More on Ron Tauranac as Tony Caldersmith analyses RALT 1

Racing cars have generally been divided into two camps; the factory produced cars and the individual special builder’s car.  Occasionally the odd special builder showed such talent that he graduated to multiple production and became a recognised successful manufacturer.  Ron Tauranac is a member of the latter group and starting out with a clever special, became a major force in racing car design and production.

To get into racing in the early post World War 2 years, there were two alternatives; you had to have plenty of funds and bought an existing car, or if you couldn’t afford that, you designed and built your own car (a ‘special’).  The Tauranacs took the latter approach.
Australian specials at the time were mainly obsolete European racing cars using large American motors or stripped production cars, as opposed to England where the 500 movement was thriving, with people making light cars, using motorcycle engines. When Ron and Austin decided to get involved in racing their approach was to design and build their own car and it was a remarkable achievement that showed a high level of design and clever thinking.

Using the light car option meant you would need to minimise the weight and maximise the handling.  Invariably that meant a minimal chassis frame and independent suspension.  Earlier triers using basically lightened Austin Seven components soon learnt that you needed to be more sophisticated to get the real advantage of a light competition car.

An effective suspension was the real test. There were plenty of designs to consider, including twin wishbone, Morgan or Lancia’s sliding pillar, trailing arm, transverse leaf-spring and split axle. There was not a lot of detail available on the more technical aspects of these alternatives, such as roll centres and swing-axle lengths, but Ron is known to have studied the available literature and decided on what suited the sort of car and performance he wanted. Typically, like any one starting out in competition, the lack of experience would be the stumbling block that made it difficult to select the most appropriate design first time up.

The first Ralt’s basic design used a 2” tubular ladder chassis, wishbone and transverse leaf spring front suspension with a swing-axle rear suspension also supported by a transverse leaf spring.  The chassis was a main tubular loop starting at top wishbone level at the front and sloping down to the lower pickup for the rear swing axles.  At the front there was an additional structure to mount the top leaf spring and the steering and lower down, the pedal pivots and inner wishbone pick-up points. A small triangle supported the front end of the steering column. The rear suspension comprised quite short swing axles and used light tubular wishbones pivoting on the same line as the axles’ universal joints. There were no signs of dampers on either the front or rear suspension on the car’s early appearances and it is reported as running in this form at its first outings.

0597 Howard 1818A FINALAbove: the initial rear suspension configuration with short swing axles and no dampers

Above: early front view with the large diameter wheels and motorcycle tyres and no dampers.

The front suspension’s geometry using a top leaf spring as the upper control arm mirrored Cooper’s design and therefore suffered the same failing, in that the resultant geometry has the longest actuating arm on the top.  This means that on roll, the outer wheel will not only mirror the chassis’ roll angle, but exaggerate it.  However, it appears that the main masses of the car were quite low slung and, combined with the high mounting of the front suspension, little adverse effects might have been evident in action (as Cooper found). The positive camber of the front wheels would also exaggerate that disadvantage and may have been designed to provide an understeering characteristic. Wheels were 19” wire fitted with motor cycle tyres.

Ron’s first outing in the car was on his way to the Hawkesbury Hillclimb when he had a bit of private practice en route. The combination of the undamped suspension and short length swinging arm rear axles suspension made the car very unstable and difficult for a novice (as Ron was then).  The result was a serious accident.
Ron only drove it once more in that form and had a further accident, before fitting the shock absorbers and revising the rear suspension to turn it into a low pivot swing-axle that reduced the camber change needed to reduce the car’s sensitivity and improve the handling.

The new arrangement would have provided a swing angle length of approx. 15”, almost double the original. It also lowered the roll centre and substantially reduced the jacking problem that would have been a major contributor to the car’s adverse handling.
The two inboard pickups for the rear lower wishbone were not parallel with the car’s centreline, but were located on the limited structural options, at the rear near the centreline, and on the chassis well forward of the rear wheels.  While this might have generated a small amount of bump steer it would have been limited by the moderate suspension movement and provided a major improvement in driveability.  The trailing arm that formed the forward part of the lower suspension, underwent modifications over a period, probably to improve its rigidity.  The original arm was quite long and made from small tube.  It was later boxed in and had a speedway style “knerf bar” added, which was probably more for adding strength than providing a safety feature.

ChassisAs part of the rear suspension change, the new rear suspension not only included new thinking in its low pivot arrangement, but also included a new rear wheel hub that included a mounting for the driveshaft outer universal joint, maximising the length of the driveshaft and minimising the angles the universals had to work through.

The universal joints of the original drive shafts, which were quite short, would have had to go through severe angles during suspension movement, which was not conducive to UJ life and smooth power delivery. The new design moved the outer UJ to the outer end of the wheel hub delivering its power via a spline mounted on the outside end of the wheel hub, thereby minimising the angles the UJs would work through and minimising power loss.
This rear suspension change was probably when the wheels were changed from 19” wire to 15” cast alloy.  15” wheels meant that Ron could take advantage of proper racing tyres, which were not available in 19”.

The front suspension was sufficiently well located to resist the braking forces and appeared to remain largely unchanged other than the addition of tubular shock absorbers.  In some early photos there appears to be a drilled top lateral location arm, which does not appear in later versions.  Ron may have been unsure about the spring’s ability to act as the locating component for the front suspension initially.  There is no sign of the drilled locating arm in later photos, although the spring looks much beefier than in the early shots.  Ron may have taken the “Cooper option” and dispensed with the locating link.

Ralt Foleys 13-7-52 aAbove: the later evolution with 15” alloy wheels and revised suspension.

BartropNowraAbove, Bert Bartrop at Nowra hillclimb on 2 November 1958.

The chassis itself seems to have remained basically unchanged, other than making modifications for the new suspension and the simple and clever bodywork remained the same, except for minor additions to the windscreen and rear view mirrors. These are difficult to position on a 500 and to isolate from the inevitable single cylinder vibration. In this evolved form, the car was very successful and had a number of successes in both Ron’s hands and its subsequent owners.

The success of Ralt 1 was the result of detailed thinking by Ron at a time where development usually meant making a car lighter and finding ways to increase the horsepower of the engine.  Developments in handling and suspension were rare iRear suspensionsn specials and Ron came up with a design that would have been at the leading edge, if he had presented it in the UK at the time.

It is interesting that the following Ralt cars retained almost none of the features of Ralt 1.  These cars moved to multi-tube frames and twin wishbone suspension and displayed to very rapid design developments that were to be a feature of the ‘50s and ‘60s. TC

Above right,  Ralt 1.2 suspension and some (later) not dissimilar types –  sketches by Tony Caldersmith. Below: the Lotus Formula 1 rear suspension of 1960 where loads were also taken out over a very wide bearing on the chassis.

Lotus 18 rear susp