Tools again - New washer for the FH tyre inflator

Some of you might have seen my post on Thapex tyre pumps - click here. As you might expect, pumps bought from eBay, autojumbles and car boot sales arrive in unpredictable condition, cracked, missing or tired washers and almost invariably without their connectors.

Some while back, I bought a nice new washer purporting to fit one of my pumps and it sat on my desk for a number of years until I came to fit it - which of course it didn't. It's about 1 mm too small.

So, time to roll out a lost art shown to me by my grandfather Leslie, who was a serious cyclist - he worked at the docks during the war, and having relocated from West Ham to Ewell had a 18 mile commute to work, which he did twice each day on his bicycle. What you do is this:

Start with a piece of leather, in my case the cuff from an old Jalatte safety boot. For a 7/8" pump, you will want a disc of about 30 mm diameter which you can cut with scissors, or however you want.

Next, punch a hole in the middle. The washer screw in a Thapex pump is 2BA, so a 5 mm punch will do. Next, we are going to form the leather into a cup; before we do that we are going to reduce the thickness of the leather around the edge, a process called 'skiving'. You use a very sharp - no, very, very sharp knife to slice a layer off the surface, reducing the thickness at the edge to perhaps half what it was (the boot was about 2.4 mm thick).

Fix the retaining washer in place with the screw and add a second washer on the back - I used an M5 repair washer on the back and an M8 washer under the screw head, to support the flat part of the washer at the right diameter - all clamped tight with a 2BA nut. Drop the whole lot in a cup of water for a few hours until it is soaked through.

This is a 22mm Jubilee clip - the inside diameter it set to match the inside diameter of the pump. I have pushed the wet washer into the clip to form the cupped shape. Make sure it is square and leave it to dry out.

And that's it - next day, we have one perfect cup washer. I smear the washers in neat's foot oil and assemble it straight away, before it has a chance to return to it's original shape.

Here it is installed: