Issue with NP208 TC - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Shamil · 08-25-2012, 06:47 AM

Hello guys, I am facing an issue with my TC it is NP208. I noted the front drive shaft is spinning slowly even when TC is on 2H. I’ve checked the linkage under the cap and makes sure it is on 2H, I noted that when I hit the gas while the truck on a slope I can feel the front shaft is spinning and I feel the same some time when hitting the gas while turning the truck. Any idea what is the problem is.

legendman · 08-25-2012, 09:22 AM

Do you have manual or auto locking hubs on the front axle?

With the truck in 2H and hubs unlocked can you get under it and turn the shaft by hand?

Shamil · 08-25-2012, 09:49 AM

i have manual hub lock, and yes with the truck on 2H and the lock on free i can turn the front shaft

legendman · 08-25-2012, 11:06 AM

It's just friction of the fluid turning the driveshaft then, I wouldn't worry about it.

**hatzie** · 08-25-2012, 12:09 PM

There's always some slight mechanical drag that could turn the front shaft.
Are you running Dexron III in this case? Service docs call for Dexron II but Dexron III is compatible. Don't fill with Dexron VI unless you feel like replacing the seals.

Gear oil will eventually burn out your case bearings it's too thick to flow at the rate the engineers set this case up for. Bronze synchros don't like he sulfur EP compounds in GL5 gear oil either. Gear oil might cause enough drag between the shift synchro and sprocket to spin the front shaft. If you pull the fill plug and it smells like sulfur drain and re-fill with Dexron III.

Shamil · 08-27-2012, 04:58 AM

i talked to my mechanic guy i found that he filled the TC with Oil 90... what you guys recommended is ATF.

Mattman2010 · 08-27-2012, 11:23 AM

All my 205 transfercases do this as well. It's just the gear lube causing it.
Posted via Mobile Device

**hatzie** · 08-27-2012, 11:16 PM

Don't use gear lube in an NP208.
Factory lube in 1982 was Dexron II ATF. Drain it and refill with backward compatible Dexron III ATF before you spin the bearings.

08-25-2012, 06:47 AM	#1
Shamil Registered User Join Date: Nov 2006 Location: Amman, Jordan Posts: 121	Issue with NP208 TC Hello guys, I am facing an issue with my TC it is NP208. I noted the front drive shaft is spinning slowly even when TC is on 2H. I’ve checked the linkage under the cap and makes sure it is on 2H, I noted that when I hit the gas while the truck on a slope I can feel the front shaft is spinning and I feel the same some time when hitting the gas while turning the truck. Any idea what is the problem is.

08-25-2012, 09:49 AM	#3
Shamil Registered User Join Date: Nov 2006 Location: Amman, Jordan Posts: 121	Re: Issue with NP208 TC i have manual hub lock, and yes with the truck on 2H and the lock on free i can turn the front shaft

08-25-2012, 12:09 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 5,014	Re: Issue with NP208 TC There's always some slight mechanical drag that could turn the front shaft. Are you running Dexron III in this case? Service docs call for Dexron II but Dexron III is compatible. Don't fill with Dexron VI unless you feel like replacing the seals. Gear oil will eventually burn out your case bearings it's too thick to flow at the rate the engineers set this case up for. Bronze synchros don't like he sulfur EP compounds in GL5 gear oil either. Gear oil might cause enough drag between the shift synchro and sprocket to spin the front shaft. If you pull the fill plug and it smells like sulfur drain and re-fill with Dexron III. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

08-27-2012, 04:58 AM	#6
Shamil Registered User Join Date: Nov 2006 Location: Amman, Jordan Posts: 121	Re: Issue with NP208 TC i talked to my mechanic guy i found that he filled the TC with Oil 90... what you guys recommended is ATF.

08-27-2012, 11:23 AM	#7
Mattman2010 Registered User Join Date: Jun 2010 Location: Pittsburg, KS Posts: 953	Re: Issue with NP208 TC All my 205 transfercases do this as well. It's just the gear lube causing it. Posted via Mobile Device __________________ 1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread

08-27-2012, 11:16 PM	#8
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 5,014	Re: Issue with NP208 TC Don't use gear lube in an NP208. Factory lube in 1982 was Dexron II ATF. Drain it and refill with backward compatible Dexron III ATF before you spin the bearings. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.



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