|05-31-2012 02:13 AM|
|05-31-2012 12:08 AM|
|05-30-2012 09:28 PM|
I just drove 1,100 miles in my 6 speed 2012 JKU with an AEV 3.5 SC and 35" KM2's the weekend after the install. My trip took me from Southern Maine to Gettysburg, PA, which had me going through rolling hills in CT, NY & PA. I'm still running the stock 3.21 gears, which meant I was running around 2,200 - 2,300 rpm in 5th at my cruising speed of 72-73. I only used 6th on some big downhills over 75 mph.
I give all this background because I can confidently say that after this trip I went from on the fence between regearing to 4.11 and 4.56 to knowing for sure that 4.56 is the right choice for me. I was hitting about the same rpms in 5th at the same speeds as I would be in 6th with the 4.11 gears. With the added rolling resistance of the 35s and added wind resistance, I had to downshift to maintain speed on any significant hill on the highway. Once I shifted down to 4th and was up in the 2,500 rpm range, the Jeep could keep going. It also did better in 5th when I stayed above 76 or so, where my rpms stayed in that 2,500 range. But it definitely struggled to find sufficient hp at those lower rpms.
As a more minor note, my calculated mileage seemed to be a little higer when I kept the rpms up a bit on the highway. I was just over 17 mpg on the tanks where I kept it running a little higher, where it dropped just below 17 mpg on the tank where I didnt downshift as much and tried to power through some of those hills. Hardly scientific, as it's a small sample size. But it aligns with what others have said.
So there you have it... My reasoning and experience that has led me to choose 4.56 gears for my '12 6 speed. I should be right around 2,550 at 70 with my KM2s which measure 33.5". Now I just need to start squirreling away the money!
Edit: I know mine is a 6 speed, but the gearing is similar, and the plus with the manual is you can control what gear you're in, which lets you simulate other gearing. So I figured I'd share.
|05-30-2012 05:38 PM|
|05-30-2012 05:31 PM|
|05-30-2012 04:48 PM|
|05-30-2012 04:04 PM|
4.10s will no doubt work great with 35s on a 3.6. But with a manual trans that only gets you to less than 2200 RPMs at 70 mph in 6th gear. Compare that to a dyno showing the power curve of the 3.6 and you'll see you're leaving quite a bit of power on the table and the engine has a long way to go while still being comfortable.
So while I've heard of course that the 3.6 with 4.10s does great with 35s, I think that's more a testament to the power of the engine rather than proper gearing. Toss some 4.56s or 4.88s in there and you'd be spinning in the 2500 to 2600 RPM range at 70 mph--still well within the engine's comfort zone--and you'd really feel it pull.
|05-30-2012 03:55 PM|
|clvnmcd||I'm running 35's in a manual JKUR with 4.10 gearing and it works fine.|
|05-30-2012 03:50 PM|
that is for a 2007-2010
4.10 at the most for the 2012 with 35's
|05-30-2012 11:13 AM|
|InvertChaos||Isn't the new carrier only like $40?|
|05-30-2012 11:11 AM|
|Johnny6||I'm running about 2200 RPM w/33" tires and stock 3.21s at 75 MPH. I was pleasantly surprised there wasn't much difference.........just a slight power loss and 1 MPG. I do plan to go to 35" tires and it looks like 4:10 is the suggestion that shows up the most for the 2012.|
|05-30-2012 10:26 AM|
|05-30-2012 07:50 AM|
Go to 4x4 shop.. Tell them what gearing you want. Talk to them about where they can get the gearing from. there are a few different manufactures out there. Pick company you want you gears from. wait for them to say come and get your jeep. pay them (1200 +/- 300). drive off with a smile
|05-30-2012 07:42 AM|
|Wharfrat||I would go for 4.56 or 4.88 myself. IMHO you can never be geared too deeply (within reason of course).|
|05-30-2012 04:00 AM|
You wouldn't need a new housing
|05-30-2012 03:10 AM|
|Braveheart12JK||I have a 2012 JK auto. I had 3.21's factory. I got a 2.5" lift and 33" Duratracs. My acceleration wasn't bad after, but it was noticeably worse passing or uphill. I talked to an excellent 4x4 shop in my area that had done my lift and tires, and we decided 4.10's with a LSD was the way to go given that I don't wheel it regularly and I still do a fair amount of hwy driving weekly. We went with an Auburn HP LSD and Jeep 4.10 gears. Paid a bit extra for Jeep ring and pinions, but they are known to be quieter than most aftermarket at that ratio. I like the power I got back and they're nice and quiet. I can cruise at 75 at 2850 RPM's as well|
|05-30-2012 01:57 AM|
|JeepHerz||You can also get 4.56 gears now.There is a 2012 gear chart around here somewhere that's really helpful. It shows rpms at 70 mph for each gear ratio/tire diameter. I've been quoted $900-$1400 for either 4.56 or 4.10s.|
|05-29-2012 11:57 PM|
|Mig888||I have 3.73 with 35s and I think it is a good fit for the 35s|
|05-29-2012 11:56 PM|
|Dylanjwhall||I'd go with 4.10s It's a good mid point an incase for some reason you go bigger it'll still work out|
|05-29-2012 11:52 PM|
|flyracin17||I currently have 3.21s, so what are suggestions for purchasing? Who's a good dealer and are the gears model of jeep specific or just d30/d44 specific?|
|05-29-2012 08:41 PM|
|dwindeck||You wouldn't need a new housing, just the carrier. and I wouldn't go lower then 4.10, and if you have 3.73 your good.|
|05-29-2012 06:58 PM|
|MTH||What gears do you have now? 3.21s?|
|05-29-2012 06:35 PM|
|pluke the 2||
we are running 37s and our 2012 with stock 410s and there isnt any issues or a need to gear lower.
.02 save your money.
|05-29-2012 06:28 PM|
Proper gearing for 2012 auto to run 35's
Ok guys. So I need to know the best place to get gears for my D30 in front and D44 in rear. I also need opinions for gear size. I want 4.10 gears but read you need to replace the housing if you go bigger than 3.73. I'd be ok with 3.73 but am having problems finding them and most websites make it seem like they are model specific. I thought the only thing that mattered for fitting was if its a D30 or D44, etc. Appreciate any help out there.