy/paste policy? or am I wrong?
04-02-2006 08:04 AM
jesse01 thanx TW.

now thats some information

04-02-2006 01:55 AM
Twistedwrench Guilty as just, I am sorry and was unaware of the copy paste policy. It has been removed.
04-02-2006 12:41 AM
1969Chevelle The NP203 is a full-time 4WD transfer case. The shift pattern (from the dash to the seat) is Lo-Lock, Lo, Neutral, High, and High Lock. High is used for normal driving. The 203 has an internal differential similar to an axle that allows driving on hard pavement (so the front and rear driveshafts can turn at different speeds). The Lo-lock and Hi-lock positions are used to lock out the differential for positive power to both the front and rear axle. You can shift between Hi & Hi-Lock and Lo & Lo-Lock on the fly. To switch ranges you have to stop and preferably put the transmission in neutral.

The only downside I have found with the 203 is that the shift linkage is a bit clunky, and sometimes it is hard to tell what gear position you are in. Also, it was not uncommon for folks to modify the 203 to part-time 4WD to improve gas mileage, in which case the shift pattern I mentioned above would not apply.

Hope this helps.
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -6. The time now is 11:20 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.