Ep 3: Sand, heat and nipples

In this episode, we dismantle a front wheel, removing the brake discs, spokes and nipples – and Trent brings out the blowtorch to free up some sticky bolts. Pete builds a sandblasting cabinet, mostly out of junk, and continues work on his KTM 950, while Rich is getting close to his BMW being back on the road.

There was no way Pete was letting me put the new twin-disc front wheel on my bike without at least giving the shabby hub a paint job. That means stripping the hub, which means breaking down the wheel, which means removing the spokes and nipples, which means replacing any that are in poor shape or simply don’t survive disassembly … you can see how this job snowballed.

The first stage is to remove the brake discs. You do this with the wheel still fully assembled – because you probably couldn’t get the spokes out with the discs still on, and even if you could, it’s easier to remove the discs while you’ve still got the rim to hang on to.

Trent advised that the bolts would probably be locked into the hub from corrosion. A big problem on bikes is that you often have different metals coming together – in this case, steel bolts screwed into an aluminium hub. Due to the different properties of unlike metals, it is a recipe for an electro-chemical reaction, which means corrosion. Trent explains in the episode how this causes bolts to seize.

His solution is to heat the hub. You could use a blowtorch, or an electric heat gun of the kind used to strip paint. Or at the side of the road, a cigarette lighter that can throw a decent flame might just get you out of trouble – don’t apply it near anything flammable, of course, such as your petrol tank and its contents. And heed Trent’s warnings about how aluminium behaves when it approaches melting point!

In my case the disc bolts are not generic, they are specially machined. In other words I can’t just go to any nut and bolt shop to buy replacements. I’ll be reusing them, so it was important not to destroy the heads in the process of undoing them.

Once the discs are off it’s time to address the spokes, which radiate out from the hub, and the nipples, which attach the spokes to the rim. A good start is to spray the nipples with a seize-busting solution such as WD-40. Leave them for a while, then attack with appropriate spoke spanners and large flat-blade screwdrivers. For the inevitable stubborn spoke here and there, you might need a set of vice grips to stop it turning while you rotate the nipple.

Even if you never rebuild one, it’s useful to know the anatomy of a wheel. On any big trip where rough roads are involved you should carry spare spokes and nipples in case of breakages, so you’ll need to know how to install them (after removing the tyre and tube, of course). Trent gives lots of know-how in this episode about the different kind of spoke/nipple/hub arrangements you might encounter.

Pete is saving us all a lot of grief by building a sandblasting cabinet. It’s hooked up to Trent’s air compressor and we’ll use it to strip paint, rust etc from parts that we’re going to repaint. There have been a few teething problems, but Pete’s getting close to turning this into a workable and very handy addition to our workshop.

Richard isn’t far off getting the BMW back on the road, and begins making some final pre-flight checks. Once this bike is mobile, we’ll start attacking his other project – an F650 fitted with long-range tanks and a set of KTM inverted forks. Sweet.

– Waz

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4 thoughts on “Ep 3: Sand, heat and nipples

  1. Best episode yet. Very informative.

    One question – In which episode will the Iowa Cat Climber be fitted to the KTM?

  2. Well spotted, Big Al.

    The Iowa Cat Climber will form part of the trials bike course that we are building in the living room …

    This being a living, breathing garage it is a ‘shared-use’ facility and we do have to clamber over a certain amount of domestic bric-a-brac to get to our bikes. But there are benefits: keep an eye out for the top half of a pet transport cage that is being used as an oil tray!

  3. Love the podcast. Sure hope to see more of them in the future. Love the idea of the sand blaster did you ever get it to work faster?

  4. Hey Greg. Our fourth episode is edited and just going through finishing touches.

    We dismantled the sandblasting gun and found it had sucked in a bit of plastic debris from when Pete was cutting up the box. We removed the blockage, reassembled the gun with thread tape on every join, and jacked up the pressure on the air compressor. I used it to strip the paint from my hub and it was fine, if a bit slow.

    Seeing through the lid is a bit of a problem. Overall the thing is a success but needs refinement.

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