Postbag

THE LATE GREAT MURRAY WALKER THE FORD GT-40 CONNECTION

The 1983 F1 Spirit Racing car In the 1980s one of the companies in my group was involved with motor racing. It was the least profitable of the eight companies by quite a margin and was my most favoured by a country mile. The interests of this company within the racing field were varied, but we were involved with the Spirit Formula 1 racing car’s development.

It would have been July 1983 and I was up at Silverstone. It was probably on the Friday night and we were working late and my chief mechanic was working in the Spirit pit on some problem or other. The weather was cold and it was raining hard. Silverstone, to me at least, always managed to be umpteen degrees colder than the rest of the world and it was so late that it was already getting quite dark. It could not have been more appalling and I could not wait to get in the car with Vince to come home. He was still working so I wandered around in a very miserable state. A chap came into the pits. He was of a cheery disposition and he raised my mood by his bright and interesting questions. He wanted to know why we were still there so late and what we were doing. He made careful notes of all the answers and inspected the work with great interest. He was like a light in the dark and improved my mood no end. Who was this man? It was the late, great, Murray Walker preparing for his commentary on Sunday. I later learned that he had probably been working all day at his marketing job and then driven up to Silverstone to effect this meticulous note taking work.

There have been many obituaries to this remarkable man, who passed away in March 2021, but his dedication to getting the facts and his irrepressible enthusiasm certainly brightened me up that night. In issue 96 of Classic MG (an American magazine) there is a mention of the steering gear on the AC Cobra. I started my apprenticeship with Cam Gears in 1963, and by about 1967 I was working in the Prototype Shop. To the best of my memory, Ford ordered the steering gears in three batches. I was detailed to assemble the middle batch of about 30 GT-40 Rack and Pinions. The unit was, or is, quite specialised. It’s based on a short MGB rack and a short pinion, in a magnesium housing. Magnesium is a tricky material – it’s very light, but it tends to burst into flames if it gets too hot. So as a lubricant/cutting fluid/coolant one used kerosene (I know it sounds counter-intuitive) but it has proved to be the best fluid to fulfil all those functions. We didn’t do the machining ourselves, we contracted it out to a specialist aircraft machine shop in Dunstable. Incidentally, the big Mercedes Benz crash at Le Mans in 1955, that was so horrific, was because large parts of the car were magnesium, and burnt very hot. My father was in the MGA pit just the other side of the road.

To the best of my memory, the GT-40 rack is about 10 inches long, which is about half the length of the B rack. To compensate for the short rack the tie rods, at each end, were very long. The rack machining was done in our Resolven South Wales factory. It’s a fascinating operation. The teeth are broached on what I can best describe as a vertical hydraulic press. The revers of the teeth form is ground into a big tool steel plate in progressively increasing size, the rack blank is solidly mounted and the broach is pushed down, amidst floods of cutting fluid, to form the teeth in the rack. It’s particularly noisy operation.

The other fun part of this production process is the heat treatment or hardening operation. This is done by induction hardening, and is quite alarming to watch. The teeth are gathered at one end of the rack and are clamped onto two electrodes, one at each end of the tooth form, by a nylon pad in the centre underneath; the free end of the rack sticks out unsupported.

When the Radio Frequency power is turned on, the rack teeth start to glow red, then orange, then yellow. As the teeth on the top get progressively hotter they expand. In doing so the rack bends, the free end moves down 3 or 3 1/2 inches. Then the quench comes on, amidst clouds of steam and the rack returns to its former shape, and all is right with the world!

I believe the reason for the short rack and long tie rods was to get around the large offset of the wide front tyres.

Peter J.H. Thornley

MIS-FUELLING

It was interesting to read Neil Cairns’ article about the expensive cost of mis-fuelling his YB saloon MG in the May issue of Safety Fast!

It reminded me of a similar mistake I made when distracted at the pump and putting diesel in the half fuel petrol tank of my MGC, ready for a Club run the next day.

Having realised my mistake I was fortunate in being able to drive the short distance home with the small amount of petrol still in the system. I then remembered that when restoring the C I’d been persuaded to buy a new fuel tank without a drain plug, thus preventing the easy theft of my petrol!

I soon found you can’t easily syphon fuel out of the tank. After some head-scratching I realised that the electric fuel pump works without the engine running, so by diverting the fuel feed under the bonnet I was able to pump out the contaminated fuel. I now had 54 litres of mixed petrol and diesel fuel – but what to do with it? I remembered an ex-lorry driver friend telling me of on old ‘trick’ to put a bit of petrol in the tank of a diesel lorry when there was a danger of it freezing overnight (diesel can start to freeze at 0°C). The same friend now ran a 1959 Burlingham “Seagull” coach with a diesel engine, and was happy to take my contaminated fuel. Win - win!

I haven’t told many people about my mistake – until now!