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post #4 of (permalink) Old 05-19-2005, 03:09 PM
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Re: Speedo Gear Larger?

That does not sound right...the gear needs to be the same physical size, otherwise it is not going to fit....unless I'm wrong about this. I changed the gear on mine and they were the same physical size, just different tooth count.

This is the slave gear that drives the speedo...hence, more teeth means it will turn slower and give you a slower speed indication. Less teeth means it turns faster. Typically, when you go to larger tires without changing gears, you need a lower tooth count. (it gets confusing sometimes)

The only reason you would want to go to a larger (more teeth) is if you went to smaller tires but did not change gears. If you changed gears to get your rpm's back to where they belong then the stock gear should be about right. In other words, the gear tells the speedo how fast the driveshaft is turning. If you go to larger tires, the driveshaft turns slower for a given speed (with 32" tires, on a stock CJ, you will indicate about 10% slower than your really going). Change your gears to 4.10 with those 32 or 33" tires, and your driveshaft is now back to turning about the same amount for a given speed. Hence, no change in speedo gear neede.

Clear as mud...right?
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