If you have a 97-06 Wrangler TJ and recently went to bigger tires, you'll probably notice that your speedometer is off. This is an easy fix by purchasing the correct gear for your tire size and ring and pinion.
NOTE:
This will not work on 03-06 Rubicon models. See the bottom of this post for more details on what to do if you have a Rubicon.
Here's a chart to help you determine the correct speedometer gear:
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The speedo gear swap/change takes a mere 5 minutes and only one wrench. This is an easy job that anyone can do.
Item's needed:
- 1/2'' wrench (socket works too).
- Some paper towels or rag. (you will drip a bit of ATF)
- Correct speedo gear for your tire size/axle gear ratio.
- New O-ring for the drive housing. (for $3 at the dealer, change it for cheap insurance)
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Once you have everything ready locate the Speedo Gear drive on the rear output shaft of the transfer case. (easily seen from the rear of the t-case skid)
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First action to take is to remove the electric connector. Push the lock clip out "the red tab" and press on the connector release and pull it off.
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Next step is to remove the 1/2'' bolt and wishbone clamp from the tail housing. Set these to the side.
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Once the clamp is removed you can now remove the drive housing. It will be secured tight in the tail housing..just work it back and forth until it pops out.
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Now it is time to remove the old gear and install the new. To remove the old just grab the gear in one hand and the drive housing in the other...pull. It pops right out with little effort.
Pull the old O-ring off of the drive housing and install the new one.
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Install the new speedo gear by pushing it into the drive sensor housing. Be careful not to pinch the o-ring when installing. (helps if you rub a bit of atf on the o-ring)
NOW...here is a little thing that a lot of people miss. The speedo gear is offset in the sensor housing. This is to adapt to different size gears. And there is 3 clocked position that you can install it. "But how do I do that?" Easy...look on the side of the drive sensor housing.
You will see the numbers....
26-31
32-38
39-45
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View attachment 110 This image has been resized. Click this bar to view the full image.
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Simply find where your speedo gear tooth number falls. When you install the unit into the rear tail housing point the number that your gear fall in down at the 5 o'clock position of the hole. Press the gear into the tailshaft.
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Install the wishbone clamp and bolt to secure the drive sensor housing. DO NOT OVER TIGHTEN the bolt. The tail housing is aluminum. Just snug it down good. Don't crank on it.
Besure you set the clamp teeth into the cuts in the drive housing.
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Plug the electric connector back in and you are done.
Here you will see the position that your speedo gear tooth count should be angled down. And a completed install. The installed speedo gear in this application was a 41 tooth gear...so 39-45 is down at the 5 o'clock position of the hole.
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How to Correct the Speedometer on Rubicon Models
This above speedometer gear change not work on 03-06 Rubicon models. The speedometer on these is electronically controlled and therefore you only have two options:
1) Some dealers are able to re-program the ECU so that it the speedometer will accommodate for different gearing and larger tires.
2) There are several electronic speedometer calibrators out there, but the one I suggest is the
Speedo Healer by Blue Monkey. It's 100% plug-and-play, and uses factory style connectors. Note that you can also use one of these speedometer recalibration gear modules on a non-Rubicon model (as oppose to swapping the speedo gear as outlined above), but I'm not sure why you'd bother wasting the time and money, when swapping the speedometer gear is both cheaper and easier.
