NP205 problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

orangeuavol · 08-22-2005, 10:09 PM

I have a NP205 mated to a TH400 in my Blazer and I am having trouble getting the TC to 'engage' in 2hi and 4hi. I can put the TC into 4lo with the tranny in park, shift into drive and all is fine. When I try to put it 2hi or 4hi I get an awful grinding noise when I put the the tranny into any gear. Any suggestions as what the problem could be? I've checked for loose motion in the linkage but doesn't seem like much if any. The shift rods seem to be engaging the detent pins but the passenger side rod does have some loose motion. the inside rod doesn't have any loose motion. Is there a trick to shifting the 205?

I bough the TC and tranny from a board member and said it had been rebuilt but had sat in his barn for a year or so.

Thanks in advance.

bouncytruck · 08-22-2005, 10:16 PM

I got an a similar grinding noise in my '69. It has a TH350/NP203 combo. It turned out to be the sprag gear in the tranny had exploded and sent the bearings all over inside the case.

Since I doubt that is your problem, I'd try putting it in gear and then starting the engine. The noises carry through the drive train, so if you can get a brave friend to look under the truck while you shift, it might help determine the source (transmission vs tcase)

orangeuavol · 08-22-2005, 10:22 PM

Its definetly the transfer case since it engages fine in 4lo and there is no grinding noise with the tranny in gear. It drives and shifts fine when in 4lo. The gear grinding noise starts when I try to put the tc in 4hi or 2hi and shift the tranny from park to any gear. We're thinking that one of the shift rods (rails?) is not lining up with the detents (proper term?). I haven't been able to find an exploded view of the 205 to know exactly what's inside.

*wolfthing2000* · 08-22-2005, 11:43 PM

I had the same problem with a Turbo 350 203 combo. If the transfercase finds neutral while the transmission is in park and you don't get it in 2 hi and move the auto shifter out of park the gears are going around in the trans and can't mesh to the transfercase. When this happens you have to turn the truck off, shift to park restart and shift into 2 hi BEFORE moving the auto trans shifter, if not you have to start over.
I would check all aspects of the shift mechanism, as mine had the problem until I tightened up the pivot bolt that the linkage works on.

Good luck!

71RestoRod · 08-23-2005, 01:29 AM

It sounds to me almost as if your range fork is disconnected. I wonder if the shift fork pin was set good during the rebuild? Fork installed in the correct orientation? There is also supposed to be a 'L' shaped end on the range shift rod that rides on the shift rail link and helps it shift into position. Is that still there? I would be tempted to pull the inspection cover on the driver side and see if / how it is shifting into high.

Here's some info. I hope the images are clear enough to read.

71RestoRod · 08-23-2005, 01:30 AM

more...

orangeuavol · 08-23-2005, 07:58 AM

71RestoRod -

What manual did that come out of? Thanks so much, exactly what I needed to see!

orangeuavol · 08-23-2005, 09:01 AM

Is there a chance that since I do not have a front driveshaft installed, that those gears do not have a load on them and causing some of the problem?

**JIMs70GMC** · 08-23-2005, 09:05 AM

This needs to be a sticky! Lots of good info!

gator2511 · 08-23-2005, 12:51 PM

I put a TH400 in my truck. I also have an NP205. Mine does the same thing, I just put the tranny in neutral and shift the transfer case. It that doesn't work I just turn off the engine and then shift it. Everything works just fine and I don't worry about it.

71RestoRod · 08-23-2005, 05:15 PM

Quote:

Originally Posted by orangeuavol

71RestoRod -

What manual did that come out of? Thanks so much, exactly what I needed to see!

Orangeuavol...

I hope it helps. I don't know what manual... I grabbed those images off of a web site quite a few years ago. Sorry, couldn't find or think of the link though, or I would have posted the link!

Resto

jhow66 · 08-30-2005, 11:12 AM

Hey guys -found our "problem" (orangeuavol's dad)
http://67-72chevytrucks.com/vboard/s....php3?t=170577

08-22-2005, 10:09 PM	#1
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	NP205 problem I have a NP205 mated to a TH400 in my Blazer and I am having trouble getting the TC to 'engage' in 2hi and 4hi. I can put the TC into 4lo with the tranny in park, shift into drive and all is fine. When I try to put it 2hi or 4hi I get an awful grinding noise when I put the the tranny into any gear. Any suggestions as what the problem could be? I've checked for loose motion in the linkage but doesn't seem like much if any. The shift rods seem to be engaging the detent pins but the passenger side rod does have some loose motion. the inside rod doesn't have any loose motion. Is there a trick to shifting the 205? I bough the TC and tranny from a board member and said it had been rebuilt but had sat in his barn for a year or so. Thanks in advance. __________________ http://1972blazer.shutterfly.com/<= blazer build pics It's called golf because all the other four letter words were taken. It's easier to ask for forgiveness than for permission.

08-22-2005, 10:16 PM	#2
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	I got an a similar grinding noise in my '69. It has a TH350/NP203 combo. It turned out to be the sprag gear in the tranny had exploded and sent the bearings all over inside the case. Since I doubt that is your problem, I'd try putting it in gear and then starting the engine. The noises carry through the drive train, so if you can get a brave friend to look under the truck while you shift, it might help determine the source (transmission vs tcase) __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

08-22-2005, 10:22 PM	#3
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	Its definetly the transfer case since it engages fine in 4lo and there is no grinding noise with the tranny in gear. It drives and shifts fine when in 4lo. The gear grinding noise starts when I try to put the tc in 4hi or 2hi and shift the tranny from park to any gear. We're thinking that one of the shift rods (rails?) is not lining up with the detents (proper term?). I haven't been able to find an exploded view of the 205 to know exactly what's inside. __________________ http://1972blazer.shutterfly.com/<= blazer build pics It's called golf because all the other four letter words were taken. It's easier to ask for forgiveness than for permission.

08-23-2005, 01:29 AM	#5
71RestoRod Registered User Join Date: Sep 2003 Location: Evergreen, CO Posts: 492	It sounds to me almost as if your range fork is disconnected. I wonder if the shift fork pin was set good during the rebuild? Fork installed in the correct orientation? There is also supposed to be a 'L' shaped end on the range shift rod that rides on the shift rail link and helps it shift into position. Is that still there? I would be tempted to pull the inspection cover on the driver side and see if / how it is shifting into high. Here's some info. I hope the images are clear enough to read. Attached Images __________________ 71 Blazer / GMPP ZZ383 / MPFI / 700R4 / 4-Wheel Disk / Ground-up frame off almost completed resto-mod Last edited by 71RestoRod; 08-23-2005 at 01:32 AM.

08-23-2005, 01:30 AM	#6
71RestoRod Registered User Join Date: Sep 2003 Location: Evergreen, CO Posts: 492	more... Attached Images __________________ 71 Blazer / GMPP ZZ383 / MPFI / 700R4 / 4-Wheel Disk / Ground-up frame off almost completed resto-mod

08-22-2005, 11:43 PM	#4
wolfthing2000 Account Suspended Join Date: Oct 2004 Posts: 1,276	I had the same problem with a Turbo 350 203 combo. If the transfercase finds neutral while the transmission is in park and you don't get it in 2 hi and move the auto shifter out of park the gears are going around in the trans and can't mesh to the transfercase. When this happens you have to turn the truck off, shift to park restart and shift into 2 hi BEFORE moving the auto trans shifter, if not you have to start over. I would check all aspects of the shift mechanism, as mine had the problem until I tightened up the pivot bolt that the linkage works on. Good luck!

08-23-2005, 07:58 AM	#7
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	71RestoRod - What manual did that come out of? Thanks so much, exactly what I needed to see! __________________ http://1972blazer.shutterfly.com/<= blazer build pics It's called golf because all the other four letter words were taken. It's easier to ask for forgiveness than for permission.

08-23-2005, 09:01 AM	#8
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	Is there a chance that since I do not have a front driveshaft installed, that those gears do not have a load on them and causing some of the problem? __________________ http://1972blazer.shutterfly.com/<= blazer build pics It's called golf because all the other four letter words were taken. It's easier to ask for forgiveness than for permission.

08-23-2005, 09:05 AM	#9
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	This needs to be a sticky! Lots of good info! __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

08-23-2005, 12:51 PM	#10
gator2511 Registered User Join Date: Mar 2005 Location: tampa florida Posts: 776	I put a TH400 in my truck. I also have an NP205. Mine does the same thing, I just put the tranny in neutral and shift the transfer case. It that doesn't work I just turn off the engine and then shift it. Everything works just fine and I don't worry about it. Last edited by gator2511; 08-23-2005 at 12:53 PM.

08-30-2005, 11:12 AM	#12
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Hey guys -found our "problem" (orangeuavol's dad) http://67-72chevytrucks.com/vboard/s....php3?t=170577 __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

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