Wednesday 15 March 2023

W/NG - Field Stand Springs

 Whilst the field stand on the W/NG is a fine thing, I don't use it very much as it's a bit of a nuisance to get it down and back up again. The stand is not quite as shown in the factory parts books and is probably not original.

The same could be said of the spring clip, which looks a bit like the earlier type but is too short - it’s not only stiff but now that I have the panniers fitted, it allows the stand to foul the pannier frame bracket.

So, inspired by fellow W/NG owner and YouTuber Alan Moore, who compiled an excellent instructional video on this subject, I resolved to make a pair. You can buy these clips now from various sources (including the AOMCC Singles Spares) but I decided carry on with the plan to make my own to prove that I could.

I started with a simple bit of wire to develop the profile of the spring:


That gave me the length and the shape I would need and I used this to make a card template. Following Alan’s example, I bought a couple of lengths of CS95 spring steel from eBay, and used the Rothenburger MAPP torch to normalise them, by heating to cherry red and cooling in air.

This process left the hard spring steel soft enough to drill and to cut to shape with the snips.


With the blank cut and drilled I could bend them to shape. The first one took a bit of faffing around with bits of round bar in the vice, pliers and swearing; for the second one I welded up this little tool which made the bending much easier. I left the sharp bend near the mounting holes until last.


Using the tool, it was easy to make those reverse bends. It’s the fact that they are so close to each other that makes bending the spring difficult without a bars fixed close together.


Once I had both springs bent up, I could fit them to the bracket on the bike and ensure that:
  • The stand would be gripped adequately
  • The ends of the spring would be open enough to allow the stand to be pushed in
I messaged Alan through YouTube to ask if he had had any problems with the bends opening during heat treatment - he hadn’t (and nor did I).


I built a little barrel furnace out of a 5 litre beer keg, some ceramic insulation, a fire brick and some fire cement. The first step was to heat the springs cherry red; you can see the torch is low on gas in this picture as the shroud is glowing. I swapped gas cylinders after this and used the almost-empty cylinder for tempering.


Next, quench in oil:


After cleaning the oil off, you can test the hardness with a file. The file just skates off the hardened steel and will not mark it. Next, you clean the oxide off with Scotchbrite so that you can see the colours form during tempering:


Next job is to temper the whole spring to 350°C, which is the blue colour you see here and quench in water to stop the process. One of these springs is polished post heat treatment, the other is straight out of the water bath. They certainly sound springy after tempering!


Here's a rather hasty picture of it in place - in fact this is the first fit though it took a while to get it there. The old springs were fitted with some oddball screws and wing nuts, possibly 3/16" BSW - I think I must have done my previous, pre-heat treatment trial fit using these screws, because the springs don't fit with the 1/4" CEI bolts I have in there now as the holes are tight on the bolts and are not quite in the right place. Silly boy. 

So, having spent ten minutes with a grinding wheel in the Dremel moving those holes a little inboard and opening them to about 7 mm had the springs fitting easily - or more easily. If I have to make another pair of springs, I would allow a bit more space for the nuts & bolts - the one closest to the camera is a bit tricky to get to.


And it works! The spring is much, much easier to use than the old one which means the field stand will get used more often - currently you have to align the stand with the spring and kick it to get it in, which is tricky if you are on the bike. Right now, with only a couple of tests the spring temper looks to be acceptable - though I wonder if I have overheated it - it's springy but not overly strong. Lastly, you can see from the picture that the field stand is now clear of the pannier frame.

So that's it - all done for the moment. I will but a safety chain or perhaps a zip tie around the field stand and the pannier frame, to keep the frame clear of the road should the spring break or the stand bounce out of it. We'll see how it goes.

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