1957 Ford speedometer runs backwards

Automotive Stud

Automotive Stud

Well-known member
My friend and I are putting together a '57 Ford with a toploader 4 speed out of a late 60's Mustang. Everything went well but the speedometer is running backwards. Is there a different gear for the cable we can use or do we have to pull the tailshaft and swap the gears inside?
 
If the angle of the teeth on both gears matches each other you'd need to change them as a pair. Changing just the gear on the bottom end of the speedometer cable can only fine tune the accuracy of the speedo (they are available with more or fewer teeth, to change the ratio) but will not change the direction.
You might be able to find an adapter that reverses the rotation of the cable. I bought a 90° adapter for the bottom of the speedo cable in my '55. Turned out it was made so it could be reversed, but it arrived damaged so I sent it back.
See this link.
https://www.google.com/search?q=ford+speedometer+reverse+rotation+adapter&ie=utf-8&oe=utf-8

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Last edited:
dmsfrr said:
If the angle of the teeth on both gears matches each other you'd need to change them as a pair. Changing just the gear on the bottom end of the speedometer cable can only fine tune the accuracy of the speedo (they are available with more or fewer teeth, to change the ratio) but will not change the direction.
You might be able to find an adapter that reverses the rotation of the cable. I bought a 90° adapter for the bottom of the speedo cable in my '55. Turned out it was made so it could be reversed, but it arrived damaged so I sent it back.
See this link.
https://www.google.com/search?q=ford+speedometer+reverse+rotation+adapter&ie=utf-8&oe=utf-8

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Click to expand...

Thanks, I found an adapter on the bay for cheap. Easier than pulling the tailshaft again!
 
Toploaders (at least mine) has the opening for the speedo cable on the right side so you have to use a different driven gear than the one for the left side.
 
If the speedo gear enters the housing on the driver side, I can tell you why it is going backward. Due to the difference in the orientation (angle in which the speedo cable hub enters the hole in the rear extension housing), you have swapped the position of the speedo driven gear relative to the worm gear from above the worm gear to below the worm gear (or vice versa).
If I remember right, the '57 transmission speedo drive gear runs below the worm gear on the tail-shaft. So the Mustang transmission rear extension housing must have the driven gear oriented so that it rides above the worm gear.
 
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