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Unread 05-10-2011, 09:56 AM   #1
ninjakid
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How many 87's came with a NP231?

Reading a topic and this popped into my head.
I don't remember where but I read somewhere that late year 87's got 231's put into them.
Do any of you know if this is true?
Because if so that might explain why I have a 231 and a couple other things that I though didn't come in 87's.
It kinda looks like my jeep was a great find for me since its my first vehicle.
87K miles with a tf999, 231 and I got a brand new weber 32/36 with the proper jetting for $200 plus I don't have rust on the body or frame.
Now if only the IPO hadn't put the wrong spark plugs in it. Then I wouldn't have had to rebuild it and I would be driving it. But at least I am learning a lot of stuff.
On a side note is it correct that the tf999 either goes by tf6 or is mostly the same?
Because that would explain why I find so many rebuild kits under that and not tf999.

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Unread 05-10-2011, 10:35 AM   #2
timatoe
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Don't know, the wiki says......
Quote:
Originally Posted by Wiki
A limited number of early 1987 model year YJ's were equipped with the NP207 transfer case
That would lead me to believe you're more likely to get one with the 231 than without.
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Unread 05-10-2011, 11:22 AM   #3
moonshinefuel
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Quote:
Originally Posted by ninjakid View Post
Reading a topic and this popped into my head.
I don't remember where but I read somewhere that late year 87's got 231's put into them.
Do any of you know if this is true?
Because if so that might explain why I have a 231 and a couple other things that I though didn't come in 87's.
It kinda looks like my jeep was a great find for me since its my first vehicle.
87K miles with a tf999, 231 and I got a brand new weber 32/36 with the proper jetting for $200 plus I don't have rust on the body or frame.
Now if only the IPO hadn't put the wrong spark plugs in it. Then I wouldn't have had to rebuild it and I would be driving it. But at least I am learning a lot of stuff.
On a side note is it correct that the tf999 either goes by tf6 or is mostly the same?
Because that would explain why I find so many rebuild kits under that and not tf999.
I would attain the info from the tag on the t-case, and from that info you should be able to find out if that is the original t-case. In the stock specs section of the yj forum here it shows this:
Transfer Cases

NP207 - "Command-Trac" part-time only - 2.61:1 ratio low range - only in 87


But as you mentioned, somewhere in 87, the 231 was put in them, how many? Not sure, interesting question though. Again the numbers on the circular tag on the t-case should be revealing.
Stock specs link > http://www.jeepforum.com/forum/f12/y...-specs-563403/
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Unread 05-10-2011, 12:07 PM   #4
ninjakid
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Quote:
Originally Posted by timatoe View Post
Don't know, the wiki says......

That would lead me to believe you're more likely to get one with the 231 than without.
thanks. I must have misread that page.
I do know for sure that I have the 231. When I was crawling around underneath finding out what shocks I have (discovered they are plain Monroe ones BTW) I noticed how the tag on the transfer was all clean and shiny compared to everything else down there. It clearly said new process 231 or something like that. Tonight when I get home from work I'll post what else it says.
Thanks. Now can anyone verify tf6 is the same as tf999?
Michael the curious.
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Unread 05-10-2011, 12:24 PM   #5
Brazuca
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Show us a picture of your '87. I'll be test driving one this evening. How difficult was the conversion to the Weber 32/26 carb and did it have the original OEM carb before ?
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Unread 05-10-2011, 02:37 PM   #6
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Quote:
Originally Posted by Brazuca
Show us a picture of your '87. I'll be test driving one this evening. How difficult was the conversion to the Weber 32/26 carb and did it have the original OEM carb before ?
Sorry didn't see your post.
It did have the crappy Carter.
The conversion isn't that hard but it definitely isn't easy.
I know somewhere on this forum is a guide that the previous person printed out and stuck in the box.
It was real helpful compared to the cryptic instructions that come with the carb.
It does take a couple hours.
More time-consuming that anything else.
I followed the guide from this forum and it really helped with pictures of every step so I'd say the hardest part is adjusting the idle and that stuff.
Tbh I left it to my dad who is a aircraft mechanic of 40 something years and has far more experience than I do.
I'd say that anyone with a free afternoon could do it.
At work currently but when I get home I'll post a pic of it. Might be a tad late then but I need to take some pictures of it anyways.
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Unread 05-10-2011, 05:00 PM   #7
Hbeaudreau
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Its an easy swap to get rid of the 207. I swapped mine out about 4 months ago. All i had to do was source one from an 4 cyl standard Yj. It bolted in behind my 6cyl 87 with the puegot transmission. waiting for my transimission to blow up now
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Unread 05-10-2011, 05:59 PM   #8
ctm
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yes the TF999 is sometimes called a TF6, but for parts and rebuild kits use Chrysler A904, and then within the A904 family there are multiple variations of parts that would comprise an a904,997,998,999 etc.

If you are looking to rebuild it I recommend tearing into it first and then make a list of parts to order, some of which would be in a rebuild kit and some not; the parts lists and kits cover literally decades of transmission variations. I like to use wittrans.com and bulkpart.com
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Unread 05-12-2011, 11:30 AM   #9
ninjakid
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Quote:
Originally Posted by moonshinefuel View Post
I would attain the info from the tag on the t-case, and from that info you should be able to find out if that is the original t-case. In the stock specs section of the yj forum here it shows this:
Transfer Cases

NP207 - "Command-Trac" part-time only - 2.61:1 ratio low range - only in 87


But as you mentioned, somewhere in 87, the 231 was put in them, how many? Not sure, interesting question though. Again the numbers on the circular tag on the t-case should be revealing.
Stock specs link > http://www.jeepforum.com/forum/f12/y...-specs-563403/
Tad late but here is the tag on it.
Clean compared to everything else on it
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Unread 05-12-2011, 11:39 AM   #10
JFcavedweller
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clearly the 231, as most apparently were in 87 (just not some of the earliest)
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Unread 05-12-2011, 12:37 PM   #11
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Quote:
Originally Posted by JFcavedweller View Post
clearly the 231, as most apparently were in 87 (just not some of the earliest)
Looks like it.
I am quite glad to have the 231 not the 207.
Did all of those tags say 231 AMC for all 231's back in the late 80's/early 90's?
Not sure if it has a meaning but I see in the serial number it has a 87 in it near the end.
Might just be a coincidence.
Assuming there is nothing more I can translate from the tag numbers?
Thanks.
My curiosity streak has awoken.
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Unread 05-12-2011, 01:59 PM   #12
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Quote:
Originally Posted by ninjakid View Post
Assuming there is nothing more I can translate from the tag numbers?
well the main other thing is that it has 2.72 ratio for 4L, but you can find that anywhere, it just further confirms that its a 231 instead of the 207
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Unread 05-12-2011, 02:45 PM   #13
soonericko
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I have an 87 that came out with the 231 and i bought one to replace it out of an 87. so i guess they are pretty common
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Unread 05-12-2011, 02:50 PM   #14
Peter Nuss
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Every Yj made after March 9th or 17th 1987 had a 231 in it.
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