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rockfla · 03-23-2020, 07:46 AM

I was working on fixing the speedo in the 39 Mercury this weekend so I pulled the front floor board and trans cover to access the speedo drive "Turtle" to install a new (good used) drive. I removed the old "turtle" and sure shootin' the drive gear in it was "convex" shaped worn right around the "middle" of the gear. SO I installed the new drive and (First question) I am assuming that IF it fits flush to the housing the drive gear of the turtle is lined up with the drive shaft???? Its fitting flush SO I connected the new speedo cable at the "turtle". Then I set about connecting the other end to the speedo which I did. Took the car for a quick little spin around the yard and NO speedo. SO I pulled back into the shop and double checked both ends to the cable....all looked good so back out of the shop down the drive to the street, NO spedo but when I got to the street and backed up to pull back in the speedo worked going back down the drive way getting almost to 20mph BUT this time when I pulled back into the shop it STAYED at 20mph. I put it in reverse and backed up and it fell back to "0", pulled back down the drive again and NO speedo, even after backing up again and pulling back into the shop. SO, I pulled the cable at the turtle and chucked my cordless drill to the cable and spun the cable to the speedo, it jumped up to 30mph.....good I thought SO I connected the cable back to the turtle and disconnected the cable at the speedo. I took the car backout on a drive and held the "speedo" end of the cable in my fingers and could feel the cable spinning in my fingers, connected it back and still NO speedo!!! ANY thoughts or suggestions???? Is there a sure fire way to make sure the turtle gear is meshing with the drive shaft?? Is it important to use some pliers to make sure that both cable ends are threaded tight on the turtle and speedo, not just as tight as I can get them b hand/fingers (I.E. could the cable ends not be engaging the drive sockets because the ends are not in far enough, I.E. not tight enough...are they that close in tolerances)???

03-23-2020, 07:46 AM	#1
rockfla Senior Member Join Date: Mar 2014 Location: Jacksonville FL Posts: 3,963	Speedomter advice I was working on fixing the speedo in the 39 Mercury this weekend so I pulled the front floor board and trans cover to access the speedo drive "Turtle" to install a new (good used) drive. I removed the old "turtle" and sure shootin' the drive gear in it was "convex" shaped worn right around the "middle" of the gear. SO I installed the new drive and (First question) I am assuming that IF it fits flush to the housing the drive gear of the turtle is lined up with the drive shaft???? Its fitting flush SO I connected the new speedo cable at the "turtle". Then I set about connecting the other end to the speedo which I did. Took the car for a quick little spin around the yard and NO speedo. SO I pulled back into the shop and double checked both ends to the cable....all looked good so back out of the shop down the drive to the street, NO spedo but when I got to the street and backed up to pull back in the speedo worked going back down the drive way getting almost to 20mph BUT this time when I pulled back into the shop it STAYED at 20mph. I put it in reverse and backed up and it fell back to "0", pulled back down the drive again and NO speedo, even after backing up again and pulling back into the shop. SO, I pulled the cable at the turtle and chucked my cordless drill to the cable and spun the cable to the speedo, it jumped up to 30mph.....good I thought SO I connected the cable back to the turtle and disconnected the cable at the speedo. I took the car backout on a drive and held the "speedo" end of the cable in my fingers and could feel the cable spinning in my fingers, connected it back and still NO speedo!!! ANY thoughts or suggestions???? Is there a sure fire way to make sure the turtle gear is meshing with the drive shaft?? Is it important to use some pliers to make sure that both cable ends are threaded tight on the turtle and speedo, not just as tight as I can get them b hand/fingers (I.E. could the cable ends not be engaging the drive sockets because the ends are not in far enough, I.E. not tight enough...are they that close in tolerances)???