It was an unusual looking car for the period with the fuel tank placed between the engine and driver which together with the short nose emphasised the forward seating position of the driver. The spaceframe chassis was constructed from 18 gauge tubes of mainly 1" and 0.75" diameter and was well-triangulated for extra rigidity. As on the Mk2 the undertray acted as a stressed member by being riveted to the chassis. At the rear the frame holding the engine and gearbox was designed for ease of removal with the frame being bolted to the four main longitudinal chassis members, it was located by tapers on the members together with taper washers to ensure a tight fit. This allowed for the engine and gearbox to be removed speedily as a single unit from the rest of the car when maintenance was required, it was claimed that one mechanic could complete an engine-change in one hour. Suspension was virtually identical to the Mk2 with a lower wishbone with adjustment for camber and toe in at the rear, as before the driveshaft and trailing link acted as a top wishbone. There were subtle changes to the front however with the coil spring and damper units being mounted behind the wishbones whilst the steering arms running from the rack and pinion steering rack to the Triumph Herald uprights are inclined rearwards instead of forwards, in addition an adjustable anti-roll bar has been added.
Although, with the adoption of a rear-engined design, the problems of the offset transmission of the Mk2 was no longer an issue the gearbox on the Mk3 was offset to the right with unequal sized castings attaching the backplates of the inboard rear brakes to the gearbox and having the effect of equalising driveshaft length. The 5-speed gearbox design would have an important place in motor racing history, the internal gears were Lola-made but the external casing was based on a VW unit and was designed and built by Mike Hewland, the first entry of a Hewland gearbox in motorsport. The Hewland design allowed for the gears to be changed with the gearbox still in situ.
Brakes were finned Alfin alloy drums at the front, at the rear a composite drum was used comprising of a cast iron drum to which is riveted an electron side with a concave shape which allowed for a longer driveshaft than would have been possible with a standard design. The brakes were operated by a twin master cylinder system. Wheels were again 13" magnesium bolt-ons with 4.50 X 13 tyres at the front and 5.50 X 13 at the rear.
The engines were, unusually for the time, dry-sumped with a wedge shaped oil tank being placed beside the fuel tank, behind the driver. Both tanks were designed to be surge resistant and the oil tank was cooled by a scoop in the bodywork. Initially the engines were 997cc Ford 105E units canted over at 15° (as on the Mk2) and fitted with two twin-choke 40 DCOE2 Webers, the units were tuned by John Young of Superspeed and 85 bhp at 7200 rpm was claimed. As the 1961 season progressed the engines would be replaced by 1096 cc units. |
