Ok first of all thank you for any help and patience. I have a 69 Cutlass. Speedometer quit working but I figured out that it is not the speedometer itself or the drive cable. Which leads me to the conclusion that the problem lies between the drive cable and the transmission or where it connects in the transmission. But I don't know what to do next, I've been able to disconnect the cable but that's easy. I just need help.

 

Well, I've never seen the little plastic gear in the transmission break. But if your sure the speedometer head and cable are good then that would be the next step. Do you have a Chassis Service Manual for your year of car? If not, create a profile on wildaboutcars.com and download the pages that show the transmission gear for the speedometer head.

But first, would you tell us how you checked the speedo head and cable?

John

 

Actually yes I do have a Chassis Service Manual. I checked the speedo by disconnecting the drive cable from the transmission, then got a drill, with no drill bit, and put it on the end of the drive cable. When I engaged the drill so did the speedo, in fact it went up to about 90 MPH.

 

If you are working with the car on the ground, lift up the left side of the car or move it to sloped ground, so you don't loose so much trans oil when you pull that speedo housing out...

 

So it sounds like you're good right up to the trans.
Next step is to remove the ⅜"-head screw and pull out the part that holds the gear.
Like YellowStatue said, tilt the car away, so you don't get a bath.
The piece just slides in, with an O-ring seal, but it may be cemented in pretty well by grit, so you may need to work it out.
Once it's out, you can inspect the drive gear and the driven gear.

- Eric