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Austin Seven and Morris Minor - Power to weight

When I began writing this page it was intended to just consider the power to weight of the Austin Seven. I introduced my Morris Minor as a comparison, but have ended up writing more about the Minor than the Austin. Anyway, I am equally proud of Katie, my 1933 Austin Seven and Morag, my 1959 Morris Minor. I hope you enjoy reading this page.

The pre-war Austin Seven was a cheap small car that saved the Austin car company from bankruptcy when it was launched in 1922. By the end of production in 1938 more than 290,000 cars, in a wide variety of body styles had been built. Amazingly, for a car which had not been made for more than eighty years, in late-2020, there were 12,310 on the world-wide register of surviving cars. DVLA in the UK alone, has 2,333 roadworthy cars registered and a further 467 on SORN. (Statutory off-road notification).

The Austin Seven, when introduced in 1922, was particularly noteworthy as the first mass-market car in the world to pioneer the arrangement of accelerator, brake and clutch which has subsequently been followed by all modern vehicles (non-automatics). With its centre mounted handbrake and gearstick this makes it particularly easy for a modern driver to adjust to driving an Austin seven.

The Seven was also noteworthy for the number of other vehicle marques which were derived from it. The Swallow variant became the first Jaguar car. When licensed as the Dixi in Germany, it became the first car to bear the BMW badge. Sevens were shipped to Australia in kit form to become the first Holden car. In America it was licensed as the Bantam and the design inspired the Willys Jeep of WW2. Nissan in Japan copied the Austin Seven to build its first Datsun but did not pay for a license. Sir Herbert is thought to have decided not to sue Nissan as Japanese car production was not expected to amount to much.

My own car is illustrated. VT9016 is an RP 4-seat "box" saloon first registered in March 1933. While the chassis number reflects that, the engine serial number suggests that it was originally fitted to a 1935 Ruby. As with most Austin sevens, it has probably been "reborn" a number of times during its existence.

  Austin Seven VT9016   Austin Sevens at Guildtown in 2019  
  1933 Austin Seven RP box saloon VT9016   A few of the 120+ Austin Sevens at Guildtown, near Perth, in 2019  

This table lists just a few of the more basic models. - Excluding the 750cc specials, such as the 100bhp, twin-carb, supercharged Ulsters which could exceed 100mph.

Austin Seven (1922-1938)
Year Model Body BHP Weight cwt Top speed mph Power / ton engine
1923 saloon 4-seat 10.5 8.5 50 24.71 747 cc
1931 saloon RL 4-seat 10.5 10.7 50 19.63 747 cc
1933 sports 65 2-seat 23 9.7 63 47.42 747 cc
1933 saloon RP 4-seat 12 11.3 51 21.24 747 cc
1934 saloon Ruby 4-seat 12 13 49 18.46 747 cc
1937 saloon "new" Ruby 4-seat 17 13 58 26.15 747 cc
1938 Big Seven 4-seat 25 14.5 56 34.48 900 cc

This table of post-war Morris Minors is shown for comparison.
The Morris Minor became the first British built car to sell a million and ultimately 1.6 million when production ended in 1971. The first version, the Minor MM, was launched by the Morris company in 1948. It used the pre-war 918cc engine of the Morris Eight. The Austin and Morris companies merged in 1952 to form the British Motor Corporation. The revised 1952 Minor Series II had the Austin A-series 803 cc side-valve engine. From 1956, the larger 948 cc OHV A-series engine was fitted to the Minor 1000 and the 1098cc OHV engine was used from 1963 until production ceased.

Morris Minor 1948-1971 (4-door saloon models only)
Year Model Body BHP Weight cwt Top speed mph Power / ton engine
1948 Minor MM 4-seat 27 14.5 64 37.24 918 cc
1952 Minor Series II 4-seat 30 15.5 62 38.71 803 cc
1956 Minor 1000 4-seat 37 15.9 72 46.54 948 cc
1963 Minor 1000 4-seat 48 15.25 73 62.95 1098 cc

It is a testament both to the Issigonis design of the Morris Minor and its loyal following that, fifty years after the last one left the production line in 1971, DVLA, the licensing authority, records in the UK alone 13,395 saloons and convertibles together with 788 Travellers (an ash-framed estate model) licensed to be on the road and a further 7973 on SORN, many of which may be in process of restoration and thus likely to come back on the road in due course. Many Minors were exported, but as far as I am aware there is no world-wide register, similar to the Austin Seven register, of surviving cars. I would not be surprised if there were as many as a hundred thousand survivors around the world.

Many restored cars have been fitted with the later BMC 1275cc engine which is an easy replacement. The Fiat twin-cam 2 litre engine was once a popular choice with little modification required, apart from upgrading the brakes. DVLA also lists 14 cars in the UK with sub-2 litre diesel engines. Unsurprisingly, there is now, in 2021, a UK company offering an electric drive-train conversion using Nissan Leaf parts. I have taken the liberty of summarising at the bottom of this page what they did to produce their Minor EV conversion.

The Minor became popular with hot-rodders and raceway enthusiasts. DVLA lists 112 Morris Minors with petrol engines larger than 2 litres. Larger engines, such as the aluminium Rover 3.5 litre and 4.2 litre V8s are not uncommon and in some cases even bigger engines have been fitted with seven cars listed with engines above 10 litres!. Clearly fitting such powerful engines, necessitates extensive changes to the drive-train, brakes and suspension, leaving merely the upper part of the original monocoque body to give the appearance of a Minor.

I have to confess that I am not really a purist. Some owners insist that everything about their car has to be original. My own car, JTS754 illustrated below, has had a few modifications to make it more practical on modern roads. I have owned it for more than 35 years and for many of those years used it for year-round commuting to work. Instead of the original 948cc engine, it has the post-1963 1098cc engine and back axle, with a Ford Sierra 5-speed gearbox. It has the larger post-1963 brake drums and a brake servo from a Morris Marina. It has radial tyres instead of the original cross-plies and a front anti-roll bar for improved road-holding. Apart from a pair of leather seats from a Ford Ka (while I save up to have the original seats re-covered) the car has the appearance of being more or less standard.

Click on any of the images for a larger view.

  Morris club in Dundee 2014   JTS754 at Stirling show 2019  
  Scotland NE Morris Minors, Dundee 2014
(I am the guy in the tweed jacket on the right,
standing next to JTS754)
  Morris Minor JTS754 at Stirling Classic Show 2019  

How to convert a Morris Minor into an EV
Here is a method of converting a Morris Minor to electric by replacing the original A Series petrol engine and fuel system with a Nissan Leaf motor and batteries.

The company preserved the originality of the car by not cutting it in anyway so the electric conversion was purely a bolt on system. The new motor was connected to the original gearbox (less clutch) using a custom billet aluminium adapter and coupler.

The engine bay was fitted with a DC/DC converter to reduce the 300 volts of the High Voltage pack down to 14 to allow the Minor's 12v battery (now located in the boot) to be charged. It also accomodated the charger to charge the battery pack which was split in two, with 6 modules under the bonnet and 12 modules in the boot. The battery modules and other parts were taken from a 30kW Nissan Leaf.

Like the donor Leaf, the electric drivetrain in the Minor should be good for 80 to 100 miles per charge. Power has been increased from the Minor's 48bhp petrol engine to around 100bhp.

The original drum brakes were found to be adequate as the motor's regenerative braking (which puts power back into the batteries) does some of the braking. The drums were backed by a remote servo and an electric vacuum pump to power it.

The reused Nissan Leaf radiator kept the Leaf motor and inverter cool, with the coolant being circulated by a 12v electric water pump.

The car inside was left very much as it had been originally with the addition of a battery meter gauge and a toggle switch to select forward neutral and reverse.

The boot of the car had the spare wheel removed to make room for the rear High Voltage battery box and 12v auxiliary battery which necessitated the height of the boot floor being raised by two inches. A tyre repair and inflation kit was provided in case of emergency.

With the drive line from the gearbox to the rear being unchanged from the original standard the car kept the same driving characteristics and as the overall weight only increasing by 75kg it handled similarly to an unconverted car.

Unlike an unconverted vehicle the driving experience was silky smooth and quiet. So quiet indeed that the occasional creak and rattle from the old car could be heard.

With this conversion no other upgrades of the car were made other than the installation of the electric drivetrain. It turned out to be a fantastic enhancement to the car making it a truly reliable, smooth and quiet drive.

The company estimate the cost of a similar conversion would be around 25000 including all labour and parts.