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Unread 08-31-2012, 05:55 AM   #1
bills79jeep
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Engine Swap - Flexplate to Torque Converter?

I'm in the process of swapping out a 4.0 for 4.0, and it's my 1st time. I got a "new" motor at the junkyard, and it's ready to go in. However, my Haynes manual says that I should index my flexplate to the torque converter with paint, so when I put it back together, I can line them up.

One, I can't do this because a different engine is going back in, so there won't be a mark on the new flexplate. I wasn't planning on swapping the flexplate to the new motor, should I do that?

Two, even if I wanted to mark them, I can't see the torque converter to make a mark on it. I have the inspection cover off, and the flexplate blocks any view I could have of the TC. Once again, the manual says to clamp the TC in so it doesn't come out with the engine, but I can't see it, let alone get a clamp on it.

I can't think of any reason they would need to be aligned in any special way, except maybe for the CPS. Are the bolt holes non-concentric, so there is only one way to bolt them up?

Thanks

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Unread 08-31-2012, 06:01 AM   #2
cruiser54
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Haynes is on crack. Bolt the flexplate to the engine. Put it in.
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Unread 08-31-2012, 08:19 AM   #3
bills79jeep
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Quote:
Originally Posted by cruiser54 View Post
Haynes is on crack. Bolt the flexplate to the engine. Put it in.
Thanks.

Do I need to do anything in regard to the CPS? I know it takes readings off the flywheel.
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Unread 08-31-2012, 08:23 AM   #4
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Quote:
Originally Posted by bills79jeep View Post
Thanks.

Do I need to do anything in regard to the CPS? I know it takes readings off the flywheel.
Need more info. What exactly are you working on and what year is the donor engine?
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Unread 08-31-2012, 08:30 AM   #5
bills79jeep
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I am taking the engine out my my 98 Cherokee, and putting in another 4.0 from a 96 Cherokee. From what I understand, it's the same motor. Currently, the donor motor has the flexplate still attached from the original Jeep.
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Unread 08-31-2012, 09:33 AM   #6
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Use the flexplate,dist,coils,sensors,intake,TB from your 98 engine on the 96 engine you are installing so your wiring connectors on your harness will be able to connect.
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Unread 08-31-2012, 10:11 AM   #7
bills79jeep
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Use the flexplate,dist,coils,sensors,intake,TB from your 98 engine on the 96 engine you are installing so your wiring connectors on your harness will be able to connect.
I am using all of the accessories from the '98. Pretty much everything but the long block portion will be switched over to the '96 engine.

I was under the impression that the flexplate for the '96 and '98 are identical, do you have a reason that you'd swap it?
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Unread 08-31-2012, 10:40 AM   #8
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I would swap it if I wasn't sure. The 6 flexplate bolts could save pulling the tranny when it doesn't run. Haven't much experience with the obd2 4.0 so err on the side of caution. I'd swap them just so I was sure.

I swapped my 95 4.0 for a 98 and connectors are all different. So I put all the 95 goodies on 98 block. Head was different also. Make sure new head has same connection. My head has 2 coolant sensors, 98 donor had 1 and no hole in the rear of block where it should have been.
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Unread 08-31-2012, 11:02 AM   #9
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I myself am not certain whether the 96 and 98 flex plates are the same for certain but I would not chance it, as the pick ups that the CPS use could be slightly different.And when you change the two out remember that the holes in the flexplate and the end of the crankshaft will only line up in one position so you can not install it wrong.
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Unread 08-31-2012, 11:13 AM   #10
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And when you change the two out remember that the holes in the flexplate and the end of the crankshaft will only line up in one position so you can not install it wrong.
Thanks. I was aware that the flexplate-to-crank connection was that way, is the flexplate-to-TC the same?
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Unread 08-31-2012, 11:38 AM   #11
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Flex to TC is simple get one bolt in and the rest will line up just get all four started before tighting them.
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Unread 08-31-2012, 07:28 PM   #12
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look at the part numbers on both flexplates & see if they match
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