Rhiando Trimax

X-Ray spec: Rhiando Trimax

Though only a bit-player on the motor racing stage, this one-off typifies the fresh thinking which led to the 500cc revolution. By Keith Howard

After the euphoria of VE day and VJ day, and the demobbing of the armed forces, Britain woke up to a post-war reality summarised in a single word: austerity. Food rationing would continue until 1954, and it was not only foodstuffs whose supply remained controlled. Engineering materials were often hard to come by too as the country struggled to work its way out from under a mountain of war debt.

In the straitened circumstances of the day, motor racing cut its suit to match its cloth. Picking up on the pre-war CAPA organisation, for cars based mostly on Austin Sevens, the 500 Club was founded in 1946 with the express intention of creating a new 500cc formula with costs low enough to encourage individual members to design and build their own cars. Beginning with hillclimbs and then graduating to circuit racing, the recipe proved so successful that in 1950 it was adopted by the FIA as the basis of Formula Three. Wherein lay its eventual demise, as bigger teams found ways to turn larger budgets into cars no privateer could hope to match.

Many of the most famous names in postwar motor racing were involved in 500s in one way or another, acquiring driving skills that would catapult them into more senior formulae or design skills which would soon displace Formula One’s centre of gravity from Europe to England. But there were many more participants who never made it into the headlines. A visit to The 500 Owners Association website (www.500race.org) reveals a host of marques whose names will be unfamiliar to anyone but an enthusiast for the era.

Although 500s were, initially at least, inexpensive to make — not least because of their reliance on motorcycle engines — and often made in tiny quantities, they weren’t universally crude. Competition was fierce, so designers put their thinking caps on in search of an advantage. An exemplar of this is Alvin ‘Spike’ Rhiando, an extrovert Canadian who had come to Britain in 1933 in a vain attempt to establish car speedway racing.

In 1949 he designed and built the Trimax, so called because it was originally intended to accommodate not one but three capacities of engine: 500, 750 and 1000cc. Only one was ever made and it wasn’t a notable success on the track, but the ambition of the car and its designer speak for themselves. Over a decade before Colin Chapman would upset the Formula One applecart with the Type 25, Rhiando built his F3 contender around a monocoque aluminium alloy chassis.

Today the car belongs to Jack Mayes, who talks about the Trimax overleaf. A Chicago architect who owns a small stable of 500s and used to race some of them, he bought the car after knowing about it since its first appearance in the 500 Club’s Iota magazine, in the mid-1990s. As yet, he has not been able to restore it fully. But as the picture below shows it is largely complete and will one day be returned to its original condition. A few years ago Spike Rhiando’s son contacted Mayes and expressed an interest in buying it but the deal was never negotiated.

In the broad sweep of motor racing history the Trimax may barely merit a walk-on part, but it does epitomise the spirit of the time. In particular it represents the ascendancy of novel thinking over brute force and tradition — the very quality that within scarcely more than a decade of the Trimax’s first appearance would see Cooper, another 500 marque, win the Fl drivers’ and constructors’ titles two years in succession.

It wasn’t only in the Trimax’s chassis construction that Rhiando took inspiration from aircraft practice — the unusual steering arrangement also owed more to aeroplane than car. “He used a sprocket and chain arrangement to pull on the steering levers,” explains Mayes. “The sprocket is mounted on the steering shaft, behind the front bulkhead. A short chain goes across that and connects to a cable that pulls on the steering mechanism in the footwell.” You can just see the cable running along the right side of the car in the drawing. This flexible linkage probably made the Trimax odd to drive, with little or no ‘feel’ through the steering wheel to warn of the front tyres’ adhesion limit.

As well as sharing its construction essentials with that of the Lotus 25, the Trimax also presaged later Fl practice by using aircraft-like bag fuel tanks within the two roughly square-section side sponsons at either side of the car, each of which held 5.25 gallons (24 litres) of fuel. These were inserted through small inspection panels and inflated with compressed air to fill the space. “But the bladder tanks had long disintegrated by the time I got the car,” reports Mayes. “It came with an upright tank behind the driver.”

Suspension springing front and rear is by Metalastik units attached between the chassis and the inboard ends of the welded steel swing arms, which are trailing at the front and leading at the rear. “It’s a rubber in torsion suspension: two short pieces of steel tube of different diameters with rubber bonded between them. The outer ring is bolted to the chassis and the inner carries the swing arm.” Despite this simplicity, which had the advantage of saving weight compared to conventional springing, wheel travel was reportedly a generous five inches.

The large handles on either side of the tub, just ahead of the cockpit, served two different purposes. The one to the right of the driver was the gear change, while its opposite acted as a handbrake. “The regulations at the time for 500s required this. As I understand it, this was because the start at Brands Hatch is slightly downhill. You had to be able to hold the car on the line yet you were using your right foot to blip the throttle because 500s don’t idle very well. You’re on methanol and the idle jet is not large enough. With a number of the cars all they did was add a handbrake with a cable which operated the balancing lever on the master cylinder. I would guess that it’s the same arrangement here but I don’t have the master cylinder so I can’t be sure.”

“The early twins, using 500 barrels, would have had a total loss oil system, as shown here, and the engine that I got with the car also has cast iron barrels, not alloy as on the later ones. So at least one high tank was needed for oil. The filler caps on top of the driver’s backrest seem to indicate two tanks, the other of which would be for methanol because the R27 carbs used a gravity feed. The small handle just visible at the driver’s left may have been a hand-operated fuel pump for use while the car was at rest. The Kieft had a battery and an electric fuel pump but that was unusual — and the battery always runs down about the time you want to race.”

Eschewing a differential allowed a simple chain drive to a sprocket on the rear axle, where a single brake drum acted on both rear wheels. To achieve the required plunge in the half-shafts without the use of splines, Layrub rubberised universal joints were used, a forerunner of the Metalastik ‘doughnuts’ used later by Lotus and many others. Because of their inherent flexibility, these also helped ameliorate the effects of not having a diff.

‘While the chassis is a monocoque, there is a small steel tubing subframe that runs both across the car and back towards the engine. It is attached to the shell by U-bolts. It has very little stiffness so apparently it was there for alignment of the running gear” The body is constructed mostly from 16 and 18swg duralumin sheet, meticulously riveted. “Whoever did the riveting on the car did so very well,” says Mayes, and his is an expert eye. “One of the reasons the car interested me was I was a riveter at Douglas Aircraft during World War II and broke all records for riveting at the Douglas plants.” Despite this advanced construction, the car was overweight. “It is quite a bit heavier than the average 500 and it’s also bigger. The Coopers are around 10ft, the Macksons 11ft and this is about 12ft long.”

“The cutaway shows a Norton ‘Doll’s Head’ gearbox. That was probably original because all the Coopers and Kieft used them at the time. But when I got the car it had a much more robust gearbox, bigger than I’ve seen in any other 500. It appears to be an Ariel Square Four unit, but I could be wrong. Rhiando had gearbox problems in April 1950 so that may be the explanation.” Another recurring problem Rhiando had was with pistons melting, which probably explains the S-shaped air duct from the car’s underside just visible ahead of the cylinder barrel, “although that is now missing from the car.”

Although the wheels themselves are alloy castings to save weight, they were fitted with chromed wheel trims — a seemingly needless piece of ornamentation that Mayes suspects was included for aerodynamic reasons. “I imagine it was an attempt at streamlining. In California when running on the salt flats they would often put a cover on the wheels to try to cut down drag, I expect this is the same idea.” Indeed, it was said at the time that the Trimax had been wind tunnel tested to refine its body shape — a claim Jack Mayes and I won’t be alone in regarding with some scepticism.