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Unread 04-12-2014, 11:51 AM   #1
joeazzj
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3.0 diesel gear changes

We just changed the gears on my friends jeep the dealer can recalibrate for the gear change . 3.73 to 3.07's a ton better ! Instead of motoring down the hwy at 70 and 3000 rpm it's more like 2000 . It's only if you drive the hwy more other wise you won't see the improvement. Just thought I'd share.

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .

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Unread 04-12-2014, 12:16 PM   #2
caddydaddy
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That's a big drop in RPM! How does the gear change affect taking off? I'd consider it, but I have a 12 foot enclosed trailer that I tow. I wouldn't want to lose the pulling power.
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Unread 04-12-2014, 12:24 PM   #3
chrali
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What did that set you back?

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Unread 04-12-2014, 12:27 PM   #4
joeazzj
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It's 2200 @ 70 Ya I wouldn't do it then. Unless you upgrade the torque converter a shift improvement kit and a cooler with a separate fan that turns on when it gets hot . What transmission does it have ?

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-12-2014, 12:30 PM   #5
joeazzj
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mms95img-794779645.jpg

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-12-2014, 12:40 PM   #6
joeazzj
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It was 1800 had to buy a front commander axle for the 3.07's but I'm sure you can just order it the rear is a 8 1/4

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-12-2014, 03:21 PM   #7
chrali
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Nice work, any idea how your fuel consumption is improved?
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Unread 04-12-2014, 03:29 PM   #8
joeazzj
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I'll know in a few weeks when he's back in town

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-12-2014, 03:39 PM   #9
joeazzj
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I just looked up peek torque it's 37? @ 2000 so it should pick up a good amount

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-13-2014, 02:14 PM   #10
Red_liner740
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How did the ECU and transmission take it?

I remember reading about another member who was in the middle of the swap and ran into huge issues with the transmission ECU going crazy due to the fact that it was seeing different wheel rpm vs transmission output RPM.

Could you give us a bit more information on the software side?

Just wanted to add that i've added taller tires two weeks ago and so far the EVIC is reading the same MPG's while the vehicle is traveling 10% farther distance.
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Unread 04-13-2014, 02:27 PM   #11
joeazzj
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We took it to the dealer and the go in and recalibrate for the new gear ratio . Only problem we had to school the dealer on their hand held . The ring and pinion for the 8 1/4 you can get the 3.07 but the front is were the problem is but you need to order a ring and pinion for a 07 commander .

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-13-2014, 03:12 PM   #12
fishinbama
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I tried 2 different dealers and they either couldn't or wouldn't do it for me, back when I did mine.
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Unread 04-13-2014, 03:25 PM   #13
joeazzj
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We're do you live ? Maybe find someone who works there it's in the computer but the don't know it. Like I said it's Dona and on the road .

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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Unread 04-13-2014, 04:48 PM   #14
scootr29
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4wd or 2wd?

I am also confused because I have never done 3000 rpms at 70mph....
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Unread 04-13-2014, 05:01 PM   #15
joeazzj
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What gears do you have ? Peak torque is at 2000 rpm the higher the rpm above that the more gas your waisting

97' zj stock till I buy up all my goodies ! 318 242 waiting to go in .
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