Gear ratio?
04-03-2011, 01:53 PM
#1
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Gear ratio?
I got my JKU about 3 months ago and ive always wondered what gearing I have. Its an 08' Sahara bought it used and it has a tow receiver. Would that mean I have the tow package? 3.78 or 3.21? I would really like to know because I want to put the right gearing into my superchips programmer.
04-03-2011, 01:59 PM
#2
JK Jedi Master
I hesitate to post this, because most people want the "computer" answer, not the answer that will show what is actually in there.
But, here goes:
If you want to know for sure, and remove all doubt, do this:
Chock the front tires, fore and aft.
Put the transmission in neutral.
Emergency brake off.
Jack the left rear tire off the ground.
Put a jack stand under the frame, just in case the jack fails (had to add this).
Put an index mark on the aft end of the drive shaft, visible from the left rear wheel.
Put an index mark on the left rear tire at the 6 o'clock position.
Rotate the left rear tire 2 complete revolutions while counting how many times the index mark on the drive shaft passes its original position.
That number will be your axle ratio.
Remove jack stand and lower jack.
Put transmission in gear or Park, apply emergency brake.
Remove chocks.
If you have limited slip, jack up both rear wheels and rotate one revolution, making sure both tires rotate equally.
If the drive shaft rotated almost 3 1/4 turns, you have 3.21
If the drive shaft rotated almost 3 3/4 turns, you have 3.73
If the drive shaft rotated a little over 4 turns, you have 4.10
If the drive shaft rotated a little under 5 turns, you have 4.88
If the drive shaft rotated a little over 5 turns, you have 5.13
But, here goes:
If you want to know for sure, and remove all doubt, do this:
Chock the front tires, fore and aft.
Put the transmission in neutral.
Emergency brake off.
Jack the left rear tire off the ground.
Put a jack stand under the frame, just in case the jack fails (had to add this).
Put an index mark on the aft end of the drive shaft, visible from the left rear wheel.
Put an index mark on the left rear tire at the 6 o'clock position.
Rotate the left rear tire 2 complete revolutions while counting how many times the index mark on the drive shaft passes its original position.
That number will be your axle ratio.
Remove jack stand and lower jack.
Put transmission in gear or Park, apply emergency brake.
Remove chocks.
If you have limited slip, jack up both rear wheels and rotate one revolution, making sure both tires rotate equally.
If the drive shaft rotated almost 3 1/4 turns, you have 3.21
If the drive shaft rotated almost 3 3/4 turns, you have 3.73
If the drive shaft rotated a little over 4 turns, you have 4.10
If the drive shaft rotated a little under 5 turns, you have 4.88
If the drive shaft rotated a little over 5 turns, you have 5.13
04-03-2011, 02:36 PM
#5
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You can try plugging your VIN in here:
hxxp://www.compnine.com/vid.php
If your jeep is in the system, it should show what gears it left the factory with. If the previous owner re-geared, then you are spinning a tire.
hxxp://www.compnine.com/vid.php
If your jeep is in the system, it should show what gears it left the factory with. If the previous owner re-geared, then you are spinning a tire.
04-03-2011, 03:08 PM
#6
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Sweet!! Im sure the gears were never swapped out. Looks like my jeep has 3.73 gears.
