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post #1 of (permalink) Old 07-03-2002, 06:44 PM Thread Starter
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Speedo gear more or less teeth? Reads 60 actual 67

Okay I have looked at a few too many calculators. I have a 33 tooth speedo gear, and my speedo reads 60mph when I am actually going 67mph. Do I need more teeth or less? I originally thought that I need 37 teeth, but now I am confused and think that I need 30 teeth. Which is it and why?

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Tom
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post #2 of (permalink) Old 07-03-2002, 06:46 PM
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Re: Speedo gear more or less teeth? Reads 60 actual 67

I think ya need one with more teeth. I'm not sure what my YJ's stock speedo gear was, but I went to a 35 or 36 tooth one.
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post #3 of (permalink) Old 07-03-2002, 06:51 PM
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Re: Speedo gear more or less teeth? Reads 60 actual 67

More teeth will reduce the indicated MPH. Look at it like a ring gear and the trans is the pinion.

To bring the indicated MPH up you need less teeth. I'd say if you have a 33 tooth now and you have 67/60 ...you should have a 29 or 30 tooth gear. You're basically off 10%
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post #4 of (permalink) Old 07-03-2002, 06:57 PM
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Re: Speedo gear more or less teeth? Reads 60 actual 67

You're probably right. I don't understand gearing AT ALL, other than lower gears are better
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post #5 of (permalink) Old 07-03-2002, 08:10 PM
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Re: Speedo gear more or less teeth? Reads 60 actual 67

The older cable driven speedometers required 1000 revolutions in a mile. I believe that this is still true ..except that the VSS (plug in appropriate nomenclature) takes the output of the gear driven sensor and integrates that into XXX # of pulses (4000 I think). Either way if you're indicating less mph than you are going the odometer is reading less than a mile in every mile travelled ....or you are short of the 1000 revolutions (xxx # of pulses) per mile. So you need to "gear up" (lower numerically) to speed up the speedo cable (or in the case of a sensor, "revolution dectector/counter) to compensate. To speed up the driven gear ...you need to make it smaller (closer to 1:1)
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