2005 42RLE Transmission Rebuild Questions

DerekRI

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Hello everyone! Just stopping by with a few questions about 42RLE rebuilding. The jeep in question has 190k and has been ours since about 150k. As far as I know, the transmission had never been rebuilt.

The first thing odd about the transmission is that it is physically difficult to shift out of Park sometimes, and this is obviously exacerbated when on any kind of an incline. I understand the issue of using the e-brake on a hill to hold the jeep so the force is not on the transmission parts, but this does often seem to be the case on flat ground as well. Once out of park, it shifts freely into the other gears as well. I know that there is the safety feature of the brake lock that could be involved with this as well. This hard shift happens often enough to destroy my shift linkage bushing relatively quickly. I've replaced it twice now.

Now, with it's features, I believe this jeep has the 3.55 gears in it. We did a 2" lift, and put 33's on it. Obviously, this bogged down the transmission, understandably. My concern is that the transmission seems to lug around in low RPMs much longer than it seems like it should. Uphill on the highway, it'll just bog down, instead of simply downshifting. Mind you, I've never felt any slipping of the clutch, and when it does shift, it's always smooth (i.e. no clunking or knocking).

I've had the fluid replaced a couple of times by mechanics, and both times they said the fluid was looking pretty dirty.

So, my questions for you folks are:

1. Does this sound like a rebuild scenario? Or should I focus my efforts for the hard shifting issue more to things like the brake lock not fully disengaging?

2. If a rebuild does happen, is there any reasonable way to change the internal gears of the transmission to make the 33's a little more manageable, or is a differential gear change the only way to achieve that effect?

Thank you!
 
You probably have 3.73 gears and the lugging you describe is normal for a 42RLE and gets worse with larger tires. Doesn't sound like a rebuild is necessary, you'll get codes when that happens. Make sure your fluid level is correct and keep up on those filter changes, you should be fine. You might look into changing your final drive ratio, re-gearing, it'll help (you can't change the ratios on the transmission).
 
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Keep this in mind... for 33s on a 42RLE you want 5.13 gears.

So you're gearing right now is so terrible (on an already terribly geared transmission) that life will suck big time.

Hell, I even re-geared to 4.88 on my 42RLE with 33s and even that felt like I didn't go deep enough.

I think the bulk of your issue (if not the entire issue) is extremely poor gearing. I mean you literally have the WORST possible gear ratio for the 42RLE and bigger tires ;)
 
That all makes perfect sense, thank you for your input. I knew that it wasn't an ideal setup to be pushing 33's, but I didn't expect it to be an almost deal-breaker haha. I used to have a 97 with the 2.5 and 4.10's and it wasn't this unhappy with 33's, I just had to stop using 5th gear lol. Guess the 4.10's were enough for that setup.

When looking into re-gearing, should we be looking to go all the way to the 5.13 range if possible? Or is there a trade-off (better MPG?) to not going quite that far?

Also, any input on the hard shift out of Park? Think it's just as simple as using the e-brake more effectively? It's just concerning because the jeep does a small surge forward as the clunky shift happens in the transmission. Doesn't feel like it likes it very much. It's definitely something I'd love to remedy if possible. At the very least, it's chewing up my bushings.
 
Oh, and one other thing I wanted to mention about pagrey's comment above saying it would throw a code if a rebuild was in order... this jeep always has the CEL illuminated. It has the weird glitch where the computer says the 02 sensors are bad, even though they aren't. We get exemptions for inspection because we have replaced all the relative parts with no solution. So the light is always on, and I never think to actually check the codes because of this. I will definitely look into that. Thank you!
 
It sounds like you have a few issues but as long as it changes gears and doesn’t slip, the transmission is probably fine.

When shifting out of park, the shift lever and cable need to rotate the manual shift level on top of the transmission case. If you get under the driver side of the Jeep, you can see the shift cable is attached to a bracket that mounts on a shaft. If the shaft is rusty, it can get hung up on the case.

I’m not sure your method applying the parking brake. My practice is to shift to neutral, engage the parking brake, then release the brake pedal and the shift into park. This places the vehicle weight on the parking brake instead of the parking pawl. When you’re ready to go, shift out of park before releasing the parking brake.

If you’re running 3.73s, you’re not properly geared, particularly in overdrive (4th gear) with the torque converter locked. It would be best to regear the axles or go down to 31” tires.

The 42RLE is electronically controlled and the PCM is generally going to lock up the TCC to save fuel. You need to learn what gear you’re in and when to turn O/D off and on. In my experience, if I turn O/D off, the TCC will lock immediately after 3rd gear engages. I’ve found it’s best to keep O/D on until the 2-3 shift occurs and then turn O/D off before the 3-4 shift occurs. This keeps the TCC from locking up too soon in 3rd gear. With the TCC locked, you’ll find 4th gear is essentially unless.

If you’re getting a clunk or hard gear engagement when shifting from neutral to drive, this is not good. Either your RPMs are too high (vacuum leak) or the transmission line pressure is too high (PCM or solenoid pack). If there is an issue with the transmission or solenoid pack, this should set a code. If the PCM is the issue, it probably won’t set any codes.

What O2 sensor codes are you getting.
 
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Honestly, I don't remember. It has been a while since we've had to address it because of getting the exemption. We were told it was a relatively common problem with this year. We had another computer installed as well, which made no change.

I'm about to go out and fiddle with things for a bit, I will update once I'm back inside. Thanks again
 
Cycle the ignition from off to on 3 times and any stored codes will be displayed in the odometer readout.

There is a TSB for I/M readiness related to the O2 sensors but this will not set off the MIL.
 
Codes are the trio of P0037, 51, and 57. Usually implies bad PCM, but as I said, we replaced that (and all the sensors multiple times) to no avail. That's how we got approved for the exemption. No transmission code though!

I was able to creatively zip tie the linkage in place for now, until the new bushing arrives. I'm honestly considering leaving the zip tie in place even with a new bushing, as it seems to stay in place nicely without effecting any of the shift linkage movement.

I also experimented with different series of parking brake application, etc, and I definitely think being conscious of that is going to help with the initial clunk out of park.

Looks like we'll go forward like this for a bit, and perhaps shift out train of thought from transmission rebuild to a regearing.
 
I hated my 42RLE until I regeared to 4.88s. For the most part its on point now, I can actually accelerate in fourth!
 
Nice! What's the general opinion on finding used parts vs getting a brand new set?
 
Gears? Personally I'd only consider new. I did gears, axle bearings and seals in the rear, and a Detroit TruTrac and my bill was $1900.