Overview
The Crown Automotive 52067639 is a dark green, 39-tooth speedometer gear for the NP231 transfer case. It fits the Cherokee XJ, Wrangler LJ, Wrangler TJ and Wrangler YJ.
The speedometer reads wrong whenever the tires or axle gears are changed from factory, because the transfer case gear no longer turns at the speed the old gearing did. A 39-tooth gear moves the reading to match the new setup. The right count for each build is set by Crown’s tire and gear ratio chart.
Key features
- 39 teeth, dark green color
- Designed for the NP231 transfer case
- Corrects MPH after tire size or axle gear ratio changes
- Used with the factory O-ring or the 6035709 part
Tire size and gearing
Speedometer accuracy depends on how far the tires travel per revolution of the transfer case output. When tire diameter or axle gear ratio changes from the original setup, the speed signal no longer matches the road speed, and the gear count has to be matched to the new combination. Choosing the count from a tire and gear ratio chart keeps the reading close to true speed.
Before changing the gear, confirm the transfer case is the NP231 and that the O-ring or the 6035709 part is ready for the job. A careful check at this stage avoids repeating the work. After installation, compare the speedometer to a GPS reading at a steady speed to confirm the setup.
- Note the original tire size before changing tires
- Keep the old gear for comparison if it is still usable
- Recheck the reading after any axle or tire change
Specifications
| Brand | Crown Automotive |
|---|---|
| Part number | 52067639 |
| UPC | 848399015300 |
| Tooth count | 39 |
| Color | Dark green |
| Transfer case | NP231 |
| Required separately | 6035709 part, unless the factory O-ring is reused |
Vehicle fitment
It fits the 1993–2001 Jeep Cherokee (XJ), 2004–2006 Jeep Wrangler (LJ), 1997–2006 Jeep Wrangler (TJ) and 1993–1995 Jeep Wrangler (YJ). It does not fit the 1987–1992 Wrangler YJ, the Grand Cherokee or any Wrangler JK. Check your vehicle’s year, model and trim before buying.
Other transfer cases and the Grand Cherokee are not covered by this list.
Installation notes
Verify the NP231 transfer case before fitting. The 39-tooth count should be checked against your tire and gear ratio chart before use, because the speedometer will read off if the count does not match the gearing.
What’s included
The 39-tooth speedometer gear is included. The 6035709 part is not included and must be bought separately, unless the factory O-ring is reused.
