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Discussion Starter · #1 ·
Ok so I am looking at swapping my motor and trans. Currently I have the 2.5 with man trans, thinking of grabbing my buddies grand cherokee, 95, with the 4.0 and auto trans and putting it In. I looked at work when I was bored and found that 90% of the sensors are the same on the motor, even the water pumps. Distributers seem to be the same even. So would I even have to change the wiring in the dash? I know Ill have to cut the motor mounts and move them back a bit and reweld them. Then Ill use the computer out of the grand and the wiring for the engine compartment, of course, I was just wondering if any one has had experiance doing this or not. Its an option to me thats affordable at this point but giving me the abuility to get to highway speeds, not kill my clutch leg in traffic, and hopefully give me a gearing in the auto trans with a bit of an overdrive. I know Ill need a new drive shaft, I got a place that will make it for 75 bucks blanced and all. Since its pre OBD 2 I shouldnt have much issue with wiring, Since the sensors are the same I should have good hookups for the gauges. Think even the speed sensor is the same so my true speed hook up will still work. Any ideas or thoughts guys? Be a few months before I get up the nerve and funds to start doing this but I want to start looking at what I need to do.
 

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Yes that swap is doable - but tons of work. I did a 2.5/AX5 to 4.0/AW4 swap last winter. As both your donor and recipient are pre OBDII, you are likely almost plug and play on wiring - but you will have to do some custom work to tie in the tranny to get all the right signals. You are luck to get shafts done for only $75 - for our swap that was the single largest expense due to drive shaft lengths. You might need to run a double CV rear shaft though to address the steep angles (assuing the Grands tranny is longer than the AX5 - which i am pretty sure is the case.) The motor mounts, I think, need to be different mounts entirely (at least they did on our TJ) they do have to be in a different spot either way.

In our case we did the swap because the 4 banger died. If your 4 is dead, ok.... do it. If your 4 is running well, sell it and buy a 4.0.

Do a search here for 4.0 swaps etc. - there have been several threads. MOst say no way dont do it... I say do it if you NEED a new engine.

Look here:

http://www.greatlakes4x4.com/showthread.php?t=108894

http://www.greatlakes4x4.com/showthread.php?t=108197

http://www.greatlakes4x4.com/showthread.php?t=93383

http://www.greatlakes4x4.com/showthread.php?t=85907
 

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Discussion Starter · #3 ·
Well the only part of the mount that seemed differnt was the actual rubber bushing part, it was a bit lager, but even the screw holes were the same I held em up and they even went one screw into hole of the other and vice versa. The only real differnce is the mount. The part on the trans length does consern me and I have thought of doing a CV swap, but not sure yet =/. You did yours on a TJ or a YJ? If you did it on a YJ can you measure from your shock mount to the middle of your motor mount for me and let me know what it is. Thanks
 

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My swap was in a TJ - so measurments wont help much. The difference in the weld on part of the mounts might be in width, as well as height. I do recall there being something simpler with the YJ 2.5 to 40 swap write ups I read online - maybe the mounts was it.

For us, the CV rear shaft was a must do - the much longer AW4 resulted in a short rear shaft, steep angles. CV shaft was needed to address driveline vibes - which are not entirely addressed - we still need to do some adjustable upper control arms to get the pinion angles dialed in properly.
 

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you would need all the wireing plus the computer and alot of nickel and dime stuff. I was thinking about it but decided against it for the overall price of it. If you have the time and the cash why not. but I think that maybe a small Chevy six motor might be easier? You would need I think differant springs for the weight also.
 

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I did something similar but mine was from and xj to a yj (with a 4.2 ) added sye and the rear drive shaft is very short with using the front xj drive shaft it had cv in it already that was good. Didn't change any of the interior wiring but added to the wiring for like trans computer and cruise control. Had to use the stop switch for the xj so that the trans and CC works properly
 

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Good point on the SYE - I forgot we ended up doing one as well (trying to get the rear drive shaft angle down. A great resource when it comes to doing the wiring work is either a service manual, or actually we found that alldatadiy.com was great - we could find all the pin out diagrams very easily and match up what we needed to wire in for our AW4.
 

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Discussion Starter · #9 ·
Ok so length sounds like the biggest issue, wiring second. I am reading and the wiring under the dash is the same, I work at Autozone and when Im bored have been looking at parts and wondering why people on other sites are saying that they had to change every thing other then the o2 sensors lol. All the sensors are the same, as is the water pump, distributer, ect. Springs are the same accourding to a write up by jp, and mine are heavy duty any ways, so I doubt theyd even drop. I guess Ill need to do the wiring on the 4.0L. I guess Ill start looking for a shorter auto with an overdrive and maybe go with that. If not I suppose I can stick a manuel in I just wanted the eas of an auto for town if Im going this far. Any one have any sites with the pinouts and wiring that I will need to change? Thanks
 

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A great resource when it comes to doing the wiring work is either a service manual, or actually we found that alldatadiy.com was great - we could find all the pin out diagrams very easily and match up what we needed to wire in for our AW4.
I heard somewhere that alldatadiy.com was great for pin out diagrams. I think they are in someway affiliated with Advance Auto though.... :poke:

For a shorter auto tranny, a good old stock YJ 3 speed TF999 (? - I think one was for sale on here recently) would do the trick - and you should be able to find some used shafts from a YJ that had that configuration stock. It is possible though, that the tranny length issue is less significant in a YJ than a TJ? I cant help ya there. Oh - the tranny in the Grand is not likely a AW4 either - so maybe it is shorter as well? Grab a tape measure and measure from front edge of bell housing to front of rear drive shaft and compare.

to make the wiring very much plug and play, find a YJ 4.0 engine compartment wiring harness - plug it into your 4.0 PCM, plug in the big plug that heads under the dash, viola - wiring done (except for dealing with tranny needs). If you run the tranny from the Grand, you may have to fabricate some wiring stuff to tie it in. Or...grab the entire engine wiring harness from the grand, modify it to physically fit and route where needed in the YJ - and you would already have the wiring needed for the tranny.
 

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You might want to consider going with a different transmission. That 95 will have the 42re, which in its stock form isn't all that great. You could probably pick up an AW4 off the board or criagslist for pretty cheap if you keep your eyes open.
 

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Discussion Starter · #12 ·
I heard somewhere that alldatadiy.com was great for pin out diagrams. I think they are in someway affiliated with Advance Auto though.... :poke:

*Cough* Autozone =p. :naughty: Not much better but its still like 25 bucks, per car. I had a free trial when we first brought it out, hope its better now lol before it was pretty bad. Anyways, I guess Ill give up on the auto trans for now, figure something out after I get a 4.0l in there, prolly just find a cherokee, regular one for now. Do you think Ill need to change the under dash wiring or no, I wouldnt think so but ya never know. I figured the computer would be it withthe main engine harness, for the injectors mainly.
 

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Discussion Starter · #13 ·
to make the wiring very much plug and play, find a YJ 4.0 engine compartment wiring harness - plug it into your 4.0 PCM, plug in the big plug that heads under the dash, viola - wiring done (except for dealing with tranny needs). If you run the tranny from the Grand, you may have to fabricate some wiring stuff to tie it in. Or...grab the entire engine wiring harness from the grand, modify it to physically fit and route where needed in the YJ - and you would already have the wiring needed for the tranny.[/QUOTE]

Sounds like what I prolly will end up doing though and just bite the bullet, it will just plug in and do it then and be good huh.
 

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The only "easy" auto tranny swap for the YJ would be a 3 speed auto as was offered in a YJ. Get a PCM and wiring harness from a YJ 4.0/speed and it would not be hard at all. Using a AW4 or 42RE no matter what you do, will require more custom work - be it in the form of wiring or drive shafts etc. All doable, but not a direct swap.

Having said that - so far we have loved the AW4 in our TJ. All the work was well worth it.
 

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Discussion Starter · #15 ·
Yea, ok another question then moving back to the swap of the motor. I figure Ill find a 5 speed for now. So at that point if I got the wiring harness fromanother wrangler with a 4.0l and used that trans, with YJ 4.0l driveshafts I should be pretty good? No extra wiring or anything right? Just weld in the new mounts, remount the trans and plug inthe new harness. All the posts I have found dont talk much on the wiring thats why I ask. Found a rust bucket cherokee I might use with a nice motor. Lastly is the TJs 6cyc 5 speed the same in the bell housing and all. I dont think so but not sure. I know the clutches are differnt, but as long as it would bolt up to the older 4.0l I have no issues. I know the trans are the same but wasnt sure on the bell housing, I think the starters are difernt too. Clutch, Id be happy with an external slave then an internal anyways (MY one in my yj has gone out like 4 times since I bought it, the napa one was awful, dealer one didnt last more then a year and a half lol, just does not like to be beat on =/) Thanks guys, just trying to see what kind of work Id be in before I get my feet wet. I know how to do most things, wiring just scares me more. But on the other hand I can have the 2.5 out in about an hour at this point.
 

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Discussion Starter · #16 ·
Well bought a motor computer and all the goodies, so the fun starts soon =D. Next step I have to find mounts. Sure Ill be ripping my hair out in about three weeks when I start and think wth are you doing.
 

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Discussion Starter · #18 ·
Ok Soi I have the new trans and motor in the jeep, the 4.0L, with the 5 speed. Had to order the clutch line. Im wiring now, I have the harness of a 94 YJ, on my 92 with the 4 banger, should it just plug into the dash or will I have to cut the old one off and match it to the wires off the 94? Any one have pin outs on this? All I have found are the ones off the computer which appear to be the same anyways. Well Thanks guys!
 

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You may be lucky, if your PCM is close to the year of the jeep itself. Save yourself a LOT of headaches - pay for a Alldata.com subscription for a 94 YJ (the harness), a 92 YJ (the Jeep) and a (??? what ever vehicle the PCM came from) - compare the pin outs to your hearts content. If all lines up you are golden. There is a good chance it will, except for maybe a few odd ball accessory items one part does or does not have. Worst case you do some minor tweaking of wiring. Other than that, the connector that ran under the dash should plug into the PCM, then the connectors that ran into the engine compartment will likewise. Plug it all in, should be good to go.

I say all that based on what played out with my TJ 2.5 to 4.0 swap - I found that pin outs were almost 100% the same (only 2 or 3 very minor differences) from a 97 TJ 2.5 underdash connector, a PCM from a 98 ZJ 4.0 (didnt use as it had a security system enabled on it) , a 97 XJ 4.0 PCM (which is what I ended up using) , a 98 XJ 4.0 engine Harness (didnt use, but considered it) and a 97 TJ 4.0 engine harness (ended up using this), all connecting to a 4.0 from a 98 ZJ, and throttle body and associated sensors from...hell I forget what now... a 98 something or another! The ONLY modifying to wiring I had to do was ONE connector to the IAC, or TPS...forget now which it was, (ignoring all the wiring work I had to do to tie in the AW4 tranny computer - but that was a separate issue from the engine needs itself)
 

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Discussion Starter · #20 ·
Well the PCM is the same as the wiring harness, the 94. From the pin outs on mitchells on demand, similar to all data, they look the same at the PCM but I cant find it at the dash harness, the firewall plug
 
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