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By Danny - 15 Years Ago
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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
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By oldcarmark - 15 Years Ago
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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?
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By marvh - 15 Years Ago
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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
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By oldcarmark - 15 Years Ago
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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.
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By marvh - 15 Years Ago
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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
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By aussiebill - 15 Years Ago
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marvh (5/5/2010)
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. I,m with you marve!
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By Danny - 15 Years Ago
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I changed the entire cable including the housing and yes the speedometer turns freely when I turn it by hand. thanks, Danny
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By Danny - 15 Years Ago
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Here is a picture of the gear: 
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By petew - 15 Years Ago
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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
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By marvh - 15 Years Ago
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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 
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By aussiebill - 15 Years Ago
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Marve, could he have a cruisomatic fitted in the 56 and then is later box and i think should have the later gear type? i,m not real sure but just a train of thought. regards bill.
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By marvh - 15 Years Ago
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Bill:
That is what I am suspecting, maybe has had a later transmission installed (ie) 57 Fordomatic or 58 later Cruiseomatic. Both these transmissions take a different driven gear to the 55/56 gear on the cable.
marv
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By Tater Salad - 7 Years Ago
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I see this is an old post, but I have a question about the 55 fordomatic speedo gear. Does the bottom picture show the 55 gear for the transmission side? Does both ends of the cable have the same gear? Will Mac's part number 66-27035-1 fit the transmission side. I also have a noisy speedometer, the cable appears to be fine. Could the gear on the speedometer side be bad anyone know the part number for it?
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By Ted - 7 Years Ago
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Tater Salad (11/27/2018)
I see this is an old post, but I have a question about the 55 fordomatic speedo gear. Does the bottom picture show the 55 gear for the transmission side? Does both ends of the cable have the same gear? Will Mac's part number 66-27035-1 fit the transmission side. I also have a noisy speedometer, the cable appears to be fine. Could the gear on the speedometer side be bad anyone know the part number for it?
The ‘55 and ‘56 speedo gears are interchangeable with each other but are different from the 1957 and newer gears. With that said, the picture at the bottom of the previous page shows the transmission gears. The speedometer end has no gear at the end of the cable. The square end of the cable or the pronged adapter on the speedometer cable end could be worn thus not allowing the speedometer head to rotate. The pictured gear on the Mac's site looks correct for the '55/'56 tranny but will not work with the 1957 and newer transmissions.
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By Tater Salad - 7 Years Ago
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Thanks for the info Ted. I will be ordering one of those gears to replace the damaged one in the transmission. I have pulled the cable out and the ends look ok. The speedometer rotates with the cable hooked to my cordless drill but makes a loud whining noise and bounces a lot. I have yet to remove the speedometer cluster to see if I can repair the head, I had previously assumed it was the gear on the speedo end making the noise. Any other thoughts on the cause of the noise is greatly appreciated.
Josh
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By miker - 7 Years Ago
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This might help if the link to here works.
http://forums.y-blocksforever.com/Topic141596.aspx
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