Hello All,

I started to swap my 4.2 for a 4.0 and everyone at 4x4wire has been helpful with all the questions that IÆve had and I appreciate it. I have at least one more.
What I have done to this point is purchase service manuals for both the 91XJ and my 89YJ, tagged & labeled everything coming out of the XJ and everything in my YJ. I pulled both engines, changed the water pump on the XJ to a 91YJ so I can run a mechanical fan, swapped out the 4.2 fuel tank and replaced it with a 91YJ 4.0, put my YJ transfer case on the XJ AX15 transmission, purchased new motor & transmission mounts, purchased a 91YJ down exhaust pipe and a couple of other preventive maintenance items.

IÆm going to install everything tomorrow. The question I have is the XJ motor and transmission is about an inch longer than the YJ motor and transmission? will I need to modify my transmission skid plate, drive line, shift & 4x4 handles that enter the cab and drive lines? will I even have room in the engine compartment between the motor and transmission (fire wall). If all this needs to be changed can I just move my motor mounts forward about an inch? If I do that will I have enough clearance for my fan and radiator?
Or am I just over thinking this and itÆs all going to fit?

Any more information will appreciated.

Thanks,

Josephelk

I can't really answer your questions, but I'll speculate. It seems to me the 4.0 and the 4.2 are the same size. 4.0's with Ax-15's are in tens of thousands of YJ's, You should be able to fit it with out too much difficulty. I would think it would be easier to make some new holes in the skid plate if needed than to relocate the engine mounts. Is there something wrong with the 89 transmission? Why don't you use it? <img src="/forums/images/graemlins/confused.gif" alt="" />

I didn't really want to drill holes in the YJ transmission for the CPS. I have heard some horror stories about getting it located perfectly? So I was going to us the XJ tranny that already has it. I was looking forward to selling my YJ tranny & engine to recoup some cash.
I think slotting the skid plate holes would be the easiest. I have a cutting torch, welder, drills, grinders and pretty much everything else needed to work on metal so if I need to modify some items I can. IÆm running out of time because hunting season is around the corner, but I donÆt want to cut any corners.
Would you think adding an inch or under in length is going to effect my drive lines like binding them? I have a 3.5ö lift with 33ö tire on my YJ also.

Thanks,

Josephelk

I think you will be OK with the driveshaft length. Just an opinion derived from the 3.5 lift.. I'd guess the existing fit is a bit short and the new fit wil be a bit long but should work fine.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

When I put the lift in it did stretch out the drive line some.

Thanks

The transmission and bell housings are bolted together, you should be able to swap bell housings from one AX-15 to another. Just a thought. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Thanks but it's already in. It looks like the transfer case drive line is fine and the main drive line from the transmission is ok also. I had to pull the passenger side motor mount off because I put the long bolt in backwards and the oil filter wouldn't fit. The easy part is done, now I get to start sorting out wires.

Thanks,

Josephelk