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Author Topic: T-case problem and shift pattern  (Read 10354 times)

Offline Godgunsrocknroller

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T-case problem and shift pattern
« on: April 29, 2006, 10:54:00 PM »
I have a 76 k10 with an np-208 t-case. I have 3 questions.

1) What is the shift pattern for the t-case (the writing is rubbed off the knob)

2) When do I "lock" and "free" my hubs?

3) My t-case will only go to the forward most and second forward most positions, its stuck and refuses to go anywhere else, am I doing something wrong? And if i'm not, is there somthing wrong with my t-case?

This is a great site, thanks in advance for your guys help!:)  

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Offline 1976Scottsdale

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Re: T-case problem and shift pattern
« Reply #1 on: April 29, 2006, 10:29:00 PM »
Being a '76, are you sure that it is an NP-208 and not an NP-203?  The 203 is much larger than the 208 and is made mostly of iron, where the 208 is all aluminum.  Try putting the transmission in nuetral before shifting the T-case.

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Offline Blazin

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Re: T-case problem and shift pattern
« Reply #2 on: April 30, 2006, 10:24:00 AM »
I agree it should be a 203 or 205. You mention locking and unlocking your hubs. It is most likely a 205, unless someone coverted a full time hub truck then it will be a 203 and most likely have the kit in the case as well. There should only be four positions for a 205 all the way back is 4 hi, next forward is 2 hi, next forward is nuetral, last is 4 low. Also a 208 does not have the shift pattern on the knob, it has an indicator like an auto trans has on the column. It is 2 hi all the way forward, 4 hi next back, nuetral, and all the way back is 4 low.
As far as hubs go if you want 4 wheel drive then thats when you need to lock them. When manuvering a trailer in a tight spot I use 4 lo with out the hubs locked for more control and less use on the clutch as in hi I would be engaging and disengaging it alot.

Edited by: Blazin at: 4/30/06 9:25 am
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Offline Godgunsrocknroller

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Re: T-case problem and shift pattern
« Reply #3 on: May 01, 2006, 10:14:00 PM »
The guy I bought it from told me it was a np-208, its sort of a frankenstein truck, lots of parts from different places. He could be wrong though. I hope he isn't though because I just filled up the transfercase with SAE 80W90. Is there any way I can tell which case it is?
Thanks!

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Offline Blazin

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Re: T-case problem and shift pattern
« Reply #4 on: May 02, 2006, 07:34:00 AM »
A 208 is all aluminum, and has a slip yoke for the output. A 205 is all cast iron and has a fixed yoke ouput. 203s are cast iron and most times will have an aluminum tail shaft housing area.  

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Offline VileZambonie

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Re: T-case problem and shift pattern
« Reply #5 on: May 02, 2006, 04:39:00 PM »
Your transfer case does not take 80w90. If it's the 208 it takes ATF. If it's an old 203 it takes 10w30  

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Offline Blazin

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Re: T-case problem and shift pattern
« Reply #6 on: May 02, 2006, 10:44:00 PM »
I have 2 budies that rebuild transmisions / tranfer cases and they both recomend motor oil in a 208.  

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Offline VileZambonie

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Re: T-case problem and shift pattern
« Reply #7 on: May 03, 2006, 05:09:00 AM »
Why?

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Offline Blazin

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Re: T-case problem and shift pattern
« Reply #8 on: May 03, 2006, 07:11:00 AM »
One of them used to work at a Chevy dealer and that is what they used instead of ATF. The other told me it was recomended to him by Transtar, the company he gets his rebuild kits from.

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Offline Godgunsrocknroller

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!!!!
« Reply #9 on: May 03, 2006, 11:50:00 AM »
Should I be worried that I put 80w90 in my t-case?!?!?!?!!??! This is not good......

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Offline Blazin

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Re: !!!!
« Reply #10 on: May 03, 2006, 01:14:00 PM »
If it is a 203 or 205 thats whats suposed to be in it. If its a 208 I would drain it and refill if it were mine with motor oil, or if keeping it original ATF.

Edited by: Blazin at: 5/3/06 12:15 pm
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Offline Godgunsrocknroller

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.
« Reply #11 on: May 03, 2006, 05:41:00 PM »
I looked at the case and stamped on there is:

C1
C-11890
6-74

and on the plate it says:

model: 20(either 3 or 8 its partially rubbed off)
ratio: 20

Im still not sure what case it is, guy who sold it to me told me it was a 208 but im not sure.

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Offline Blazin

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Re: .
« Reply #12 on: May 04, 2006, 06:22:00 AM »
Is it cast iron or aluminum?  

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Offline VileZambonie

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Re: .
« Reply #13 on: May 04, 2006, 04:50:00 PM »
Blazin I worked at a chevy dealer for 4 years and there was never one class I took or TSB I ever saw that said to use motor oil instead of ATF.

Take a magnet and see if it sticks to the transfer case.

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Offline Godgunsrocknroller

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Re: .
« Reply #14 on: May 04, 2006, 11:08:00 PM »
Yep, its a 203. I drained the gear oil and put some 10w40 in it. I still don't understand how to shift the thing, it drove in all the positions, then it only drove all the way forward, and it grinds when I move the shifter to different positions, it goes ERRRRRRGGHHHHHH. It also goes CLANG CLANG CLANG when I try to shift it and to be honest it scares the crap out of me.... in fact I shut off the truck and lied in the fetal position crying for quite a while in the garage. Please show me the ways of the mighty transfer case!

Also I have the locking hubs where I have to get out and turn the thing from "free" to "lock". But it drives in "free" in the furthest forward position, which I beleive is 4low, which would mean the previous owner put a part-time conversion kit on it?

Thanks for putting up with all the questions, you guys are great!

Edited by: Godgunsrocknroller at: 5/4/06 10:35 pm
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