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SPEEDOMETER GEAR #2682838
07/30/19 08:06 PM
07/30/19 08:06 PM
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WV
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JohnH Offline OP
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69 B Body 440 engine,, 727 transmission.. My speedometer is running about 12 MPH slow. 355 rear, tires 26" outside diameter measurement.. According to the chart I seen, looks like the gear I need is P/N 2538936. Does this sound right? Thanks for any info...

Re: SPEEDOMETER GEAR [Re: JohnH] #2682856
07/30/19 08:49 PM
07/30/19 08:49 PM
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Lincoln Nebraska
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RapidRobert Offline
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I went by the MP chart once & it was dead on. But if the speedo for instance is 12 MPH slow at say 60 MPH (shows 48 MPH) you would need 20% (12 divided by 60) less teeth on the pinion than what is in there now to speed it up 20%. For example if it has a 30 in there now you'd wanna get a 24. Jack up the car as high as you can on the dr side to minimize fluid loss & as you know clock the pinion adapter on the side of the trans to match the tooth count of your new pinion.


live every 24 hour block of time like it's your last day on earth
Re: SPEEDOMETER GEAR [Re: JohnH] #2683102
07/31/19 01:24 PM
07/31/19 01:24 PM
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Rio Linda, CA
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Actual math shows you need a 35.79 tooth pinion but I would check the odometer for accuracy first. If the odometer is correct and the speedo is off, the problem is in the speedo head.


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Re: SPEEDOMETER GEAR [Re: John_Kunkel] #2684374
08/04/19 05:09 PM
08/04/19 05:09 PM
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JohnH Offline OP
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I had the speedo overhauled...

Re: SPEEDOMETER GEAR [Re: JohnH] #2684383
08/04/19 05:55 PM
08/04/19 05:55 PM
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lewtot184 Offline
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factory would have been 36 tooth.

Re: SPEEDOMETER GEAR [Re: lewtot184] #2684512
08/05/19 12:23 AM
08/05/19 12:23 AM
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Hamilton, Ontario Canada
Magnum Offline
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What is the gear in the transmission now and 12 mph off at what speed? As Kunkel mentioned the odometer is a better check because 12 off is not 12 off at 0 mph or still 12 off at a higher speed. If it was, the problem would be a bent needle.


69 Super Bee, 93 Mustang LX, 04 Allure Super
Re: SPEEDOMETER GEAR [Re: Magnum] #2685481
08/07/19 07:52 PM
08/07/19 07:52 PM
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JohnH Offline OP
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Off 12 MPH at about 55

Re: SPEEDOMETER GEAR [Re: JohnH] #2688590
08/16/19 10:34 PM
08/16/19 10:34 PM
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Hamilton, Ontario Canada
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Originally Posted by JohnH
Off 12 MPH at about 55


and how much at 0 mph?


69 Super Bee, 93 Mustang LX, 04 Allure Super






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