1971 Cooper S

While the simple questions of how a 1971 Cooper S differs from its earlier counterparts are quite easy to answer, the big question is just why BMC Australia even built them.

Australian Design Rules (ADRs) were introduced in January 1969 to ensure all vehicles sold in Australia met minimum safety, noise and other standards.

The most obvious change in the Cooper S, and all Minis for that matter, to meet 1971 ADRs was with the doors.

Under ADR 2, which came into effect from 1 January 1971, all cars were required to have burst-proof or anti-burst door locks that would prevent the doors from bursting open in the event of a crash.

Also, in the interest of pedestrian safety, door handles could not protrude from the profile of the door. The result was the troublesome lift-up, or letter-box, design door handle.

Another requirement was that door hinges had to meet certain minimum strength standards. Interestingly, while the door locks previously on Minis did not meet the standards, the existing external door hinges did.

According to former Product Engineering Manager Peter Davis, the tooling to replace the external hinges with the UK’s ADO20 concealed design was costed at around $250,000. As the original hinges met the ADRs this cost was considered unnecessary.

The doors with these changes are usually, though erroneously, referred to as Clubman doors. However, they are more correctly called ADR-compliant, or burst-proof doors.

It wasn’t a simple matter to change the door though, as the whole profile of the B-pillar had to be changed, requiring new side body panels. The trailing edge of the door was also modified, as were the locks and mechanisms on the door and the B-pillar.

Another significant change for 1971 was in relation to windscreen demisting. Rules that made some form of windscreen demisting mandatory had existed since about 1968.

However, ADR 15, which also came into effect from 1 January 1971, provided standards for the volume of air and speed of demisting. This meant an entirely new heater design was required for the Mini.

The resulting plastic-bodied heater became a standard fitting in all Australian Minis, and is again incorrectly, if universally, referred to as a Clubman heater. These heaters had a tremendously strong fan and could just about clear a fogged-up windscreen quicker than you could wipe it clear with a cloth.

Until the production of the Clubman model Minis began in May 1971, the controls for the new heater were mounted on a unique bracket, located under the parcel shelf, between the steering column and the door. There were two push-pull knobs operating cables – one of which activated the water tap mounted on the side of the heater to control temperature, the other to control the direction of the air to the cabin floor or the windscreen. A central on-off switch was for the fan.

Ducting directed fresh air from just behind the grille to the heater, through a hole in the firewall above the brake booster. However, the single large-diameter hose from the Mini K could not be used on the Cooper S because of the obstruction caused by the brake booster. The Cooper S therefore had a unique adapter plate that fitted the single large pipe inside the car, to two smaller pipes under the bonnet.

If you would like to read the rest of this story, order your copy of Issue 23 of The Mini Experience. <plumshop>39</plumshop> <plumshop>40</plumshop>

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