Is the KJ for me?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Donnie

Full Access Member
Joined
Nov 28, 2006
Messages
62
Reaction score
0
Yeah, where is it? I ran like that for a while, looked GREAT at first, then... I grew to miss the spare hanging on the back.

Hey, I just realized... Donnie has the 45RFE! :D

I just like it better without it. Whats the 45RFE??? Something good I hope lol.
 

2003KJ

Member
Joined
Sep 13, 2004
Messages
5,283
Reaction score
6
Location
Planet Earth
I just like it better without it. Whats the 45RFE??? Something good I hope lol.

Yes, the 45RFE is a very good thing.

Over the course of the KJ's production, there were two automatic transmissions that were put behind the 3.7L, the 45RFE, and the 42RLE. The tricky part is who has what. In most cases it's obvious, but it was originaly thought by most of us, based on the reports we were seeing from others that the change over had occured sometime during the April 2003 run of KJ's. However, lately we are finding out that this may not be the case, and it may be slightly later than that.

While both transmissions are very solid, personally, the 45RFE suits the the KJ and the 3.7 better. The 45 can be found behind the Dodge Ram (not sure which models of the Ram off the top of my head), and I believe it was designed for the Ram (so designed for a truck, consequently means it's going to be built to last compared to others).

The 42RLE was one that that was originally designed for lighter duty use, and had to be adapted to fit to a rear wheel drive application, such as the KJ. General complaints towards the 42 are the quirky shifting.....especially once you get into OD. The 42 is often searching for the right gear at about the point where OD kicks in, especially if you're climbing up even the slightest of hills....it will often times kick down into 3rd, then hop right back into 4th again.

I had the opportunity to drive my old neighbors KJ back from the airport a couple of years ago. This was a 2002 sport, decked out about the same as mine is, only he had the 45RFE, and my KJ has the 42RLE. I noticed a nice difference in performance, and the KJ felt like it had more pep to it. The shift points were slightly lower, and it pulled a lot better in 4th/OD crusin down the road (I could actually pass people with out it kicking down a gear). I also liked the firmer, quicker shifts.

So bottom line, while both transmissions are proving to be very reliable, if you have the 45RFE (which you do), consider yourself lucky. I encourage you to test drive a 2004+ KJ if you ever get the opportunity, and take note of the change in responsiveness.

As for who's got what.....here's what we're certain on (bear in mind this is only with KJ's equipped with the 3.7L....the CRD gets a different transmission specifically for the CRD:

ALL 2002 models have the 45RFE.

2003 is the switch over year. Earlier 03 models tend to have the 45, later tend to have the 42. However it varies on the later 03's as to which transmission is equipped. It's almost one of those "which ever is first on the shelf, gets put in this KJ" type deals....which is why it's hard to determine the change over date

I'm pretty certain that just about all 2004's have the 42RLE...however I have seen a couple of exceptions lately.

ALL 2005 - Current have the 42RLE

As far as the nit picky stuff, Marlon knows the insides of Chrysler better than the damn CEO himself....so i'm sure he'll chime in and correct any of my errors

Hope this helps! :)
 

Donnie

Full Access Member
Joined
Nov 28, 2006
Messages
62
Reaction score
0
Nice info! It's good to know if I ever want a v-8 the ****** is already there :).
 

JeepJeepster

Full Access Member
Joined
Dec 15, 2004
Messages
8,907
Reaction score
296
Location
Dem hollers in Ky
The 545RFE is also used behind the hemi in the rams and Jeep.. Ive heard that it is alittle different than the normal 45rfe though. I read so much crap on the internet Im not sure whats right and whats not.. So I could be wrong.

Muffler time..
 

smileyboy

New Member
Joined
May 23, 2007
Messages
17
Reaction score
0
Cool, I found a red 02 with 65000 miles on it. Sounds like that will be be perfect for what I want to do.
 

Marlon_JB2

Kombat Edition Jeep
Joined
Nov 20, 2004
Messages
15,052
Reaction score
106
Location
Harrison Township, MI
You look for this, the Transmission Control Module mounted on the passenger side fender, under the hood.

You must be registered for see images attach


The Libertys with the 42RLE don't have it there.

EDIT: That is the 545RFE Control Module. The 45RFE Control Module is different BUT IS STILL mounted in the same location.

Also, the reason for the 3.7L/45RFE combination feeling quicker, is because of gearing.

Donnie, what is your build date?
 
Last edited:

Latest posts

Members online

Top