Options for those who want overdrive on their TJ (42RLE vs AW4 vs ?)

[Negreac]

So have been considering options to get OD on a multi purpose TJ (70+mph freeway long distance, Dune riding and Rock Crawling) and seems like the only 2 reasonable options while keeping a 4.0L are the 42RLE and the AW4. Below is what I could gather about both options but looking for some more input from those with more experience with each or any other alternatives I am missing.

To preempt the OD and Automatic haters, I am aware and have owned the 32RH as well as an AX15, they are great transmissions but one is not an auto and the other does not have OD. This discussion is meant to be focused on options for those that have decided they are willing to trade some reliability and efficiency for an Auto with OD cause they do a lot of high speed driving and prefer Auto for their type of wheeling.

Gearing chart I created comparing many options to stock gearing at 70mph and when in 4 low (I didn't include all the 4:1 T-case options for simplicity in the list but obviously that would help further with the crawl ratios over the 2.72:1):

OD RPM target for 70mph is 2500 to minimize excessive downshifting and power loss in lower speed driving. Have accounted for 4% reduction in overall tire diameter while aired down for crawling. Not so sure about the OD RPM/Speed calc. I just dropped in 2400rpm for both transmissions and what the speed would be at. Need to do some more research on the OD triggers.


AW4:
Pros:

• Cheap, Abundant and well documented install
• Generally considered good strength but don't have any definitive power limit numbers
• Hydraulic controls seem to be preferred over the electronic controls on the 42RLE

Cons:

• Less efficient that the 42RLE, I believe I read reports of it robbing as much as 10% more power from @mrblaine
• Requires good external cooling as it is known for overheating in hotter climates
• To prevent it from upshifting from 1st to 2nd gear when crawling a separate circuit/switch needs to be installed or a stand alone TCU is needed
• No default OD off switch but it can be added
• ~3" longer than a 32RH but not clear if it is any longer than the 42RLE

42RLE:
Pros:

• Higher OD (0.69 vs 0.75), which I know some would consider a con if you aren't regearing with it in mind
• Option for the Rubi crawler to doubler to be added without extending overall trans length
• OD off switch option

Cons:

• Less abundant and much more involved to install on any TJ made prior to 2003 (New PCM, wiring, switch to coilpack ignition, etc. on pre 2000)
• Requires good external cooling as it is known for overheating in hotter climates unclear whether it is any better than the AW4
• Generally considered less reliable than the AW4 from a strength perspective but have no info on actual power limitations
• Unaware of any stand alone TCUs for the 42RLE other than this new one without much info ( https://etranscontrol.com/shop/tcm-432-kit/ ) or HPTuners from my understanding can adjust the shift points

 

[mrblaine]

So have been considering options to get OD on a multi purpose TJ (70+mph freeway long distance, Dune riding and Rock Crawling) and seems like the only 2 reasonable options while keeping a 4.0L are the 42RLE and the AW4. Below is what I could gather about both options but looking for some more input from those with more experience with each or any other alternatives I am missing.

To preempt the OD and Automatic haters, I am aware and have owned the 32RH as well as an AX15, they are great transmissions but one is not an auto and the other does not have OD. This discussion is meant to be focused on options for those that have decided they are willing to trade some reliability and efficiency for an Auto with OD cause they do a lot of high speed driving and prefer Auto for their type of wheeling.

Gearing chart I created comparing many options to stock gearing at 70mph and when in 4 low (I didn't include all the 4:1 T-case options for simplicity in the list but obviously that would help further with the crawl ratios over the 2.72:1):

View attachment 642932

OD RPM target for 70mph is 2500 to minimize excessive downshifting and power loss in lower speed driving. Have accounted for 4% reduction in overall tire diameter while aired down for crawling. Not so sure about the OD RPM/Speed calc. I just dropped in 2400rpm for both transmissions and what the speed would be at. Need to do some more research on the OD triggers.


AW4:
Pros:

• Cheap, Abundant and well documented install
• Generally considered good strength but don't have any definitive power limit numbers
• Hydraulic controls seem to be preferred over the electronic controls on the 42RLE

Cons:

• Less efficient that the 42RLE, I believe I read reports of it robbing as much as 10% more power from @mrblaine
• Requires good external cooling as it is known for overheating in hotter climates
• To prevent it from upshifting from 1st to 2nd gear when crawling a separate circuit/switch needs to be installed or a stand alone TCU is needed
• No default OD off switch but it can be added
• ~3" longer than a 32RH but not clear if it is any longer than the 42RLE

42LE:
Pros:

• Higher OD (0.69 vs 0.75), which I know some would consider a con if you aren't regearing with it in mind
• Option for the Rubi crawler to doubler to be added without extending overall trans length
• OD off switch option

Cons:

• Less abundant and much more involved to install on any TJ made prior to 2003 (New PCM, wiring, switch to coilpack ignition, etc. on pre 2000)
• Requires good external cooling as it is known for overheating in hotter climates unclear whether it is any better than the AW4
• Generally considered less reliable than the AW4 from a strength perspective but have no info on actual power limitations
• Unaware of any stand alone TCUs for the 42RLE other than this new one without much info ( https://etranscontrol.com/shop/tcm-432-kit/ ) or HPTuners from my understanding can adjust the shift points

The AW-4 has a default OD off. The shifter is 1-2 for the first position, D, then OD. The other problem you mentioned is keeping it in 1st. That is a non-issue. We never had one shift to 2 when it was not okay to do so. The difference between .75 and .69 is one gear step or about the same 5%.

I've never said 10% because I have no way to quantify that. If driving around with what feels like dragging an anchor is quantifiable, then assign a number. Otherwise just understand that they are power robbing pieces of shit.

 

[Moglocker]

So have been considering options to get OD on a multi purpose TJ (70+mph freeway long distance, Dune riding and Rock Crawling) and seems like the only 2 reasonable options while keeping a 4.0L are the 42RLE and the AW4. Below is what I could gather about both options but looking for some more input from those with more experience with each or any other alternatives I am missing.

To preempt the OD and Automatic haters, I am aware and have owned the 32RH as well as an AX15, they are great transmissions but one is not an auto and the other does not have OD. This discussion is meant to be focused on options for those that have decided they are willing to trade some reliability and efficiency for an Auto with OD cause they do a lot of high speed driving and prefer Auto for their type of wheeling.

Gearing chart I created comparing many options to stock gearing at 70mph and when in 4 low (I didn't include all the 4:1 T-case options for simplicity in the list but obviously that would help further with the crawl ratios over the 2.72:1):

View attachment 642932

OD RPM target for 70mph is 2500 to minimize excessive downshifting and power loss in lower speed driving. Have accounted for 4% reduction in overall tire diameter while aired down for crawling. Not so sure about the OD RPM/Speed calc. I just dropped in 2400rpm for both transmissions and what the speed would be at. Need to do some more research on the OD triggers.


AW4:
Pros:

• Cheap, Abundant and well documented install
• Generally considered good strength but don't have any definitive power limit numbers
• Hydraulic controls seem to be preferred over the electronic controls on the 42RLE

Cons:

• Less efficient that the 42RLE, I believe I read reports of it robbing as much as 10% more power from @mrblaine
• Requires good external cooling as it is known for overheating in hotter climates
• To prevent it from upshifting from 1st to 2nd gear when crawling a separate circuit/switch needs to be installed or a stand alone TCU is needed
• No default OD off switch but it can be added
• ~3" longer than a 32RH but not clear if it is any longer than the 42RLE

42RLE:
Pros:

• Higher OD (0.69 vs 0.75), which I know some would consider a con if you aren't regearing with it in mind
• Option for the Rubi crawler to doubler to be added without extending overall trans length
• OD off switch option

Cons:

• Less abundant and much more involved to install on any TJ made prior to 2003 (New PCM, wiring, switch to coilpack ignition, etc. on pre 2000)
• Requires good external cooling as it is known for overheating in hotter climates unclear whether it is any better than the AW4
• Generally considered less reliable than the AW4 from a strength perspective but have no info on actual power limitations
• Unaware of any stand alone TCUs for the 42RLE other than this new one without much info ( https://etranscontrol.com/shop/tcm-432-kit/ ) or HPTuners from my understanding can adjust the shift points

Don’t know what year tj you have,but I love my 2002 32rh and would love to have o/d we drive it all over the country to get to wheeling spots(none in Florida)but I think it would be pretty difficult to add a tcm to my setup.so we just get in the shitbag lane and keep it at 2800 rpm -63 mph.(lol)

 

[Rickyd]

If i ever stretch my tj to LJ length I'll build a 42re with v8 parts and use that.

 

[Moglocker]

If i ever stretch my tj to LJ length I'll build a 42re with v8 parts and use that.

It’s been done,a guy in cali installed a trans out of a Cherokee in his tj.

 

[Negreac]

If i ever stretch my tj to LJ length I'll build a 42re with v8 parts and use that.

How much longer is the 42RE that you would need a stretch? Seems like many people use the AW4 with an SSYE to gain back the 3" the AW4 robs from a 32RH. I don't know how much longer a 42RLE is just know it is longer then the 32RH.

 

[ColoJeep]

The AW-4 has a default OD off. The shifter is 1-2 for the first position, D, then OD. The other problem you mentioned is keeping it in 1st. That is a non-issue. We never had one shift to 2 when it was not okay to do so. The difference between .75 and .69 is one gear step or about the same 5%.

I've never said 10% because I have no way to quantify that. If driving around with what feels like dragging an anchor is quantifiable, then assign a number. Otherwise just understand that they are power robbing pieces of shit.

Any thoughts why the A340F in a Toyota feels so different , they are very similar if not the same . I always thought it was because a 4Runner had 4.10 axle ratio instead of the Cherokee's 3.55 . However I haven't driven an AW-4 swapped into a Jeep TJ. Thanks.

 

[Rickyd]

It’s been done,a guy in cali installed a trans out of a Cherokee in his tj.

Only issue is they are a few inches longer than an ax15/42rle/nv3550. So I'll wait until a stretch.

 

[Moglocker]

How much longer is the 42RE that you would need a stretch? Seems like many people use the AW4 with an SSYE to gain back the 3" the AW4 robs from a 32RH. I don't know how much longer a 42RLE is just know it is longer then the 32RH.

I think they had to cut off some of the shaft from trans to t-case.the entire list is on the webs,reading about it a bit back.

 

[Rickyd]

How much longer is the 42RE that you would need a stretch? Seems like many people use the AW4 with an SSYE to gain back the 3" the AW4 robs from a 32RH. I don't know how much longer a 42RLE is just know it is longer then the 32RH.

42re is longer than the 42rle. How much i forget,but i know if you have a lift it isn't an option

Any thoughts why the A340F in a Toyota feels so different , they are very similar if not the same . I always thought it was because a 4Runner had 4.10 axle ratio instead of the Cherokee's 3.55 . However I haven't driven an AW-4 swapped into a Jeep TJ. Thanks.

Idk man. The older automatic tacomas feel like total turds to me compared to the manuals. They get way worse mileage too.

Tough transmission but not an efficient one

 

[Negreac]

Only issue is they are a few inches longer than an ax15/42rle/nv3550. So I'll wait until a stretch.

Why is it you like the 42RE? Just a quick search online and I see it getting a lot of hate from Mechanics and XJ guys.

 

[mrblaine]

It’s been done,a guy in cali installed a trans out of a Cherokee in his tj.

I've done about 10 of them, does that count?

 

[mrblaine]

Why is it you like the 42RE? Just a quick search online and I see it getting a lot of hate from Mechanics and XJ guys.

View attachment 642943

I could have written this for Novak.

 

[Rickyd]

Why is it you like the 42RE? Just a quick search online and I see it getting a lot of hate from Mechanics and XJ guys.

View attachment 642943

It isn't much different than v8 dodge automatics of the era. It can be upgraded with v8 parts. It doesn't take a lot to adapt one and it's tcm from a grand Cherokee.

It isn't a boat anchor like the aw4 or as weak as the 42rle.

 

[mrblaine]

Any thoughts why the A340F in a Toyota feels so different , they are very similar if not the same . I always thought it was because a 4Runner had 4.10 axle ratio instead of the Cherokee's 3.55 . However I haven't driven an AW-4 swapped into a Jeep TJ. Thanks.

Not any more than I can fathom why when you take a perfectly wonderful AW-4 out of the XJ where it has few if any faults and then it falls on it face the second you toss it into a TJ. I can absolutely tell you that axle ratio doesn't matter except to make it worse as they get higher. (lower numerically)

As I've stated many times, I have a friend who is Mr. XJ. I was explaining the problem and pondering possible solutions. He was mystified. I had him take Kat's for a spin. He came back and wanted to know WTF was wrong with it. He said it acts like it is dragging an anchor and that's with 5.38's and 35's.

 

[ColoJeep]

42re is longer than the 42rle. How much i forget,but i know if you have a lift it isn't an option


Idk man. The older automatic tacomas feel like total turds to me compared to the manuals. They get way worse mileage too.

Tough transmission but not an efficient one

Of course the 5 spd. manual bitch slaps the auto . we have both and there is no comparison . But the AW-4 Cherokee's seem like dogs . the 4Runner is a dog only to the manual Taco.

 

[ColoJeep]

Not any more than I can fathom why when you take a perfectly wonderful AW-4 out of the XJ where it has few if any faults and then it falls on it face the second you toss it into a TJ. I can absolutely tell you that axle ratio doesn't matter except to make it worse as they get higher. (lower numerically)

As I've stated many times, I have a friend who is Mr. XJ. I was explaining the problem and pondering possible solutions. He was mystified. I had him take Kat's for a spin. He came back and wanted to know WTF was wrong with it. He said it acts like it is dragging an anchor and that's with 5.38's and 35's.

Good to know .

 

[mrblaine]

Of course the 5 spd. manual bitch slaps the auto .

I've had a few try to tell me that. Then they tried to outrun my 04 with the 42 and 200,000 miles on it. None of them have yet.

 

[Negreac]

Strange that the AW4 would act any different in an XJ than a TJ since it literally has no way of telling what vehicle it is in. Wonder if it has something to do with specific combinations.

A few years back I was discussing purchasing an AW4 TJ with 33s and 4.56 gears that was custom built up by an experienced Ultra 4/Off Road race/builder for his wife to compete in the Rebelle Rally (which it won along with the Nevada Trophy and Fury Rode) and he did mention to me that in his particular case the AW4 "only stayed up shifted into OD locked up too long" "But leave it in 3rd and don't hit OD unless over 4500" which was different then a local guy with an AW4 with 4.88s and 37s who said his downshifted to early. Seems there may be some varying experiences with AW4 swaps that nobody has fully figured out.

Here are some pics of that AW4 TJ for reference:

The Builder:

 

[ColoJeep]

I've had a few try to tell me that. Then they tried to outrun my 04 with the 42 and 200,000 miles on it. None of them have yet.

I was referring to the Tacoma 5 spd. manual vs. 4Runner A340F auto. The 5 spd. will easily out run the auto , both with a 3.4 l V-6 . with 230,000 miles each.
Actually the Tacoma will out run both our 99 and 04 4.0 TJ's on the highway , offroad is a totally different story. I look at the 04 Tacoma TRD as my 4X4 El
Camino and road vehicle.

I wonder if the torque convertor stall speed plays a major factor in the poor performance of the swapped AW-4 . Thanks for your AW-4 experience Blaine .