At 01:16 PM 11/23/2006 -0700, Colin Parkinson wrote:
" Perhaps you can tell me how to get the innards out of a speedo case? I have got the knob off the trip spindle, and removed the 2 screws on the back, so it is all loose. But I cannot maneuver it out of the case."

Twist the front trim ring to remove the ring, glass, seals and light guard. Remove two screws in back to free the works from the case. Tilt forward to bring the faceplate slightly ahead of the case on the right side. Peek in behind the faceplate on the right side to find the reset gear and shaft assembly shown in these pictures.

Note the position of all parts for reassembly later. At the bottom inside there should be a felt dust seal, a thin metal pressure washer, and a long spring to hold the dust seal in place. Above this find the reset gear with another stronger spring on top. The gear sits on top of an alignment plate and is held on the shaft with a small split pin.

Rotate the shaft as necessary for access to the pin. Use a small flat blade screwdriver or small long nose pliers to un-bend the legs of the split pin and reform it to straight condition. Rotate shaft again for access to the head of the pin. Use a crochet hook or small long nose pliers to pull the pin and free the gear from the shaft. Pull the shaft out the bottom and catch the small bits that fall out as you remove the works from the case.

Reassembly is the reverse of disassembly, but of course you get to fiddle more with the small tools to get all the little bits back in place.

Addendum December 2008:
I wrote this page when someone was asking how to get the mechanism out of the case. It appears this is still a problem for many people. I was told the little gear in the picture above is upside down, which it is, but that's not the problem. Apparently there are some variations on this design. The input shaft shown is straight and plain on top so the shaft can be pulled out of the gear. Some others may have a flange cold headed at top end of the shaft so the shaft will not pull out the bottom even after removing the split pin. One person has reported removing the split pin, then moving the obstructing reset arm a bit to one side, and then pushing the shaft upward enough to allow removal from the case.

I have only worked with a couple of these speedometers, so I don't have the greatest array of exposure to this problem (yet). Next time I get my hands on a spare I will take it apart promptly for the experience. Meanwhile, if anyone has good suggestions about removing the works from the case, do tell. Pictures could also help.

Addendum January 2010:
Not sure I would recommend cutting the case, but here's a suggestion from Dave Headrick.

Slotted central hole elongated to allow easy removal of mechanism. Doesn't help getting it out the first time but does help reassembly and future interventions. To keep dust out of the case I fabricated a plate to cover the hole and used a rubber gasket.