Speedometer needle replacement

The speedometer needle was broken when I bought it. They were not intended to be taken apart, so it's a bit of a pain to work on them. The front face, through which the internals are removed, has a metal lip folded over which has to be peeled back.

Screwed to the back is an elbow which accepts the speedometer cable and turns it 90 degrees:

The front with the cover removed:

The gears inside:

Once I had it apart, I needed to attach the new needle (a red straw from a spray can) in the correct position. There is a small spring which returns the needle to zero mph, and the springs exerts a small amount of tension at this position to hold the needle steady.

I ended up using a small piece of tape on one side of the needle so I could superglue from the other side once I had it positioned correctly. I hooked a drill up to the speedometer cable and ran it all full speed, and timed how long it took to go one mile on the odometer. On two separate runs, it took 49 seconds, which works out to a little over 73 mph. I then started tweaking the needle so that it read 73 mph when the drill was running at full speed.

Glued in place:


Two things I almost screwed up: The needle should be low profile and straight so it doesn't touch the face, and short enough it doesn't touch the rubber seal that goes around the circumference (it barely clears as it is now).

Copyright (c) 2009 Paul Miner <$firstname.$lastname@gmail.com>