42RLE/How Many Gears-REALLY

[Dave]

Does the 42RLE have an extra o/d gear or what? I'll try to explain this.

This is what happened...........so I'm in o/d on the highway with the cruise set on 70 and coming to a mountain grade where I always kick it off and use my foot....... But this one time I leave it on (never did this before)......... About 1/4 of the way up the grade it downshifts to what I think is drive. So I hit the o/d lockout button to keep it in what I thought was drive but it downshifts again and now I know it is in drive for sure. (tach at about 2,800 rpm at 70mph with o/d locked out so it was not second gear)

It just acted like there was another gear in between drive and overdrive.

Dave

 

[kj924]

Probably the lock out torque converter that dropped out first then the downshift of the ****** when you hit the o/d button. Not sure, but it would be the most likely scenario.

 

[JeepJeepster]

It will unlock the torque first to let the rpms go up a bit then shift into 3rd if its needed. If you push the O/D off button, it will go to 3rd and lock the torque back. If you let the ****** downshift on its own, it will go to 3rd and leave the torque unlocked which produces more heat.

 

[o8k]

iv heard a large variety of comments on this topic, but a mechanic at my Dodge dealer said that the only difference between the 45RFE and the 545RFE is that the 545RFE shifts through both 2nd gears on its way up to final drive. the 45RFE will only downshift into both of its 2nd gears(and only upshift through one of them)

Several sources claim (including the wiki), contrary to what ive stated above, this is the setup...
Gear Ratios:
1st 3.00:1
2nd 1.67:1
2nd Prime 1.50:1
3rd 1.00:1
4th 0.75:1
Reverse 3.00:1
545RFE only:
5th 0.67:1
Thus indicating one has 5 gear ratios and the other, 6...

I dont really know for sure, but ive owned vehicles w/ both and believe the former to be true over the latter. They both have a varient of the 1950's 3 speed torqueflite auto ****** w/ an extruded High/Low gear on top of that (thus the 6 different gear ratios) So weather or not they use all the gear ratios or not, there are 6 in there.

Since you have the 42RLE, i'd venture to say the same confusion applies.

 

[Dave]

08...maby it is in the programing since the 545RFE and 45RFE and 42RLE trannies are electronicaly controlled??? I think the the first 2 are Full Electronic and the 42RLE is Limited Electronic.........That's what I thought anyway. So maby the 45RFE is a 545Rfe programmed to only use 4 gears?????

I'm confused.

Dave

 

[o8k]

I agree, confusing, maybe i should have just kept quiet till someone that knows the whole story can chime in like that guy w/ the orange jeep. He seems to know tons about this, hope he chimes in...

 

[tjkj2002]

iv heard a large variety of comments on this topic, but a mechanic at my Dodge dealer said that the only difference between the 45RFE and the 545RFE is that the 545RFE shifts through both 2nd gears on its way up to final drive. the 45RFE will only downshift into both of its 2nd gears(and only upshift through one of them)

That would make a 6 speed auto,the 545RFE has the exact same ratios with a 2nd overdrive which is the 5th gear for the 545RFE.Your mech at the dealer is wrong.

 

[Marlon_JB2]

I didn't want to say this the last time we had this discussion, but here goes:

How does this explain how it is entirely POSSIBLE to flash a 45RFE to become a 545RFE?

Splain that please... someone.

 

[tjkj2002]

08...maby it is in the programing since the 545RFE and 45RFE and 42RLE trannies are electronicaly controlled??? I think the the first 2 are Full Electronic and the 42RLE is Limited Electronic.........That's what I thought anyway. So maby the 45RFE is a 545Rfe programmed to only use 4 gears?????

I'm confused.

Dave

The 45RFE/545RFE is actually able to have (if I remember right) 8 forward ratios and 3 reverse ratios,depending on the gear set installed.But basically the 545RFE is a 45RFE with a 2nd overdrive.And you are right about the 42RLE is only a limited electronic ******.

 

[tjkj2002]

I didn't want to say this the last time we had this discussion, but here goes:

How does this explain how it is entirely POSSIBLE to flash a 45RFE to become a 545RFE?

Splain that please... someone.

There is not,a different gear set needs to be installed,you can however get full use of the 2nd "2nd" gear that is only used for highway speed downshifting.The 545RFE has a 2nd overdrive from a different gear set then the 45RFE has.The 2 trannies are very similar but have different guts.

 

[AlexKJ]

I think the the first 2 are Full Electronic and the 42RLE is Limited Electronic.........That's what I thought anyway.

According to Wikipedia (http://en.wikipedia.org/wiki/List_of_Chrysler_transmissions) the 'L' stands for 'Longitudinal'.

The first letter of the name refers to 'Drive' (Rear), the second refers to 'Orientation' (Longitudinal or Transverse) and the third (and in some cases the fourth) refers to 'Control System' (Electronic, Fully Electronic or Hydraulic)

So, the thing should be like this:

42RE: 4 speeds, torque rating '2', rear, electronic
42RLE: 4 speeds, torque rating '2', rear, longitudinal, electronic
45RFE: 4 speeds (but we know that is more there), torque rating '5', rear, fully electronic
545RFE: 5-4 speeds (weird way to say "2 seconds and 2 overdrives"), torque rating '5', rear, fully electronic.

The torque rating goes from 0 to 8. Greater the number, greater the torque it can handle. NOTE: There isn't any torque rating between 2 and 5. The only options are 0, 1, 2, 5, 7, 8.

About the 'Drive' item... well, I haven't found yet a Chrysler ****** with other letter than 'R'. It seems when is a front wheel drive car they don't put anything.

One thing that I found weird is that the 42RE and the 42RLE aren't the same ******

 

[JeepJeepster]

One thing that I found weird is that the 42RE and the 42RLE aren't the same ******

What is different about them? We have both trannies and Ive always wondered. I have a shift kit that fits both of them.

 

[AlexKJ]

The 42RE, formerly A500, is a derivative of the A904 TorqueFlite ******. The 42RE was introduced in the 1989 and it was the first light-duty Chrysler four-speed automatic (3 speeds plus an overdrive). It has a GCVW of 7800 lb (3540 kg). Was replaced by the 42RLE in 2003. A KJ never has equipped with a 42RE.

Gear ratios:
1 2.74
2 1.54
3 1.00
O 0.69
R 2.21

The 42RLE is a modified 42LE ******. The 42RLE was introduced in 2003 specially for the KJ. The 42LE was an upgraded version of the A604/41TE Ultradrive, modified for longitudinal engines. The 41TE was one of the first electronically-controlled automatics featuring adaptive shifting.

Gear Ratios:
1 2.84
2 1.57
3 1.00
O 0.69
R 2.21

Bottom line: The 42RE and the 42RLE, although seems alike (share a big part of their names and the 3rd, Overdrive and Reverse ratios) the truth is they have a totally different ancestors and the only model found in a KJ is the 42RLE (which is the best scenario after looking their 1st and 2nd gear ratios).

 

[JeepJeepster]

Yea, I meant we have two jeeps, one with the 42re and one with the 42rle. Both have been great trannies so far. Although they shift alittle to smooth.

Thanks for the info. Did you see how many different cars they use the 42rle in? I had not idea it was used in that many.

• 2005-present Chrysler 300
• 2007-present Chrysler Aspen
• 2006-present Dodge Charger
• 2005-present Dodge Dakota
• 2004-present Dodge Durango
• 2005-present Dodge Magnum
• 2007-present Dodge Nitro
• 2003-present Jeep Liberty
• 2003-present Jeep Wrangler

 

[Big A]

Yea, I meant we have two jeeps, one with the 42re and one with the 42rle. Both have been great trannies so far. Although they shift alittle to smooth.

Thanks for the info. Did you see how many different cars they use the 42rle in? I had not idea it was used in that many.

• 2005-present Chrysler 300
• 2007-present Chrysler Aspen
• 2006-present Dodge Charger
• 2005-present Dodge Dakota
• 2004-present Dodge Durango
• 2005-present Dodge Magnum
• 2007-present Dodge Nitro
• 2003-present Jeep Liberty
• 2003-present Jeep Wrangler

Thats good info for us! At least we know that this ****** is readily availabe for some time to come and it is reliable! (I hope!)

 

[Dave]

There is not,a different gear set needs to be installed,you can however get full use of the 2nd "2nd" gear that is only used for highway speed downshifting.The 545RFE has a 2nd overdrive from a different gear set then the 45RFE has.The 2 trannies are very similar but have different guts.

tjkj......Ok, the fog is starting to clear now. So despite the programming, it's what's inside that counts. (which gearset for the 45 and 545 RFE's)

So for the 42RLE (my ******) what I felt was definately the torque converter and not another gear. It did feel like another gear and that's why I posted.

Dave

 

[Dave]

AlexKJ......and Blake.......interesting info......thanks.

Dave

 

[AlexKJ]

This was found in http://www.jeepsunlimited.com/forums/archive/index.php/t-357495.html

I am a tooling engineer for transmissions for DC and our Advanced Manufacturing Engineering group bought and installed the 42RLE transmission lines at the Kokomo Transmission Plant this past year.
Now I have to say that my own 42RLE was replaced last month, but it was due to the torque convertor. Chrysler wanted the whole transmission to test, so they installed a new on in my rubi.
The 42RLE has been put on the Dyno test equipment and tested in every torque rating up to and including 7 thus far, none have failed. A torque rating of two is all that is expected to be needed in the Rubicon, but we test and test again, raising the bar each time till one breaks, then we start on another. So far, NONE have been broken. That does not mean that a flaw in a torque convertor, electronic component or clutch pack can't send to to the dealer for a replacement, but it is under waranty.

A different thing is the lower 1st ratio (3.00 vs 2.84) of the 45RFE and its two 2nd gears and two overdrives (5-45RFE only)... Everything else, the 42RLE seems a pretty tough one...