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Unread 10-09-2013, 04:40 AM   #1
Hoppy269
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2011 JK Wrangler 
 
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Auto Transmission options are there any?

Are there any options to replace the 42lre auto for the 3.8 engine? Does the newer 5 speed mate to the 3.8, any Chevy options that might or other Mopar trannys?

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Unread 10-09-2013, 07:03 AM   #2
panthermark
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Nope....

It would cost you more to fab something up than to trade in the vehicle on a +2012
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Unread 10-09-2013, 08:02 AM   #3
JIMBOX
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There are two valuable benefiting SELF options-

Install a $75 buck aux cooler-no more overheating

Regear the Differencials and you'll getta new vehicle/more applicaple power/better mileage/better performance/better throttle response/pleasing hiwy/off-road performance-

Getta AEV Procal Module and modify tranny shift points and you can use the O/D "button" with confidence and relatively minor "downshifting"--

Good luck

JIMBO
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Unread 10-09-2013, 03:25 PM   #4
taoshum
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Quote:
Originally Posted by JIMBOX View Post
There are two valuable benefiting SELF options-

Install a $75 buck aux cooler-no more overheating

Regear the Differencials and you'll getta new vehicle/more applicaple power/better mileage/better performance/better throttle response/pleasing hiwy/off-road performance-

Getta AEV Procal Module and modify tranny shift points and you can use the O/D "button" with confidence and relatively minor "downshifting"--

Good luck

JIMBO
Is there someplace to read up on ProCal options?
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Unread 10-09-2013, 03:32 PM   #5
JIMBOX
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Either buy one from AEV and/or


Quote:
Originally Posted by taoshum View Post
Is there someplace to read up on ProCal options?
google "AEV Procal Module"--lotta info

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Unread 10-10-2013, 09:02 AM   #6
duneslider
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Despite all that, the auto transmission is still the biggest issue with the 3.8 jk. If it had a better transmission, life would be better. I don't know if it is all just programming issues or gearing, or both. Either way, I think the transmission could be better.

I have an Aux cooler, 5.13's, and the procal and still think it could be better. I am not going to go trade it in but I think it could be better.

Jimbo, what exactly do you mean by modifying the shift points? I have my tires set and the 5.13 set. Is there something else I should do/could do?

With the new gearing I don't see much need to use the OD button. What are you doing with it? It would be nice to have the OD button in a better location though, like on the shifter or near the steering wheel.

If I am missing something with the procal I would love to hear it. Maybe setting the gearing to things other than what gears you have to trick the transmission?
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Unread 10-10-2013, 09:35 AM   #7
Godholio
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Shift points are computer-controlled and can be modified.
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Unread 10-10-2013, 09:58 AM   #8
JIMBOX
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I have 5.38 gears and I have set my shift changes using the AEVPM--you can't really "trick" the auto tranny, it'll go by rpm/engine load for shifting parameters-


Quote:
Originally Posted by duneslider View Post
Despite all that, the auto transmission is still the biggest issue with the 3.8 jk. If it had a better transmission, life would be better. I don't know if it is all just programming issues or gearing, or both. Either way, I think the transmission could be better.

I have an Aux cooler, 5.13's, and the procal and still think it could be better. I am not going to go trade it in but I think it could be better.

Jimbo, what exactly do you mean by modifying the shift points? I have my tires set and the 5.13 set. Is there something else I should do/could do?

With the new gearing I don't see much need to use the OD button. What are you doing with it? It would be nice to have the OD button in a better location though, like on the shifter or near the steering wheel.

If I am missing something with the procal I would love to hear it. Maybe setting the gearing to things other than what gears you have to trick the transmission?
I've also set the speedo/TPMS/shift and based on using Hankook 33.6" MTs tires, I use the O/D whenever I use the freeway, get 17/19mpg and I have very infrequent tranny downshifts-

I think your main trouble is 35" tires/5.13 gears and you're right back to the stock JK situation-

I'll never goto 35"/37" tires in a JKU, unless I swap in Dana 60s, the Dana 44s just won't accomodate the diff. gears required for the 3.8l v6/42RLE auto-

There ain't no reason forit, it's just the way we doit-

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Unread 10-10-2013, 03:30 PM   #9
duneslider
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So, what RPM are you running with 33's and 5.38 on the freeway at say 65-75? I just can't see how 33's, 5.38's, OD off, and 75mph would be a good thing.

With 5.13's and 35's I am turning 23-2500 rpm, if I hit the OD button I am over 3k rpms at freeway speeds and there is no way in hell you will get 17-18 on the freeway at those rpms.

Ironically, I didn't see any mpg increase going from 4.10 to 5.13.

When I am cruising at say 40-45 I do hit the OD button to keep it out of 4th at 1300rpm.
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Unread 10-10-2013, 03:47 PM   #10
ncb
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Jimbox- are the tires 33.6 inches with weight on wheels? Or is that the spec measurement?
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Unread 10-10-2013, 03:48 PM   #11
JIMBOX
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At 70 mph , I'm turning 2600 rpm in O/D-at 65 mph, I'm turning 2400+ rpm in O/D, at 60 mph, about 2250 rpm in O/D and avg 18mpg--


Quote:
Originally Posted by duneslider View Post
So, what RPM are you running with 33's and 5.38 on the freeway at say 65-75? I just can't see how 33's, 5.38's, OD off, and 75mph would be a good thing.

With 5.13's and 35's I am turning 23-2500 rpm, if I hit the OD button I am over 3k rpms at freeway speeds and there is no way in hell you will get 17-18 on the freeway at those rpms.

Ironically, I didn't see any mpg increase going from 4.10 to 5.13.

When I am cruising at say 40-45 I do hit the OD button to keep it out of 4th at 1300rpm.
When I had stock 4.10 gears my avg mileage at pre mentioned speeds, was 15.2 mpg, my gas mileage has gone up 15%20% avg-

When towing my off-road trailer, I avg 14.9mpg and on long level freeway I can use O/D, untill the tranny temp starts to climb above 180F-

The 3.8L v6 has to cruise at 2200/2400 rpm for optimum mileage and thats cruising only on cruise control-

It's a jungle out there-

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Unread 10-10-2013, 04:20 PM   #12
duneslider
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I was getting 16-17 with 4.10 and 33's and 17-18 on long highway trips if I was keeping speeds 65-70.

35's dropped me to high 14, low 15 with 4.10's. Now with 5.13's I am still seeing high 14's and low 15's. I really thought I could see more mileage with the gears.

I could get 16 with 33's 4.10's and my 2700lb tent trailer. Kept strictly to 65 with the OD off.

2500 is the sweet spot for the 3.8 and that is where I see the best mileage.

I haven't done a lot of hills yet since the change to 5.13's but my transmission temp has seemed to go down.
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Unread 10-10-2013, 05:23 PM   #13
JIMBOX
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Hankook advertises them (LT295/75x16), at 33.6" and installed at 30psi, they are 33.2"

Quote:
Originally Posted by ncb View Post
Jimbox- are the tires 33.6 inches with weight on wheels? Or is that the spec measurement?
Thats why the tach reads 2600 at 70 mph (3.8l graph/w O/D on)-

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