The square drive key for the AutoMeter 5291 speed sender may become disengaged from the speedometer gear. There is an easy solution to solve this. You can off-center the bushing on the drive key.
- With the drive key removed, grab a 3/16”, ¼-drive, deep well socket.
- Slide the socket over the drive key to make contact with the center bushing, and tap it lightly with a hammer. This does not take much to move the bushing.
- You are looking for “roughly” a 1/3 to 2/3’s offset. No need to be critical here in your measurement. Re-install the drive key with the longer end now toward the transmission and the shorter end toward the speed sender. Comparison of the standard, and modified drive key shown in the picture below.