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Old 09-03-2012, 02:02 PM
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5.38's

I'm going from 3.73's to 5.38's with an ARB locker next week. I'm only doing the rear axle for now and have two questions. I'm only doing the rear for two reasons money and I'm replacing the front D30 with a TaraFlex front 44. Plus I'm only gonna drive it for three weeks before I deploy again and then the front will be done while I'm gone.

Should I need to do anything more than pull the front shaft?
Are 5.38's to much gear for an automatic with 35's?


I have read many threads about gears and the mighty 3.8 motor. I have 35's right now and wish to maybe do 37's if I can make them fit (another thread right now) I'm looking for more power and gas milage isnt my first concern, well unless it goes down to 7.


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Old 09-03-2012, 02:10 PM   #2
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I assume the gears are being done on both axles at once, and the locker is going in once you deploy, right. Worded it funny. Your gonna want to add sleeves, gussets and sector shaft reinforcement. Also replace factory ball joints and get a jks frame reinforcement plate for the steering box. Even on a D44. You can do that after your deployed, just dont go wheeling before you leave. Consider better axle shafts also in front and rear, so you can run it without worry.5:38 is a great ratio for an auto with 35's and 37's

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Old 09-03-2012, 02:12 PM   #3
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PS,

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Old 09-03-2012, 02:36 PM
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Nop gonna do the rear axle and pull front shaft. Just have two wheel drive only. Just for three weeks. Thought about keeping the D30 but figured if I spend all the money getting it beefed up a little more money will replace it.
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Old 09-03-2012, 10:18 PM
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anyone with 5.38's have some input...
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Old 09-03-2012, 10:30 PM   #6
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I don't think it will be to deep. If you end up going with 37's it will be just right. My buddy has 5:13's and 37's in his auto and it could use a little deeper gear set for highway driving IMHO.
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Old 09-03-2012, 10:42 PM   #7
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Quote:
Originally Posted by Dave2011
anyone with 5.38's have some input...
I had 5:13 and 37's and it kinda sucked on hills. So I changed to 5:38 and it was perfect.

It will be low with 35's but livable. If you even think of going to 37's get the 5:38's so you don't end up doing twice like I did.

And yes just pull your front drive shaft and you will be fine until you get your new front axle.
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Old 09-03-2012, 11:00 PM
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I had 5:13 and 37's and it kinda sucked on hills. So I changed to 5:38 and it was perfect.

Thanks for the input. 37's may be coming soon.. I'm hoping to be able to do burnouts and high speed passes at the track. HAHAHAHA just kidding,
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Old 09-03-2012, 11:21 PM
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I had 5:13 and 37's and it kinda sucked on hills. So I changed to 5:38 and it was perfect.

Thanks for the input. 37's may be coming soon.. I'm hoping to be able to do burnouts and high speed passes at the track. HAHAHAHA just kidding,
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Old 09-04-2012, 06:43 AM   #10
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If you keep your ride in 2wd there is no reason to pull the driveshaft. If you had a rig with awd or full time fwd then you would have to pull the shaft. But if your in 2wd your front axle is free to spin however it wants to. Just don't put it in 4wd for anything.
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Old 10-16-2012, 09:29 AM
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5.38's installed in the rear. 70mph at 2600RPM. I went on vacation in the mountains and it pulled up highway hills no problem, dropped into passing gear only on steep grades. 16mpg average. I was getting 11 before the swap. I'm very happy with the gear choice. It feels so much better than it did. Added a ProCal module and that got the gears and tire changes input so the speed-o reads correctly now....
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Old 10-16-2012, 07:54 PM   #12
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Glad to here it worked out.
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Old 10-18-2012, 08:02 AM   #13
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To tag onto this thread, I am looking at a 07 JKU hopefully today which has the 5.38 but only 31.5's. I plan to move to 33 or 35's, but would keep this setup for a while.
Any info on how that will go?? Worried a little about gas mileage as Idon't want it way down if possible....
Thanks
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Old 10-18-2012, 08:10 AM   #14
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Should have added it is a 6 spd. What attracts me is that it also already has lockers front and rear, presently I have a stock 08 with 3.73 gearing and ~16mpg.
Was looking for better 4WD, but since that is only 1 weekend a month not sure it is worth it...?
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Old 10-18-2012, 08:12 AM   #15
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Thanks for posting this question, the results and most importantly, THANK YOU FOR YOUR SERVICE AND SACRIFICES.
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Old 10-18-2012, 08:19 AM   #16
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Quote:
Originally Posted by mtfisherim
To tag onto this thread, I am looking at a 07 JKU hopefully today which has the 5.38 but only 31.5's. I plan to move to 33 or 35's, but would keep this setup for a while.
Any info on how that will go?? Worried a little about gas mileage as Idon't want it way down if possible....
Thanks
That thing is going to he screaming going down the highway. I am running 5:38's a six speed and my tires measure out at 36 1/4 inch tall. I am doing 2800rpm @ 70mph.
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Old 10-18-2012, 08:19 AM   #17
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I ran 5.38's with 38's powered by a 327 and it performed well but turned a few more rpm's than I would have liked at highway speeds with the 3 speed tranny..with an overdrive it would have proably been great...I currently am running 5.13's with 37's powered by a strong 4.0 , automatic and it performs good to me..some might want a little more acceleration but it's fine for me and gets 16 mpg
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Old 10-18-2012, 09:32 AM   #18
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OK, that is what I was concerned about. Great on the trail but probably not going to make as a DD as well. I will definitely run it on the highway to see what it runs like anyway if I do drive it.....

Thanks!

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