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Are they wheely from an Austin?

by

Niall McLoughlin


wheel options

For our wonderful machines, there are a number of options when it comes to wheels:

I was looking over wheel options for the Pembleton – I do love the look of wire wheels, I think they look more authentic. I did think about Phils lightweight wire wheels, but they come at a serious premium. I wanted bolt-ons, as it helps to do a quick swap or removal for any further works down the line.

Another popular option is the 48 spoke 15" wheels from an MGA or Triumph, fitted with the MWS adaptors. I did actually buy a pair of 16" 48 spoke wheels and sanded them back and painted them. They're very very heavy, and the wheels I had were centre laced, meaning with the adaptor too, the track was increased a lot. Add into this the tyres, which were only available at 185+ wide and expensive, I decided to bail out of this idea.

So the hunt was on for an alternative solution. As I scoured Ebay and other selling sites, I noticed that Austin 7 wheels were 3 stud bolt-ons, reasonably inexpensive, and readily available. I expected the PCD would be different, but how hard would it be to make an adaptor?! (As it happens the PCD difference between the two was actually the smallest issue)

Duncan kindly measured an Austin wheel he had, and I measured a 2cv stub axle.

Hmmm... this is where I realised that it wasn't quite as simple as I'd hoped! The difficulty is that the 2CV stub axle has a raised dome in the centre and then topped off with the castellated hub nut, and the OD of the stub axle is slightly larger than the ID of the pressed wheel hub centre.

2cv stub axle

There was a chap on EBay selling utterly shot Austin wheels, so he cut the centre out of the worst one and posted it to me for not much more than the price of P&P. After a tickle with a wire wheel and a lick of etch primer it gave me a good frame of reference. There's nothing like trying to fit 2 bits together when they're in front of you!

austin wheel hub
both together

I'm a CAD design engineer by trade, working almost entirely in the virtual world in design software called NX. I measured the 2 components to be mated together carefully and re-created them in CAD.

Where I work is fairly flexible, and they don't mind you doing "home work" so long as it's off the clock and you're not doing it for commercial gains etc. NX as a computer package is £10k per annum for a single licence, so the likelihood of someone having an honest copy at home is slim.

I created the adaptor with drawings and made a number of tweaks to reduce the number of overall operations, as well as doing a few 1:1 print-outs to make sure I wasn't barking up the wrong tree. After looking at how the wheel fitted on an Austin (Duncans Suggestion), I realised that the locating bosses on the drum were pretty fundamental to the design and should be included. I could have made the adaptor much lighter, but the number of processes and machine time would have increased a lot, along with the price. To make a feasible solution, each adaptor had to be as cheap as possible. I got it down to one turn and one mill operation, with the bosses machined separately and pressed in.

image 5 – adaptor
image 5 – adaptor

I sent the drawing off to a few machine shops and the best returned with a price of about £75 +VAT each for a batch of ten, machined from 42CrMo Steel from a company in Lithuania. Vince had already enquired about a set of four adaptors for a project he was working on, I needed four too (2x three wheelers) and it made sense to get another pair made up for spares or to sell to anyone else who wanted to do the same (since been snapped up by Duncan)– I discussed with Vince and after a bit more research we decided it was worth the risk to get them made in Eastern Europe.

wheel adaptors

4 weeks later the parts were delivered – here they are!

I'll make no bones about it, this wheel/adaptor combo probably aren't as light as Phils wheels, but neither are they as hefty as extremely heavy MGA 15" wires, tyres, adaptors and spinners. For reference I measured the weight of an MWS adaptor and spinner and it came in at 3.4kgs. I'm unsure of the weight of an MGA wheel and tyre. The 2CV wheel/tyre measured on my bathroom scales is a shade over 9kgs. My A7 adaptors are 2.3kgs each, and the 17" A7 wheels/tyres I source off ebay are around 10kgs each – I plan on fitting 19s to the next one. It would be good to get a reference weight for one of Phils lightweight wheel/tyre combo... anyone?

I need to sort out some mudguards and brackets as they obviously now don't fit!

wheel adaptors
wheel adaptors

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