I have had 2 (19 teeth) speedometer gears go out in the last 2 months on my 1956 ford crown victoria with 292 and fordomatic transmission. The first gear came with the car which I have had about a year. The second was a reproduction speedometer gear from Tee-Bird Products in PA.  I had a retired mechanic friend install the new reproduction gear. Both failures occurred while driving approximately 65 MPH. Any ideas on what could be causing this? I also replaced the speedometer cable after the first gear failure.

Thanks,

Danny

Hello Danny! Did you replace the complete cable or just the inner one?does the speedo head work freely or do you notice a noise or the needle not moving properly?

  

Could you shoot us a picture of the speedo gear. The 55-56 gear is different from the 57 gears.



Maybe you were given a 57 gear.

marv

Hey Marvh! I dont think the 57 style will even go on a 56 cable.57 was the 1st year for the gear that had a pushon clip to hold it on the end of the outer cable.Still would be helpful as you said to see a pic.

  

Mark:



Yes; the 57 will not fit the 56 cable if the cable being used is a proper 56 cable.



There has to be a reason it is eating gears. If someone changed the transmission to a 57 trans the output shaft would be different. Maybe I am reading too much into this, however it ate 2 gears.



A picture of the gear would tell which gear was used

I,m with you marve!

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

I changed the entire cable including the housing and yes the speedometer turns freely when I turn it by hand.

thanks,

Danny

Here is a picture of the gear:

Danny,

Have your mechanic pull the speedo gear out and look into the hole to check the condition of the gear that drives the speedo gear. It is located on the trans output shaft .

Pete

The picture of the gear appears to be 56 gear.

Here is a couple pictures for comparison of a 56 and a 57 speedo gear.

The top picture is inside the speedometer hole inside the tailshaft housing of a 56 Fordomatic. You can see the little aluminum piece that the speedo gear rests upon. Have your mechanic check inside the hole with a mirror and flashlight to see if that aluminum tab has a drilled hole in it or not. The 56 tailshaft housings did not have a hole whereas the 57  housing had a hole for the aligning pin on the end of the 57 speedo gear. This will tell you if someone has changed the transmission to a later unit during its lifetime. Other ways to tell is if the trans output shaft spline is 28 or 17 spline. 28 splines are 57 and later for a Ford 292, some 56 with 312's were supposed to have 28 spline output shafts.

If everything is correct for a 56 with 292 engine and as you wrote a new cable and housing was installed along with new gear as well speedo head turns freely another thing possible is the speedo cable has not been feed properly from the transmission through firewall onto speedo head. Maybe has a sharp bend so cable is not moving freely inside the housing. Did the new cable have some light grease coating the cable for lubrication. Have your mechanic check.

marv