Southern Tablelands Heritage Automotive Restorers Club Inc.

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10^th Anniversary Dinner July 2011	Car of the Month

Lawrie and Jane Nock’s 1973 Rolls Royce Corniche Drophead Convertible

Article and photos by Lawrie and Jane Nock. Additional photos by Steve Cole.

Because I have been a very good lad and been doing as I have been told I have earned enough brownie points to get another toy. An unfortunate aspect of this toy is that I am going to have to share it because Jane also likes it.

I really wanted a Corniche convertible when we started our adventure with old cars and there was one available at the time but the starting price was a bit too difficult for our circumstances and even if I could have found the funds I would have lacked the knowledge to confidently embark on such a process. I nearly got there with the Bentley coupe which I still like very much and it passes my test as a sports car in all respects except for the roof.

If I could have my choice I would like a pre-1977 (chrome bumper overriders) Rolls Royce Corniche in a drop head configuration but with a steel top like the new Mercedes or VWs. Unfortunately they didn’t make such a machine. Ian’s 450SL Mercedes has a detachable steel top and this is such a great idea I don’t know why others such as Crewe didn’t take it up. Anyway, they didn’t and our friend in Sydney found something which is almost as good as I would specify and is certainly as good as it is going to get for us. The car was sold new in the UK and lived in that region until about 1983 when it arrived in Australia and was treated to its first service at York Motors in Sydney. Its history after that is a bit obscure until it emerged from a collection in a Brisbane warehouse in 2008. I haven’t managed to get any better at judgement of motor vehicles but I have a little list of the names of a few people who are good at it and I am prepared to trust the call to them.

Having bought the car, we had hoped to be able to roll back home after our trip to visit Jane’s parents driving our new old wheels and turn up in it for the high country run or at least the next meeting. Our registrar had been briefed so that the necessary documentation could be completed in our absence but patience had to be put to the test. We had to come home in a borrowed car and given the weather over that weekend and subsequent events, probably just as well. We then looked forward to being able to use the new acquisition for its first official engagement to attend the next club meeting but were denied that one too.

Eventually, what is probably our last serious acquisition was here and just in time for winter. For the majority of the population it is a metallic burgundy car with sheepskin seat covers. For the rest of us it is a regal red 1973 Rolls-Royce Corniche drop head coupe (2 door convertible) with magnolia interior (they did produce the Corniche as Bentleys also, but not often). It is a topless one but it does have a recently refurbished soft top that comes with it as standard equipment.

When the Corniche was unveiled in 1971 it was met with more than a little acclaim. The home delivery and European cars were fitted with what was referred to as the “Gamma” motor. Cars destined for the USA were fitted with the normal 6.75 litre Shadow motor because the Gamma did not comply with USA emission control regulations. My understanding is that the Gamma motor is basically the 6.75 litre Shadow series motor but it has some camshaft and exhaust modifications which result in about 10% more power output than the normal Shadow series motors. This means that effectively the car has about 300 brake horsepower. It had no output in KW because the British didn’t use that system at the time. At about 2300 kg kerb weight it needs the extra power just to offset the massive stiffening required to compensate for the absence of the solid metal roof.

This extra power gave the car a maximum top speed of about 120 miles per hour. Motoring write ups of the period regularly gave the top speed as 125 miles per hour (200 KPH) which was fairly quick at that time. I shudder to think what the fuel consumption would be under full power. With careful driving fuel consumption is much the same as normal Shadows at about 16 litres per 100 km. The transmission is the standard 3 speed General Motors 400 automatic used throughout the model range.

The bodies for the Corniche were hand finished at the Rolls-Royce owned Mulliner Park Ward body factory. Fitting of the retractable roof was a complicated business which basically doubled the build time to almost 6 months per car. The retractable roof required that the rear seat be moved forward which reduced the rear seating leg room considerably. The rear seat is a snug fit for adults and a not very comfortable one for large adults. The car was fitted with all of the normal Shadow features such as electric windows, electric seats, central locking, air conditioning and independent suspension all round with self levelling hydraulic suspension at the rear. This was the most luxurious and expensive production version of the series. Given that it is basically a two seater cruiser it was right up there with the most expensive cars available on a cost per seat basis.

When we collected it we discovered that it does go extremely well, with the emphasis on go. As we wheeled off into the Sydney traffic on our way home we felt very grand. Not far down the road we encountered our first problem. Both brake warning lights lit up. As we approached an intersection we became very aware that going well isn’t everything. It didn’t want to stop. Fortunately we had plenty of separation and were able to pull up on the remaining circuit. After a little down time we decided that leaving the car in Sydney wasn’t a great idea. The morning traffic was very light and we decided that we could safely attempt the drive home and have the problem dealt with on our turf.

We enjoyed a lovely drive top down to Marulan. The ability to carry on a conversation in an open top car at 110 kph was impressive, even more so when we could actually hear one another. It was only early afternoon but with increasing cloud cover and decreasing temperatures it started to feel a bit cold on the highlands so we tried out the roof. It went up beautifully and provided a very comfortable cruising capsule when in place.

I now know why open top touring has an obligatory cap for the driver. I had not previously understood what the absence of a roof did for driving into the sun. The sun blasts in through the windscreen which is fairly normal and sun visors can be helpful for that, but it also attacks over the windscreen. The sun visors do not work on this second front. Other minor problems for those of us lacking a full head of hair can also be tackled by a hat. As pretentious or cowardly as it may seem I will continue to wear one.

Day two of ownership was spent draining brake lines and trying to find the cause of the problem. A new master cylinder didn’t work. Bill Coburn was kind enough to make a call. A neighbour spent Saturday morning trying to help me find bliss but it beat him too. We pumped brake fluid through all of the lines but still couldn’t get the second warning light to go off. Bill thought we had a problem with the front hydraulic pump and he said that wasn’t too much of a problem – I hoped he was correct. He was correct about the problem but not about the solution.

Rolls-Royce developed a very special braking system for the Shadow and T series cars. In 1965 when the cars hit the market, disc brakes were not commonly fitted to passenger motor vehicles. Cars weighing over two tonnes added to the worries of engineers contemplating fitting this relatively new technology so they compensated a bit. Two sets of callipers were fitted to each of the front wheels to ensure that the brakes had adequate stopping capacity. A dual braking system was also designed into the cars. The base hydraulic technology was licensed from Citroen.

After a little examination, Bill’s diagnosis was confirmed. The braking hydraulics in these cars are a bit unusual. Two pumps operating off the cam shafts, one off each side feed hydraulic fluid to two liquid nitrogen filled accumulators, one for each braking circuit. These accumulators then feed the pressure to the brake callipers via a complicated looking little unit under the floor which is commonly referred to as the rat or mouse trap. From that point onwards the system is fairly normal.

Unfortunately the pump didn’t come off easily. In fact it wouldn’t come off at all. The special tool for removing the pump was not as strong as the bond between the pump and the valley plate between the two banks of pistons. The end solution was to remove the valley plate which meant removing nearly everything off the top of the block. The plate removed it was eventually bolted to a steel post supporting a building and with about 2 metres of torsion pipe on the end of a wrench, it eventually let go. The second pump at the rear of the plate wasn’t any easier to remove. Both of the pumps were overhauled, the brake pressure accumulators were reconditioned and everything eventually went back together in the engine bay. The problem was attributed at least in part, to a prolonged rest in a warehouse without any regular running. Having repaired the pumps the next prudent step was to pursue the flow to the brake callipers at each corner. Eventually the job was completed and it now goes and stops very nicely thank you.

This car is a great cruiser and quite a novelty for most people who encounter it either as passengers or as spectators at static displays such as Summernats, Terribly British Day, Wheels or any number of the other events where our club participates with a display of members’ cars.

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