97 ZJ with 42RE cracked case, will WJ 42re work? - JeepForum.com
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Unread 10-29-2012, 09:11 AM   #1
azvinnie
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97 ZJ with 42RE cracked case, will WJ 42re work?

Hi Guys,

I have a 1997 with a 4.6 stroker, 42RE, and a 242 transfer case. The transmission case is cracked (long story) so it's not rebuildable (OK it might be rebuildable with some TIG welding but I don't want to go there if I don't have to.)

It is much easier to find a decent 1999-2001 42RE from a WJ than one from a ZJ. Since I have OBDII, assume the plugs are the same. I'm also assuming the all the 242 selec-trac TC's are the same so it will bolt up to the newer transmission. Is this correct or is that old saying about "assume" at work here?

Anyone have any experience how the 42REs hold up long term behind the strokers? Should I spend the money to get a high perf trans or do the 42re's hold up OK?

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Unread 10-30-2012, 10:46 AM   #2
azvinnie
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what's different about the electronics?

From reading the other threads I gather that the electronics are different. I guess my real question is "how different?" What exactly are the differences?

Any difference in solenoids?

Is the crank position sensor in the same location?

is the speed sensor the same?
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Unread 10-30-2012, 10:54 AM   #3
xcaliber81
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im curious about this too, would a newer 42 re be better than mine in a 94. Mine has obd1
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Unread 10-30-2012, 03:16 PM   #4
ratmonkey
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solenoids, valve body restrictor plate, connectors are different.
designed to run at different pressures and slightly different timings. this kind of revision was done about every other year on the 42re making actual, exact interchange somewhat limited.
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Unread 10-30-2012, 03:30 PM   #5
azvinnie
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Thanks for the info... seems like different pressures wouldn't make much difference since that is all confined to the internals of the trans. Connector differences seems like it could be easily worked out... timing differences might cause problems depending how the solenoids are controlled...

Has anyone actually tried?
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Unread 10-30-2012, 03:34 PM   #6
Foundrydude
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You're playing with fire by continuing this line of thought. Focus those resources on finding the correct transmission within your budget.

good luck
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Unread 10-30-2012, 03:55 PM   #7
azvinnie
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playing with fire? really?

I own a 48 CJ-2A with a Buick 4.1L with Chevy 4.3L TBI. Hint: that engine never came with fuel injection.

I also have a 55 Willys Wagon with a Chevy TBI 350, 700r4 and blazer axles. I fabricated all the engine and transmission mounts and again put the TBI from a later model 350 on the earlier engine.

Where is your sense of adventure? I have a really hard time imagining that putting a '99 42re in a '97 is playing with fire... it might take some hacking and fabrication but I'd bet that someone with the right skills could do it... but that's just me...
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Unread 10-30-2012, 04:06 PM   #8
NC_ZJames
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I know this is for a Dodge truck, but might be some help. In the Dodge 2500-3500 diesel trucks, 96-02 had 47re's in them, but the 96-99 had one electronic style and the 00-02's had a different electronic style. They were the exact same transmission, except for the OD/lock-up solenoids and the governor sensors which changed the pressure and shift somewhat. In these trucks you could swap out the OD/lock-up solenoid and the governor sensor and the bracket holding the solenoid on the valve body and it would work perfectly.
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Unread 10-30-2012, 04:14 PM   #9
NC_ZJames
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Ok just looked up the OD/lock-up solenoids and the governor sensors, they are the same part numbers for 42RE / 46RE / 47RE and listed the same way, one for up to 99 the other 00 and up.
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Unread 10-30-2012, 04:14 PM   #10
Foundrydude
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Quote:
Originally Posted by azvinnie View Post
playing with fire? really?

I own a 48 CJ-2A with a Buick 4.1L with Chevy 4.3L TBI. Hint: that engine never came with fuel injection.

I also have a 55 Willys Wagon with a Chevy TBI 350, 700r4 and blazer axles. I fabricated all the engine and transmission mounts and again put the TBI from a later model 350 on the earlier engine.

Where is your sense of adventure? I have a really hard time imagining that putting a '99 42re in a '97 is playing with fire... it might take some hacking and fabrication but I'd bet that someone with the right skills could do it... but that's just me...
Fixing the either of those trucks back to stock would've been more cost/time effective, but you chose to spend money/time to customize with parts that have more capability. That is a totally different situation, and it's poor advice to parallel your situation to his.

If you go into this needing to fix a late model, even a little bit of custom work in the swap makes the conversion exceed the cost of direct replacement parts. That's the playing with fire. Don't spend new money to install used parts which are no better, just different.

Now if there is technical justification to wanting a newer transmission, it's worth investigating.
But it doesn't seem the case, here it's just different, not better.

A sense of adventure doesn't factor into this at all. I have walked this path many times and the right answer requires a person to seperate the BS machismo out of the conversation. Cause there's always somebody who thinks the right answer has to involve the most fabrication, and it's usually delivered with a dose of condescending attitude about tackling needless work

good luck to the OP!
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Unread 10-30-2012, 04:35 PM   #11
azvinnie
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Actually 25 years ago when I did the conversion parts were impossible to get for the 48... The Carter WO carb for the L134 engine had been out of production for decades. I bought the donor car and adapter for what a carb would have cost. The TBI came later.

the dana 41 (not a typo) rear axle got replaced with a 44 because parts could not be had for the 41... etc, etc...

That is sort of like the problem I'm having with the ZJ. I can't find a transmission in a wrecking yard. a no-core rebuilt are in the $2k range...
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Unread 10-30-2012, 04:38 PM   #12
ratmonkey
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the pressures are mapped in the TCU, which is a part of the PCM. the valve body springs, restrictor plate, and switch valves are designed around those pressure maps(or the other way around, however you like to state it)
this can either result in slightly funky shifts that you don't really notice all the way to hunting and accumulator buzzing or really sloppy shifts depending upon how wide the programming gap was. this is especially apparent with the v8 transmissions at the 99/00 transition point. but has been seen in other year gaps.
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Unread 10-30-2012, 04:43 PM   #13
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Here is a post I made on a diesel forum a couple of years ago, it shows the differences between the two. I did a quick search on 42re valve bodies and judging by the pictures they are very look very similar to the 47re. Again, these pictures are of a 47re valve body, but should be close to the 42re.


On the 96-99 there is a C-clip on the inside that holds the governor sensor on place, while the bracket holds it in place on the 00-02's.





1- Governor Sensor
2- Governor Solenoid (same on all 47RE's)
3- the bracket that you will need off your 01 valve body (holds the governor solenoid in place and on the 00-02 it also holds the governor sensor in place, which is why you need it)
4- OD and Lock-up solenoids

On the 96 valve body
-unplug the governor sensor and solenoid
-remove the bracket and governor solenoid
-remove the C-clip holding the governor sensor and remove the sensor
-unbolt the OD/lock-up solenoids and the harness (all one piece)
-get the bracket off the 01
-use new sensors/solenoids and put everything back together using the 96 vb and the 01 bracket.
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Unread 10-30-2012, 05:13 PM   #14
ratmonkey
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the solenoids aren't a problem. the revised ones have better filter baskets and different connectors. that's really it. the issue is the tcu programming vs the hydraulic programming in the valve body.
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Unread 10-30-2012, 06:07 PM   #15
NC_ZJames
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Quote:
Originally Posted by ratmonkey View Post
the solenoids aren't a problem. the revised ones have better filter baskets and different connectors. that's really it. the issue is the tcu programming vs the hydraulic programming in the valve body.
In the Dodge's, the PCM programming was different between between the two different styles, the values the sensor picked up are different and would also use the solenoids to control the pressures different. You could connect the plug on the transmission on an older truck, but would cause it to go into limp mode if it had the newer sensor/solenoid in it.

Searching for the 42re valve body, it comes up with only two different versions. One with the old style electronics and one with the new style, all internal parts are the same.
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