Transmission compatibility? - JeepForum.com
 
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post #1 of 7 Old 01-11-2020, 08:43 AM Thread Starter
Bee4570
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Transmission compatibility?

In the ongoing saga of me Tony-Starking my 2001 Jeep Grand Cherokee back from the grave, I've often heard, and read, that the 42RE transmission is a weak link in the system, and that the 45RE is a much better transmission, and available behind the 4.7L V8 in the WJ, and that the later 545RE is paired behind Hemi Rams just fine. Well, I figure I might as well do my research now, so is there any dimensional differences between the 45RE and the 545RE? Would the computer throw a fit by me giving it another gear to play with? The transmission was a planned upgrade from the get-go, just something I intend to do down the line.

Or, you know, when it's needed. My roommate asked to borrow my WJ for the day and I know he's a bit stabby on the throttle. He's never driven anything that uses a throttle cable instead of throttle-by-wire. Bless his heart.


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post #2 of 7 Old 01-11-2020, 09:48 AM
smokeyyank
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If you're asking if you swap out the 42re in favor of the 545re found in the V8 no. Really theres nothing to swap in place of the 42re. Agitated pancakes did a swap of a ax15 but was tons of work and has a permanent CEL.

As for the 45re and 545re they are the same tranny just that the 545 had a reflash to allow for a "5th gear".

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post #3 of 7 Old 01-11-2020, 10:06 AM
jtec
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KISS use a 42RE, you are limited as its a 4.0L .

The good news you have the legendary 4.0L engine.

1st mod - install a trans cooler.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 7 Old 01-11-2020, 11:49 AM Thread Starter
Bee4570
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Welp, this is why I'm askin'. Figure it'd be smarter to ask now, rather than down the line after I dropped $1200 on a rebuilt transmission. Now I know it ain't gonna wanna play nice. Thanks much.

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post #5 of 7 Old 01-11-2020, 12:44 PM
rjbruzan
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The bellhousing bolt pattern is different between the 6 and 8 cylinder.

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post #6 of 7 Old 01-12-2020, 07:08 AM
Purcell69
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What about the AW-4 from the XJ? You'd still have the permanent CEL, but the AW-4 is a much more resilient transmission than the 42RE for use behind the 4.0.

-Joe
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post #7 of 7 Old 01-12-2020, 11:13 AM
smokeyyank
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Pretty sure the war wont work because of the PCM. That would be ideal though wish they would have used the aw4 instead of the 42re.

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