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Topic Review (Newest First)
04-29-2014 02:54 AM
JeepHerz
Quote:
Originally Posted by cjyorks View Post
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.
04-28-2014 10:34 PM
cornfedksboy
Quote:
Originally Posted by cjyorks View Post
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.
04-28-2014 10:23 PM
cjyorks 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?
08-23-2013 12:27 AM
mflint1513
Quote:
Originally Posted by groovebus View Post

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.
07-01-2013 12:22 PM
groovebus
Quote:
Originally Posted by JeepHerz View Post
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
05-22-2013 07:51 PM
MichaelEdwardsDO
Quote:
Originally Posted by MikeK46 View Post
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.
05-22-2013 12:54 AM
JeepHerz 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.
05-22-2013 12:27 AM
MikeK46 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?
05-20-2013 09:48 PM
MichaelEdwardsDO Attachment 251709

It's alive! I feel like dancing. Drive is awesome!
FYI starting in 3rd feels like starting in 1st did before the swap
05-20-2013 08:04 PM
MichaelEdwardsDO
Quote:
Originally Posted by JeepHerz View Post
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
05-20-2013 06:40 PM
JeepHerz 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!
05-20-2013 06:35 PM
MichaelEdwardsDO 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
05-18-2013 09:03 AM
MichaelEdwardsDO
Quote:
Originally Posted by ohioviper View Post
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)
05-18-2013 01:01 AM
ohioviper You have to use a procal and set gear ratio.
05-17-2013 10:43 PM
MichaelEdwardsDO 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
05-15-2013 12:52 PM
dawhitesJKU ^ 22mpg thats awesome!!!
i'm averaging 19-20mpg on 33's w/ 3.21 driving to sustain ECO light.
05-15-2013 12:34 PM
MichaelEdwardsDO
Quote:
Originally Posted by JeepHerz View Post
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.
05-15-2013 12:32 PM
JeepHerz 22 MPG? I didn't even get that with 3.21s! Right foot has high lead content.
New Gears Woo Hoo
05-14-2013 09:16 PM
MichaelEdwardsDO Attachment 249278
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!
05-04-2013 12:31 PM
mflint1513 Agreed! I'm just glad I don't have to run the highway in Fourth gear while my Jeep fights the winds!
05-04-2013 02:13 AM
JeepHerz 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.
05-04-2013 12:12 AM
mflint1513
Quote:
Originally Posted by JeepHerz View Post
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!
05-03-2013 11:52 PM
MichaelEdwardsDO 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.
04-30-2013 12:29 PM
JeepHerz G2. 4.56s were hard to find.
http://www.g2axle.com/Ring-and-Pinio...nion-gear.aspx
04-30-2013 12:12 AM
MichaelEdwardsDO
Quote:
Originally Posted by JeepHerz View Post
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 brand of ring and pinion gears did you choose?
04-29-2013 11:41 PM
JeepHerz 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!
04-29-2013 09:34 PM
Xcrossbow Just came back from Jeep Beach. Google maps says that my home to Daytona Speedway is 260 miles using my chosen route (@100 miles of country road 55mph, @160 miles of Interstate).

Speedometer has not yet been recalibrated for my 35's. Driving down, with 1500 miles of usage on the MPG "estimator" I started out with a reading of 13.1. Driving rules were to stay at or around 58mph in 55 MPH areas and 63 MPH in the 65 & 70 MPH areas both on the uncalibrated speedometer. When I arrived at Daytona my MPG average had climbed to 16.3 MPG. I was actually pretty happy with this even if the "estimator" is only an estimate.

Returning home I reset the MPG "estimator" to zero and my average was 17.3 MPG when I arrive home using the same return route and driving by the same "rules". Again I was pretty happy.

All in all I have been very satisfied with the 3.21 but the Jeep is not my daily driver and I have 2 other vehicles that can give me my occasional torque fix. If I feel the 3.21 lug coming on I will usually manually shift the automatic down a gear or speed up to get thru it.

A question I do have is if my unrecalibrated speedometer is slow because of the bigger tires does that mean that the MPG "estimator" is off and slow or lower also?

Right now, I would not be able to justify the cost of a re-gearing.
04-29-2013 06:35 PM
MichaelEdwardsDO I now share op's obsession
01-21-2013 07:36 PM
cornfedksboy subscribe
01-21-2013 07:32 PM
JeepHerz I don't have any issues on the freeway actually- but I do pop it in 4th for the hills or mountains thanks. I am not crazy about driving it in "manual" for city driving (where I have most of the issues.) You can be in 2nd gear at 3000 RPMS and barely notice. What gear am I in? LOL. I need some engine noise, a clutch and a normal torque curve to enjoy shifting.
Thanks for the read DB- I'll have to kick my feet up and have a glass of wine before I can get through it. Or a Shock Top Midnight Ale. Almost 5pm...hm.....
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