Re Gearing

Jk4lfe

Jk4lfe

New member
Im about to PCS to Ft wainwright alaska, Im going to be taking a small uhaul trailor with me, I have stock 4.10 gears on a 2011 JKUR, and 35" tires, daily driver and at hwy speeds hunts for OD. Im looking at going with 5.13 or 5.38s. Not sure which would give me the best preformance or gas milage.... Please give me some feed back.
 
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Auto or Manual? For Auto I would go 5.13s but a manual I would do 4.88s unless you plan to go 37s some day. I personally wouldn't even consider 5.38s and 35s for any kind of highway use.
 
Jk4lfe said:
Im about to PCS to Ft wainwright alaska, Im going to be taking a small uhaul trailor with me, I have stock 4.10 gears on a 2011 JKUR, and 35" tires, Im looking at going with 5.13 or 5.38s. Not sure which would give me the best preformance or gas milage.... Please give me some feed back.
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5.13's. 5.38's are way too high and your RPM's will be way high at highway speeds. Even 5.13's will be a bit high but the extra power will be nice to have.
 
its an Automatic.... and, I looked a a chart and 5.13s were in the green instead of yellow. I appreciate the responces, but Im thinking about going up to 37s on the next tire change... it also wont be a whole lot of hwy speeds in Fairbanks haha
 
Jk4lfe said:
its an Automatic.... and, I looked a a chart and 5.13s were in the green instead of yellow. I appreciate the responces, but Im thinking about going up to 37s on the next tire change...
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Even more reason why you should go with 5.13's. They will be a good match for 37's.
 
will that give me any better gas milage, especially towing say 1000 lbs? not really familar with the whole gearing thing
 
4.10 just dont cut it at hwy speeds, its constantly hunts for OD at 70 pulling nothing....dont really care about gas milage just figured id ask as a side effect.
 
Hoyt Ag said:
Same response for a 2008 auto on 33s?
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On a 3.8 JK with the auto just go straight to 5.38. It has a very tall overdrive gear that lowers rpms much more than the auto behind the 3.6 does. You'll likely regret anything less than 5.38.
 
highoctane said:
On a 3.8 JK with the auto just go straight to 5.38. It has a very tall overdrive gear that lowers rpms much more than the auto behind the 3.6 does. You'll likely regret anything less than 5.38.
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Seriously??? Are you trying to blow their motor? Even if the engine could stay in overdrive (which I doubt with the 3.8L gutless wonder) that would be 2650ish RPM @ 70MPH (which most consider pretty slow).

Edit to add: Should a downshift happen on the interstate the engine would be close to the red line due to the large gear change from OD that you mentioned.
 
Yeah, I'd have to agree, with 33" tires, 5.38's are way too much. I personally wouldn't run them with anything smaller than a 37" tire but, that's just me.
 
I have a 2011 JKR automatic that has run 32's, 33's, 35's, and 37's are being installed this week with some other upgrades. I'm currently running 5.13's that were installed with the 35's.

In my opinion:

33" 4.56-4.88
35" 4.88-5.13
37" 5.13-5.38

With the higher numbered gear ratio for each range, your RPM will be a little high at highway speeds (65-70mph) but you will probably appreciate the extra power around town and you can step up to the next tire size without re-gearing.
 
Very nice, so the general consensus im seeing is 5.13s, thanks guys! I really appreciate the input, again ill be towing a uhaul at aprx. 1000 lbs so ill need the extra power!
 
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