Grey Flash 2751

The history and restoration of a Vincent HRD Grey Flash

All Vincent racers were supplied with Axle bolts rather than the T-bar arrangement seen on the roadgoing models. This is quite an obscure component and falls into the “not a lot of people know that” category… This rare racing part is depicted in the Spare Parts List.

We can see that these are waisted for lightness.
And not “wasted” as some are wont to write! 🤤

2751 was missing these important parts and they needed to be made for the project. Where to start… No drawings or dimensions exist and few original items survive. Many years ago Vincent legend Big Sid sent me some pics of some NOS racings parts that he held and was looking to sell – these, I believe, ended up being used in the Gunga Din rebuild.

These three images appear to depict the just the one axle – an H25/3AS front item. In addition, I had a few pics of this component in situ on various bikes.

The above two images show the bolt/nut clearly – this is the Ehret Black Lightning. Note the protruding tapered “lead”.
The rear of the same bike.
Here seen on another Grey Flash.

Working in conjunction with David Dunfey, and cross-referencing our available info, a drawing was made and tweaked until we were as satisfied as could be. Down in Australia, Stuart Penn kindly pulled one of the axles on his uncle’s BL and sent me the dimensions.

This is also a front bolt. Above it are two Series D axle bolts and a hollow axle, for purposes of comparison.

Yes, the Series D also utilises bolts rather than the T-bar configuration – these are available new from the VOCS and could be adapted? Well, no… In addition to the waisted centre portion, the threaded portion features a tapered end or “lead” to enable the axle to be pushed home and locate quickly under racing conditions. This taper means that the racing items are a little bit longer than they would need to be on a roadgoing bike. In addition, the bolt head is actually a nut brazed into place…

First the waisted axle shafts were machined up.
Nuts brazed on and dressed.
In situ. Note repair to rear fork.

A lot of research was required to enable these axle bolts to be manufactured – the waisted portion had to be right to prevent catastrophic failure. Machined from high tensile steel, they will now need to be finished and would originally have been cadmium plated. I would like to thank David Dunfey, Stuart Penn and Franco for their assistance. 🙏🏻

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