4.0 HO conversion and transmission questions

[dj69firebird69]

I have a 1987 Wrangler with the 4.2 and I just bought a 1991 Cherokee with the idea of swapping the 4.0 HO into my YJ. I am trying not to spend too much because money is tight right now so I need to get some opinions on what I should do. If I use the trans out of the XJ it is an AW4 and i will have the CPS sensor and not have to buy the conversion kit for the front crank pulley. But it is a little longer so my driveshafts will be different. But then I have the TF999 from my wrangler which was rebuilt not too long ago but I believe it needs a new torque converter and I would have to buy the CPS conversion kit or make my own opening for the CPS. Or should I buy a different trans all together? If anybody has any suggestions it would be very helpful. I want to get this all figured out before I move any farther on the project. Thanks

[WrenchMonkey]

Sell the YJ. Build the XJ.



Robert

[dj69firebird69]

XJ was wrecked in the front. The kid rearended somebody going 35mph. Its still fixable but I would rather build up my YJ.

[jmb8813]

thats a terrible idea (to build a xj)

[Coppertop]

Sell the YJ. Build the XJ.



Robert

X2
Jeep cherokees rule....

Nick

[GPER]

Sell them both and get a CJ, it will keep you busy.
http://www.cjoffroad.com/forums/default.asp
Go to the 4.0 section, there is a lot of info there for the swaps.

[nick]

I have been in the process of installing a 4.0 in a cj for about 5 years. It is my 2nd jeep. I was just goin to dd this one and wheel easy if my other was down. I cut the cj trans to accept the cps its easy. I would have rather used auto tranny but my transfer was passenger drop. You will have to get a yj water pump or go electric fan. Swap is only supposed to take a weekend. Good luck

[WrenchMonkey]

I have been in the process of installing a 4.0 in a cj for about 5 years... Swap is only supposed to take a weekend. Good luck

That's good stuff right there...

But I think he hits on a valid point, that the rest of us were beating around:

Putting a computer controlled engine in a rig it was never intended for, is a pretty major undertaking. It's not likely to be quick, cheap, or easy.

Is your 23 year old YJ really worth it?

Robert

[dj69firebird69]

Thanks GPER for the CJ link, there is a lot of good information in there which is exactly what I have been looking for.

[dj69firebird69]

Its definately going to be worth doing this and I am trying to stay hard on this project so it doesn't turn into a five year project. I know that it won't be cheap but to get it running good with the old 258 would have cost a bunch of money too and now i have a XJ to part out when I'm done and some stuff to sell from the YJ so I won't be in too deep.

[jmb8813]

why cant anyone answer the questions on here and deal with what people are working with.....the question wasnt should i waste my time on the xj

[GPER]

For what it is worth my 31 year old CJ had to be towed home once. While my 16 year old XJ with the 4.0 has been towed twice in the couple of years I used it for a DD.

My CJ doesn't have all the electronic crap to go out. My next CJ motor will be a 258 with the 4.0 head, Crane torquer cam, Clifford intake for the 4.0 head to fit a Motorcraft 2100, CDI, Team Rush upgrade and the 4.0 exhaust manifold

[kyrel69]

well if you are going to use the computer out of the XJ then it will be easyer to use the tranny to, b/c if you do not you will either have to get another computer or get yours reflashed. The computer in XJ are hooked up to the auto tranny. Also the tranny in the XJ have a overdrive so it will make your YJ a better DD.

[dj69firebird69]

Many people didn't suggest it, thought i couldn't do it, or told me I should fix the XJ rather than the YJ. Well I did it with almost no help from anybody. I ended up parting out my XJ, making enough to cover this project completely. I bought a 92 YJ Motor, Trans, T-Case, Computer, and Wiring Harness, dropped it in the YJ without a problem. Spent many nights trying to figure out wiring and at last I got it to turn over. Now it is running but still needs some things finished and the doghouse put back on. This is the best upgrade that this jeep has ever had and I am glad that I continued on with this project even after being told by many people that it was a bad idea. If anyone is trying to do a 4.0 swap I may be able to help some and don't listen to people who have never done it before because they do not know what they are talking about.

[mckeddie]

you can run the xj computer with a yj tranny fine. i ran an xj computer in my yj for about 200,000 miles after i accidentally put a hole saw through the original computer in it. pulled the computer out of a buddy's xj, and actually it ran better than it ever had before (91 yj, with the 4.0l out of a 2001 tj, with a 94 xj computer).

greg