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Transmission swap

Pgw1995

NAXJA Forum User
Location
Arkansas
Hi everyone, new here. I have a 98 XJ classic. Only has a 6.5 long arm lift, rest is stock. My question is the tranny has begun to slip, has hesitated going into reverse since I purchased it, which has only been about a month ago. I also have a 2000 Grand that I am building, would the tranny out of the Grand fit my XJ. They both have 4.0. Believe the Grand is a 42RE and the XJ is a AW4. Will they interchange?
 
It would physically work but you would have to come with electrics plus it's a "downgrade" tranny.
 
Ok, thanks. I also thought about swapping everything over to my Xj. I just had the motor completely rebuild on the Grand, just because it had a lot of miles. My only fear is I have the good 7120 head on my XJ and the Grand has the 0331, it is the Tupy though. Is there another tranny that you would recommend over the AW4? That would be a direct swap or just rebuild the AW4?
 
Have you tested the shift solenoids and confirmed that the AW-4 is filled with Dexron-III/Mercon and not ATF ? The AW-4 is one of the most durable and long living transmission you can have behind your Jeep 4.0L engine. They are plentiful and low cost at the junkyards. You can buy a 1/2 dozen or so used one for the price of a rebuild.

The TUPY 0331 is fine, or you can re-use your 7120 if it passes inspection.
 
42re is absolute junk. Aw4 is solid and honestly I'd just swap in a used one and keep rumbling. No need to get a rebuilt just swap in a used one and you'll be good.
 
No I haven’t checked any of that yet, but it is planned before I start dropping it. When I put it into 1-2 it won’t shift out of 1st. When I manually shift it to 3rd it will go ahead and shift out to 2nd then 3rd. Shift it to overdrive and it will shift right in. When it is cold it will go into reverse okay and shifts out fine, maybe a little harder than normal but not bad. Once it warms up and you put it in reverse you have to sit a couple seconds before it will engage. When it’s warm it when it starts shifting from OD to 3rd, back and forth with normal highway driving. I haven’t tried to just drive it in 3rd.
 
In 1-2 you have to rev the crap out of it to get it to shift to 2nd. Have you tried servicing the trans and adjust the TV cable? Trans doesn't sound totally junk yet.

When mine died at 290k hard ruthless miles, I got a used one for $150 off cl, works like a champ. Used route is cheap, trans is stupid easy to pull.
 
I did rev it up really high, it didn’t shift. I will check out the cable and solenoid tomorrow. Is there anything I need to look for when testing those. (Resistance etc) (of the solenoid) I am an electrician so I know the how to check it all just don’t have a book. What is a good reading and what’s bad? On the cable, am I just looking for it to be broke? I will service it this weekend because I am not sure what the previous owners used in it. I have only had it about 3 weeks. Knew about the reverse but it seems like the OD to 3rd switching is getting worse.


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I did rev it up really high, it didn’t shift. I will check out the cable and solenoid tomorrow. Is there anything I need to look for when testing those. (Resistance etc) (of the solenoid) I am an electrician so I know the how to check it all just don’t have a book. What is a good reading and what’s bad? On the cable, am I just looking for it to be broke? I will service it this weekend because I am not sure what the previous owners used in it. I have only had it about 3 weeks. Knew about the reverse but it seems like the OD to 3rd switching is getting worse. The trans has 142,000 on it.


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Have you tested the shift solenoids and confirmed that the AW-4 is filled with Dexron-III/Mercon and not ATF ? The AW-4 is one of the most durable and long living transmission you can have behind your Jeep 4.0L engine. They are plentiful and low cost at the junkyards. You can buy a 1/2 dozen or so used one for the price of a rebuild.



The TUPY 0331 is fine, or you can re-use your 7120 if it passes inspection.
This.

Smell the fluid. If it smells burnt, it is. Drain and replace to proper level. Mine was acting up, slow weak shifts. Drained and replaced with Dex 3. Working great now.

Solenoids sound fine, try new fluid. I bet it comes back alive

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