Question 5.13 or 5.38's with 37's and Auto.
Thread Starter
JK Newbie
Joined: May 2009
Posts: 94
Likes: 0
From: Corona, CA
Question 5.13 or 5.38's with 37's and Auto.
There is no question! As you have seen in my past post in the last 3 weeks. I just bought my 2010 Rubi 4 door Auto. I just had 5.13's put in before Moab and put 900 miles on it I had 5 days of break in before I towed it) and my rear gears went.
I had also not liked the hwy performance and it would downshift to 3rd gear to have any acceleration and could not keep it over 65 on flat fwy in overdrive, the RPM's were just not high enough.
I had the 5.38's installed this week.
OMG!!!!!! I can drove 75 miles and it only dropped into 3rd gear 2 times for climbing a hill. I can now run in overdrive and my MPG is increasing about every 5 minutes on the road. I can accelerate in overdrive with the higher RPM's.
I am loving my JK now!
I wasn't the last 5 weeks with my 5.13's.
Catch you out on the trails!!
This is my opinion on gears and 37's!
Chido
I had also not liked the hwy performance and it would downshift to 3rd gear to have any acceleration and could not keep it over 65 on flat fwy in overdrive, the RPM's were just not high enough.
I had the 5.38's installed this week.
OMG!!!!!! I can drove 75 miles and it only dropped into 3rd gear 2 times for climbing a hill. I can now run in overdrive and my MPG is increasing about every 5 minutes on the road. I can accelerate in overdrive with the higher RPM's.
I am loving my JK now!
I wasn't the last 5 weeks with my 5.13's.Catch you out on the trails!!
This is my opinion on gears and 37's!
Chido
Last edited by woolybully; Apr 29, 2010 at 08:29 PM.
JK Enthusiast
Joined: Sep 2007
Posts: 384
Likes: 0
From: NSL, UT
I swapped 5:13s for 5:38s and am just as pleased. I actually got 19 mpg on the way back from Moab. 5:38s are definitely the right choice with 37s and the auto trans.
On my 08 to reset the avg mpg and other data you simply push and hold the stem below the display. I assume the 10 would be the same.
On my 08 to reset the avg mpg and other data you simply push and hold the stem below the display. I assume the 10 would be the same.
JK Freak
Joined: Jun 2009
Posts: 929
Likes: 3
From: Marshall, Texas
There is no question! As you have seen in my past post in the last 3 weeks. I just bought my 2010 Rubi 4 door Auto. I just had 5.13's put in before Moab and put 900 miles on it I had 5 days of break in before I towed it) and my rear gears went. They were singing and vibrating like a SOB! 
I had a second set of rears installed by the same guy and he took pictures this time of the wear pattern with the paint. They were right on! I got my jeep back last Monday and he had even driven it 24 miles. I drove it to Orange County on Tuesday and on the way home had the same thing happen. 
now with 95 miles on the gears.
I had also not liked the hwy performance and it would downshift to 3rd gear to have any acceleration and could not keep it over 65 on flat fwy in overdrive, the RPM's were just not high enough.
So, after talking to the gear manufacture they said they would swap the 5.13 rear that was defective for a 5.38 and I would have to buy another 5.38 for the front. I paid extra for labor for the front gears to be fair and the front gears. I have heard that some of the gears now are not as hard as they should be. Most are now made in India and you can tell if they have a circle and a k in the circle.
So my mechanic installed them, took pictures and sent them to me and drove it 95 miles to make sure everything was fine. I just picked the jeep up and drove it home..
OMG!!!!!! I can drove 75 miles and it only dropped into 3rd gear 2 times for climbing a hill. I can now run in overdrive and my MPG is increasing about every 5 minutes on the road. I can accelerate in overdrive with the higher RPM's.
From what I can tell my Speedo is going 56 when I am really going 65.
Question how do you reset your Average MPG so I can see what it is?
I am loving my JK now! I wasn't the last 5 weeks with my 5.13's.
Catch you out on the trails!!
This is my opinion on gears and 37's!
Chido
I had a second set of rears installed by the same guy and he took pictures this time of the wear pattern with the paint. They were right on! I got my jeep back last Monday and he had even driven it 24 miles. I drove it to Orange County on Tuesday and on the way home had the same thing happen. now with 95 miles on the gears.I had also not liked the hwy performance and it would downshift to 3rd gear to have any acceleration and could not keep it over 65 on flat fwy in overdrive, the RPM's were just not high enough.
So, after talking to the gear manufacture they said they would swap the 5.13 rear that was defective for a 5.38 and I would have to buy another 5.38 for the front. I paid extra for labor for the front gears to be fair and the front gears. I have heard that some of the gears now are not as hard as they should be. Most are now made in India and you can tell if they have a circle and a k in the circle.
So my mechanic installed them, took pictures and sent them to me and drove it 95 miles to make sure everything was fine. I just picked the jeep up and drove it home..
OMG!!!!!! I can drove 75 miles and it only dropped into 3rd gear 2 times for climbing a hill. I can now run in overdrive and my MPG is increasing about every 5 minutes on the road. I can accelerate in overdrive with the higher RPM's.
From what I can tell my Speedo is going 56 when I am really going 65.
Question how do you reset your Average MPG so I can see what it is?
I am loving my JK now!
I wasn't the last 5 weeks with my 5.13's.Catch you out on the trails!!
This is my opinion on gears and 37's!
Chido
U have GOT TO GET THE COMPUTER UPDATED WITH UR CORRECT GEAR/TIRE COMBO so that the Odometer is correct along with the gas milage-it is all a lie until that is corrected and if left that way could invalidate any form of warranty work since ur Odometer is invalid.
aev procal or superchips or any other programmer that works with jeep should have the function to correct this problem without a trip to the dealer.
on a side note, you have talked me into 5.38 when i lift and tire my rig, i have been on the fence on what gear to get to stop that damn constant downshifting from overdrive.
my plan is also 37's with an auto so this is good info for me.
i have been reading up on the various opinions of who has what gear but few have had both to see which is better on the same vehicle.
what brand was the 5.13 and the 5.38? was it the same company?
JK-Forum Founder
Joined: Jul 2006
Posts: 36,534
Likes: 16
From: Laguna Niguel, CA
with 37's, yeah, i'd have to say that 5.38 is the ratio i'd want to run. the only thing you have to be concerned with is that the pinion is really small at this ratio and on a dana 44. granted, i was running 40" tires with mine but i was able to trash my rear 5.38 in about two months time and 9 hard wheeling trips. and, for those who know me, they know i go real easy on the skinny pedal too. i still run 5.38s now but in a set of pro rock 60's
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JK Enthusiast
Joined: Jul 2009
Posts: 103
Likes: 0
From: Bremerton, WA
they recently released an update for the 2010. i will be getting it i just don't have the cake right now. there are a bunch of posts about it. call David at Northridge 4x4 he has a bunch in stock and will ship for free
here is a link to their post
https://www.jk-forum.com/forums/show...-Now-Available!
Last edited by fyrguy; Apr 26, 2010 at 07:28 AM.