4.0 HO conversion and transmission questions

dj69firebird69 · 01-09-2010, 04:36 PM

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 · 01-09-2010, 05:43 PM

Sell the YJ. Build the XJ.

Robert

dj69firebird69 · 01-09-2010, 05:54 PM

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

jmb8813 · 01-09-2010, 06:56 PM

thats a terrible idea (to build a xj)

Coppertop · 01-09-2010, 11:51 PM

Quote:

Originally Posted by WrenchMonkey

Sell the YJ. Build the XJ.

Robert

X2
Jeep cherokees rule....

Nick

GPER · 01-10-2010, 09:51 AM

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 · 01-10-2010, 11:05 AM

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 · 01-10-2010, 02:22 PM

Quote:

Originally Posted by nick

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 · 01-10-2010, 06:02 PM

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 · 01-10-2010, 06:09 PM

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 · 01-10-2010, 06:46 PM

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 · 01-10-2010, 07:25 PM

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 · 01-12-2010, 09:22 AM

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 · 03-28-2010, 10:40 PM

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 · 03-28-2010, 11:31 PM

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

dj69firebird69 · 03-28-2010, 11:55 PM

The only reason I ended up getting all the parts from a 92 YJ was because I came across a trans for pretty cheap which would save me from drilling a hole for the crank position sensor and the guy also had a np231 with slip yoke eliminator and cv driveshafts. When I got there the guy decided to hook me up with the engine and wiring harness because it was easier to take it all out as an assembly. I got it for dirt cheap and I needed a couple brackets off of the engine anyways that were damn near impossible to find. Im glad I did it that way because it made it much easier. But i still have the 92 XJ engine, harness, computer, and trans just in case this motor has problems.

WrenchMonkey · 03-29-2010, 03:02 AM

Hey, congrats!

I sure didn't mean to discourage you, glad it all worked out and you're happy with the outcome!

Robert

01-09-2010, 04:36 PM	#1
dj69firebird69 Join Date: Dec 2009 Posts: 15	4.0 HO conversion and transmission questions 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

01-09-2010, 05:43 PM	#2
WrenchMonkey Mechanical Animal - CORE Member - - Moderator - Join Date: Feb 2008 Location: Beechmont Posts: 1,883	Sell the YJ. Build the XJ. Robert __________________ DIRTY DEEDS, DONE DIRT CHEAP Whatever doesn't kill you makes you stranger

03-28-2010, 11:31 PM	#15
mckeddie Join Date: Apr 2007 Location: van wert oh Posts: 583	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 __________________ zuk buggy.....it'll be a jeep eventually.

03-29-2010, 03:02 AM	#17
WrenchMonkey Mechanical Animal - CORE Member - - Moderator - Join Date: Feb 2008 Location: Beechmont Posts: 1,883	Hey, congrats! I sure didn't mean to discourage you, glad it all worked out and you're happy with the outcome! Robert __________________ DIRTY DEEDS, DONE DIRT CHEAP Whatever doesn't kill you makes you stranger

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01-09-2010, 05:54 PM	#3
dj69firebird69 Join Date: Dec 2009 Posts: 15	XJ was wrecked in the front. The kid rearended somebody going 35mph. Its still fixable but I would rather build up my YJ.

01-09-2010, 06:56 PM	#4
jmb8813 01 jeep tj Join Date: May 2009 Location: the city that offers nothing Posts: 153	thats a terrible idea (to build a xj)

01-10-2010, 09:51 AM	#6
GPER Join Date: Feb 2007 Location: Kettering, Ohio Posts: 811	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.

01-10-2010, 11:05 AM	#7
nick wheeler Join Date: Jun 2008 Location: owingsville ky Posts: 25	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

01-10-2010, 06:02 PM	#9
dj69firebird69 Join Date: Dec 2009 Posts: 15	Thanks GPER for the CJ link, there is a lot of good information in there which is exactly what I have been looking for.

01-10-2010, 06:09 PM	#10
dj69firebird69 Join Date: Dec 2009 Posts: 15	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.

01-10-2010, 06:46 PM	#11
jmb8813 01 jeep tj Join Date: May 2009 Location: the city that offers nothing Posts: 153	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

01-10-2010, 07:25 PM	#12
GPER Join Date: Feb 2007 Location: Kettering, Ohio Posts: 811	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

01-12-2010, 09:22 AM	#13
kyrel69 Join Date: Jan 2007 Location: Middletown, Ohio Posts: 372	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.

03-28-2010, 10:40 PM	#14
dj69firebird69 Join Date: Dec 2009 Posts: 15	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.

03-28-2010, 11:55 PM	#16
dj69firebird69 Join Date: Dec 2009 Posts: 15	The only reason I ended up getting all the parts from a 92 YJ was because I came across a trans for pretty cheap which would save me from drilling a hole for the crank position sensor and the guy also had a np231 with slip yoke eliminator and cv driveshafts. When I got there the guy decided to hook me up with the engine and wiring harness because it was easier to take it all out as an assembly. I got it for dirt cheap and I needed a couple brackets off of the engine anyways that were damn near impossible to find. Im glad I did it that way because it made it much easier. But i still have the 92 XJ engine, harness, computer, and trans just in case this motor has problems.