Jump to content

Recommended Posts

I Have a 86' Jeep Comanche in it has a 2.5 4cyl motor in it and i would like to put a 4.0 Inline 6 from a Jeep Cherokee in to my truck but I know I will need a swap for it and i would like to keep my 5 speed Transmission if at all possible. Has anyone done this swap before or Know were I may be able to get a swap for this. Thanks comanche.gif

Link to post
Share on other sites
I Know its a 5 speed standard transmission from a 86' jeep comanche with a 2.5L 4cyl motor. Where Should I look to see the Part Number on My Transmission.

 

you should not bother looking for the part number on your transmission. IT WILL NOT WORK WITH A 6 CYL 4.0 SWAP!.

 

 

this needs to go in the tech section. you have an ax4 or ax5. you need an ax15 or ba10/5

Link to post
Share on other sites

The ax-4 (4-speed) or ax-5 (5-speed) that is behind your 2.5 isn't even close to being beefy enough to last behind a 4.0L, and the bellhousing pattern doesn't match up to the 4.0L either. If you swap in a 4.0L, you'll have to modify your firewall and the front radiator area of your jeep because it is an '86. The dimensions of an ax-15 are different. It is usually all bolt-in for most Cherokees, but yours might not be because it is an '86 and they didn't have the 4.0L until '87 IIRC. One popular swap is to put in a 3.4, which will mount up to your ax-5. A better option, unless you have a lot of money into the BODY of your XJ, is to simply buy one with a 4.0L/AX-15, then swap everything you want from your cherokee onto the 4.0L one and sell your current one.

Link to post
Share on other sites
The ax-4 (4-speed) or ax-5 (5-speed) that is behind your 2.5 isn't even close to being beefy enough to last behind a 4.0L, and the bellhousing pattern doesn't match up to the 4.0L either. If you swap in a 4.0L, you'll have to modify your firewall and the front radiator area of your jeep because it is an '86. The dimensions of an ax-15 are different. It is usually all bolt-in for most Cherokees, but yours might not be because it is an '86 and they didn't have the 4.0L until '87 IIRC. One popular swap is to put in a 3.4, which will mount up to your ax-5. A better option, unless you have a lot of money into the BODY of your XJ, is to simply buy one with a 4.0L/AX-15, then swap everything you want from your cherokee onto the 4.0L one and sell your current one.

 

You are correct as the 4.0L will not fit into an '86 MJ. They redesigned the whole engine compartment in '87 to fit the longer 4.0L in there. I've seen GM 3.4L and 3.8L engines swapped in place of the 2.8L but haven't seen too many 4cyl's upgraded. There was an AX-5 behind the 2.8L in mine but that was only cranking out a whole whopping 140hp.

 

I chose to swap in a Chevy 350 instead of fighting with the 4.0L (was looking at putting more power in there so was either going to be a 5.7L V8 or 4.7L stroker). Novak makes adapters to put an AX-15 behind the engine and they make motor mounts to fit, but the motor mounts will have to be slightly modified to fit the '86.

 

I'm not sure exactly what you're planning on doing with this Jeep but you will need an AX-15 5sp manual trans if you intend on going with anything larger than the V6.

Link to post
Share on other sites
The ax-4 (4-speed) or ax-5 (5-speed) that is behind your 2.5 isn't even close to being beefy enough to last behind a 4.0L, and the bellhousing pattern doesn't match up to the 4.0L either. If you swap in a 4.0L, you'll have to modify your firewall and the front radiator area of your jeep because it is an '86. The dimensions of an ax-15 are different. It is usually all bolt-in for most Cherokees, but yours might not be because it is an '86 and they didn't have the 4.0L until '87 IIRC. One popular swap is to put in a 3.4, which will mount up to your ax-5. A better option, unless you have a lot of money into the BODY of your XJ, is to simply buy one with a 4.0L/AX-15, then swap everything you want from your cherokee onto the 4.0L one and sell your current one.

 

You are correct as the 4.0L will not fit into an '86 MJ. They redesigned the whole engine compartment in '87 to fit the longer 4.0L in there. I've seen GM 3.4L and 3.8L engines swapped in place of the 2.8L but haven't seen too many 4cyl's upgraded. There was an AX-5 behind the 2.8L in mine but that was only cranking out a whole whopping 140hp.

 

I chose to swap in a Chevy 350 instead of fighting with the 4.0L (was looking at putting more power in there so was either going to be a 5.7L V8 or 4.7L stroker). Novak makes adapters to put an AX-15 behind the engine and they make motor mounts to fit, but the motor mounts will have to be slightly modified to fit the '86.

 

I'm not sure exactly what you're planning on doing with this Jeep but you will need an AX-15 5sp manual trans if you intend on going with anything larger than the V6.

 

 

I bet you haven't seen even 1 3.8 buick swap into one.

 

that said, the only difference in the firewall requires a hammer massage, and the header panel/upper rad supports and front crossmember weld right in from a 4.0l

Link to post
Share on other sites
  • 2 years later...

So the for 87 you wouldn't have to change the fire wall to put the 4.0 in on a 4 cyl? What about the engine mounts how much would they need to be changed? could you just yank the motor and motor mount from a xj an put it in?

 

Thanks, hunter

Link to post
Share on other sites

Yes, for an 87 the firewall has already been modified to fit a 4.0. Never compared them closely, but I imagine the engine mounts would need to be changed. I also imagine that part is a bolt in affair.

 

Most of the work would be the front: radiator, radiator support, and all the little pieces that go with it.

 

If you get an 87-90 XJ, you will have everything you need and it should bolt in. This includes the computer, TCM if automatic, and engine bay wiring harness. You will also need to pull the fuel pump assembly from the tank and swap out the 2.5 fuel pump on it for the larger 4.0 one. Don't forget to put a new sock on it at the same time.

 

I would suggest getting an entire XJ. Just like a 4x4 swap this will ensure you will have all the little parts you'd probably forget about otherwise.

Link to post
Share on other sites

Yes, for an 87 the firewall has already been modified to fit a 4.0. Never compared them closely, but I imagine the engine mounts would need to be changed. I also imagine that part is a bolt in affair.

 

Most of the work would be the front: radiator, radiator support, and all the little pieces that go with it.

 

If you get an 87-90 XJ, you will have everything you need and it should bolt in. This includes the computer, TCM if automatic, and engine bay wiring harness. You will also need to pull the fuel pump assembly from the tank and swap out the 2.5 fuel pump on it for the larger 4.0 one. Don't forget to put a new sock on it at the same time.

 

I would suggest getting an entire XJ. Just like a 4x4 swap this will ensure you will have all the little parts you'd probably forget about otherwise.

 

 

:agree:

Link to post
Share on other sites

Yes, for an 87 the firewall has already been modified to fit a 4.0. Never compared them closely, but I imagine the engine mounts would need to be changed. I also imagine that part is a bolt in affair.

 

Most of the work would be the front: radiator, radiator support, and all the little pieces that go with it.

 

If you get an 87-90 XJ, you will have everything you need and it should bolt in. This includes the computer, TCM if automatic, and engine bay wiring harness. You will also need to pull the fuel pump assembly from the tank and swap out the 2.5 fuel pump on it for the larger 4.0 one. Don't forget to put a new sock on it at the same time.

 

I would suggest getting an entire XJ. Just like a 4x4 swap this will ensure you will have all the little parts you'd probably forget about otherwise.

 

I did the 4.0 swap on my '87, and ^^^^ is 100% correct. You do need to swap the frame horn engine brackets, the holes are already there in the framerails to accept them. You also need 4.0 motor mounts (the 2.5 ones look the same, but they are not and won't work.) The 4.0 radiator bolts straight into the header panel, but you need the two upper rubber mounts, don't forget to snag them also. I used an '89 wiring harness/ECU that came from an automatic MJ, everything plugged in 100%. If I ever decide to switch to an automatic at some point, all I have to add is the tranny and a TV cable, all the wiring and TCU is already there for me :)

 

Jeff

Link to post
Share on other sites
  • 8 months later...

Ok so perhaps I had my lines crossed. When people said wiring harness I thought that meant rewiring the whole truck front to back! So all I have to get (as long as it has the c101) is the "under hood" wiring? If so, that works out because I am a novice. And was not looking forward to dropping the dash and yanking the interior. ....may have an 88 donor lined up

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...