Rob Frankham wrote: ↑Wed Aug 28, 2024 5:22 am
You really need a special tool to remove the old one with any certainty of not damaging the spindle and perhaps more to the point, setting the new needle in the right place is difficult if you intend to have any resemblance to accuracy. Because the needle normally rests against the stop, simply pressing it on to the spindle at 0 will give an instrument that overeads by a substantial amount.
The OP's speedo appears in the photo to be already resting at 0 mph which is odd as my experience like yours was that when not constrained by the stop, the resting position should be a fair bit below 0 mph. That doesn't bode well for the basic condition of the speedo.
What I did is flip the needle over the stop to find it's natural resting position and then mark that position as a reference for when the needle was replaced before flipping it back over the stop again. There is no hole in the needle boss to use a proper needle extraction tool so I had no choice but to carefully lever it off the spindle using the minimum force necessary. Although I was apprehensive it didn't seem to cause any damage.
There is a proper tool for the job, made for clockmakers to pull clock hands. Two types, one bears on the central spindle and so is no use for this application. The other is a small two legged puller that has a clip in the middle to fit under the needle boss. Alternatively, it is very simple to make one. Below are images of one I knocked up from odd bits of metal. Very crude but works perfectly. A couple of bits of plastic to protect the clock face, slip the clip under the needle boss and tighten the nut on the rear. It doesn't take a lot of force and it ensures that the pull is perpendicular so that the spindle isn't bent.