The Ford Barn - View Single Post - speedo gear-in tranny

Daves55Sedan · 11-18-2021, 06:27 PM

Before you install your '57 small case FOM, remove the rear extension housing from the '57 trans and remove your old '55 rear extension housing and look at the speedo drive gear on the tail-shaft. If they are different, remove the drive gear off both and install your '55 drive gear on the '57 tail-shaft. Now install the '55 rear extension housing on the '57 transmission. Once the trans has been installed in the car, you can plug-in your original '55 speedo driven gear into the hole in the extension housing and it will work as originally.
If you don't do any of this, the speedo cable will rotate backwards (if it rotates at all) and it will not register on the speedometer.
BTW, the speedo drive gear is held on the shaft with a big "C"-ring, which you can re-use to re-install the drive gear on the shaft.

11-18-2021, 06:27 PM	#16
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: speedo gear-in tranny Before you install your '57 small case FOM, remove the rear extension housing from the '57 trans and remove your old '55 rear extension housing and look at the speedo drive gear on the tail-shaft. If they are different, remove the drive gear off both and install your '55 drive gear on the '57 tail-shaft. Now install the '55 rear extension housing on the '57 transmission. Once the trans has been installed in the car, you can plug-in your original '55 speedo driven gear into the hole in the extension housing and it will work as originally. If you don't do any of this, the speedo cable will rotate backwards (if it rotates at all) and it will not register on the speedometer. BTW, the speedo drive gear is held on the shaft with a big "C"-ring, which you can re-use to re-install the drive gear on the shaft.