Author Topic: 4l80E to a NP208  (Read 8395 times)

Offline nighthawker5

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4l80E to a NP208
« on: June 10, 2016, 09:56:12 PM »
Hello,

This is my first post to this forum.  Here's my story.  I have an 86 K20 LWB that had a 350 4bbl and a th400 with a NP208 transfer case.  I am swapping a 6.0L LQ4 and a rebuilt 4L80E into it.  My dilemma is with the transmission and the transfer case.  I know the bolt patterns are the same but the adapter on the transfer case won't bolt up because the Transmission mount bolts hit the transmission pan.  Does anyone know where I can find the correct adapter?  I've looked and there are hundreds out there and I'm not sure which one fits.  Heres a pic

Online 1967KaiserM715

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Re: 4l80E to a NP208
« Reply #1 on: June 11, 2016, 10:08:57 PM »
Any one from a 90's Chevy that had the 4l80e should work, I'm fairly positive that all the transfer cases had the same bolt pattern, at least the Borg Warner I had did, and it was the heavy duty one


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Offline nighthawker5

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Re: 4l80E to a NP208
« Reply #2 on: June 11, 2016, 10:12:16 PM »
Thank you very much.  That's will get me in the right direction


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Offline Irish_Alley

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Re: 4l80E to a NP208
« Reply #3 on: June 11, 2016, 10:19:17 PM »
is this a 208 off a th400? never did that much research on the 208 only the 205. i know you cant just take the th400 adapter and slap it on the 4l80 for the 205. think its the same problem.
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Offline nighthawker5

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Re: 4l80E to a NP208
« Reply #4 on: June 11, 2016, 10:37:07 PM »
Yeah it's the 208 off the 400.  The bolt patterns match it's just too short


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Offline frotosride

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Re: 4l80E to a NP208
« Reply #5 on: June 12, 2016, 07:04:22 AM »
https://www.novak-adapt.com/catalog/adapters/transmission-to-transfer-case/4l80e-to/kit-4l83/

Scroll down to the last item listed. It is the 4l83-c kit and made to adapt all the NP cases to the 4l80e. This is my plan when I get to that point!
« Last Edit: June 12, 2016, 07:09:24 AM by frotosride »
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Offline hatzie

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Re: 4l80E to a NP208
« Reply #6 on: June 12, 2016, 10:37:14 AM »
I assume you didn't get the 15724745 1999-2007 4L80E to New Venture transfer case adapter with the tranny.  The yard goons seem to like to pull the adapter and pitch it in the smelter or evilbay em.
Pick one up from Amazon and try it for fit.  I'd be willing to bet this will take care of your problem.  If it doesn't fit return it.
 
The TH400 and 4L80E have the same 32 spline output shaft so that shouldn't be an issue.
« Last Edit: June 12, 2016, 02:14:31 PM by hatzie »
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Offline nighthawker5

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Re: 4l80E to a NP208
« Reply #7 on: June 12, 2016, 10:47:38 AM »
Thank you very much.  That should clear up the issue


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Offline hatzie

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Re: 4l80E to a NP208
« Reply #8 on: June 12, 2016, 03:22:05 PM »
Thank you very much.  That should clear up the issue


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The only mild problem is where the 88up LH drop vs 87 down RH drop puts the transfer case bottom.  You can get clocking rings to fix this...  if it's an issue.

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« Last Edit: June 12, 2016, 03:33:40 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
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Offline Irish_Alley

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Re: 4l80E to a NP208
« Reply #9 on: June 12, 2016, 03:37:22 PM »
are you sure its the adapter hitting and not the output shaft is too long and stopping on the input shaft of the transfer case?

this should work if it is inface the the shafts hitting each other
http://www.cutthroat4x4.com/catalog/product_info.php?products_id=122
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Offline nighthawker5

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Re: 4l80E to a NP208
« Reply #10 on: June 12, 2016, 03:40:35 PM »
Right now it's definitely the adapter.  I might get the new adapter on and get it in another 1/4" only to find the output shaft is too long too. 


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Offline hatzie

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Re: 4l80E to a NP208
« Reply #11 on: June 13, 2016, 12:18:23 PM »
If the output shaft is a little long that's not the end of the world.   The 1999-2007 T800 chassis used LH drop and the squarebodies are RH drop.  When you swap sides like that the transfer case may hang too high or too low...  For some reason I got away with it on my NV4500 when I bolted on the military surplus NP208C.  You'll probably want to re-clock the transfer case for ground clearance and you'll need 7/8" - 15/16" for the Novak clocking ring.
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
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Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline nighthawker5

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Re: 4l80E to a NP208
« Reply #12 on: June 13, 2016, 12:21:17 PM »
If i do that do i need to do anything with the front differential or driveshaft?

Offline hatzie

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Re: 4l80E to a NP208
« Reply #13 on: June 13, 2016, 02:21:31 PM »
If i do that do i need to do anything with the front differential or driveshaft?
If you raise it to near the original position nothing.

I did forget to mention one of the 6 bolts is asymmetric.  The clocking ring can give you back the 6th bolt.

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« Last Edit: June 13, 2016, 02:29:55 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline nighthawker5

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Re: 4l80E to a NP208
« Reply #14 on: December 27, 2016, 09:21:44 AM »
I assume you didn't get the 15724745 1999-2007 4L80E to New Venture transfer case adapter with the tranny.  The yard goons seem to like to pull the adapter and pitch it in the smelter or evilbay em.
Pick one up from Amazon and try it for fit.  I'd be willing to bet this will take care of your problem.  If it doesn't fit return it.
 
The TH400 and 4L80E have the same 32 spline output shaft so that shouldn't be an issue.

This fixed it.  Ordered it from Amazon and put it right on with sealant.  Evertyhing bolted up like it should.  Thank you