Spring PullerBy Hans Muller
Ever tried to install the original rear stand spring of a WDM20? Not an easy job, to say the least. To apply brute force to stretch the spring is impossible, there is simply no way to grab the spring and pull it.
Commonly Offered Solutions
Some use a longer or weaker spring, but the problem with that is a more or less freely up-and-down bouncing rear stand while riding.
Then the 50 penny method: find a stack of pennies (or suitable washers), bend the spring and insert a penny on one side. Bend in the opposite direction, and insert another penny, and so on. In theory this will stretch the spring enough to hook it over the mushroom. But no luck, I could not even insert 10 pennies (in my case: Euro 2 cent pieces).
Some say they first hook on the spring and then bolt the stand on. But they failed to repeat the act when I asked them to show.
My Solution - a Spring Puller Tool
At first I made a simple tool, consisting of a 10 mm steel bar, with a slightly off centre hole, leaving only a half-moon of steel. That did not work for the BSA spring, it was too strong, slid off the mushroom shaped pins and went into orbit in my garage. It works however on one-piece springs, like those used on Triumphs (for the non-initiated: the spring on the BSA is a three-piece spring; at both ends there is a separate eyelet, secured to the spring proper by tapering ends).
So I went through my odds-and-ends box, and there was a bicycle rear fork expander, a rather common item used to remove the rear wheel on older bikes (the modern ones are so floppy you don't need the thing anymore).
For the rest, look at the pictures; never mind the workmanship, I was in a hurry and it works which is the most important thing. The two small forks grip the spring ends, then you turn the screw and the spring is stretched and stretched safely until it slips over the mushrooms, and Bob's your uncle as the `murricans say. And of course removing the spring also becomes easy.
A Somewhat Simpler Tool
Henk Joore (of WDM20 fame) made a much simpler but equally effective tool based on the same principle. And that's of course the way to follow when you don't have that fork expander available!