Looked at a YJ tonight that is in decent shape. For 500.00 I can get the yj with the 4.2 less the tranny and transfer case, but he has another 4.0l\auto\transfer case out of an 89 cherokee he'll throw in along with the front and rear axles. He said the 4.0 runs decent and the 4.2 ran but he isn't quite sure how well. They bought the jeep only for the tranny since reverse was shot in his other one. The frame seems decent however where the seat belts bolt to the floor is shot and a few other little places. Can I bolt the cherokee auto to the 4.2? How hard is it to install the 4.0 and all the wiring sh!t? I don't have the wiring btw. What options do I have to get this thing running? Advice needed TIA.
Also, money is in short supply.

I should also add that I am mechanically inclined and a former Toyota guy but I'm new to the Jeep stuff.

It should physically bolt up but if it was not an Auto to begin with then you will probablly need to change out the flywheel. I'm not sure on that but on a lot of vehicles the flywheel differs between an auto and a manual. I don't think the 89 Auto had any computer controls on it, but I'm not sure its right on the edge of those being introduced.

I'd get the 4.2 running as it should be the cheaper of the two to get running, passing emissions might be a whole nother story though.

The seat belt holes are going to be an issue, but not a bad one. you will need to make a patch panel made and welded in there and painted well.

The wiring isn't that hard. The main thing is to get a complete Harness for a 4.0 including the computer. The bad thing is the harness probably won't fit correctly, as you will probably have to go with a cherokee 4.0 harness (not the 4.0 H.O.) The H.O. harness & computer might work but my guess is that the Fuel Maps are slightly different, If the Fuel Maps are different then you will run slighty lean or rich off of Idle. and the Injectors may fire at the slightly wrong time causing the fuel to liquidfy and not burning fully.

"a lot of times the flywheel differs between an automatic and a manual".

Well shit, i think your right!!! last time i checked autos had flexplates???

I'm not certain, but I would bet that the 4 speed auto out of the cherokee combined with a normal jeep t-case is going to give an awefully short driveshaft, you may need a SYE to make it work.

Putting the tranny/t-case behind the 258 is possible, and probably not too hard, but I think using the 4.0 would be better way to go. It sounds like you have the makings of a neat project, but if you need to get on the road quickly, you may want to look at other alternative

Chad

Originally posted by DEnd

I'd get the 4.2 running as it should be the cheaper of the two to get running, passing emissions might be a whole nother story though.

The wiring isn't that hard. The main thing is to get a complete Harness for a 4.0 including the computer. The bad thing is the harness probably won't fit correctly, as you will probably have to go with a cherokee 4.0 harness (not the 4.0 H.O.) The H.O. harness & computer might work but my guess is that the Fuel Maps are slightly different, If the Fuel Maps are different then you will run slighty lean or rich off of Idle. and the Injectors may fire at the slightly wrong time causing the fuel to liquidfy and not burning fully.

I'm thinking I may get the 4.2 running at this point and try it out. Perhaps get the auto running with the 4.2 and then when I come across a comp and wiring harness for the 4.0 I'll swap motors. Would this be the HO motor? Everythng was under a tarp and snow so I am just going on what my buddy is telling me.

Originally posted by chadl
I'm not certain, but I would bet that the 4 speed auto out of the cherokee combined with a normal jeep t-case is going to give an awefully short driveshaft, you may need a SYE to make it work.

Putting the tranny/t-case behind the 258 is possible, and probably not too hard, but I think using the 4.0 would be better way to go. It sounds like you have the makings of a neat project, but if you need to get on the road quickly, you may want to look at other alternative

Chad

Would the auto from the cherokee be different from the one offered in the yj? Now this is a really newb question but what do you mean by sye? CV d-shaft in the rear?
I'm not concerned for when I get this on the road. Just a project to occupy my time.

Did the 89 cherokee come with a d44? :confused:

Originally posted by ShawnM


Would the auto from the cherokee be different from the one offered in the yj? Now this is a really newb question but what do you mean by sye? CV d-shaft in the rear?
I'm not concerned for when I get this on the road. Just a project to occupy my time.

I'm pretty sure YJ's always came with 3 speed auto's that were shorter to accomodate the short wheel base. I think new TJ's have 4 speeds, but I don't know how long they are or if it's the same tranny as you have.

SYE - jeep in it's infinite wisdom used a T-case with an extra 8" or so hang off the back it accomodates the driveshaft slip, and stock they use a solid drive shaft. A SYE (slip yoke eliminator) removes this portion of the t-case, allowing for a longer tradition driveshaft with the slip built in. Most SYE come with a CV type shaft, but it isn't really a requirement.

Chad

Originally posted by sandusk
"a lot of times the flywheel differs between an automatic and a manual".

Well shit, i think your right!!! last time i checked autos had flexplates???

A flexplate is a form of a flywheel. Auto's could use a standard flywheel, but you loose efficency. Plus an Auto doesn't need a big heavy flywheel as the torque converter won't allow the engine to stall (well it shouldn't anyway) from stopping the movement inside the tranny. 99.99999999999% of the time Auto's use a flexplate. But because I'm not 100% sure of that on that application I;m not going to state it as fact. :flipoff2: