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42, 44, 46 transmission.


Which is better?  

  1. 1. Which is better?

    • 42
      0
    • 44
      0
    • 46
      0
    • They're all junk. Use a TH400
      0


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Probably a more important question would be' How do you tell them apart?' I can tell the RE by the bulge in the pan but how do you identify the 42, 44 and 46 from each other? Book says they can be identified by a marking on the left side flange. All I see is a code, telling me nothing.

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The 42 has the AMC 6cyl bolt pattern housing. 44s/46s fit the V8s. In ZJs, 5.2s had the 44RE, 5.9s had the 46RE. I'm more a fan of the 46 than the 44. Its beefier and stronger, the 46 also had a larger output shaft. Plus 44REs have a reputation for giving up on life too soon, I just replaced one at 130K, some last longer, I've read about them going out as soon as 75K. It'll often throw the Torque Converter Control Solenoid error code and sometimes the TCC solenoid can be swapped without pulling the transmission and then all is well. I suspect some of these that go out early, just have a faulty TCC solenoid.

 

I've had two 46REs still healthy and vibrant with over 200K on them with normal driving. Only issue I've had is a badly leaking NSS, easy fix. In 44s, a lot of guys recommend replacing the OD gears with straight cut gears, bypass the radiator cooler with an external (important one!), and to use a Precision TC.

 

Someone correct me if I'm wrong,,,but I'm fairly sure that you've got to match the transmission control module to the vehicle PCM though, I don't believe you can mix and match unless you get custom programming. Also, RHs are hydraulically controlled and REs are Electric, maybe an RH is the way to go,,,not sure what you're putting it in.

 

You can get a 46RE from a Dodge truck and there's a lot of aftermarket support and programming for them. I pulled this from one of the dodge truck forums:

 

1994-1995 Dodge Rams:

-V6 4x2s had 42RH

-V6 4x4s had 46RH

-V8s had the 46RH

 

1996-2001 Dodge Rams:

-V6 4x2s had 42RE

-V6 4x4s had 46RE

-V8s had the 46RE

 

1992-1996 Dodge Dakotas:

-V6s had 42RH (RE in 1996)

-V8s had 46RH (RE in 1996)

 

One issue I know the 5.9 PCM and 46RE has is the coast down feature. I guess it does this to keep engine rpms up when coasting for a smoother transition to acceleration. I recently exchanged a few emails with Scott Mueller who wrote some good articles on the 5.9s ZJs. Here's a quote from him on the coast down feature, I don't think he'd mind me posting it.

 

"Unfortunately the Mopar Perf. PCM still has one of the most irritating "features" I've ever experienced in a factory PCM calibration. I'm talking about what is called the "coast down" part of the programming, which is what happens when you take your foot off the gas at speed. Both the stock and Mopar Perf. PCMs have the coast down part of the calibration programmed to actually *add* fuel if you begin the coast down below around 60mph, which severely reduces the amount of engine braking provided. However if you are above around 60mph and take your foot off the gas, the coast down calibration then properly reduces fuel such that good engine braking is experienced all the way down to about 20mph (then it starts adding fuel again).

 

I often manually downshift from 4th to 3rd (by pressing the OD button on the dash) or even from 3rd to 2nd when approaching a stop or coasting down a hill, but in the 5.9 if you do that below 60mph you have virtually *no* engine braking due to the goofy programming....

 

...For reference I have a 2001 Durango R/T 5.9, and the coast down and engine braking in that PCM calibration is perfect. If I could I'd just install a Durango PCM in the Jeep, but of course there are many differences in the wiring harness and other features that makes that impossible."

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I though the 94 to 98 ZJs with the 5.2 all got the 44RE, and the only 46(RE, not RH) was behind the 5.9 that was available in 98 only without a 46RH being available in any Grand Cherokee.

 

But it is also quite possible I have been misinformed. Wouldn't be the first time. :dunno:

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I was off a year. The 46RH was offered on the 5.2 from 93-95 on the ZJ. I still like it. You can upgrade the crap out of it and it will take a beating. It was even put behind the early CTD. it was not a good behind the diesel though.

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