40/41 speedometer problem

[41LjH]

Need a little help!
Found out the speedometer gear is not turning. When I got the truck in 2009 the speedometer was erratic. So I found another turtle with a good gear and put it in(photo 1&2). Now the cable end, also new does not turn. When I took the turtle off it looked like the gear on the drive-shaft had moved back(photo 4). So I moved the drive-shaft gear forward (photo 3), put it back together, started it on the lift, put it in gear and still nothing. Pulled it back apart and the drive-shaft gear had moved back again(photo 3).
I don't know how to engage the turtle to the drive shaft gear. Really need some help!

[Lawson Cox]

Photo 3 looks about right for the drive gear. there are spacers to use to center the drive gear. Also, do you have the correct speedometer cable and housing?

[41LjH]

I think everything is correct. Where do I get spacers and how do I install them?

[Terry,OH]

There is only one spacer (washer) between the drive shaft gear and the bearing to the rear of the gear. The gear should move back and forth about 1/4" or less, when properly installed. From your photo it appears the snap ring to the front of the drive shaft gear has moved forward of it's recess on the drive shaft. You want to move it rearward until it snaps into the recess. This will decrease the amount of end play the drive shaft gear has and should keep it under the turtle gear. With the cable installed on the turtle turn the turtle gear by hand and the speedo should react slightly. This will check out the cable and all of it's connections.

[ken ct]

The turtle could have the wrong gear in it smaller gear[less teeth on gear makes it smaller] and wont engage the drive gear. Its happend before.ken ct.

[41LjH]

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Moved the snap ring til it seated and the turtle is a 19 same as what came on the truck. Still won't engage. I assume with everything installed and the truck on the lift when I start it in gear (3rd) and rev to 2,000 RPM the cable should turn, right?
After nothing happened I took the turtle off and the drive shaft gear had moved back to the position in photo 4.

[41LjH]

Guys, still no solution for this problem! I didn't want to bore everyone with details but I am interfacing with a Stewart Warner electronic speedometer using a Dakota Digital speedometer generator. I mention this because it eliminates the cable and original speedometer as possible reasons for the problem. Haven't seen this done before, but without the turtle gear meshing with the speedometer gear on the torque tube, nothing will work. Because I am using an electronic speedometer I think any gear that will mesh (18,19,21) should be OK because I will calibrate the speedometer after the new tires are on the truck.. I have cleaned the turtle gear and it spins freely. I have hooked to a new speedometer cable to see if it turns and the cable does not turn.I checked the stamping on the rear end and a 19 is correct for the rear end. Everything on the torque tube seems correct and the snap ring is now in place. I must be missing something simple and welcome any ideas. I really don't want to unbolt the torque tube!!
Thanks

[Charlie ny]

41,
Take a look at the nose of the turtle.....SOME cable drives do not have a
female square drive but instead use a tang drive. In those turtles the square male
end of the cable has nothing to grab on to.
Charlie ny

[41panelmark]

I had a similar problem when I changed the gears in my rear end and then had to change the turtle. I had 2 turtles that had the same number but had different depths. Ended up getting a N.O.S. one off of the net, works fine.