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post #1 of 5 Old 10-15-2011, 10:39 AM Thread Starter
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Manual Transmissions compared

I have heard that the new 2012 manual 6spd is the same transmission used on the 3.8 but with only a OD gear ratio change. Is this correct?


Just test drove a 2012 and it turns out the test vehicle was a 2012 Sahara 5spd auto with 3.21 base gears. Compared, the 08 with Superchips is comparable in acceleration when in the right gear, therein lies the big difference. Manually shifting the auto in the 08 makes a big difference. The 5 spd auto seems to always be in the right gear whereas the 4spd, especially with bigger tires struggles to find the right gear. I can see now that a Rubicon with the new auto and 4.10 gears will be great for those that want bigger tires. I would personally like to see a head to head comparison between a programmed 3.8L vs 3.6L with the manual transmission which has supposedly not changed for 2012. This would determine if the auto trans and factory programming is truly the failing point of the 3.8L and not the engine itself.

Has anyone compared these two?

Jeff _(OllllllO)_



08 Black and Khaki JK Sahara Unlimited, Dual Tops, MyGig, Tow pkg, Trax-Lok Rear Diff,
Mods -- 3.5" Rock Krawler front springs, 2.5 TerraFlex BB rear, Mopar D44HD/J8, OX Locker, RCVs, 37x12.50x17 Pitbull Rockers on ProComp 7069, AEV Premium front bumper, Smittybilt X2O 12K Comp winch.
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post #2 of 5 Old 10-15-2011, 08:41 PM
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I dont know about the gear ratio change but I do know the 2012's still have the NSG-370

2008 Jeep JK Unlimited Rescue Green NSG370
RK 3.5 X Factor mid arm
37x12.50 Nitto Trail Grapplers
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post #3 of 5 Old 10-15-2011, 09:46 PM
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Yes, the 6th gear is changed on the 2012 manuals. They changed it from 0.84 on 2007-2011s to 0.797 in the 2012s. I wish they left it alone as it would've been much better with my 35s.

But I can say even with all the steep grades here, that I have no need to regear at all. I feel like I have -more- power and better response with my 35s and new engine than I did with my 3.8L, regeared to 4.88, and superchipped. The only thing I'm not fully thrilled with is 6th gear, which I blame on them gimping the gear ratio for fuel economy but it is still just fine. It just could've been better if they had only left it alone.

My old Jeep: 2007 2-Dr Rubicon, Manual Transmission, 4.88 Gears, Superchips 91 Octane Tune, 3.5" Lift, 35x12.50 KM2 Mud Terrains, and armor

Current Jeep: 2012 4-Dr Rubicon, Manual Transmission, 4.10 Gears, 3.5" lift, 35x12.50 KM2 Mud terrains, and armor

-Brett
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My Jeep: 2012 Jeep Wrangler Unlimited Rubicon, 6-Spd Manual, Cosmos Blue
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Last edited by BrettDez; 10-15-2011 at 09:51 PM.
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post #4 of 5 Old 10-15-2011, 09:48 PM
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Quote:
Originally Posted by BrettDez View Post
Yes, the 6th gear is changed on the 2012 manuals. They changed it from 0.84 on 2007-2011s to 0.797 in the 2012s. I wish they left it alone as it would've been much better with my 35s.

But I can say even with all the steep grades here, that I have no need to regear at all. I feel like I have more power with my 35s and new engine than I did with my 3.8L, regeared to 4.88, and superchipped.
9% change is pretty decent. I bet they got a 1/2 mpg out of that to claim the 20 on the window sticker

I have a 6spd 4.10 Rubicon on 35s with a tuner near dallas if there is a '12 6spd Rubi on 35s that'd like to hit the 1/8 mile

SOLD - '09 2dr Rubicon - 1.0Gal | 6spd | 37s | 4.88s |
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post #5 of 5 Old 10-15-2011, 10:06 PM
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Quote:
Originally Posted by Goodysgotacuda View Post
9% change is pretty decent. I bet they got a 1/2 mpg out of that to claim the 20 on the window sticker

I have a 6spd 4.10 Rubicon on 35s with a tuner near dallas if there is a '12 6spd Rubi on 35s that'd like to hit the 1/8 mile
Not sure about the MPG, but remember 9% is the total torque change. At 2000 RPMs there is actually roughly a 20% difference.





This is from a Motortrend article where they tested the 0-60 times with a manual transmission.
Quote:
The new engine offers excellent response and a noticeable improvement in power -- the Pentastar is significantly faster from a stop and when passing. Also, the engine sounds much more upscale than the coarse 3.8-liter, and the exhaust note is throatier. Paired with either transmission, it feels much more refined. Where the 3.8 feels pokey, the 3.6-liter actually makes the JK feel spry. Jeep estimates that the new engine reduces 0-60 times by 2-3 seconds with either transmission, and when we took a Wrangler Sport manual to the track, we confirmed this estimate. The new Jeep hit 60 mph in 6.7 seconds, while all of the 3.8-liter Wranglers took between 9.8 and 10.2 seconds.
See http://www.motortrend.com/roadtests/...er_first_test/ for the full article.



So, you can see a pretty significant difference there. I did a VERY informal 0-60 run myself when I found myself on an empty road while on lunch one day. By my "mississippis," I got somewhere between 10-12 seconds and that's with my 'heavily' modified Jeep. Which nearly matches the stock 2011 times the article quoted. Of course mine was informal, maybe one of these days I will be able to convince the wife to take a video and do a more formal timing. Oh and I have NO racing experience...so I probably suck at "power shifting" too, lol.

-Brett
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My Jeep: 2012 Jeep Wrangler Unlimited Rubicon, 6-Spd Manual, Cosmos Blue
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Last edited by BrettDez; 10-16-2011 at 10:32 AM.
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