Can you swap a 42RLE in for a 32RH in a '99 TJ?

moab

TJ Enthusiast
Dec 15, 2018
233
75
California
#1
So I'm pretty sure my '99 TJ needs a new AT transmission. It has a 32RH in it. Can I put a 42RLE in it from a 2010 Rubicon? If so, what is involved? And would it be more expensive than having another 32RH installed? Would I need a new console? I've read about the overdrive in town shifting alot - unless you turn the overdrive off. But I don't mind that. As most of my driving is around town. And I could just shut it off. But when I do go on a long trip I wouldn't mind it.

ALso the 42RLE is used with a reported 60k on it. Guy says he took it out because he did a LS2 engine swap in his Rubicon. Does that make sense?

Just trying to find the least expensive option here. I can have it rebuilt for $1200. But I don't have complete confidence in the shop that will do it for that.
 

Chris

Administrator
Staff Member
Sep 28, 2015
33,275
20,459
Salem, Oregon
#2
A 42RLE from a JK will not fit.

A 42RLE from a TJ will fit, but it will be way more headache than it’s worth.

The cheapest and best route is to put in a replacement 32RH, which many (myself included) consider to be a better transmission than the horrible 42RLE.
 
Likes: Nominal
Dec 26, 2018
49
35
Fairborn, OH
#4
A 42RLE from a JK will not fit.

A 42RLE from a TJ will fit, but it will be way more headache than it’s worth.

The cheapest and best route is to put in a replacement 32RH, which many (myself included) consider to be a better transmission than the horrible 42RLE.
@Chris
On a separate note are these mutually exclusive? Mine has the 42RLE nearing 200k.. If it went out would only a 42RLE TJ fit and not a 32RH or JK 42RLE?
 

Chris

Administrator
Staff Member
Sep 28, 2015
33,275
20,459
Salem, Oregon
#5
@Chris
On a separate note are these mutually exclusive? Mine has the 42RLE nearing 200k.. If it went out would only a 42RLE TJ fit and not a 32RH or JK 42RLE?
If your 42RLE in your TJ went out, the only other 42RLE that would fit it would be the 42RLE from a 03-06 TJ / LJ.

The JK 42RLE would not fit.

The 32RH would physically bolt-up, but your PCM is expecting a transmission to be there to control the shifting (and the 32RH isn't controlled via computer), so you'd have to shut the TCM module off via the PCM. There would likely be other little things that would need to be addressed as well.

Putting a 32RH in a TJ originally equipped with a 42RLE should be easier than putting a 42RLE in a TJ originally equipped with a 32RH.

The 42RLE was used in a variety of vehicles. But while that may be the case, the only one that will fit in your TJ, is one that came from another TJ. The ones used in the other vehicles (including the JK) have a lot of things different about them (length, bell housing, etc., etc.).
 
Likes: Nominal
Dec 26, 2018
49
35
Fairborn, OH
#6
If your 42RLE in your TJ went out, the only other 42RLE that would fit it would be the 42RLE from a 03-06 TJ / LJ.

The JK 42RLE would not fit.

The 32RH would physically bolt-up, but your PCM is expecting a transmission to be there to control the shifting (and the 32RH isn't controlled via computer), so you'd have to shut the TCM module off via the PCM. There would likely be other little things that would need to be addressed as well.

Putting a 32RH in a TJ originally equipped with a 42RLE should be easier than putting a 42RLE in a TJ originally equipped with a 32RH.

The 42RLE was used in a variety of vehicles. But while that may be the case, the only one that will fit in your TJ, is one that came from another TJ. The ones used in the other vehicles (including the JK) have a lot of things different about them (length, bell housing, etc., etc.).
Great information. Thanks as always, I'll keep this in mind if mine ever shits the bed.
 
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Chris

Administrator
Staff Member
Sep 28, 2015
33,275
20,459
Salem, Oregon
#7
Great information. Thanks as always, I'll keep this in mind if mine ever shits the bed.
The number one killer of the 42RLE (and automatic transmissions in general) is heat.

If you want that 42RLE to last a lot longer than it otherwise would, do what most of us do and get the Derale direct fit automatic transmission cooler for the 42RLE.

It's easy to install and will drop transmission temperatures by up to 40 degrees. This is one of the absolute must haves for anyone with a 42RLE.
 
Likes: Nominal
Dec 26, 2018
49
35
Fairborn, OH
#8
The number one killer of the 42RLE (and automatic transmissions in general) is heat.

If you want that 42RLE to last a lot longer than it otherwise would, do what most of us do and get the Derale direct fit automatic transmission cooler for the 42RLE.

It's easy to install and will drop transmission temperatures by up to 40 degrees. This is one of the absolute must haves for anyone with a 42RLE.
Before I even bought the Jeep I read about this on the forum.. Great bit of advice but the part that scares me is that mine is already at 199k so I'm not sure how much extra longevity I will get out of it by adding the cooler at this point.. For $300 an extra 10k doesn't seem too worth it to me if I'm probably going to have to have it rebuilt soon anyway.

Plus the farthest I really plan on driving it is an hour or so, so hopefully it doesnt get too stressed under that sort of condition. What do you think?
 

Chris

Administrator
Staff Member
Sep 28, 2015
33,275
20,459
Salem, Oregon
#9
Before I even bought the Jeep I read about this on the forum.. Great bit of advice but the part that scares me is that mine is already at 199k so I'm not sure how much extra longevity I will get out of it by adding the cooler at this point.. For $300 an extra 10k doesn't seem too worth it to me if I'm probably going to have to have it rebuilt soon anyway.

Plus the farthest I really plan on driving it is an hour or so, so hopefully it doesnt get too stressed under that sort of condition. What do you think?
With close to 200k, your transmission will need a rebuild soon. Generally they last around 200k miles or so, sometimes up to 250k.

My advice would be when you install new transmission, put one of those coolers on it and it will last even longer than 200k. Any amount you can keep those transmission temps down adds to the longevity, even if it's just in-town / daily driving.
 
Likes: Nominal