Velocette Fork Slider Soldering

November 14, 2018

Velocette Fork Slider Soldering

Velocette has likely never been accused of copying engineering solutions from others. In fact, they seem to have come up with their own clever approach to designing these coveted motorcycles. The telescoping front fork of the later models is a good example of this.

Each of the lower sliders is made up of two castings soldered onto each end of a tube. It is the chromed part seen in the photo below.

Unfortunately, it seems that the solder joint done at the factory was enough to hold the parts together, but not always enough to keep the damper oil in. In turn, many have been known to leak at the lower solder joint. Leak at exposed solder joint seen below:

When faced with this on my own Velocette, I reached out to the experts around me to find out what they used for this repair. Most of the responses that I got lacked specifics and in turn I was not sure what procedure to use.

I reached out to a friend, Velocette owner and plumber. He offered to help me solder these up and pointed me to a flux and solder used for copper plumbing work. When the time came, he generously came to my shop to demonstrate the proper pipe soldering technique. It was a mess and did not work. The short story is that the solder was not adhering to the steel tube or casting.

So, I did some more homework and found a solution that I want to share in this article. I used Harris Stay Brite 8 solder with a Stay-Clean liquid flux.

https://www.harrisproductsgroup.com/en/Products/Alloys/Soldering/Lead-Free-Solders/stay-brite-8.aspx

https://www.harrisproductsgroup.com/en/Products/Alloys/Soldering/Fluxes/Stay-Clean-Liquid-Flux.aspx

1. The first step is to remove the paint from the slider assembly.

2. Once that has been done, it is time to separate the tube from the casting. The factory used a low temperature solder. In turn, it will not take a lot of heat to separate the two parts. I put the casting in the soft jaws of my vice and used a MAP torch to gently heat just the casting. With a welding gloved hand, I simply pulled the tube up when the solder has molten. Once you have the tube out, you will see the lack of solder and the reason that it was leaking. Here are a few examples:

3. Properly clean both parts to be soldered. I have a glass bead blasting cabinet, so this makes for a quick clean up.

4. Before an attempt should be made to assemble the parts, they should both be "tined". In other words, the solder should be applied to both parts and fully adhered. I use an acid brush to coat the part with flux and then I gently heat the part using my MAP torch. While heating, I apply the solder and spread it evenly using a small stainless steel wire brush. One does not need to apply a lot of solder at this point, just enough to cover the part. Once tined, it should look like this:

5. Once both parts are tined, it is time to assemble them. I return the casting to the vise and partially install the tube. It likely will not slide down all of the way because the hardened tining solder will not allow it. I gently heat the casting until the tube drops down into place. Make sure that it does go all of the way down. Now I keep the heat on just enough to keep the solder molten and feed in more solder. It will take quite a bit and will form a nice continuous chamfer at the joint. If you feed too much it will likely come out on the inside, so be careful to avoid this. Should this happen, take it apart and clean up the solder on the inside. The flux should be removed with a gentle wire brush, soap and warm water. Here is the finished solder joint.