The story of . . . Diva
No Prima Donna
In the early ‘sixties, Diva cars burst into British racing and were extraordinary successful in the popular small-engined class. With literally hundreds of victories — including two class wins in the Nurburgring 1000 km, and the promise of a road car, it seemed that Diva might become an established part of the scene. But things did not quite work out that way.
Like most companies which build racing cars, the story of Diva is largely the story of one man. Don Sim first came to the attention of the motor racing fraternity in the late ‘fifties when he was one half of Yimkin Engineering, a tuning company which also built a handful of sports cars for club racing.
Born in London in 1931, Don had an early ambition to be an aircraft maintenance engineer and, after National Service in the RAF, he found himself at the Chelsea College of Automobile and Aircraft Engineering. He was already hooked on cars and racing, and since his class mates included Mike Hawthorn and Jackie Epstein he had to do something.
The ‘something’ was a Riley Nine special with a mildly tuned engine and “a horrible body” which Don had cobbled together as cheap transport but which, by degrees, eased into high trials and handicap races.
Later he bought a 1500cc dohc blown Alfa Romeo from a man called Mike Handley. Apparently it had been a works car brought over to Ireland for a Phoenix Park meeting. There was no body but the two men built one up along the lines of the original. Don says: “I used to enter it in handicaps but was given impossible targets. That’s what happens when a car’s previous driver is Nuvolari!”
Don and Mike then set about designing a monocoque 1172 car: “Mike did the main design, I put in my tuppenceworth.” While Mike, Jackie Epstein and others worked in Don’s shed, Don himself had to go where there was work and so spent time in Beirut working on large civil aircraft.
By the time he returned in 1956, the car was on its wheels. He had doubts about the design, so to prove the components designed a simple ladder frame to take the running gear. This little special was named Yimkin, from the Arabic word for “maybe”, a wry comment from Don on his own engineering. It was used solely as a road-going test-bed and never raced.
Having built one car, however, Don had the taste, and set about the design of a more sophisticated successor. The Alfa Romeo, the ladder frame Yimkin, and the unfinished monococque car were sold and work began on one with a multitubular frame.
Originally conceived for the 1172 Formula, it had a simple cycle-winged 20 gauge aluminium body curved round the chassis frame, and followed the popular special builders route in having Standard Ten wishbones, Morris Minor steering, hubs, and brakes, and a solid Austin A35 live axle. This was located with a combined “A” frame-cum Panhard rod suspended on coil springs and dampers.
Don raced the prototype for a couple of years but quickly found he hadn’t the finance to compete with the better 1172 Ford tuners, and switched to a modified BMC Series A engine and to the 1000cc sports car class. The switch of engines and categories brought some recognition and, with Mike Handley, Don started Yimkin Engineering, which specialised in converting BMC engines while selling Yimkin cars.
Then John Parkinson bought a car which he shared with Don Sim and the pair achieved some success with it. In 1960 Yimkins won ten of the twelve races in which they were entered.
The little company, based just off Sloane Street, published a high-toned brochure which included phrases like “individually tailored” and “millionaire or penniless enthusiast, the Yimkin is designed for you.”
Like other, similar, firms, Yimkin suggested that its car could double for Formula Junior, not to compete against the likes of Lotus and Cooper, but in an anticipated Club FJ with a maximum price limit. This never, in fact, materialised.
With the option of either Stage III BMC or Ford 105 B engines, the Yimkin FJ car cost just £800 assembled and ready to go. You could buy a rolling chassis kit for £500 and provide your own engine and gearbox and the company would assemble it for £50.
Despite the impressive brochure, just six Yimkins were sold, four going abroad, two of them primarily for Formula Junior. We wondered why Don did not make a proper FJ car. He says, “I didn’t think I was up to a single-seater and, besides, I wanted to make a road car.”
Though Yimkin Engineering was one of the more successful of the car conversion firms of the time, a business which would support two bachelors was not necessarily strong enough to support two families. Since Mike and Don had both married, they decided to wind it up at the end of 1960. Don went back to flying as an engineer on Lockheed Constellations.
During the Yimkin days, one of the customers had been Leo Bertorelli, who owned a TR3 which was given the Yimkin treatment. After Bertorelli had beaten Sid Hurrell, then the TR specialist, in the Brighton Speed Trials, he formed a very high opinion of Sims work.
Bertorelli rallied a succession of Triumphs and, having taken over the lease of a garage in Penge, invited Don to run it and an accompanying business, Tunex Conversions, which would modify Triumphs and prepare Bertorelli’s cars for rallying.
Don accepted, and to the business brought the design for a new car, based on the Yimkin but with a wider and much more complex frame. “We didn’t know what to call it but Mike Jeffrey, our cam grinder, suggested Diva. ‘I’m not building a prima donna,’ I said, to which he replied: ‘It’s got sexy curves and plays best on the high notes.’
“To finish it quickly we completed the first one with a live rear axle, after the Yimkin, and we used a Heron coupe fibreglass body which was originally made for 750 Specials. It covered the car (in fact the 6ft 9in wheelbase was determined by the body and not vice versa) but for eventually proved too tight a shape for development.
“Despite the fact it wouldn’t sell any of our Triumph conversions, we fitted the car with a Ford 105E engine tuned by Ted Parker. We eventually got the car ready and invited John Bloomfield to drive it at Goodwood in early June.”
Bloomfield finished second in class, but within few weeks began to win, and after the end of July was undefeated. His final tally for 1962 was ten events, seven wins, two seconds and a third.
In the meantime, Don had built a second car, this time with IRS by bottom inverted wishbones, top radius arms, Watt’s linkages, adjustable Armstong dampers, coil springs, and anti-roll bar. Braking was by 91/2in discs (Triumph Herald assemblies) at the front, and 9in drums (Morris Oxford) at the rear. A new body was made but it looked so awful that it was removed on the preview day of the 1963 Racing Car Show and a Heron shell was later fitted to it.
Diva GTs were offered as a kit complete with a Ford 105E engine fitted with two 40 DCOB Webers, special manifolds and a modified sump, for £860. A further £170 would bring a customer’s car up to full works spec, with 85-90bhp and a close-ratio gearbox.
Apart from the first two Heron-bodied cars, Diva GTs were clothed with a fibreglass body designed by Don and the works foreman. Building its own body gave Diva more control, particularly where suspension and wheel width were concerned, and was in line with Don’s policy of making as much as possible in house.
Realising that it would overstretch the resources of the little company to run a car from the works, the second Diva chassis was loaned to Doug Mockford, a rapid Lotus Seven driver. Mockford, who had begun racing at the age of 40 in 1959, used various Ford engines ranging in capacity from 997cc to 1650cc to notch up eight wins.
John Bloomfield’s one-litre car was very nearly as successful while Don Sim himself raced a couple of times and picked up a couple of victories. Mockford also finished runner-up for the BRSCC’s ‘500’ Club Trophy and, in 1100cc form, won the John Davy GT Championship.
Throughout Diva’s production period, it was always intended to market a road version, but almost every time a chassis was earmarked for building into a road car, someone would come along and buy it for competition. Only two of the 65 Divas made were road-going cars, though the 1964 brochure listed a road car as a production model.
At £940 in 1964, the road car was cheaper than the basic racing version, which had crept up in price to £980, but which even so was an extremely attractive proposition. In addition there was a ‘strengthened’ model for more powerful engines up to the 1600cc twin cam.
After the first year of production, Diva moved from Leo Bertorelli’s premises in Penge to a couple of railway arches behind John Bloomfield’s garage in Camberwell. It was an amicable parting, Bertorelli remaining a director, customer, and friend. But had become increasingly difficult to run both a construction business and a garage in tandem and Diva needed more space.
Among the young drivers who turned to Diva for the 1964 season were John Miles and Jackie Oliver, both of whom went on to Formula One. With others, they piled success upon success, so that having been in the business for just two years, Diva was able to point to 53 firsts, 37 seconds and 15 thirds. Most were in British club events, but the score included a win in the 1000cc GT class of the 1964 Nurburgring 1000 km (John Miles/john Peterson).
In 1965 John Miles raced a 1650cc Diva and his was a brilliant season, with 16 wins from 17 starts in the Redex Trophy series. Doug Mockford and Ian Alexander came first and second in the 1150cc class and Mike Walton third in the 2500cc class with his 1650cc Diva Valkyr GT.
The Valkyr was a mid-engined car of striking appearance, in profile bearing some similarity to the later Chevron B6. Its public debut came at the 1965 Racing Car Show where it was presented as the Diva Demon and displayed with a Hillman Imp engine. Marcus Chambers, the Rootes Group’s Competitions Manager, was interested in running a couple with Imp engines alongside the Sunbeam Tigers the company was racing, hence the engine and the name (Imp/Demon) when the car first appeared. When this arrangement failed to materialise, the car became the Valkyr.
Don had originally conceived it as a Ford-powered monocoque but had strayed on the side of caution and built it as a ‘birdcage’ spaceframe. Designed to take engines up to 300bhp (one of the five built had a 2.7 Coventry Climax FPF unit) it had an unusual front suspension with long base wishbones and horizontal coil spring and damper units.
Rear suspension followed usual Diva IRS practice. Depending on the engine to be used, it had a Hewland Mk 5 or HD gearbox. With fibreglass body complying to International Group 6 requirements, discs all round and fat tyres (7in wide at the front, 9in at the rear), it weighed 1150 lbs dry with a 2.7 Climax engine and 1040 lbs with a Twin Cam.
The first two cars went to Mike Walton (Imp engine) and Doug Mockford (Ford engine), but they were plagued with handling problems. Once these were sorted out the cars went well, Mockford picking up several wins, and Walton finishing third in class in that year’s Redex Trophy.
Leo Bertorelli, who was an an ice cream manufacturer, sold his business to Lyons, who retained him on a service contract. One of the clauses in the deal was that he relinquished all other business interests so he made over all his shares to Don who thus became sole owner of Diva Cars.
By this time Diva was marketing engine conversions under its own name for Minis and Fords, the Tunex Triumph conversions having been quietly dropped. Don felt that the only way Diva could put itself onto a sound basis was by building a road car.
To do that would require an injection of capital and he made a classic mistake by allowing others to buy into the company until he had lost overall control.
According to Don, the new directors were long on enthusiasm and promises, and short on common sense. They managed to alienate the work force and dispense with some key personnel. What had been an upward curve of achievement and success became a downward spiral. Don left and went back to flying, and the company remained active for very little longer.
Diva GTs continued to win. John Corfield took the 1966 Scottish GT Championship in a car which he wrote off at the Nurburgring the following year. In 1977 John bought another Diva for HSCC racing and he has twice won the Classic Sports Car Championship outright (1979 and 1983). Last year he tied for the title on points but lost it on a tie-break. He currently holds more class lap records in HSCC racing than anyone else with a single car.
1968 was the last year when Divas scored outstanding success in their own era of racing, Doug Mockford winning the 1300cc GT class in the Nurburgring 1000km, by which time Divas had garnered over 200 wins.
The firm changed hands in 1967 and joined a group which included JAP and Royal Enfield. Plans to market a Diva electric car came to nothing and the company disappeared the following year.
In all, about 65 Diva GTs were built, and five Valkyrs. Don believes one Valkyr eventually finished up as a test bed, fitted with a diesel engine, and pounding around MIRA. If that car still exists, it is the only one remaining in Britain.
Twenty years after his last association with car-making, Don still has his dream of making a road car, and is currently building an Alfasud-engined prototype, to be sold in component form, which he hopes to have running this year. ML