New pentastar motor, re-gearing with 35's?

C

cssnider1

New member
Hey guys, I have a 2014 JKU freedom edition with an auto tranny and 3.73's. Living in east texas the terrain varies from flat to a little hilly.


I'm wanting to go with 35's but I'm curious how they will do as far as power loss and fuel mileage, without having to bump up to 4.56 or somewhere in that range.

My buddy has a 2011(old motor) rubicon with 35's and his power loss was dramatic, not to mention his fuel mileage dropped to about 10 mpg's or so.

I know the new motor has quite a bit more power. Have you guys had any experience with this? Will I need to re-gear? Will the motor handle it? Will the AEV Procal do the trick for the time being? Any help would be appreciated.
 
It all depends on if ur an auto or manual I have an auto and love my 513s with 37s having said that most companies don't offer 456 they push 488 cuz 456 it's much of an uograde if I was u I wud go 488 then if u ever decide to go to 37s it will still be driveable


I don't always wheel , but when I do I keep it tight......... Stay dirty my friends.
 
cssnider1 said:
Hey guys, I have a 2014 JKU freedom edition with an auto tranny and 3.73's. Living in east texas the terrain varies from flat to a little hilly.


I'm wanting to go with 35's but I'm curious how they will do as far as power loss and fuel mileage, without having to bump up to 4.56 or somewhere in that range.

My buddy has a 2011(old motor) rubicon with 35's and his power loss was dramatic, not to mention his fuel mileage dropped to about 10 mpg's or so.

I know the new motor has quite a bit more power. Have you guys had any experience with this? Will I need to re-gear? Will the motor handle it? Will the AEV Procal do the trick for the time being? Any help would be appreciated.
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Hey brotha, I'm in Corpus Christi, running 3.73 with 35 mud grapplers in my jku 2013.

It's a noticable difference but it's not that bad, I have a 20 mile comute to work and 20 mile home so I see a lot of highway, a simple procal tuner would help with the shift changes but regearing isn't a bad idea either, I plan on going to 5.13's , not recommended for a dana 30 but I plan on going prorock 44 eventually so when the dana 30 fails I'll already have a 5.13 gear in the rear once I get my pr44

4.88 is a perfect gear for the 3.6 too. Take you back to stock power
 
cssnider1 said:
Hey guys, I have a 2014 JKU freedom edition with an auto tranny and 3.73's. Living in east texas the terrain varies from flat to a little hilly.


I'm wanting to go with 35's but I'm curious how they will do as far as power loss and fuel mileage, without having to bump up to 4.56 or somewhere in that range.

My buddy has a 2011(old motor) rubicon with 35's and his power loss was dramatic, not to mention his fuel mileage dropped to about 10 mpg's or so.

I know the new motor has quite a bit more power. Have you guys had any experience with this? Will I need to re-gear? Will the motor handle it? Will the AEV Procal do the trick for the time being? Any help would be appreciated.
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Your buddy needs to properly calibrate his speedometer so that the shift points are back to where they need to be. That'll help him quite a bit.

For your purposes, once calibrated, you should be fine running 35's and 3.73 gears. I ran 37's on 4.10's and, while there was some power loss, it wasn't too bad. Regearing to 4.56 will bring your Jeep back up to stock performance and 4.88 (what I would get) will give you a bit more power.
 
I'm on 3.21's with 35" toyos and the 3.6 motor automatic. I think you'll be fine with just a programmer as stated
 
I'm on 35's with 3.73s on my 2013 JKU and I'm actually getting quite decent mileage with only a little power sufferance. I was averaging around 12-13Ltr/100km with the stock tires (18's) and now average around 15-16 with the 35's.
 
I'd do 4.88 for 35's, 4.56 wouldn't be bad. Definitely 4.88 if 37's are even a remote possibility. Also go lower if you drive on a lot of hills or mountains.

A friend of mine says that when in doubt, go one set lower (numerically higher).
 
No need

Ditto on that (what Eddie said)-2013 JKU with 35 Toyos in Hill Country Area of TX and no plan to regear until I go up in tire size. It was definitely something I was concerned about before installing my lift, but like all things in life, the stuff you worry about usually ends up not being a big deal....So too with the 3.6/3.73/35 combination. I did install an airaid CAI and dynomax exhaust after my lift which helped a bit as well, as did my superchips flashcal. I'd save the money on a regear and get some good armor/bumpers/winch/skids - stuff you'll want every time you go out.
 
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Mikead40 said:
Ditto on that (what Eddie said)-2013 JKU with 35 Toyos in Hill Country Area of TX and no plan to regear until I go up in tire size. It was definitely something I was concerned about before installing my lift, but like all things in life, the stuff you worry about usually ends up not being a big deal....So too with the 3.6/3.73/35 combination. I did install an airaid CAI and dynomax exhaust after my lift which helped a bit as well, as did my superchips flashcal. I'd save the money on a regear and get some good armor/bumpers/winch/skids - stuff you'll want every time you go out.
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Thanks for that info. I have the AEV pro cal already. Just debating tire size. I'm pretty set on 35's after hearing you guys

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I was leaning towards 4.56 with my 35s but in Colorado (I live at 6,000 feet and mostly drive well above that) I am starting to consider 4.88. Will do this next year.
 
I have 35s with 3:21, it's flat here so it's tolerable but gutless. The "original" plan was regear to 4:88 but as time goes on I see a PR44, 5:13s, and 37s in the future. If I stay 35's 4:88 all the way.
 
I have a 13' JKUR auto on 2.5" lift and 35" Toyo MTs. Recalibrated with SC flashcal. The power loss was fairly profound. In my observation the problem is the gap between gears, the drop in rpm when upshifting. Unless you're going down hill the drop between second and third just dogs the engine. You can compensate by shifting manually, but I didn't buy an auto to shift manually. The tranny is otherwise superb in my opinion. It hunts frequently because it is overgeared but 4.56:1 or 4.88:1 would certainly fix this.

Whether you get better or worse mpg depends entirely on where and how you drive. I live in Seattle and rarely get north of 60mph, lots of stop and go. I'm also frequently deep into the skinny peddle. And there is not much here resembling flat ground, lots of steeps. There is zero doubt in my mind that my mpg would improve with 4.56 or 4.88 gears. If I were living in flatland and setting the cruise at 70mph I'd likely get better mileage with 3.73 or 4.1s. Either way there is no valid argument against the mechanical advantage gained by numerically larger gears. It does, however, come at the cost of performance in the upper rpm range. If your plans include hauling extra weight or a trailer that should also factor into your decision.

You can think of changing gear ratios as moving the fulcrum of a lever. Move the fulcrum one way and you can lift more mass but it doesn't travel as far. Move it the other way and the opposite is true. This is basically synonymous with changing gear ratios.
 
I have 35's with the 3.73. On flat ground no issue. But you do run much higher rpms in the hills for longer periods which increases your engine temp. Go with the regear when funds allow. I plan on regearing this summer when the jeep fund is funded again. Kickstarter might be a great way to get money sooner!
 
I have a 2013 JKU auto with 35's and 3.21 and was filling up with gas every 2 day driving around SF bayarea at 12.5 mpg, I re-geared two weeks ago to 4.88 and I'm averaging 17/18 mpg now. I like how the RPM's are back up in the power band.
 
LVJeepney said:
I have a 2013 JKU auto with 35's and 3.21 and was filling up with gas every 2 day driving around SF bayarea at 12.5 mpg, I re-geared two weeks ago to 4.88 and I'm averaging 17/18 mpg now. I like how the RPM's are back up in the power band.
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I'm torn between 4.56 and 4.88. How are you liking your 4.88s? Does it feel wound up on I5 at 70?
 
I drop a gear and it gets the RPM around 2,800 or so. Feels a bit high so I am still torn too. Not sure how it will be after a few hours on the highway. My 4Runner revs around 2,000 at 70 so it's quiet and smooth on the highway. 2800+ seems high anyway. The upside of 4.88 is you can use gears made by US Gear. They are the only ones I am aware of that are made in the US and the metal is supposed to be stronger. I think Dynatrac recommends them highly. They are more expensive but if I go 4.88, I'll definitely get those.
 
OverlanderJK said:
Bullshit..
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I second this. I have a 12' manual JKU Rubicon (4:10's), stock I was getting 18-22 highway running 70-75 mph. Now I seem to get 14.5-16 on 35's no matter how I drive. Yes I recaliberated the speedo. When I go 37's I'm going to 5:13's
 
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