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Old 05-03-2013, 10:52 PM   #31
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After much hand ringing and discussion and recognizing that I'm just not patient enough to wait on next year's Rubicon, here is the plan that Dan at Truck Pro Shop in Jacksonville and I have formulated. 4.56 gears front and rear, eaton true trac in the rear, and a Hypertech 755006 to calibrate and bump the horsepower a tad. We are Gonna shoot for week after next as we have to wait on the rear gears to get here from California.

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Old 05-03-2013, 11:12 PM   #32
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I suppose I could up-date my thread: no more 3.21s. Re-geared to 4.56s and LOVE it. Now most upshifting drops me to 1500 RPMs minimum (as opposed to 1200). Bye Bye 3.21 lug!
What kind of MPG are you getting now? I'm about 13.5-15 highway with my 35s and 4.56s and manual. It's nice to not shift down to third through Cajon Pass on I-15 but the mileage sucks!

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Old 05-04-2013, 01:13 AM   #33
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I get a little better by about a gallon- more like 15-16. 13.5-14.5 city. If I could manage to drive 65mph I know I could get 17 MPG but I gave up on that. If I had to drive Cajon Pass daily we'd probably be about the same. Recent trips to Big Bear and Calico were so nice- I didn't even notice the trach. or tranny- exactly what I wanted.
Even stock tires and 3.21s were a pain up Big Bear.
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Old 05-04-2013, 11:31 AM   #34
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Agreed! I'm just glad I don't have to run the highway in Fourth gear while my Jeep fights the winds!
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Old 05-14-2013, 08:16 PM   #35
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Dropped it off at the gear shop. Should have 4.56's and a true lock rear diff by tomorrow afternoon or Thursday morning. Good bye gas mileage; hello fun!
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Old 05-15-2013, 11:32 AM   #36
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22 MPG? I didn't even get that with 3.21s! Right foot has high lead content.
New Gears Woo Hoo
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Old 05-15-2013, 11:34 AM   #37
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22 MPG? I didn't even get that with 3.21s! Right foot has high lead content.
New Gears Woo Hoo
It's very flat here in Florida and that was a few days of driving as lightly as possible.
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Old 05-15-2013, 11:52 AM   #38
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^ 22mpg thats awesome!!!
i'm averaging 19-20mpg on 33's w/ 3.21 driving to sustain ECO light.
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Old 05-17-2013, 09:43 PM   #39
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Argh. Went to pick up "big red" from the shop after the ring gear swap and kept getting an error code "1st gear ratio is incorrect". Called Dan at ProTrucks jacksonville, who did the work, and he came back up from dinner and met me at his shop to see if he could figure it out. Unfortunately no joy. He has to wait on tech support unless anybody out there knows why a flashcal cannot seem to get this right. 3rd gear in limp mode does feel great between 35 and 65mph with the 4.56's however
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Old 05-18-2013, 12:01 AM   #40
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You have to use a procal and set gear ratio.
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Old 05-18-2013, 08:03 AM   #41
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You have to use a procal and set gear ratio.
We did that. Actually used a superchips flashcal. (Amazingly, They are made by the same manufacturer in Sanford Florida of all places)
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Old 05-20-2013, 05:35 PM   #42
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So here is the update: the flashcal programming was wrong. The engineers at hypertech rewrote the code and its been reflashed. I was told it is working correctly. Sadly I couldn't get to the shop before closing but Dan may be bringing it to my house tonight if not I'm going to get it first thing tomorrow
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Old 05-20-2013, 05:40 PM   #43
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So is it your Flashpaq or the shops? Interested in the tune options.
Hopefully you can get it back and enjoy your 4.56s. My Jeep is so much more fun to drive!
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Old 05-20-2013, 07:04 PM   #44
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So is it your Flashpaq or the shops? Interested in the tune options.
Hopefully you can get it back and enjoy your 4.56s. My Jeep is so much more fun to drive!
Mine. They sell them but I bought it before I dropped it off with them when I dropped the jeep off
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Old 05-20-2013, 08:48 PM   #45
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It's alive! I feel like dancing. Drive is awesome!
FYI starting in 3rd feels like starting in 1st did before the swap
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Old 05-21-2013, 11:27 PM   #46
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What all is involved in swapping from 3.21's to 4.56's aside from the actual gearset in the front & rear diffs and re-calibrating with a ProCal? Does the diff itself (carrier) need to be changed as well?
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Old 05-21-2013, 11:54 PM   #47
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Yes- front carrier has to be replaced on the D30. The rear is fine. Perfect time to throw in a locker though.
If you're installing yourself its a big tool list.
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Old 05-22-2013, 06:51 PM   #48
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What all is involved in swapping from 3.21's to 4.56's aside from the actual gearset in the front & rear diffs and re-calibrating with a ProCal? Does the diff itself (carrier) need to be changed as well?
I used a flashcal instead of a procal it was cheaper and has more features.
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Old 07-01-2013, 11:22 AM   #49
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Not so fast. I get a whopping 14 MPG. Stepping on the throttle to correct the upshifting I am sure. And I drive mostly city. Even on a trip to Vegas (flat; all freeway) I only averaged 16.9 MPG.
Where in CA do you live? I'm in Orange county and there is alot of uphill/downhill traveling between here and Vegas. The Cajon Pass, then after Barstow it's pretty much all up hill climb to 4500ft until the CA/NV state line. Then it's a steep downhill drop into NV. The way back is worse but you are only doing about 20mph in the middle of the burning desert anyway due to traffic. LOL
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Old 08-22-2013, 11:27 PM   #50
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Where in CA do you live? I'm in Orange county and there is alot of uphill/downhill traveling between here and Vegas. The Cajon Pass, then after Barstow it's pretty much all up hill climb to 4500ft until the CA/NV state line. Then it's a steep downhill drop into NV. The way back is worse but you are only doing about 20mph in the middle of the burning desert anyway due to traffic. LOL
That's why I went to 4.56 gears with the 35s. Now my mpg is about 15 highway fighting terrain and weather from the IE through the high desert.
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Old 04-28-2014, 09:23 PM   #51
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I'm lifting my 2014 sahara 3.5 inches and putting on 35x12.5 18 inch. Is it true that on the 2014 the computer will make all the adjustments after about 100 miles and I don't need a tuner to manually reset?
also, new to the whole gearing situation. Do I need to upgrade?
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Old 04-28-2014, 09:34 PM   #52
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I'm lifting my 2014 sahara 3.5 inches and putting on 35x12.5 18 inch. Is it true that on the 2014 the computer will make all the adjustments after about 100 miles and I don't need a tuner to manually reset? also, new to the whole gearing situation. Do I need to upgrade?
If you have 3.21s and are going to 35s you will probably want to regear. You can always drive it and see.
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Old 04-29-2014, 01:54 AM   #53
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I'm lifting my 2014 sahara 3.5 inches and putting on 35x12.5 18 inch. Is it true that on the 2014 the computer will make all the adjustments after about 100 miles and I don't need a tuner to manually reset?
also, new to the whole gearing situation. Do I need to upgrade?
You need a tuner to tell your engine computer what tire size you have. Otherwise your speedometer and odometer will be incorrect- it is programmed for your stock tire size. Doesn't matter what engine or year you have. A Procal is $150.
Do you need to re-gear? Rather than re-hash- go to JK General Discussion. "Search forum" and type in 3.21. You'll get a good 21 pages of threads. Those are just the recent ones. The quick answer is probably yes, you'll want to re-gear- and then it's a matter of when. That said- there are plenty of folks that run 35s with 3.21s that find it "ok". Bottom line you will lose performance and it won't drive like it did on stock tires. Whether or not that bothers you is subjective.

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