Myth Posted September 27, 2013 Share Posted September 27, 2013 Good morning everyone. So I am new to the Comanche club however I have been following the forums for quite some time now. I came by two comanches very cheap however 1 has a damaged frame and the other one has a blown 2.5 so I will be swapping the 4.0 and driveling into the 2.5. Now the trucks are as follows. 1988 swb comanche with 2.5l 2wd dana 35.not sure what transmission havent checked. 4 speed stick. Aside from engine truck is in great shape. 1989 (11 month) lwb comanche with 4.0l ax15 np231 and a dana 35 out back dana 30 front. This truck is in really bad shape frame and body wise. Now I am no stranger to engine swaps just a couple comanche specific questions. Being both renix do I need to change all engine bay wiring and if so will I run into c101/c100 issues. If I do run into issues there will I need to swap cab wiring as well? Will I need to change fuel pump/sending unit? If so will both tanks be the same lwb/swb. Lastly are there any comanche related engine swap issues I should look out for that I might not now about. Thanks for your time all and I look forward to your expert advice. Link to comment Share on other sites More sharing options...
Myth Posted September 27, 2013 Author Share Posted September 27, 2013 Starting in 15 min so any advice would be appreciated. Link to comment Share on other sites More sharing options...
airspeed Posted September 27, 2013 Share Posted September 27, 2013 I have never done a swap but from what I have read on the forum I think all engine associated wiring including the ECU and forward will need to be changed. The 4.0 will need a different fuel pump and I believe the drive shafts will need to be changed, at least the rear one. Link to comment Share on other sites More sharing options...
airspeed Posted September 27, 2013 Share Posted September 27, 2013 I have never done a swap but from what I have read on the forum I think all engine associated wiring including the ECU and forward will need to be changed. The 4.0 will need a different fuel pump and I believe the drive shafts will need to be changed, at least the rear one. I have never done a swap but from what I have read on the forum I think all engine associated wiring including the ECU and forward will need to be changed. The 4.0 will need a different fuel pump and I believe the drive shafts will need to be changed, at least the rear one. I just reread your post and realized you want to go from a 2wd to 4.0 4wd. that is a whole different story. That is a lot more work, search the forum, I know it has been done a number of times. Link to comment Share on other sites More sharing options...
coyote kid Posted September 27, 2013 Share Posted September 27, 2013 If its a 4 speed its a ax4 Link to comment Share on other sites More sharing options...
mvusse Posted September 27, 2013 Share Posted September 27, 2013 Engine harness is completely different between the two and will need to be changed. ECU is different as well. Chassis harness and I believe dash harness should be the same.The 2.5 would have an AX4 in it.The sending unit should be the same, although the length of the rod on the float might be different. The pumps are different and you will have to swap the 4.0 pump along with the engine, either by swapping the entire sending unit, or by swapping the pump onto the swb sending unit. You should also swap the front springs because the 4.0 springs have a higher spring rate than the 2.5 ones. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted September 28, 2013 Share Posted September 28, 2013 Here you go... currently working on this exact project now. Some things I'm doing are '86 specific, but the general principle is the same. http://comancheclub.com/topic/39539-links-for-25l-to-40l-swap/ Also, check out my build thread for my MJ. Lots of pictures and things that should help. Happy swapping! Link to comment Share on other sites More sharing options...
Myth Posted September 28, 2013 Author Share Posted September 28, 2013 Thank you all for your help. So I have both drivelines out and engine wiring pulled out of one. Will be starting back first thing in the am. My drive shaft is going to alberta driveline to be cut down on monday. On that note my truck will be getting a 6.5 lift. How much longer should the driveshaft be? Thanks again. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted September 28, 2013 Share Posted September 28, 2013 If you're going from a 2.5/AX4 to a 4.0/AX15, you would have to shorten the rear drive shaft on a stock height MJ. Now, with 6.5" lift, that will likely change some things. I would highly advise you wait till you get everything in place before you worry about drive shaft modifications. Once you have everything where you like it, you can then base your drive shaft needs on actual measurements. No one here will be able to tell you with 100% certainty how long/short the drive shaft will need to be. Link to comment Share on other sites More sharing options...
Myth Posted September 28, 2013 Author Share Posted September 28, 2013 That makes sense. Thanks Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted September 28, 2013 Share Posted September 28, 2013 No problem. Take/post a lot of pictures of how everything goes. :yes: Link to comment Share on other sites More sharing options...
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