NP205 TH400 question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

orangeuavol · 05-08-2005, 03:35 PM

Noticed for the first time today that when I shift the transmission from park to drive I get a gear grinding sound from the transfer case. When I put the tcase in 4lo, start the engine, ans shift gears its fine. But it makes that noise in 4hi and 2hi. Is this just the nature of the beast or is the tcase not fully engaging?

I've only moved the blazer in 4lo. Should I try to put it in 2hi and drive down the driveway to see it still makes that noise? First NP205 TH400 combo I've had so I don't know what to expect. Thanks in advance.

update:
the only t case position that will hold when the trannt is in park is 4lo (i.e with tranny in park it rolls like its in nuetral in 4hi and 2hi).

orangeuavol · 05-08-2005, 08:19 PM

Bueler...Bueler...Bueler...

Anyone?

smokekiki · 05-09-2005, 09:57 AM

Wouldn't want to jump to conclusions,but it doesn't sound good to me.It should hold in high.Should not be any grinding.

bouncytruck · 05-09-2005, 10:06 AM

My '69 had a gear grinding noise in similar situations. The rear sprag clutch in my TH350 exploded. The sound was the fragments of bearings being tossed around inside the case until one wedged between the case and other internal parts and shattered more internals and cracked the case. I was sitting still in the driveway trying to determine where the noise was coming from - I thought it was my t-case.

I'd check/change fluid in the 205 first. If all looks good, I'd pull the pan in the tranny and look for metal.

*Medicanman71* · 05-09-2005, 01:24 PM

mine does it too sometimes but so far so good.... show it who's boss

Blazer1970 · 05-09-2005, 05:55 PM

The t-case is not shifting properly. Your truck is not going to move if you try it in 4HI or 2HI. It is only shifting halfway from low to high.

orangeuavol · 05-09-2005, 08:33 PM

Figured it out! Its a combination of slop in the shifter, shifter linkage rod, and the cross bar that connect the two shift rods. Whew, thought I was going to have to tear that thing apart.

smokekiki · 05-10-2005, 08:10 AM

Glad it was something simple.

05-08-2005, 03:35 PM	#1
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	NP205 TH400 question Noticed for the first time today that when I shift the transmission from park to drive I get a gear grinding sound from the transfer case. When I put the tcase in 4lo, start the engine, ans shift gears its fine. But it makes that noise in 4hi and 2hi. Is this just the nature of the beast or is the tcase not fully engaging? I've only moved the blazer in 4lo. Should I try to put it in 2hi and drive down the driveway to see it still makes that noise? First NP205 TH400 combo I've had so I don't know what to expect. Thanks in advance. update: the only t case position that will hold when the trannt is in park is 4lo (i.e with tranny in park it rolls like its in nuetral in 4hi and 2hi). __________________ 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. Last edited by orangeuavol; 05-08-2005 at 04:53 PM.

05-08-2005, 08:19 PM	#2
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	Bueler...Bueler...Bueler... Anyone? __________________ 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.

05-09-2005, 09:57 AM	#3
smokekiki Mike Join Date: Jan 2003 Location: west chester pa Posts: 2,473	Wouldn't want to jump to conclusions,but it doesn't sound good to me.It should hold in high.Should not be any grinding. __________________ 70'c/10, 71 suburban4x4 402bb, 72suburban 4/6 drop, 72k/5 4x4 blazer 4" lift 35 tires

05-09-2005, 10:06 AM	#4
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	My '69 had a gear grinding noise in similar situations. The rear sprag clutch in my TH350 exploded. The sound was the fragments of bearings being tossed around inside the case until one wedged between the case and other internal parts and shattered more internals and cracked the case. I was sitting still in the driveway trying to determine where the noise was coming from - I thought it was my t-case. I'd check/change fluid in the 205 first. If all looks good, I'd pull the pan in the tranny and look for metal. __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

05-09-2005, 05:55 PM	#6
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	The t-case is not shifting properly. Your truck is not going to move if you try it in 4HI or 2HI. It is only shifting halfway from low to high. __________________ Tim

05-09-2005, 01:24 PM	#5
Medicanman71 Account Suspended Join Date: May 2005 Location: Where the Wild Things Are Posts: 696	mine does it too sometimes but so far so good.... show it who's boss

05-09-2005, 08:33 PM	#7
orangeuavol GO VOLS! Join Date: May 2001 Location: Knoxville, TN Posts: 724	Figured it out! Its a combination of slop in the shifter, shifter linkage rod, and the cross bar that connect the two shift rods. Whew, thought I was going to have to tear that thing apart. __________________ 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.

05-10-2005, 08:10 AM	#8
smokekiki Mike Join Date: Jan 2003 Location: west chester pa Posts: 2,473	Glad it was something simple. __________________ 70'c/10, 71 suburban4x4 402bb, 72suburban 4/6 drop, 72k/5 4x4 blazer 4" lift 35 tires



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