89 YJ 4.2 auto to manual swap help

v8haha

v8haha

New Member
Joined
Sep 9, 2024
Messages
2
Location
Pennsylvania
Good afternoon Jeep folks. I am enlisted to help a friend replace the engine and transmission in his 89 YJ with a 4.2l 6 cylinder automatic with an 89 YJ 4.2l 6 cylinder and 5 speed AX15 transmission. I am looking for any resources that might be helpful in this endeavor. I'm jeep literate but haven't done a swap before.

We have the complete running assembly from a rotted out wrangler. It's appears complete from carb to transfer case, so a lot of the "need to source" components are there. We did not pull the set, so I don't know if it might be missing a sensor or two, but it has a lot of the vacuum lines, wiring etc. with it. We replaced the clutch and flywheel along with the internal slave cylinder (I know, I know, the external is better).

We also have the shift boots and plate, shifters, new master cylinder and hydraulic line, clutch pedal assembly, transmission mount, new motor mounts, and fluids

What I'm looking for is guidance or confirmation on the little things I'm thinking about;

Neutral Safety Switch
Reverse Lights
Auto Steering Column - disconnect and leave?
Driveshafts (different lengths, same between auto/manual?)
Any sensors needed or swapped, ie crank position etc., for an 89?

Thanks in advance!
 
Evening...I've got a '90 4.2/AX15 that's 45k miles from new and never butchered. Motor still has all of the vacuum hook-ups, etc....I'm not bragging here, but as an original example to go by I can tell you a couple of things:

1.) I'm not sure about driveshaft lengths
2.) As far as I can tell I don't have a neutral safety switch...my YJ will start without the clutch pedal depressed
3.) The back-up light switch is located on the passenger side of the AX-15 if memory serves, but I'm not sure if the harness from an auto trans will mate up to it
4.) If aesthetics are an issue, recommend swapping the steering column from your donor, other wise your have the auto shift lever mount range and PRNDL indicator still attached to your colu.n
5.) Carbed 4.2s are pretty straight forward, I don't believe sensor swap will be necessary...there are no crank sensors installed that I'm aware of
6.) The transmission cooling lines go to a closed loop circuit inside the radiator. Once you disconnect them and drain the fluid from the radiator you shouldn't have to worry about plugging the holes


I defer to the Forum members to cross a check my math, but hope I've helped a bit...good luck with the swap...
 
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