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REVIEW OF TRACK TEST OF COSTIN-NATHAN GT AT BRANDS HATCH JULY 2023

Updated: Jan 30





This is the first time after an epic 3-year restoration that the Costin-Nathan GT has been driven. Originally, this was the Roger Nathan Racing Ltd. Show car at the International Racing Car Show at Olympia in January 1967. A similar model competed at the International Le-Mans 24 hour race that year.


This car and the open sports racing prototype that preceded it was designed by Frank Costin and built in collaboration with Roger Nathan at the works near Muswell Hill, in North London. Both cars are unique in having an all wooden monocoque that in itself is a work of wooden art.


Both models were immediately successful and won most races in which they were entered and gaining class lap records. In 1968 the GT model won both the National Motoring News and Tootal GT Championships. The open car only weighed 772lb (350kg) the GT 830lb. (386kg) with a monocoque torsional rigidity of 3,200 lb ft. per degree, this gave excellent handling and braking characteristics.


At was thrilling to once again Rev, the highly tuned Hillman Imp 998cc engine in the pit lane at Brands Hatch. I could feel the engine power transmitted through the rigid monocoque with it’s crip exhaust note echoing in my ears. Engage first gear of the 5-speed transaxle and then rapidly accelerate along the pit lane to the circuit. The acceleration of this light machine in particularly in the lower gears was breathtaking, Passed the green light at the end of the pit lane and out onto the circuit that I first competed in 1961 in a standard Austin Healey 3000, what a difference.


My programme for this shake-down test was to ensure that all systems worked correctly,

namely oil pressure was consistent as with a wet sump the oil can surge causing dropping

pressure resulting in a catastrophic engine failure. Secondly, to ensure the water temperature remained in limits around 80/85c and also checking the oil temperature.


Once I had satisfied myself that these items were satisfactory and no wheels had fallen off! I began to increase the speeds and immediately noticed that it was difficult to select gears when changing up and particularly down. There was no ‘feel’ of the neutral position when changing gear and it was uncertain if the selected gear was indeed engaged. I had to be careful, in racing you put you foot hard down on the accelerator after changing and if the gear is not properly engaged will over Rev and possibly wreck the engine. This problem is audibly noticeable in the video when I am trying unsuccessfully, to change down the gears approaching a corner, it was slightly easier changing upwards but not satisfactory.


It was not possible to rectify this problem on the day. I continued driving at reduced speed to consider the handling characteristics, these cars had a built-in tendency for slight understeer, that I preferred to oversteer. (In American parlance, Push and Loose). I was not altogether happy with the rear suspension and called into the pits to have the rear shock absorbers made stiffer and increased the tyre pressure all round aby 3 PSI.


Onto the circuit again and I felt these small changes had made a modest improvement. Not wishing to unnecessarily use the car as it was not possible with the gear selection problem to drive at race speed and that apart from this, the car overall was fine, I ended the test session and have planned another test day when the gear selection has been resolved. The car will then be displayed in the Silverstone Museum.

With thanks to my eldest son Paul who took the video.


End.

31-7-23


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