Info for 4 speed manual to TH400 conversion

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SRT6
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Location: Hilton Head, SC

Info for 4 speed manual to TH400 conversion

Post by SRT6 »

Howdy. I purchased a donor 1977 J20 TH400 / QuadraTrac parts truck to convert my 1979 J10 360 V8 4 speed Manual to AUTO. Unfortunately the donor car was without axles, sitting on the ground, so I did not see that the QuadraTrac had grenaded and slung it's chain through the case. Is there an adapter that would allow the donor TH400 auto to mate with the existing Dana D20? Since I cannot use or rebuild the QT Xfer case?
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FLeetFox
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Re: Info for 4 speed manual to TH400 conversion

Post by FLeetFox »

https://www.novak-adapt.com/catalog/ada ... o/kit-124/

Not cheap, but well engineered, and good tech support.

Fleet Fox
I do things my way, and I pay a high price.... JCM

Topic author
SRT6
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Joined: Mon Jan 21, 2019 9:46 am
Location: Hilton Head, SC

Re: Info for 4 speed manual to TH400 conversion

Post by SRT6 »

FLeetFox wrote: Wed Apr 14, 2021 9:49 am https://www.novak-adapt.com/catalog/ada ... o/kit-124/

Not cheap, but well engineered, and good tech support.

Fleet Fox
Thank you. I saw that, and got very excited. Then I called Novak and they let me know that you have to completely disassemble your automatic transmission and remove literally every single part out of your TH400 automatic transmission to install a new part that sticks out the back to mate with the Jeep transfer case! That sounds terrifying :shock:
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Stuka
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Re: Info for 4 speed manual to TH400 conversion

Post by Stuka »

Its not as bad as it sounds. You have to pull the pan and filter, pull the valve body and check balls. Then the main "guts" come out in sub-assemblies. I think there is 3 of them before you get to the last one which is the output shaft. There are videos on YouTube of guys pulling it apart down to that level in 15-20 mins.

You can also have a transmission shop do it. If you trans is already in good working order, it should not cost much. If you need a rebuild anyway, well, good time to have that done too.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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FLeetFox
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Re: Info for 4 speed manual to TH400 conversion

Post by FLeetFox »

What he said. Most of us start with an unknown. If the Qtrac grenaded, chances are the TH400 probably needs a good go over. Yeah I know, $600 for the kit, plus the cost of a trans rebuild. Stuff adds up. there are no cheap drivetrain swaps.

Fleet Fox
I do things my way, and I pay a high price.... JCM

Topic author
SRT6
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Joined: Mon Jan 21, 2019 9:46 am
Location: Hilton Head, SC

Re: Info for 4 speed manual to TH400 conversion

Post by SRT6 »

FLeetFox wrote: Wed Apr 14, 2021 8:39 pm What he said. Most of us start with an unknown. If the Qtrac grenaded, chances are the TH400 probably needs a good go over. Yeah I know, $600 for the kit, plus the cost of a trans rebuild. Stuff adds up. there are no cheap drivetrain swaps.

Fleet Fox
Hmmm. You both raise good points. I will keep u posted.
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1978J10REDWHITE
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Re: Info for 4 speed manual to TH400 conversion

Post by 1978J10REDWHITE »

I have this very setup too, yet bought the thing this way.
They put a B&M box type shifter W/ Cable in it, works great!

To go thru a TH400 is fairly easy for a layman who never did it before, as I did one in the 80’s, it was quit doable straight forward.
New things in the running gear is always good.

Topic author
SRT6
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Joined: Mon Jan 21, 2019 9:46 am
Location: Hilton Head, SC

Re: Info for 4 speed manual to TH400 conversion

Post by SRT6 »

Well. I managed to pick up another 1977 J10 Auto parts truck. So I have a spare TH400, Spare 360 V8, and a QuadraTrac that at least has it's chain inside versus out. Let the conversion begin!
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FLeetFox
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Re: Info for 4 speed manual to TH400 conversion

Post by FLeetFox »

Cool. just remember the adage "free parts can often cost you the most money" with regards to trying to make them fit!

Keep us informed, all here to help.

Fleet Fox
I do things my way, and I pay a high price.... JCM
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