HOW TO: Convert your 2wd XJ to 4wd

Well, i got tired of searching through this forum and reading "it's been discussed before", and never finding where it was discussed before...so here goes.

What you'll need:
Transmission/transfer case
Front/rear driveshafts
Front axle
Linkage and handle
Vacuum setup (depends)

Transmission/Transfer case:
These can be out of any year, to my knowledge. Obviously lower mileage is better. If you get a newer transfer case, you won't have to deal with the vacuum setup (mine came from a '98 and is vacuum-less). Crossmember is the same from 2wd to 4wd.

Tips:
-Make sure the torque converter is FULLY seated. You should NOT be able to get a finger behind it. Try to drain the fluid out of it while the trans is out of the car as well.
-You will notice there are three transmission electrical connectors. One of them is different between 2wd and 4wd transmissions, the other two are the same. The one that is different has 5 wires, instead of 3 on your 2wd transmission. If you look closely, you'll notice that 3 wires on the 5 wire plug are the same color as the 3 wires from your 2wd connector. The other 2 wires are for the switch that turns your 4wd light on.
My solution was to cut and splice the 2wd connector onto the 3 corresponding wires, and leave the 2 wires that turn the 4wd light on disconnected. You can do it however you want, though

Front/Rear driveshafts:
There are at least two different lengths of these, and two different styles.

Length: There may be a difference between 2- and 4-door models, i'm not sure. There is a difference of 1" between the manual and automatic driveshafts. Make sure you get the right length!

Style: The older transfer cases will use a rear driveshaft that slips inside the transfer case, newer transfer cases use a driveshaft that sits externally and has a rubber boot. Make sure you get the right kind!

Front Axle:
Not much special here. Get a front axle with a ratio matching your rear axle. Older axles are vacuum disconnect and can be actuated via a vacuum switch (search around on here), newer axles are non-disconnect and don't require any extra work (that's the route i took!). Everything is interchangeable between the front 2wd "axle" and the real 4wd axle...spindles, rotors, calipers, everything.

Linkage and handle:
I had at least 3 people tell me it had to be out of the same year, but i don't think it does. I installed '95 linkage in my '93. The only differences are between the auto and the manual--get the correct one for your application. The linkage is adjustable and will need to be adjusted once installed. It seems that around '95 the mount that goes on the
trans tunnel was updated with rubber bushings, so that's the one i chose. All the holes are already in position for the mount and the handle, but it pays to have a buddy on this part.

Adjustment: Once everything is installed, you'll need to adjust the linkage. Loosen the bolt located on the rod coming from the 4wd handle. While pushing forward on the bolt area, press backwards on the rod. This will force the handle "down" into the 2wd area and ensure that you have enough throw on the handle to make it into 4LO. Make sure to snug up the bolt.



Vacuum Setup:
Can't help much here, i went with a newer trans/transaxle and front axle, neither of which use vacuum. If you have a vacuum actuated transaxle, i would recommend picking up an entire vacuum harness from a junkyard. For the front axle, search on here, i believe people have been using HVAC switches.


Good luck, it doesn't get much easier than this! Everything is bolt-in, and the only difficulties are with the sheer weight of some things.

:viking:

~Chris

crossmember? the transmission mount/exhaust hanger assembly is different on 2wd and 4wd.

On mine (a 1993 using a 1998 trans) there was no need to change the crossmember or the trans mount, it just bolted right up. Is it possible i just rotated the crossmember 180...?? I never touched the new trans mount.

The exhaust hanger was different (2wd uses a half-moon shaped hanger, my 4wd mount had a 1/2" hole instead), but i think you could probably get by without changing it...i just had a new exhaust made while i was at it, so it was no problem

I'm certainly not an expert on these Jeeps, so please feel free to add to this thread!

Would it not be far FAR easier to sell the 2x and jsut buy a 4x4?
Sounds like a PITA to do all that work.

sounds like an easy job, and less than 400 dollars worth of parts. +50 for pizza and soda.

any pics of your install?

Porch951 said:

Front/Rear driveshafts:
There are at least two different lengths of these, and two different styles.

Length: There is no difference between 2- and 4-door models. There is a difference of 1" between the manual and automatic driveshafts. There is also a difference depending on what rear axle the donor vehicle is equipped with. Make sure you get the right length, it is best to get the front and rear driveshaft from the donor vehicle, if not get driveshafts from a vehicle equipped with the same transmission, era of transfer case (early tail cone vs. late), and rear axle!

Front Axle:
Not much special here. Get a front axle with a ratio matching your rear axle. Older axles for the 231 transfer case are vacuum disconnect and can be actuated via a vacuum switch (search around on here), shimmed in place with washers, or actuated with a cable setup, newer axles and axles for the 242 transfer case are non-disconnect and don't require any extra work (that's the route i took!). Everything is interchangeable between the front 2wd "axle" and the real 4wd axle...spindles, rotors, calipers, everything.

Disconnect axles will always have the weaker 260x axle shaft u-joints, late model (I don't recall exactly when they started, but it's guaranteed with 97+) axles will have the stronger 297x u-joints (which are directly replaced by 760). Also all ABS equipped XJ's (ABS was an option from 1989 onward) will have the stronger u-joints, you can spot ABS from either the brake master cylinder (you'll see the solenoids and such nearby), the sensor wiring going to the caliper (no wiring with non-ABS), or the tone ring on the stub shaft (the small part of the axle shaft, the tone ring looks like a gear).

Linkage and handle:
I had at least 3 people tell me it had to be out of the same year, but i don't think it does. I installed '95 linkage in my '93. The only differences are between the auto and the manual--get the correct one for your application. The linkage is adjustable and will need to be adjusted once installed. It seems that around '95 the mount that goes on the
trans tunnel was updated with rubber bushings, so that's the one i chose. All the holes are already in position for the mount and the handle, but it pays to have a buddy on this part.

Adjustment: Once everything is installed, you'll need to adjust the linkage. Loosen the bolt located on the rod coming from the 4wd handle. While pushing forward on the bolt area, press backwards on the rod. This will force the handle "down" into the 2wd area and ensure that you have enough throw on the handle to make it into 4LO. Make sure to snug up the bolt.

Note: The shift gate for the transfer case shifter (the metal bracketry in the cab that has the stops for the ranges) differs between the 242 transfer case and the 231 (because the 242 has one extra range), get the correct one for your application.

Vacuum Setup:
The early 231 transfer case (and some cases before, my pre 1987 knowledge is spotty here) used a vacuum disconnect front axle for fuel economy purposes. This consists of a vacuum diaphragm on the passenger (long) side of the front axle that controls a shift fork, that fork moves a collar between the intermediate shaft and the final shaft.

The transfer case has a vacuum switch at the tail cone area of the case where the electric 4WD switch would be on a later 231. This switch would switch the vacuum depending on what range you were in, this would move the shift collar and also went to a vacuum operated switch for the 4WD indicator lamp.

I do not recommend using the OEM vacuum harness as their rubber connectors do not age gracefully (I have had to replace them in my Jeeps). If you are going to use a vacuum operated front axle disconnect lay your own vacuum lines, just make sure to keep them away from the hot exhaust.

Another option is to use any 231 and plugging the vacuum switch hole (or putting a later style electric switch in place) and manually controlling the front axle. This can be done in a few ways. One is to shim the shift fork in the 4WD position with washers. Another is a cable lock system. The most "graceful" way would be to use a vacuum operated switch, I recommend using the 4WD - 2WD switch from early model Cherokees, I forget the case this was for but it is a switch that goes in place of the coin holder in the early model consoles, you may have to grab the early model black console inlay to use this switch as they stopped making the coin tray removable in later Jeeps (if you have an earlier Jeep, at least up to 1989, you'll notice that the coin tray is held in by four screws on the underside, the switch is mounted with these four screws).

Click to expand...

I edited it a bit for you.

mscans said:

sounds like an easy job, and less than 400 dollars worth of parts. +50 for pizza and soda.

any pics of your install?

Click to expand...

only $400 in parts for the driveshafts, transfercase, everything?
I have a 01 2wd. for a daily driver, this sounds like a project when I get the next car...

side question, how can you tell if you have the 0331 crack prone head?

RTFM said:

Would it not be far FAR easier to sell the 2x and jsut buy a 4x4?
Sounds like a PITA to do all that work.

Click to expand...

Not if you enjoy working on junk. I was rebuilding an 89 when I picked up this really clean 1996 2-door, 2wd, 4.0, AX-15 XJ with bad engine for $600. I got it cheap because it was 2wd. I put the 99 engine, reused the external slave bellhousing on the 4wd AX-15 - 231 combo I had and moved the 89 axles under the 96 and got this. I also sold the 89 body with 2wd axles and title for $300 and sold the 2wd AX-15, so I pretty much got my money back. Had a great time building it and it doesn't have near the body issues my 89 had.

Awesome write up!

cheese

great write-up, but you should specify that this is for a 4.0/auto swap, and that you MUST make sure that you have the correct trans for your engine (i.e. 2.5 trans DON'T interchange with 4.0 trans)

also, the 2wd and 4wd front axle parts are DIFFERENT on most models. Be aware that you just lucked out having parts compatible systems. an older 2wd axle beam doesn't share the same rotors, caliper, etc. that any 4wd axles have.

RTFM said:

Would it not be far FAR easier to sell the 2x and jsut buy a 4x4?
Sounds like a PITA to do all that work.

Click to expand...

I have found several pristine 4x2 Cherokees that have only seen dust in a shopping mall parking lot and have often debated the same question. I think a conversion would definately have its advantages.

Thanks for the write-up. That's one to keep.

My only question is I have a 98 XJ, 2WD w/ a 5speed manual transmission.

Is there any way to make that into 4WD w/o changing out the Trans?

If not what Trans would you Recommend? I want to stick with Manual.

This is my Second XJ.