Should I re-gear my Jeep? - JeepForum.com

 
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post #1 of 13 Old 06-01-2012, 06:07 PM Thread Starter
NickOdachowski
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Should I re-gear my Jeep?

Okay so I got a 4.0l 6cyl 2001 TJ with a 3.5 inch lift and 33s. I have a cold air intake mod and thats it. When i got this jeep a couple months ago I knew it was gonna suck up alot of gas but I didnt think itd be this bad. coming from a family of jeeps, my dad guessed my jeep gets around 9 mpg, but were still in the process of actually finding the real number of miles per gallon. So I know many people get their engines recalibrated or programmed to mods like mine, and Im just really confused on where to go from this point. Right now the only solutions ive come up with are reprogramming the car with something like the Flashpaq,
possibly re-gearing my manual tranny to cope with the new mods, or maybe some kind of free flow exhaust, or performance chip? I'm sorry though i do not know my gear ratio but hopefully somebody will know the stock gears for my type of jeep. Right now im focused on mpg cause im runnin out of cash and patience. Thanks

Oh I found out I have a 3.07 gear ratio, which I know blows. hoping to regear when I have the money


Last edited by NickOdachowski; 11-09-2012 at 09:03 AM.
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post #2 of 13 Old 06-01-2012, 06:18 PM
JBTJ
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First off you need to replace the speedometer gear so it will reflect the true speed and MPG's for the 33" tires you have, look at your differentials, either the front or back and there should be a metal tag that will tell you your gear ratio, something like 3.07 or 3.73. Second, the CAI is not a mod but a down grade. Don't waste your money on anything else, as it won't do you any good. The 4.0L has been refined over the years to be as good as it's going to be. Regearing for the tires is the only thing you can do to achieve any thing you are asking about. But remember, anytime you change tire size or gear ratio you will need to change the speedo gear. You are not getting 9 MPG because everything is out of wack due to the 33's on the JEEP. Welcome to the Forum and the world of JEEP's.
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post #3 of 13 Old 06-01-2012, 10:32 PM
tommzz
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If you're running 33s you'll want to regear to a 4.56. 4.56 gearing will also be a good ratio for any future upgrades to 35s. When you put in the speedo gear insist on a replacement o ring (I learned the hard way it cost me a transfer case).
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post #4 of 13 Old 06-01-2012, 10:42 PM
Line58
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What transmission do you have? That will also influence what differential gear ratio you want.


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post #5 of 13 Old 06-01-2012, 10:45 PM
maximus1000
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Regear for 33s? nah, not unless you plan on going bigger.

People ask "what year is your jeep", I answer "which part?".
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post #6 of 13 Old 06-01-2012, 11:08 PM
postal719
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Regear!

You have to regear. Do a search and learn from the forum. It is the best mod you will ever do. 410's or 456's. It must be done.
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post #7 of 13 Old 06-02-2012, 07:20 AM
1999TJRED85000
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Search the forum and read. It doesn't sound like you like to read. 33's and a manual transmission require a 4.56. However, don't bother switching out the speedo gear. Do it electronically and you can change it in the future and it won't cost anything. Additionally, even the correct speedo can be off by as much as 5%. SpeedoHealer is a 5 minute install that you can set dead-on with a GPS. I have one on mine and if I ever change tires, I just reprogram it.

F U
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post #8 of 13 Old 06-02-2012, 08:02 AM
JBTJ
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Quote:
Originally Posted by 1999TJRED85000 View Post
Search the forum and read. It doesn't sound like you like to read. 33's and a manual transmission require a 4.56. However, don't bother switching out the speedo gear. Do it electronically and you can change it in the future and it won't cost anything. Additionally, even the correct speedo can be off by as much as 5%. SpeedoHealer is a 5 minute install that you can set dead-on with a GPS. I have one on mine and if I ever change tires, I just reprogram it.

Mine wasn't, dead on, verified with 3 different GPS's. Speedo Gear $40, Electronic Box $80+
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post #9 of 13 Old 06-02-2012, 08:19 AM
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Quote:
Originally Posted by JBTJ

Mine wasn't, dead on, verified with 3 different GPS's. Speedo Gear $40, Electronic Box $80+
What if you change more than once?

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post #10 of 13 Old 06-02-2012, 08:27 AM
Jason
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Quote:
Originally Posted by JBTJ View Post
Mine wasn't, dead on, verified with 3 different GPS's. Speedo Gear $40, Electronic Box $80+
Because of varying setups, and even varying sizes withing the same labeled "size" of tire, not everyone is so lucky. There's no adjustment in speedo gears; just +/- teeth. The electric boxes allow a more precise adjustment. My OCD wouldn't allow a X% variance if I "corrected" the speedo with a new gear.

Some speedo gears are has high as $80. Even with $40 gears, if one changes their tire size more than once, they've hit the break even point. If one goes back and forth between two (or more) sizes, a few buttons on the box is easier than pulling the gear out and putting a new one in each time.
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post #11 of 13 Old 06-02-2012, 08:39 AM
JBTJ
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Oh I agree completely. If I had known about the electronic boxes when it came time I would have bought one. I was just showing the OP the price differences between the two. The box is the way to go.
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post #12 of 13 Old 06-02-2012, 09:44 AM
Y1ann188
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You could also get the AEV procal module for 150 which I'm pretty sure adjusts the ECM for larger tires, shift points on auto, and speedo calibration, plug it it wait for the horn to honk and your good to go, you'll still need to regear to help MPG though

Edit: and you can reuse the procal when/ if you go to 35s and after regearing, also they're no worry about changing the speedo gear

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post #13 of 13 Old 06-02-2012, 11:22 AM
biffgnar
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Quote:
Originally Posted by Y1ann188 View Post
You could also get the AEV procal module for 150 which I'm pretty sure adjusts the ECM for larger tires, shift points on auto, and speedo calibration, plug it it wait for the horn to honk and your good to go, you'll still need to regear to help MPG though

Edit: and you can reuse the procal when/ if you go to 35s and after regearing, also they're no worry about changing the speedo gear
Does Procal work for TJs? I was under the impression it was a JK product.

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