Page 5 - The Origin of the Species

THE ORIGIN OF THE SPECIES 5
fitted with specially sourced electric overdrive units from Laycock
de Normanville, which operated on second, third and fourth gears,
providing seven forward speeds in total;
•
Larger hand-fabricated oversized petrol tank installed in the boot with
exposed fuel filler mounted on the rear scuttle;
•
Special clutch assemblies from the Lockheed Competition
Department were fitted;
•
Special-ordered Armstrong DAS10 dampers and stiffer
front damper valves were fitted;
•
Increased thickness anti-roll bars were fitted;
•
Girling 11 x 2¼-inch twin trailing-shoe front drum brakes
with Mintex M20 competition lining materials;
•
Lucas competition electrical equipment with wiring installed
under the supervision of the Lucas Competition Department,
including the installation of a racing generator and battery;
•
Although not installed at all times, when fitted, the vehicles
were provided with aluminum alloy bumpers from Wilmott
Breedon;
•
Dunlop 5½ x 15-inch racing tires were fitted.
The chassis frames, which had been fabricated at John Thompson
Motor Pressings in Wolverhampton, were then strengthened and modified
at Warwick with repositioned gearbox mountings and reinforced suspension
unions, with weight eliminated throughout with the use of numerous lightening
holes. Following these modifications, the completed chassis were delivered to
Jensen in West Bromwich, where the lightweight bodies were added and the
shells painted in a metallic light green finish that was chosen to avoid running
afoul of Donald Healey’s personal aversion to the traditional British Racing
Green that most British competition cars relied upon.
The powerplants installed in these four vehicles were more robust and
powerful than their production brethren. “The experimental department at
Austin built these engines with special care,” Geoffrey Healey wrote, “paying
particular attention to the clearance between the rear oil scroll of the crankshaft
and its housing. This type of oil sealing arrangement
was known to be suspect on the Austin engine and
liable to give trouble at high engine speeds. In this
form, the engines produced around 100 bhp at 4,500
rpm and were to prove very reliable.
“We were also aware that the gearbox would have
a very small margin of safety and could have been the
weak link in long-distance races. At this time, Austin
were making a four-speed gearbox with wider shaft
centers for the London taxis that withstood the most
diabolical treatment by the worse cab drivers for over
100,000 miles. The ratios were far from ideal, but some
changes to the gears resulted in a box, which when
coupled to the Laycock de Normanville overdrive, gave
(BELOW) One of the first
four Special Test Cars, SPL
225B was completed in early
1953 alongside the pre-
production versions of the
standard 100. Fitted with
Birmabright alloy body panels,
the quartet also received
tuned engines and the four-
speed gearbox from the
contemporary Austin taxicab.
(The Graham Robson Collection)
(BELOW) An internal
document containing the
chassis numbers used on the
Special Test Cars. (The Donald
Healey Collection)