Proof 2012 Rubicons on 35s need 456 gears
#21
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I’ve mentioned this before and I wish someone could help me with it. That chart that gets posted once in a while is not right. It says at 70 with 35’s my rpm should be 2081 with 3.73’s. My jeep, at 70 reads 2400 rpm. That’s 70 being cross checked with a GPS. Even saying they are not 35 inches tall but 34 on that chart it says an rpm of 2142. I’ve measured the height of them and they are 34.75 inches tall. According to that chart I have 4.10’s but they are not. I’ve done the driveshaft count. When I ordered the Pro Rock for the front I had them put in 3.73’s as that’s what I thought was in the rear. Then that chart showed up again and had me so worried my jeep did come with 4.10’s that I jacked it up and put it on four jack stands. I locked the front and rear differentials and put a piece of tape on the top of the front and back tire. Started it up and put it in gear. Sure enough both pieces of tape went around in perfect unison. So I was satisfied that it does indeed have 3.73’s and that chart can’t possibly be right. Sorry I'm off topic!!
Dave
Dave
#22
Have a '12 auto with 315/70/17 and honestly can't tell the difference. Climbs up to 10K feet without problem, accelerates fine, etc. Regearing never even crossed my mind.
Moving to 37s soon. Not even sure I'll do it then.
Moving to 37s soon. Not even sure I'll do it then.
#23
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Prob cost that here too, not real sure. Regardless that is a lot of coin for something that is preference. When i had 35s on my 12 i thought it actually performed better than stock. Rpms were lower in top gear at cruising speeds, better mpg at 55 mph. I liken 37s on the 3.6 with 4.10 to my 2010 with 3.73 on 35. Feels similar but i do have better off the line acceleration in my 12 and 5 speed tranny
BTW: Congrats on the 12 :-)
#24
Originally Posted by eumel789
Makes sense what you are saying!
BTW: Congrats on the 12 :-)
#25
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Originally Posted by scemracing
I have a 2012 JKU with 3:21's and 35" tires and it drives fine so yeah you can spend the money to regear I plan on it when I upgrade my axles but I have had plenty of people tell me how much faster it is then re-geared 3.8 liter engines. So it is staying at 3:21 for now.
I've got the same tire/gear combo and I honestly have ZERO need for a re-gear!!!!
Maybe with 37's...... Maybe....
#26
Originally Posted by Black_JKU
Finally!!!! Someone else that feels the way I do!!!!
I've got the same tire/gear combo and I honestly have ZERO need for a re-gear!!!!
Maybe with 37's...... Maybe....
To those who slam, no I did not buy my JK for it's awsome mpg but I drive 110 miles a day min, so I do keep an eye on it.
#27
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Originally Posted by JKbender
I also have 3.21's... Do either of you know what kind of mpg you are getting with these gears and 35's? A lot of people with the 3.8L say that they need the regear to get the mpg back, but you are the first guys with this setup on a '12 that I have run across.
To those who slam, no I did not buy my JK for it's awsome mpg but I drive 110 miles a day min, so I do keep an eye on it.
#28
Originally Posted by scemracing
I get 20-21 on the highway but I drive like a grandma. I found with the auto, 3:21's, and 35's I get better mileage by putting into 4th on the highway.
#29
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Join Date: May 2012
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I have a 2012 JaKe with 3.73 gear sets running 35" Toyo's and driving on the highway keeping my rig rpms at 2000 /68 mph i have ranged from 18.2-18.8 MPG.......Off the line speed is still impressive given the extra weight over a bone stock JK........I paid $50 extra for the optional 3.73's over the stock 3.21's.......making that change at purchase saved me $$$ doing a gear change later.......I'm happy with the 3.73's and feel no need whatsoever to change them......even if i go with a taller tire for DD use it's only going to lower my RPMs at that speed anyway.......my thoughts
Cheers
Cheers
#30
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Thanks man. Hit 16k on the odo this weekend. Stock tires for the first k, 35s fir the next 14k and now 37s for the last k. I really think that 37s will become the new tire of choice with the 3.6 and the new auto. Its just too easy to run them and you dont have all of the performance problems of the 3.8. We will see because it will definately be easier to break "shit" on the trails with the 37.