Mods and Consequences
Launched in 1956, the Rootes Audax range comprised the Hillman Minx, Singer Gazelle and Sunbeam Rapier. The range may seem complex – nine series of Minx and Gazelle, five of Rapier – but changes between one series and the next were generally minor. There were just two engine families: an overhead-valve unit (1390cc, 1494cc, 1592cc, 1725cc) and a 1497cc overhead-cam lump, the latter fitted only to the Series 1 and 2 Gazelle.
In period, Brabham, Alexander, Hartwell, Castles of Leicester and Nerus offered tuning kits and Rootes marketed performance parts and accessories. In most cases, earlier cars can be fitted with the running gear of later models. So a Series I Minx can be given a 1725cc Holbay race-spec engine from a Hillman Hunter, doubling the power, despite being basically the same engine.
Rootes parts specialist Mike Langley comments: ‘ You’ll need to do your homework when it comes to the detail. For example, early cars had drum brakes while later models were fitted with discs, but there are two iterations of disc brake and individual parts are not generally interchangeable.
‘Conventional tuning options (electronic distributor, gas- flowed head and exhaust) improve efficiency and power and these days it’s possible to turbocharge, supercharge and add fuel injection. Rootes cars have been fitted with Mazda engines, Rover V8s and there’s an electric Singer Vogue in Australia (electricvogue. blogspot. co.uk). You could even fit the running gear from a Sunbeam Tiger, but I’ve come across that only once.’
In 1964 Rootes introduced a fourspeed synchromesh gearbox that’s slick, strong and often has overdrive. It was used in the Hunter and is a great conversion for any earlier car; you need to fit a Hunter clutch on a suitable flywheel. These overdrive 1964-66 gearboxes sell for £450.
Mike adds: ‘These cars can be upgraded to keep up very happily with modern traffic, although I have yet to build one that feels as comfortable as a modern car on a
GO HOLBAY For the ultimate engine, fit a Holbay H120. Balanced and fitted with an alloy cylinder head, twin DCOE Webers, four-branch manifold and hot cam, it’s quite a complex conversion, but the parts are out there if you search. BRAKE UP If you’ve got an early Audax with drum brakes, it’s simplicity itself to fit the front suspension – complete with disc brakes – from a 1964-67 model. The parts are readily available and needn’t cost more than £100. UPRATE THE CARBS The original single-Zenith carburettor is unreliable and inefficient, which is why fitting a Weber 34 ICH is popular. It’s easy to source and will fit a Minx or Gazelle, but for a Rapier fit a downdraught twinchoke Weber. CLUTCH BAG The 7½in diaphragm clutch used from 1966 tends to be weak – earlier spring clutches are more reliable. You can switch between the two but you’ll need to source a suitable flywheel with the dowels and bolts in the right places. TIME TO IGNITE A lot of these cars are fitted with a Lucas distributor that’s seen better days, while the points go out of adjustment. Many owners fit electronic ignition for easier starting and smoother running. SEAT STUFF Like many 1950s cars, Audax seats are not very supportive, which can lead to back pain. Thanks to the floor being flat, all sorts of replacements can be fitted. Expert Mike Langley favours Alfa Romeo seats as they’re readily available. FEELING EXHAUSTED £2000 £100 £150 £150 £100+ £50 £200+ Lots of exhaust systems are available. Some owners fit a standard pattern in stainless for reliability, others get gas-flowed pipes made for extra power and a throatier sound – though a good set can cost £600.