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Everything you ever wanted to know about the AW4

Hi everyone! This is an extremely informative thread. Thanks to all who contributed.

I recently picked up a very clean (for the Northeast) 2000 XJ Limited 2wd. The plan is to convert to 4wd so I set out to convert the 2wd AW4 to 4wd using a 97 4wd AW4 donor I had kicking around. I have access to a transmission shop so I decided to do a complete overhaul since the transmissions needed to be completed disassembled to assess the snap right securing the output shafts into the transmission housings. I found on the hard way that the 97 AW4 didn't make a great donor as it uses a different output speed sensor, thus, mounting hole in extension housing is different, snap ring groove on output shaft used to secure the speed sensor pick-up is in a different location, etc. I took some pictures of these differences and can share if anyone would like.

Anyway, I picked up a reman torque converter from Transtar and installed it into the transmission tonight. I measured the distance between the bell housing and one of the mounts on the converter and got ~0.825", where as the spec in the 1997 FSM says 0.650". Is there a difference in the factory spec between '97 and '00? I don't have a '00 FSM.

Should I be concerned about this? I know the TC will pull out slightly when installed on to the flex plate but I don't want to shear the drive lugs off the inner pump gear if it pulls out too far. I have the original factory TC that came out of the '00. I plan to measure the overall height of it and compare to the height of the reman TC to make sure the reman unit wasn't welded incorrectly.

Please let me know if you have any insight.

Thanks,
Noah
 
Hi everyone! This is an extremely informative thread. Thanks to all who contributed.

I recently picked up a very clean (for the Northeast) 2000 XJ Limited 2wd. The plan is to convert to 4wd so I set out to convert the 2wd AW4 to 4wd using a 97 4wd AW4 donor I had kicking around. I have access to a transmission shop so I decided to do a complete overhaul since the transmissions needed to be completed disassembled to assess the snap right securing the output shafts into the transmission housings. I found on the hard way that the 97 AW4 didn't make a great donor as it uses a different output speed sensor, thus, mounting hole in extension housing is different, snap ring groove on output shaft used to secure the speed sensor pick-up is in a different location, etc. I took some pictures of these differences and can share if anyone would like.

Anyway, I picked up a reman torque converter from Transtar and installed it into the transmission tonight. I measured the distance between the bell housing and one of the mounts on the converter and got ~0.825", where as the spec in the 1997 FSM says 0.650". Is there a difference in the factory spec between '97 and '00? I don't have a '00 FSM.

Should I be concerned about this? I know the TC will pull out slightly when installed on to the flex plate but I don't want to shear the drive lugs off the inner pump gear if it pulls out too far. I have the original factory TC that came out of the '00. I plan to measure the overall height of it and compare to the height of the reman TC to make sure the reman unit wasn't welded incorrectly.

Please let me know if you have any insight.

Thanks,
Noah

I'll be curious as to what you find out. The torque converter and rebuild kit will be here tomorrow for my 2000 but I haven't made plans for my teardown yet.
 
Although I don't think this matters, I did use the pump body with gears and stator support shaft from the 97 donor trans as it was in better shape than the 2000 unit. To my knowledge, the pumps were the same for the A340 and AW4 from 1985 and up.

The ATSG manual says the spec should be 0.689" on 4cyl and 0.650" on 6cyl but doesn't specify years. The 1997 FSM agrees with ATSG. AllData says 0.112" for 2000XJ with AW4, but I must say AllData has been wrong in the past.

I look forward to hearing from someone who may have knowledge about this
 
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I took a look at the wear marks on the original pump inner gear from the 2000 xj and it looks like the drive lugs weren't fully engaged during operation. In one picture you can see the pump sitting flush on the TC with full lug engagement and in the other picture you can see the pump sitting proud ~0.180". I think this should be okay but I'm surprised the FSM spec is so far out from what I am measuring. I wish I measured the gear thickness of the 97 pump. Based on tolerance stack, the pump body with gears is located off the transmission housing and the converter hub bottoms out against the stator support. The measurement in the FSM references the bell housing to mounting pad on TC. Are the bell housings different between 1997 and 2000? I'm fairly certain I am using the original 2000 bell housing.

FYI, the factory TC measured 0.018" taller than the reman, which doesn't explain the ~0.180" discrepancy between my measurement and the FSM.

Thoughts?
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I've got a '97 XJ, and cannot find a '97 in our area. I have shifting problem into 3rd gear, freewheels in 3rd, until shifts back to 2nd. Disconnected TCU, trans will not shift out of 1st gear. trans bad, right? got a '98 trans. swapped tail-housings between '97 and '98. ok to bypass ISS from '98 trans to run in '97? to swap harness out of '97 trans, its extremely brittle. anyone make aftermarket harness or advice please! Non-NSS connector different on '97 and '98.

tried:4882174, 83503722, 56009463, 56009385

Thx for any advice!
 
I'd have to look at the wiring diagrams to confirm my memory, but I believe the 98 NSS added a wire to detect the (D) position. If you wanted to use the 98 NSS, you could splice the wiring from the 98 NSS and just not connect the extra wire.
 
I'd have to look at the wiring diagrams to confirm my memory, but I believe the 98 NSS added a wire to detect the (D) position. If you wanted to use the 98 NSS, you could splice the wiring from the 98 NSS and just not connect the extra wire.


I was wrong. Looking at the FSM for 97 and 98, the pinouts and wire colors for the NSS are identical.
 
Did you check and test the three electric solenoids in the valve body of the AW4, check for continuity in the wiring harness from the TCU to the transmission and the 3 solenoids, did you change the fluid and did you use Dex III fluid, did you try some Trans-X additive to clean any varnish from the valve body, and how do you know what gear it was in with and with out the TCU connected??? Did you shirt from 1-2 to 3 and then to drive with the TCU disconnected or did you have it in Drive the whole time? TCU bypassed second gear never engages unless the engine rpm hits some crazy like 3500+ RPM in the 1-2 selection. Is the large wiring harness connection clean with no bent pins. Did you try a new valve body first?????



I've got a '97 XJ, and cannot find a '97 in our area. I have shifting problem into 3rd gear, freewheels in 3rd, until shifts back to 2nd. Disconnected TCU, trans will not shift out of 1st gear. trans bad, right? got a '98 trans. swapped tail-housings between '97 and '98. ok to bypass ISS from '98 trans to run in '97? to swap harness out of '97 trans, its extremely brittle. anyone make aftermarket harness or advice please! Non-NSS connector different on '97 and '98.

tried:4882174, 83503722, 56009463, 56009385

Thx for any advice!
 
Did you check and test the three electric solenoids in the valve body of the AW4, check for continuity in the wiring harness from the TCU to the transmission and the 3 solenoids(continuity yes)

did you change the fluid and did you use Dex III fluid (YES)

, did you try some Trans-X additive to clean any varnish from the valve body (NO)

and how do you know what gear it was in with and with out the TCU connected??? (with selector in D, transmission works perfect starting 1st, shifted smooth to 2nd, then freewheeling in 3rd, until 2nd reengaged. manually shifted up, starting in 1-2, then 3 freewheels)

Did you shirt from 1-2 to 3 and then to drive with the TCU disconnected(YES)

or did you have it in Drive the whole time?(NO)

TCU bypassed second gear never engages unless the engine rpm hits some crazy like 3500+ RPM in the 1-2 selection (never shifted, 4000+rpms)

. Is the large wiring harness connection clean with no bent pins.(YES)

Did you try a new valve body first????? (NO)
 
Swapping a COMPLETE '98 4x4 drivetrain into a '97 2wd possible without swapping wiring harnesses or chopping them up?

Apologize if I missed the info in this 40 page thread....
 
Swapping a COMPLETE '98 4x4 drivetrain into a '97 2wd possible without swapping wiring harnesses or chopping them up?

Apologize if I missed the info in this 40 page thread....


Read the very first post in the thread where it discusses swapping between years. There is a difference in the transmission rear speed sensor, trans computer and it's wiring harness. The easiest approach would be transplanting the 98 computer and it's wiring harness over. Otherwise, I believe the engine and it's sensors are the same so no changes needed to the engine computer or it's wiring harness.
 
I've got a '97 XJ, and cannot find a '97 in our area. I have shifting problem into 3rd gear, freewheels in 3rd, until shifts back to 2nd. Disconnected TCU, trans will not shift out of 1st gear. trans bad, right? got a '98 trans. swapped tail-housings between '97 and '98. ok to bypass ISS from '98 trans to run in '97? to swap harness out of '97 trans, its extremely brittle. anyone make aftermarket harness or advice please! Non-NSS connector different on '97 and '98.

tried:4882174, 83503722, 56009463, 56009385

Thx for any advice!

Should have went with like a 96-91 tranny. Much easier to swap.
 
Read the very first post in the thread where it discusses swapping between years. There is a difference in the transmission rear speed sensor, trans computer and it's wiring harness. The easiest approach would be transplanting the 98 computer and it's wiring harness over. Otherwise, I believe the engine and it's sensors are the same so no changes needed to the engine computer or it's wiring harness.

Read it a few times...I have heard '97 still has some "transition" year wiring nuisances. I wonder if swapping the '98 ECU along with the drivetrain will be enough...Or if swapping the harness will be necessary as well...
 
Agreed. I still have no solid info on 97 TCU+trans in 98+, nor 98+TCU+trans in 97.
I can add my experience. Converting a '98 XJ 2wd to 4X4, I bought a 4X4 AW-4 which I believed to be a ''98. Whatever year it is/was, it lacked an input shaft speed sensor. The boss for the sensor was not even machined.

Cutting to the chase, it didn't work. I can shift the transmission manually, from first to third to fourth. P, R, and N ok, but no second, and no TC lockup. And 'check engine' light staring me in the face. (I have cobbled together an electrical work around to make the jeep drivable, including cigarette lighter power for the lock up TC)

I now have a '00 AW-4 sitting on the floor and will install it in my XJ very soon. After a great deal of research, and after reading every word of this excellent thread, I came to the conclusion -- as did the op -- that installing a '97 or earlier AW-4 in an XJ that came with a '98 AW-4 is possible, but impractical.

So far as installing a '98 into a '97, I cant' help.

I do want to add this, however: I am nearly certain that my 'no ISS AW-4' did in fact come from an XJ with a 1998 VIN. Hence I believe that Jeep's changeover to the AW-4 with the ISS did not precisely coincide with the 1998 model year. Beware.
 
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You used that allegedly 98 trans with what TCU?
 
You used that allegedly 98 trans with what TCU?
This one. (see the amazon URL below) It was and is in my '98 2WD XJ that featured, among other things, an input shaft speed sensor, and four armed output shaft reluctor. Just in case I screw up the image, it is the one with the French curve mounting ears.

I think if one is considering a transmission from a '97 or '98 XJ, for whatever purpose, it would be wise establish whether it has an input shaft speed sensor irrespective of what the VIN indicates. An 'early' transmission (one with an input shaft speed sensor) won't work in a 'later' jeep without l a lot of extra work. Wish I knew then what I know now. Or to put it more simply, I wish I had read, studied and digested this entire thread before reaching for my wallet.

https://www.amazon.com/photos/all/gallery/9qB23NGKRtW7dR3kZdkorg
 
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Image isn't working for some reason. That last sentence really hits home for me, by the way, because I only knew enough to write this thread because I did exactly the same thing by buying a 98 trans for my 96. Spent money first, learned later...
 
I do want to add this, however: I am nearly certain that my 'no ISS AW-4' did in fact come from an XJ with a 1998 VIN. Hence I believe that Jeep's changeover to the AW-4 with the ISS did not precisely coincide with the 1998 model year. Beware.

We've had some posters lately who bought a used Cherokee, only to discover the previous owner swapped in an incompatible year trans and it didn't shift correctly. Was the 98 that it came out of running with this trans?

In your other post, I noted that the wire colors on the harness appeared to match up with a 94 or 95 trans.
 
I think I need someone standing behind me to show me how to post images!

I don't think that you can determine which transmission you have by the color of the solenoid wires. But I'm not sure. I would not rely on that indicator.

I am about 90% sure that my semi-automatic, non ISS AW4 came from a '98 XJ, but I can't be sure. I never put my eyes on the VIN: I relied on what the seller told me. Never wise, but not always stupid. I think that some '98's may have come with the old style trans. But that's also what I want to think because it makes me look less stupid than I probably am.

In any case, the principal (and in my case, fatal) difference between what I now call the 'early' and 'late' AW4 is the presence of an input shaft speed sensor on the 'late' one. The 'early' one has the boss for the ISS cast into the xmission case, but it is not machined. There are other differences too, but the easiest way to tell is the ISS. And you can tell by merely having a look w/o taking anything apart.

Bottom line: If you're farting around with a '96 - '98 XJ, make damn sure that you're aware of which transmission you have. To say that installing the early trans in a late body is NOT PLUG AND PLAY is to put it mildly.

Here's another bottom line: Had I known of, and absorbed this thread before I started, I'd have an extra two grand to pee away on cheap whiskey as well as enjoying lap dances with my Medical Doctor friends down at the truck stop.
 
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I feel your pain. Sort of. I pulled a transmission from a 98. I verified it was a 98 too. It didn't have an ISS and the output speed sensor was the old 1 pulse per revolution reed switch style. Not a big deal for me though, as I was going to rebuild the unit anyway, and all I had to do was build my 2wd transmission with the 4WD output shaft (with my 4 pulse output speed sensor). Once that was all done I put the transfer case adapter piece on instead of the tail cone and wham-o. 4wd AW4.

BTW, do you still have the 2wd unit? If you do, I'm curious as to what the output shaft spline count is. I kind of wonder if it's as easy as cutting it down and bolting on the extension housing to make it 4wd. I never really could get a straight answer from all the internet searches as to what the spline count was. I have long since tossed the old transmission.
 
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