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Phatton

Posted 2016-06-10 9:04 PM (#513858)
Subject: Speedometer gears

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Location: Camptown PA

I have a 60 Dodge Dart Convertible with the orginal torqueflite and rear. I am running 215 75 R14 tires (26.7" diameter). The speedometer is reading 6 miles per hour higher than the car's actual speed. Will the speedometer gears from a newer torqueflight fit the 60 trans or did ma Mopar change the housing? Thanks

NicksGarage

Posted 2016-06-10 9:11 PM (#513859 - in reply to #513858)
Subject: Re: Speedometer gears

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Location: Ramona, CA

The part numbers are different between my 1960 and 1964 parts books. Looks like they changed in 1962 when they went to the aluminum Torqueflite.

(speedo_pinions.jpg)

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speedo_pinions.jpg (122KB - 133 downloads)

imopar380

Posted 2016-06-10 9:59 PM (#513861 - in reply to #513859)
Subject: Re: Speedometer gears

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Location: Victoria, BC, on Vancouver Island, Canada

One of the factors that your speedometer is registering high is the fact that your 215-75R14 tires are too small. The overall height of those tires is about 3" less than the original 800 x 14's the car used. It might not be 6 MPH but it could easily affect it by about 3 mph from different sized tires I've used.

wizard

Posted 2016-06-11 3:07 AM (#513864 - in reply to #513858)
Subject: Re: Speedometer gears

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The speedometer cable changed in '62 and the new generation of gears cannot be used on the older gearboxes.

There's only a slim chance that you'll find a speedometer gear that will correct the error on the speedometer.
If you will keep your tire dimension, then a gauge repair shop could calibrate your speedometer instead.

BigBlockMopar

Posted 2016-06-11 6:06 AM (#513870 - in reply to #513858)
Subject: Re: Speedometer gears

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Location: Netherlands

Speedometers are off by a percentage, not actual mph.

If it's reading 6 mph too fast, you need to specify at which (real) speed this is.
Say, at 60mph (gps), a speedo reading 6 mph fast is 10% too fast. You'll need a transmission-speedo gear that has 10% more teeth.
That same speedo will read 12mph too fast at 120mph, or just 3mph too fast at 30mph.

Phatton

Posted 2016-06-11 8:08 AM (#513878 - in reply to #513858)
Subject: Re: Speedometer gears

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Location: Camptown PA

Thanks for the info

57chizler

Posted 2016-06-11 1:22 PM (#513892 - in reply to #513870)
Subject: Re: Speedometer gears

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Location: NorCal

I never rely on the speedo to determine the correct pinion. The odometer is direct-geared and is a much more accurate than the spring-loaded speedometer.

I recently had the speedo in my '57 checked by a commercial speedometer shop and the error was greater at low speed.

BigBlockMopar

Posted 2016-06-11 3:47 PM (#513900 - in reply to #513858)
Subject: Re: Speedometer gears

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Location: Netherlands

Speedo-correctness is easy enough to check these days with the GPS in your smartphone and one of the plentyful speed-measuring apps.

Phatton

Posted 2016-06-12 9:07 AM (#513927 - in reply to #513858)
Subject: Re: Speedometer gears

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Posts: 174
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Location: Camptown PA

Speaking of odometers - the numbers on my odometer are below the cutout. To read the numbers, I have to get my head above the speedometer and look down. I removed the trim and could not find a way to get the numbers centered - any ideas?

hemidenis

Posted 2016-06-12 1:17 PM (#513943 - in reply to #513858)
Subject: Re: Speedometer gears

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Location: Northen Virginia

I checked my speedometer some years ago with my Garmin GPS, and I did a video of the very accurate readings ..Theses are pictures frames of the video..