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Unread 01-16-2013, 08:27 AM   #1
wanabejeeper
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out of curiosity xj to yj question

If was to do an xj to yj 4.0mpfi head swap using the entire computer and wiring setup and since I have a tf909 could I also take the tf999(actually AW4 as noted by 94chb below) and take advantage of the 4 speed or lock up converter (not sure which it has)? I intend to replace the NP207 that I have with a 231 with an SYE when I do a lift in the spring if I have driveline issues. Would it make more sense to wait and use the 231 from the xj?

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[QUOTE=Anticanman;14767780]It goes in that barrel you wheel out to the street once a week.[/QUOTE]


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Unread 01-16-2013, 09:12 AM   #2
94chb
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xj doesnt have a tf999 but a AW4 , my 89 yj came with a tf999 but when i went FI i discovered i couldnt use my trans because there is no CPS or even a spot for one. i found a aftermarket kit that puts a CPS on the front of the crank but it was expensive. so i just went ahead and went to the ax15
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Unread 01-17-2013, 08:23 AM   #3
wanabejeeper
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bump any other suggestions.... I'd like to get away from the 3peed auto to a 4 speed auto. Is it possible the way I'm thinking?
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[QUOTE=Anticanman;14767780]It goes in that barrel you wheel out to the street once a week.[/QUOTE]


My build thread [url]http://www.jeepforum.com/forum/f12/new-build-thread-867043/[/url]
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Unread 01-17-2013, 08:29 AM   #4
dillonjm
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You can run an AW4 in a YJ, I do.

Sounds like you're wanting to just swap the whole shebang over which isn't a bad idea, especially if you can get all the wiring/computer/TCM. It will save you some wiring for the tranny if you decide to use the AW4.

Or am I misunderstanding your question?
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Unread 01-17-2013, 09:13 AM   #5
wanabejeeper
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Nope you have it right. I have a freshly rebuilt 4.2 but the older 909 and 207. My thinking is if I take the 4.0 mpfi and associated computer wiring etc, why not take the 4 speed tranny and the 231. I'm just wondering what hoops I'll have to jump through as par tof the install.

I've planned to do the MPFI upgrade from the very beginning and have learned about the SYE as part of the lift. The SYE is only available for the 231 that I can find. I plan on ditching the shackle lift that is on it and going to OME or Black diamond 2.5 to 3"" springs 1" booms and an SYE assuming the SYE is necessary. So that lead me to wonder if I'm getting the MPFI from the cherokee and the 231 why just not put the whole shebang in and getting a 4 speed while Im at it.

The big question is above and beyond the mpfi. What mechanical changes/ adaptors/ linkage changes will I need to overcome?
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[QUOTE=Anticanman;14767780]It goes in that barrel you wheel out to the street once a week.[/QUOTE]


My build thread [url]http://www.jeepforum.com/forum/f12/new-build-thread-867043/[/url]
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Unread 01-17-2013, 09:40 AM   #6
dillonjm
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Pretty much everything will be new.

You'll need motor mounts, tranny mount, etc. You can fab a transmission mount that uses the yj style rubber isolator and mates to your current skid plate very easily- it just requires some 1/4" flat bar. You can use the factory xj transmission shifter and cable, it actually mounts to the yj tranny pan very nicely. You'll have to fab up a t-case shifter.

You'll also want to clock the tcase up a little, the xj clocking hangs it down farther than you'd want in a YJ. This just requires drilling new holes, very easy as well.

There is lots of info on putting an aw4 into a YJ on the net. Any of those write ups address the linkage/mounting issues. The engine stuff will be the same as any swap. You'll need to burn in some motor mounts and address plumbing and wiring.

Jerrod
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Unread 01-17-2013, 09:48 AM   #7
wanabejeeper
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The big question then is can I keep the 4.2 block?
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[QUOTE=Anticanman;14767780]It goes in that barrel you wheel out to the street once a week.[/QUOTE]


My build thread [url]http://www.jeepforum.com/forum/f12/new-build-thread-867043/[/url]
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Unread 01-17-2013, 10:06 AM   #8
94chb
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my was the 4.2 and 909, im now 4.0 from newer jeep and mpfi and ax15, also lifted 4.5 and no SYE also my lift is up for sale cheap. im now going SOA and d44 front and rear and stretching around 10 in.


yes you can keep your 4.2 block if you want to, everything bolts up the same as 4.0 block
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Unread 01-17-2013, 10:48 AM   #9
YJ4LIFE
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Quote:
Originally Posted by wanabejeeper View Post
The big question then is can I keep the 4.2 block?
there was a thread last week about it being externally balanced and having issues with an aw4.
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