Transfer Case Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

smith · 10-23-2002, 09:01 PM

Need a little help...

I've got Automatic Transmission fluid in the transfer case of my 71 Jimmy (It's been in there since I bought it and I've never changed it). If I remember right my old 72 Blazer had 80W-90 in the transfer case and the Haynes manual I have for 67-87 truck says that 67-80 vehicles get 80W-90 in the transfer case.

I've got 2 ?'s:
What kind of tranfer case do I have (NP203,205?)or other? The front driveshaft goes forward on the passenger side if that helps identify it...

I've taken this truck on several long trips (Four 7-8 hour trips) and never had any problems. Keep the cherry juice or switch? is it the right fluid for my transfer case.

Just want to do a little preventive maint. and change the fluid.

Ratpowerd67 · 10-23-2002, 09:58 PM

NO. THATS NOT THE CORRECT FLUID FOR YOUR TRANSFER CASE. UNLESS YOU HAVE A 208. YOU HAVE EITHER A 203 OR 205. MOST LIKELY A 205. THE RED FLUID TELLS ME THAT YOUR RUNNING AN AUTOMATIC TRANS, RIGHT? THERE IS A SEAL BETWEEN YOUR TRANS AND CASE THAT KEEPS THE FLUIDS APART. THE SEAL IS WORN AND NEEDS TO BE REPLACED. ATLEAST CHANGE THE OIL IN THE CASE IF YOU DONT REPLACE THE SEAL. THE TRANS FLUID WILL EVENTUALY THIN OUT THE OIL AND CAUSE PROBLEMS.....HOPE THIS HELPS.......RAT

smith · 10-23-2002, 10:20 PM

Correct. I do have an auto transmision. I went ahead and drained the fluid... pure Auto trans. fluid, not a mixture of ATF and 80W-90, Hmmmm... How do I tell what transfer case I've got? I guess it might be a NP208 but don't know. There's a # on the rear of it: C-88404. I'm a little hesitant to switch fluids since I 've had the truck 4 years and have taken it on long trips.

O'l Buck · 10-24-2002, 02:01 AM

If the seal between the transmission and transfer case is shot, it should be over filling the t/c, but if it isn't all that bad, but seeping a little, theoretically, if you put 80/90 in the t/c, it could get in the automatic, and that's a bad thing, the clutch discs will not like that heavy sticky gear oil, not to mention what it will do to the valve body.

Duallie · 10-24-2002, 02:12 AM

Is the transfer case iron or aluminum? If iron, it should have a round data disc riveted to the front side and it should read "New Process" and 203 or 205 and a manufacture date. If no data disc, the 203 chain drive full time Tcase has coaxial shift linkage and no "2WD" on the shift knob, while the geardrive parttime 205 has two shift rods that go in/out and has a "2WD" position on the knob. If aluminum, it most likely is a chain parttime 208, but a 241 could have been swapped in.

Fluids:
205: 80-90
203: 30w motor oil
208: ATF

Ratpowerd67 · 10-24-2002, 05:41 AM

I HAVE ALSO SEEN 80W 90 IN THE RED COLOR ALSO. ARE YOU SURE ITS AUTOMATIC FLUID? IF YOU HAVE A 208 THE SHIFTER WILL SHIFT IN A "Z" PATTERN. NOT JUST FORWARD AND BACK LIKE THE 203 AND 205. .......RAT

gmcnorton · 10-24-2002, 07:24 AM

I THINK YOU DON'T HAVE TO WORRY ABOUT LEAKS FROM TRANS TO CASE OR VISE-VERSA BECAUSE BOTH SEALS WOULD HAVE TO BE BAD... IF TRANS WAS LEAKING IT WOULD MOST LIKELY SHOW UP ON THE GROUND BECAUSE THERE IS NO GASKET ON EITHER SIDE OF THE ADAPTER HOUSING....IF YOUR REAR OUTPUT ON THE CASE IS A YOLK YOU SHOULD BE RUNNING 80/90 IF ITS A SLIP IN PROBALLY SHOULD BE TRANS FLUID.... JUST MY OPINION

Blazer1970 · 10-24-2002, 07:30 AM

The transfer case is an NP205. It is VERY common for the seals to fail allowing ATF to leak from the tranny into the transfer case. In later years, GM specified ATF to be used in the NP205 because of this problem, and the chance that gear oil might leak into the automatic tranny. The NP205 will work fine with ATF, as you have already proven. You could change over to gear oil in the t-case if you want to.

mrein3 · 10-24-2002, 07:46 AM

Unless somebody changed something you have a TH350 automatic transmission and a NP205 transfer case. Between the two there is an "adapter". Inside the adapter there is a "drive sleeve". This drive sleeve couples the output shaft of your transmission to the input shaft of the transfer case.

The drive sleeve seals the transmission like the front oil seal on your engine. There is an oil seal in the adapter and the drive sleeve rides around on this seal keeping the tranny fluid in the tranny.

When I converted my straight stick/205 to a th350/205 I bought a new adapter and drive sleeve. The 205 I bought for the th350 was full of tranny fluid. Once you remove these items you'll know why I spent the money and installed new pieces. Besides my adapter was cracked like EVERY used adapter I've ever seen.

I have the part numbers you need squirreled away somewhere if you are interested. I would at a minimum buy a new drive sleeve and a new seal for the adapter.

smith · 10-24-2002, 10:06 AM

Thanks to everyone for the info.

I'm pretty sure it's all ATF that was in there...too thin to be gear oil.

My transfer case is iron and not aluminum, so I'm assuming it's a NP205, I'll look when I get home tonight to see if I can see a marking on the front side, and the shift pattern is straight and I can put it in 2WD.

That explains why the transfer case seemed to be "overfilled" when I took off the plug to check the level.Hmmm.

I think I'll go ahead and keep ATF in the transfer case..."If it ain't broke, don't fix it" but probably need to go ahead and put a new drive sleeve in. How big of a job is that? I've never dropped a transfer case before and might need a little advice.

What does everyone else run in their NP205's ATF or gear oil?

mrein3 · 10-24-2002, 12:58 PM

Big job.

I was allowed to use the shop and hoist where I used to work.

To remove the old manual/np205 I took the fire wrench out and removed the rivets from the center of the crossmember. The whole assembly was then lowered with a tranny jack.

When I installed my th350/np205 I bolted them together on the ground. Then I used a cherry picker to place the assembly on a tranny jack. That whole assembly was then raised into place and the crossmember reinstalled with bolts where the factory rivets were. I had two other guys there helping me horse the thing into place while it was still on the jack.

The drive sleeve was on the order of $90 at the local chevy garage. You probably want a new seal in the front of the adapter too.

There are two types of adapters that look identical when installed. One has bearings. The new one I bought just has the oil seals on each end and no bearings.

**Classic Heartbeat** · 10-24-2002, 01:39 PM

I wouldn't worry about it, like Blazer1970 says, this is a commen problem with the t-350 and np205 combination. I had the same problem with my 72 Blazer and ran it that way for over 10 years without any issues. I only had the problem fixed a couple of years ago because I was having my transmission rebuilt anyway. I had the tranny shop check the transfer case for any damage and they couldn't find any. Tranny fluid won't hurt the t-case so unless you have a leak because of it being over full I would not worry about it, untill sutch a time that you need to tear it apart for other reasons. WES www.ClassicHeartbeat.com

Beast388 · 10-24-2002, 03:01 PM

Here is a picture of an NP205. Like most everyone has previously stated.....an NP205 was stock in your 71 Jimmy.

bouncytruck · 10-24-2002, 03:47 PM

The 203 actually looks very similar to the 205. The easiest way to tell the difference is the 203 doesn't have the small round cover in the middle.

If you have a 203, you should be running engine oil (10W-40).

Here is a web site that will help you identify what you have.http://www.chuckschevytruckpages.com/drivetrains.html

Vince M · 10-24-2002, 09:44 PM

If you end up repairing or replacing the adapter there are two oil seals in it but also there is a o-ring on the t-case input shaft that should also be changed. It can also allow seepage into the t-case if it is broken or worn.
Pulling the t-case can be an adventure. It is hard to wrestle with it because it's center of balance is so offset and it hangs in there at an angle. I did mine alone and hope I never have to do it again.
Mine also had ATF in it when I bought the truck. I've switched to gear oil and it's been running great since.

Blazer1970 · 10-25-2002, 07:48 AM

Take a piece of plywood, and nail a block of wood to it that fits under that boss that sticks out the drivers side of the 205, and you can make a fixture that allows you to EASILY lift the t-case into place with a floor jack. Takes about 15 minutes to make and will save you many times that in time and aggravation.

mrein3 · 10-25-2002, 08:05 AM

Blazer1970,
I'm interested to know more about your NP205 lifting fixture. Can you provide more details? I think I know what boss you are talking about on the transfer case but I can't picture what you did in my mind. Can you take a digi-photo and post it?

I'm guessing this fixture fits in or on a floor jack. Right?

NP205s are HEAVY little suckers.

smith · 10-25-2002, 08:10 AM

When you switched to gear oil did you "flush" the ATF somehow? or just let it drain for a while? I know a mixture of both probably wouldn't be good. I checked and I do have a NP205. I think for right now I'll put ATF back in it since that worked fine before and run it like that- and I know fluid is leaking for the transmission into the the transfer case so I'd end up getting a mixture of ATF and gear oil anyway.

This isn't my daily driver so I don't put too many miles on it per year and none at all in the winter (heaters broke and hard top is too much of a pain to re-install every winter). So I'll probably leave it as is until something else goes wrong with it.

Thanks for all the info. It would seem like what fluid is correct for the transfer case would be an easy question to answer, but I guess it isn't?

10-23-2002, 09:01 PM	#1
smith Registered User Join Date: May 2000 Location: Durham ,NC Posts: 94	Transfer Case Help Need a little help... I've got Automatic Transmission fluid in the transfer case of my 71 Jimmy (It's been in there since I bought it and I've never changed it). If I remember right my old 72 Blazer had 80W-90 in the transfer case and the Haynes manual I have for 67-87 truck says that 67-80 vehicles get 80W-90 in the transfer case. I've got 2 ?'s: What kind of tranfer case do I have (NP203,205?)or other? The front driveshaft goes forward on the passenger side if that helps identify it... I've taken this truck on several long trips (Four 7-8 hour trips) and never had any problems. Keep the cherry juice or switch? is it the right fluid for my transfer case. Just want to do a little preventive maint. and change the fluid. __________________ Dan Smith 1971 Jimmy

10-23-2002, 10:20 PM	#3
smith Registered User Join Date: May 2000 Location: Durham ,NC Posts: 94	Correct. I do have an auto transmision. I went ahead and drained the fluid... pure Auto trans. fluid, not a mixture of ATF and 80W-90, Hmmmm... How do I tell what transfer case I've got? I guess it might be a NP208 but don't know. There's a # on the rear of it: C-88404. I'm a little hesitant to switch fluids since I 've had the truck 4 years and have taken it on long trips. __________________ Dan Smith 1971 Jimmy

10-24-2002, 02:01 AM	#4
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	something to think about If the seal between the transmission and transfer case is shot, it should be over filling the t/c, but if it isn't all that bad, but seeping a little, theoretically, if you put 80/90 in the t/c, it could get in the automatic, and that's a bad thing, the clutch discs will not like that heavy sticky gear oil, not to mention what it will do to the valve body. __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska

10-24-2002, 02:12 AM	#5
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	Is the transfer case iron or aluminum? If iron, it should have a round data disc riveted to the front side and it should read "New Process" and 203 or 205 and a manufacture date. If no data disc, the 203 chain drive full time Tcase has coaxial shift linkage and no "2WD" on the shift knob, while the geardrive parttime 205 has two shift rods that go in/out and has a "2WD" position on the knob. If aluminum, it most likely is a chain parttime 208, but a 241 could have been swapped in. Fluids: 205: 80-90 203: 30w motor oil 208: ATF __________________ Just as if I knew what I was doin'

10-24-2002, 07:24 AM	#7
gmcnorton Registered User Join Date: Aug 2002 Location: Middleport, Pa. 17953 Posts: 737	LEAKS I THINK YOU DON'T HAVE TO WORRY ABOUT LEAKS FROM TRANS TO CASE OR VISE-VERSA BECAUSE BOTH SEALS WOULD HAVE TO BE BAD... IF TRANS WAS LEAKING IT WOULD MOST LIKELY SHOW UP ON THE GROUND BECAUSE THERE IS NO GASKET ON EITHER SIDE OF THE ADAPTER HOUSING....IF YOUR REAR OUTPUT ON THE CASE IS A YOLK YOU SHOULD BE RUNNING 80/90 IF ITS A SLIP IN PROBALLY SHOULD BE TRANS FLUID.... JUST MY OPINION __________________ 70 GMC SHORT STEP , 71 BLAZER ,72 JIMMY,72 BLAZER, JUST NEED THAT SUBURBAN NOW......WANTING MORE

10-23-2002, 09:58 PM	#2
Ratpowerd67 Registered User Join Date: Aug 2002 Location: Trenton ,Texas Posts: 328	NO. THATS NOT THE CORRECT FLUID FOR YOUR TRANSFER CASE. UNLESS YOU HAVE A 208. YOU HAVE EITHER A 203 OR 205. MOST LIKELY A 205. THE RED FLUID TELLS ME THAT YOUR RUNNING AN AUTOMATIC TRANS, RIGHT? THERE IS A SEAL BETWEEN YOUR TRANS AND CASE THAT KEEPS THE FLUIDS APART. THE SEAL IS WORN AND NEEDS TO BE REPLACED. ATLEAST CHANGE THE OIL IN THE CASE IF YOU DONT REPLACE THE SEAL. THE TRANS FLUID WILL EVENTUALY THIN OUT THE OIL AND CAUSE PROBLEMS.....HOPE THIS HELPS.......RAT

10-24-2002, 05:41 AM	#6
Ratpowerd67 Registered User Join Date: Aug 2002 Location: Trenton ,Texas Posts: 328	I HAVE ALSO SEEN 80W 90 IN THE RED COLOR ALSO. ARE YOU SURE ITS AUTOMATIC FLUID? IF YOU HAVE A 208 THE SHIFTER WILL SHIFT IN A "Z" PATTERN. NOT JUST FORWARD AND BACK LIKE THE 203 AND 205. .......RAT

10-24-2002, 07:30 AM	#8
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	The transfer case is an NP205. It is VERY common for the seals to fail allowing ATF to leak from the tranny into the transfer case. In later years, GM specified ATF to be used in the NP205 because of this problem, and the chance that gear oil might leak into the automatic tranny. The NP205 will work fine with ATF, as you have already proven. You could change over to gear oil in the t-case if you want to. __________________ Tim

10-24-2002, 07:46 AM	#9
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	Unless somebody changed something you have a TH350 automatic transmission and a NP205 transfer case. Between the two there is an "adapter". Inside the adapter there is a "drive sleeve". This drive sleeve couples the output shaft of your transmission to the input shaft of the transfer case. The drive sleeve seals the transmission like the front oil seal on your engine. There is an oil seal in the adapter and the drive sleeve rides around on this seal keeping the tranny fluid in the tranny. When I converted my straight stick/205 to a th350/205 I bought a new adapter and drive sleeve. The 205 I bought for the th350 was full of tranny fluid. Once you remove these items you'll know why I spent the money and installed new pieces. Besides my adapter was cracked like EVERY used adapter I've ever seen. I have the part numbers you need squirreled away somewhere if you are interested. I would at a minimum buy a new drive sleeve and a new seal for the adapter. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

10-24-2002, 10:06 AM	#10
smith Registered User Join Date: May 2000 Location: Durham ,NC Posts: 94	Thanks to everyone for the info. I'm pretty sure it's all ATF that was in there...too thin to be gear oil. My transfer case is iron and not aluminum, so I'm assuming it's a NP205, I'll look when I get home tonight to see if I can see a marking on the front side, and the shift pattern is straight and I can put it in 2WD. That explains why the transfer case seemed to be "overfilled" when I took off the plug to check the level.Hmmm. I think I'll go ahead and keep ATF in the transfer case..."If it ain't broke, don't fix it" but probably need to go ahead and put a new drive sleeve in. How big of a job is that? I've never dropped a transfer case before and might need a little advice. What does everyone else run in their NP205's ATF or gear oil? __________________ Dan Smith 1971 Jimmy

10-24-2002, 12:58 PM	#11
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	Big job. I was allowed to use the shop and hoist where I used to work. To remove the old manual/np205 I took the fire wrench out and removed the rivets from the center of the crossmember. The whole assembly was then lowered with a tranny jack. When I installed my th350/np205 I bolted them together on the ground. Then I used a cherry picker to place the assembly on a tranny jack. That whole assembly was then raised into place and the crossmember reinstalled with bolts where the factory rivets were. I had two other guys there helping me horse the thing into place while it was still on the jack. The drive sleeve was on the order of $90 at the local chevy garage. You probably want a new seal in the front of the adapter too. There are two types of adapters that look identical when installed. One has bearings. The new one I bought just has the oil seals on each end and no bearings. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

10-24-2002, 01:39 PM	#12
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,766	I wouldn't worry about it, like Blazer1970 says, this is a commen problem with the t-350 and np205 combination. I had the same problem with my 72 Blazer and ran it that way for over 10 years without any issues. I only had the problem fixed a couple of years ago because I was having my transmission rebuilt anyway. I had the tranny shop check the transfer case for any damage and they couldn't find any. Tranny fluid won't hurt the t-case so unless you have a leak because of it being over full I would not worry about it, untill sutch a time that you need to tear it apart for other reasons. WES www.ClassicHeartbeat.com __________________ On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys

10-24-2002, 03:01 PM	#13
Beast388 Suburbans RULE! Join Date: Jan 2000 Location: Clinton, IA 52732 Posts: 689	Here is a picture of an NP205. Like most everyone has previously stated.....an NP205 was stock in your 71 Jimmy. Attached Images __________________ --Ben 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, TH350, NP205, 8-lug D44, 14BFF w/ Detroit, 4.10:1 gears, 4-Wheel Disks 4" Lift, 35" MT/R's.

10-24-2002, 03:47 PM	#14
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,049	The 203 actually looks very similar to the 205. The easiest way to tell the difference is the 203 doesn't have the small round cover in the middle. If you have a 203, you should be running engine oil (10W-40). Here is a web site that will help you identify what you have.http://www.chuckschevytruckpages.com/drivetrains.html __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

10-24-2002, 09:44 PM	#15
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	If you end up repairing or replacing the adapter there are two oil seals in it but also there is a o-ring on the t-case input shaft that should also be changed. It can also allow seepage into the t-case if it is broken or worn. Pulling the t-case can be an adventure. It is hard to wrestle with it because it's center of balance is so offset and it hangs in there at an angle. I did mine alone and hope I never have to do it again. Mine also had ATF in it when I bought the truck. I've switched to gear oil and it's been running great since. __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.



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10-25-2002, 07:48 AM	#16
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Take a piece of plywood, and nail a block of wood to it that fits under that boss that sticks out the drivers side of the 205, and you can make a fixture that allows you to EASILY lift the t-case into place with a floor jack. Takes about 15 minutes to make and will save you many times that in time and aggravation. __________________ Tim

10-25-2002, 08:05 AM	#17
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	Blazer1970, I'm interested to know more about your NP205 lifting fixture. Can you provide more details? I think I know what boss you are talking about on the transfer case but I can't picture what you did in my mind. Can you take a digi-photo and post it? I'm guessing this fixture fits in or on a floor jack. Right? NP205s are HEAVY little suckers. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

10-25-2002, 08:10 AM	#18
smith Registered User Join Date: May 2000 Location: Durham ,NC Posts: 94	When you switched to gear oil did you "flush" the ATF somehow? or just let it drain for a while? I know a mixture of both probably wouldn't be good. I checked and I do have a NP205. I think for right now I'll put ATF back in it since that worked fine before and run it like that- and I know fluid is leaking for the transmission into the the transfer case so I'd end up getting a mixture of ATF and gear oil anyway. This isn't my daily driver so I don't put too many miles on it per year and none at all in the winter (heaters broke and hard top is too much of a pain to re-install every winter). So I'll probably leave it as is until something else goes wrong with it. Thanks for all the info. It would seem like what fluid is correct for the transfer case would be an easy question to answer, but I guess it isn't? __________________ Dan Smith 1971 Jimmy

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