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Ok guys, let me start off by saying that I'm swapping from a 2.5L/AX4/NP207 to a 4.0L/AX15 (external slave)/NP231 or NP242 (not sure which yet). Past few nights, I've been working on tearing out the 2.5 in my '86.  I have a '90 XJ with AW4 as my donor.  However, lets forget about it being an '86 for a second because I have a few general questions about the 2.5 to 4.0 swap that I haven't quite been able to find in the vastness that is the interwebz...  Here goes (they'll be more as issues arise):

 

On the AX4/5 equipped MJs, the end of the exhaust downpipe, where it stops just behind the transmission crossmember, I know that it won't work when I move the crossmember back for the AX15.  My question is, can I or do I use the downpipe from the XJ donor, or will that not work either due to length?  If not, what would be the best way to remedy this?

 

Next, I know that I need to upgrade the fuel pump when going from TBI to MPI.  With that also comes replacing all the rubber lines with high pressure fuel injection line.  My question in regards to this is, can I reuse the steel lines that are currently under my MJ or would I/could I use the lines from the donor XJ?

 

Also, since we're on fuel pumps for the moment, will the fuel pump and fuel level floater (fuel sender assembly I guess it's called) interchange between the XJ and MJ tank?  Will there be any wiring issues or is this not a concern since they're both Renix?

 

Now, when I get ready to remove the drivetrain, I plan to remove the engine, tranny and transfer case all in one shot.  How do I remove the AX4's "stick" or shifter arm to clear the belly of the beast?  My MJ sits at stock height and I have only 2.5 ton jacks to work with here.

 

Also, will the transfer case shifter linkages work when going from the 207 to the 231/242?  I also should note that I have the shifter handle, linkages and brackets from the '96 XJ that the AX15 came out of.  (Don't have the transfer case though.)

 

Forgot to add, with the added weight of the engine, will I need to grab some 4.0 coils or will the 2.5 coils suffice?

 

On a random note, I think my AX4 is an external slave setup.  I was under the impression that early AX4's were internal slaves.  But, the PO did say the engine was from a later model Wrangler.  Perhaps the AX4 came from the same Wrangler?  Just a guess.

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On the AX4/5 equipped MJs, the end of the exhaust downpipe, where it stops just behind the transmission crossmember, I know that it won't work when I move the crossmember back for the AX15.  My question is, can I or do I use the downpipe from the XJ donor, or will that not work either due to length?  If not, what would be the best way to remedy this?

 

Use the donor downpipe.

 

Next, I know that I need to upgrade the fuel pump when going from TBI to MPI.  With that also comes replacing all the rubber lines with high pressure fuel injection line.  My question in regards to this is, can I reuse the steel lines that are currently under my MJ or would I/could I use the lines from the donor XJ?

 

Reuse the lines that are in your truck.

Also, since we're on fuel pumps for the moment, will the fuel pump and fuel level floater (fuel sender assembly I guess it's called) interchange between the XJ and MJ tank?  Will there be any wiring issues or is this not a concern since they're both Renix?

 

The pump will swap over, the fuel gauge sender won't. You should be able to use the sender from the 2.5L fuel pump. (I think.)

 

Now, when I get ready to remove the drivetrain, I plan to remove the engine, tranny and transfer case all in one shot.  How do I remove the AX4's "stick" or shifter arm to clear the belly of the beast?  My MJ sits at stock height and I have only 2.5 ton jacks to work with here.

 

Remove the boot inside the cab. There are four bolts holding the shifter into the tranny. Remove bolts, pull out shifter.

 

Also, will the transfer case shifter linkages work when going from the 207 to the 231/242?  I also should note that I have the shifter handle, linkages and brackets from the '96 XJ that the AX15 came out of.  (Don't have the transfer case though.)

 

Use the linkage that goes with the tranny and transfer case you will be installing.

 

Forgot to add, with the added weight of the engine, will I need to grab some 4.0 coils or will the 2.5 coils suffice?

 

You need 4.0L front springs.

 

On a random note, I think my AX4 is an external slave setup.  I was under the impression that early AX4's were internal slaves.  But, the PO did say the engine was from a later model Wrangler.  Perhaps the AX4 came from the same Wrangler?  Just a guess.

 

The '86 had an external slave.

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Have another question for you...  When I get a transfer case to mate to the AX-15, I'm going to opt for a 231 or 242 from a later model (for the sealed output shaft).  The thing that I have a question about is the speedometer gear and cable.  The later model uses an electronic speed sensor with shorter speedo gear.  Obviously the early Jeeps use the cable driven style with longer shaft.  Can I use the cable driven speedometer on the later model transfer case?  Also, would I use the shorter shaft speedo gear or the longer shaft one?

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You can replace the electronic speedo drive with a mechanical. I don't know if you need the long or short gear, however.

 

Don't use the later transfer case unless you plan to do a slip yoke eliminator. The output shaft is VERY long, it is prone to vibration, and it is also prone to causing breakdowns when subjected to serious off-road use. It's a half-baked solution -- Jeep should have done a factory equivalent of a true slip yoke eliminator and used a sealed output, short tailshaft, and put the slip joint in the driveshaft.

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Some more questions as of tonight...

 

I pulled the large collection of wires that run from the driver's side, around the front crossmember, and back up the passenger side.  With that being said, that large collection of wires dead ends into the back of the fuse panel.  My question is, do I remove the fuse panel and pull all those wires out to replace them all with the ones from my '90 XJ donor?

 

Also, how do I remove the steering shaft from the steering gear box?  I need to remove it as it is leaking from the pitman arm.

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