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Old 09-06-2013, 04:27 PM   #1
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Smile Help me with Understanding Gears Ratio and Lift??

Hello my fellow Jeepers! I have a 2004 Jeep Wrangler X, Sitting on 33x12.5 R15 Bfg's KM2 MTS. I have stock axles (35 Back/ 30 Front) a while ago I went on a binge of sprucing it up and making it look nice. Needless to say this is my daily driver so for right now the off road days is behind it.....For now. Currently I have Placed a cold air intake from K&N on it since I don't go mudding any more, and a poison spyder Hood Louvre on it to reduce the heat, because it was peeling off my Kamo Paint job. I am ashamed to say that I don't really know anything about Gear ratio, unfortunately I was an idiot and took off the tag on the Rear differential cover to paint the cover and put in new fluid. In doing so when I opened the cover the oil smell was so bad I vomited all over the place and said to hell with it just paint it and put it back on with new fluid. so I kind of left off the tag. (could you blame me?). Yet now I am wondering if the previous owner swapped out gears or not? I just want to know if there are anyways of determining gear ratio by looking at them? I plan to take off the diff covers again and replace them with Poison Spyder Diff covers. Ill take photos later and maybe one of you guys could help??? And I don't know what size of lift I have on this thing either??? HELP??
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Old 09-06-2013, 07:36 PM   #2
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put it on jackstands and see how many rotations the driveshaft makes for every one rotation the tire makes.

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Old 09-06-2013, 07:54 PM   #3
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put it on jackstands and see how many rotations the driveshaft makes for every one rotation the tire makes.
Whats the equation on this? How many rotations should I do? What is the stock gears? And what gears should be on 33 in tires?
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Old 09-06-2013, 07:57 PM   #4
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Drive at 60mph in 4th if you have a manual tranny or third if its an auto and record your RPM's then look up the chart. Its on here somewhere.
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Old 09-06-2013, 08:13 PM   #5
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Drive at 60mph in 4th if you have a manual tranny or third if its an auto and record your RPM's then look up the chart. Its on here somewhere.
Ummm, I usually am at 3,300 rpms I think at around 60mph I struggle to get to 70mph
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Old 09-06-2013, 08:16 PM   #6
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Ummm, I usually am at 3,300 rpms I think at around 60mph I struggle to get to 70mph
Crap, need the tire size also.
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Old 09-06-2013, 08:17 PM   #7
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Ummm, I usually am at 3,300 rpms I think at around 60mph I struggle to get to 70mph
Ok i saw u have 33's. so u have a manual tranny then?
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Old 09-06-2013, 08:19 PM   #8
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Crap, need the tire size also.
Im riding on 33x 12.5 R15 Bfg Km2
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Old 09-06-2013, 08:20 PM   #9
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And is it by 60 mph on your speedo or a GPS? Because if your speedo hasnt been recalibrated your speed is off by probably 8-10 mph at 60.
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Old 09-06-2013, 08:32 PM   #10
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Standard tranny ideal gear with 33'' tire is 4.56 .Thats four and 1/2 rotations of your driveshaft to one tire rotation.
Want more info. search like i just did::
http://www.wranglerforum.com/f5/4-56-gears-259409.html
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Old 09-06-2013, 08:34 PM   #11
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And is it by 60 mph on your speedo or a GPS? Because if your speedo hasnt been recalibrated your speed is off by probably 8-10 mph at 60.
I have an automatic , and this is with my speedometer, im to poor for gps lol... I never thought about that, so my speedometer may need to be recalibrated if it was regeared?
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Old 09-06-2013, 08:40 PM   #12
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I have an automatic , and this is with my speedometer, im to poor for gps lol... I never thought about that, so my speedometer may need to be recalibrated if it was regeared?
Not if regeared. Your tires are bigger than factory therefore the make less revolutions than the factory size making your speedo read slower than you are going and they also effectively make your gear ratio higher. In final drive which is a 1:1 ratio( not overdrive) record your rpm... Ah hell jack the thing up and count how many times the drive line spins when you make a full rotation with the tire.
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Old 09-06-2013, 08:57 PM   #13
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Not if regeared. Your tires are bigger than factory therefore the make less revolutions than the factory size making your speedo read slower than you are going and they also effectively make your gear ratio higher. In final drive which is a 1:1 ratio( not overdrive) record your rpm... Ah hell jack the thing up and count how many times the drive line spins when you make a full rotation with the tire.
Ill have to do that soon then

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