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-   -   2013 JK Regear (http://www.jeepforum.com/forum/f96/2013-jk-regear-1537522/)

razor1115 06-17-2013 07:00 AM

2013 JK Regear
 
Ok guys, want good opinions on those that have 4.10 or 4.56 diff gears.

I have a 2013 4d JK, 3.6L manual, with a 3.21 diff ratio. The JK gearing chart was dead nuts on for me on stock 29" tires and wheels at 70mph.

I lifted 4" and added 18" Fuel wheels wrapped in 35x12.5" Nitto Trail Grappler M/Ts. Actual tire measure 34.5".

I reviewed the gearing chart many times. At 70mph, 3.73 gear gets me back to stock performance, but a little doggier.

The 4.10 gears seem to be the right choice, making it a little peppier than stock with my current set-up.

The 4.56 gears would seem to give great power at a fuel cost at 70mph on the highway, but great town drivability.

I travel to CO a couple times a yr to 10-14k feet. I also combo drive highway and street.

I am leaning towards 4.56 as opposed to 4.10, but wanted to hear from some Rubi (and others who swapped in 4.10) guys who already have the 4.10 and swapped to 35" tires, and those that decided to go to 4.56.

I am wanting to maximize driveability, balanced with fuel economy of a daily driver.

Thanks for your opinions and insights in advance!

wranglerboy13 06-17-2013 07:24 AM

I have not done the install yet but what makes me lean towards 4.56 is they are substantially cheaper than the 4.10 as the only manufacturer that seams to make them is dana/Spicer and they are nearly $500 per axle. Also finding 4.10 for a Dana 30/44 was not easy. Just some help from somebody who has done some research. Good luck with the new jeep. Sounds like you have a nice start. I am interested in how the 35's are with the 3.21. Livable until the regear happens or is the regear something that should happen first?

Thanks!

Yendor 06-17-2013 08:23 AM

Someone with some hands on experence will chime in and give the answer, But IMHO, manufacturers gear just about everything too tall, out of the box. The miniscule mpg gain isn't worth the loss in pep. Mustang 3.7 V6 guys have gone form 2.73 to 3.73 rear ends, and that's a big jump, and have lost only 1 or 2 mpgs. In other words, from aprox 30 mpg real world, to 28.5. But they're having a whole lot more fun with the car.

You have big ol tires thrown into the mix. Driving habits have a lot to do with mpgs. I'm interested in the practical answer.

razor1115 06-17-2013 08:59 AM

Quote:

Originally Posted by wranglerboy13 (Post 15571199)
I have not done the install yet but what makes me lean towards 4.56 is they are substantially cheaper than the 4.10 as the only manufacturer that seams to make them is dana/Spicer and they are nearly $500 per axle. Also finding 4.10 for a Dana 30/44 was not easy. Just some help from somebody who has done some research. Good luck with the new jeep. Sounds like you have a nice start. I am interested in how the 35's are with the 3.21. Livable until the regear happens or is the regear something that should happen first?

Thanks!

The 35s are liveable AT SEA LEVEL until the regear. Granted it's only day 1 driving it. The new 3.6L helps, as I drove a Rubi 3.8L Auto set up and was appalled at how bad it was on 4.10s.

At lower speeds with stock set up, I would go to 6th gear. Now, about 40-45, need 5th gear. But, IMO, that's what on overdrive 6th gear is for - highway speeds.

I am going to CO next week; that will be the tell tale sign of 4.10 vs 4.56.

brianjw 06-17-2013 09:29 AM

I have a 2012 rubicon unlimited six speed with stock 4.10s, running 35s on a 3.5" lift.
At sea level it works "pretty well". Occasionally I wish for level gearing at home as it does require more downshifting. I've spent the last 9-10 days in the high desert/mountains of Utah, Arizona and Nevada (up to 9k ft) and it struggles up here. Getting passed by semi trucks on slight inclines on the highway sucks. Getting moving at 9k ft without much clutch means a veeeery sluggish start. Trying to maintain freeway speed often means extended periods of driving at 70-80 in fifth gear gear wide open, up hills at 60 in fourth wide open.

So my advice is 4.56. I think you'll lose more mileage with 4.88 but then again there isn't a huge difference between the two.

razor1115 06-17-2013 11:09 AM

Quote:

Originally Posted by brianjw (Post 15571668)
I have a 2012 rubicon unlimited six speed with stock 4.10s, running 35s on a 3.5" lift.
At sea level it works "pretty well". Occasionally I wish for level gearing at home as it does require more downshifting. I've spent the last 9-10 days in the high desert/mountains of Utah, Arizona and Nevada (up to 9k ft) and it struggles up here. Getting passed by semi trucks on slight inclines on the highway sucks. Getting moving at 9k ft without much clutch means a veeeery sluggish start. Trying to maintain freeway speed often means extended periods of driving at 70-80 in fifth gear gear wide open, up hills at 60 in fourth wide open.

So my advice is 4.56. I think you'll lose more mileage with 4.88 but then again there isn't a huge difference between the two.

Excellent, real world experience and advice I was seeking...

razor1115 06-17-2013 08:19 PM

Quote:

Originally Posted by razor1115 (Post 15571541)
The 35s are liveable AT SEA LEVEL until the regear. Granted it's only day 1 driving it. The new 3.6L helps, as I drove a Rubi 3.8L Auto set up and was appalled at how bad it was on 4.10s.

At lower speeds with stock set up, I would go to 6th gear. Now, about 40-45, need 5th gear. But, IMO, that's what on overdrive 6th gear is for - highway speeds.

I am going to CO next week; that will be the tell tale sign of 4.10 vs 4.56.

I rescind the statement that it's liveable at sea level. Lower speeds like 45 in town, I can get to 6th and maintain it, but it lugs the engine. I cannot achieve and then hold highway speeds in 6th gear. It cannot accelerate in 6th G either, so it's basically useless until regear. Looks like 4.56 for me.

06bluebeast 06-18-2013 09:04 AM

I can't speak for the high elevation stuff, but I have a 13 with a manual and 35's on my Rubicon, and I wish I had a little more for the hills, 4th gear climbs are pretty common for me. I would vote 4.56.

razor1115 06-18-2013 09:12 AM

Quote:

Originally Posted by 06bluebeast (Post 15576311)
I can't speak for the high elevation stuff, but I have a 13 with a manual and 35's on my Rubicon, and I wish I had a little more for the hills, 4th gear climbs are pretty common for me. I would vote 4.56.

Agree 100%. I believe for my needs the 4.56 is ideal for my daily driver in IL, take a small hit on fuel economy driving across country to CO, but have plenty of gear for the mountain elevations.

jaidmaster 06-18-2013 10:32 AM

I have stock 4.10's on my '12 Rubicon (auto) and just put the 35's on last week. Live in CO at ~8200ft. I have only lost a few tenths on gas mileage (from stock 32's), which is nice. It's not bad with the auto, and will probably not regear, but on high speed hills, downshifts are more common. If you are already regearing, I'd also say 4.56...
Enjoy CO! :)

rayder1 06-18-2013 11:16 AM

Quote:

Originally Posted by jaidmaster
I have stock 4.10's on my '12 Rubicon (auto) and just put the 35's on last week. Live in CO at ~8200ft. I have only lost a few tenths on gas mileage (from stock 32's), which is nice. It's not bad with the auto, and will probably not regear, but on high speed hills, downshifts are more common. If you are already regearing, I'd also say 4.56...
Enjoy CO! :)

I'm going to agree. Mine (13 rubi jku)works great at all altitudes with the 4:10 on the stock 33" KM's at 8-9k feet on the road and wheeling on rocks and granite at 9.5k I assume appropriate gearing ratio increases are proportionate to tire size to maintain similar performance.

I'll find out when my tires wear out and I start my tire/ suspension mods. My 86 wrangler, needed gearing for the 35's I dropped on it, but it was gutless out of the box anyway. The Pentastar is not.

spyder6 06-18-2013 12:19 PM

Stock KMs are actually 31.75" tall

jpin321 06-18-2013 07:43 PM

Not running 35's but here is my thread and results when I was shopping for gears. I posted a video of my 2013 6 speed, with 33's at 70mph. Hope this helps.
http://www.jeepforum.com/forum/f96/4...sport-1490155/

razor1115 06-20-2013 08:33 AM

Quote:

Originally Posted by jpin321 (Post 15579124)
Not running 35's but here is my thread and results when I was shopping for gears. I posted a video of my 2013 6 speed, with 33's at 70mph. Hope this helps.
http://www.jeepforum.com/forum/f96/4...sport-1490155/

Great thread, and I actually read that one before posting. I am going to go with 4.56. Should put me at 2480rpm or so at 70mph on 34.5" tires. Additionally, we aren't running 70mph every second, so less mph= less rpm = better fuel economy as long as not lugging the engine.

TrailRated2011 06-30-2013 08:18 AM

Jeep Wrangler Pentastar Gear Ratio Chart
 
@razor5111: Is this the Gear Ratio Chart that you are referring to for your decision making?

http://www.tnjeeps.com/uploads/galle..._46_253610.jpg


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