The Jappic Brooklands bred
Nearly 90 years after it went up in flames in France, the Jappic is back – in New Zealand.
In the mid ‘twenties, the mecca of motorised sport for both motorcycles and cars was Brooklands, the huge concrete circuit south of London. The circuit had been in existence since 1907, but after the interruption of WW1, it really took off thereafter. Back then, the few off-the-shelf racing machines that were available were prohibitively expensive to all but a select few, so the most common method was to build your own. One such creation was the Jappic Cycle Car – a combination of car and motorcycle components and thinking, which was initially fitted with a 344cc twin-port J.A.P. engine, chain-driven via a three-speed gearbox to the rear wheels, which like the front wheels, had motorcycle origins. Only the rear wheels had brakes which were hand operated by a lever. The Jappic was designed by Mr H.M. Walters, who had been a very successful motorcycle racer and engine tuner at Brooklands, with the chassis and bodywork done by Jarvis of Wimbledon Ltd. The frame itself was made from Ash timber, held together with steel flitch plates and tubular crossmembers, and the body contained two seats for driver and passenger, although the latter had to sit sideways with one arm out the rear. The engine sat behind the front axle, linked by chain to the gearbox which was located under the driver’s knees.
The rear axle was located by long tubular radius rods incorporating friction dampers at the front anchorages, which were aligned with the gearbox main shaft to avoid variation in chain tension and spring deflection. The Jappic was displayed at the 1925 London Motor Show on the Jarvis stand, and over 150 enquiries were received from prospective buyers, but Walters had no interest in producing further cars. First entered at Brooklands on Easter Monday 1925, the ultra-lightweight Jappic (the driver contributed one-third of the all-up weight), set a new flying mile class record of 70.33 mph – not bad for a 350, which was producing 42 horsepower running on Cleveland Discol alocohol fuel. The following year Walters replaced the original engine with a 500. After a few more outings, Walters sold the car to Mrs Gwenda Stewart, who re-fitted the 350 engine and renamed the car the Hawkes-Stewart (HS). In 1928 Ms Stewart drove the car at Monthléry, near Paris and averaged nearly 71mph for 100 miles. The high-banked circuit was very popular for racing and record breaking, and the car’s co-owner Douglas Hawkes took one of the permanent workshops which were located under the immense bankings. Unfortunately in 1932, the workshop caught fire and the car, along with several others, was destroyed. Since then, a handful of Jappic replicas have been created, one by ex-Formula 1 engineer Adrian Ward in Britain, and another by Garth Thomas in New Zealand. Garth’s father Bryan has had his marvellous work featured many times in this publication, but his son is no less talented. Working from drawings and photographs, Garth spent many hours, beginning in 2012, making his own drawings before a single component could be made. “Some parts had to be made twice,” Garth explains with a wry grin. “I only found the actual dimensions of the
originally car after I had started building. I scaled everything off photos, knowing that the wheels were 21 inch and working from there. The chassis is made in two halves from laminated Ash wood with steel flitch plates used to attach the suspension and axle components. Wherever possible, I like one bolt to do more than one job. For instance one bolt holds the steering column, flitch plates and fuel tank. I thought, ‘Why use two bolts when one will do?’. “The engine I found on the local NZ internet trading site – Trademe. 90% of the bits were present but in a sad state. It was very fortunate I located it as JAP dual exhaust port engines are not two-a-penny. The engine is a “KOC” with 500 cc 85.7mm x 85mm bore and stroke, I think about 1928. Bryan with some input from myself refurbished it to tip top standard. So that the magneto drive would be true to pattern, located at the front of the engine (rather than top-rear), I manufactured wooden patterns, cast and machined the front mag drive; the front mag drives are very hard to come by. The Magneto itself is an N1, with a modified points cap which houses a carbon brush running on the points, wired to a kill switch located on the gear change lever, the kill switch has two functions, to kill the spark and stop the engine, the other is to “interrupt” the spark when changing gear, thus saving use of the clutch. “The gearbox is an Albion 4-speed (forward), from a Train jigger, although the original was a Sturmey
Archer 3-speed; these too are very hard to locate (at a reasonable price). Having said that the 4-speed I believe will be better performance-matched with the 500cc JAP engine. For the bodywork, a request went out to Steve Roberts in Wanganui – the ‘Plastic Fantastic’ creator. He accepted the challenge and did a brilliant job, as with everything Steve does. In true 1920’s design, the steering column was fabricated using bicycle parts, the head and lower end bearings were taken from a bicycle steering head, using a peddle crank as the pitman arm, the steering wheel hub was CAD designed and laser cut, with kahikatea wood glued to the hub and machined with the use of a 1/4 round radius router.” The fuel tank, which came from a J.A.P. stationary engine, is pressurised up to 3 pounds by a hand pump operated by the passenger, and Garth has added a saddle on a cross member above the gearbox to stop whip and stress on the chains. The car has an unusual rear axle design; to support the rear axle centre from flexing there is a centrally mounted bearing supported by a triangulation of three tensioned support rods. Quarter-elliptical springs come from an Austin 7. It is a very tight fit for the driver – so tight that the steering wheel has to be cut away to give leg room. With the correct sized 2.5 inch beaded-edge tyres fitted, the Jappic measures the original 29 inches to the ground. At one stage threatened with demolition, the Autodrome de Linas-Monthléry, where the original Jappic perished, is still operational (albeit in truncated form) and holds bi-annual Vintage Revival meetings. Garth and his Jappic replica plan to be there soon.
Teamwork! Walters demonstrates the lightness of his creation at Brooklands.
Rolling chassis. Twin-port JAP power, just like the original. Under construction in Garth Thomas’ workshop in New Zealand.
Rear axle with its centre bearing. Tubs for driver and passenger.
Gwenda Stewart in the car at Monthléry, France.
Swooping exhaust with obligatory ‘Brooklands Cans’. Fuel tank came from a JAP stationary engine. Albion gearbox is supported from cross beam to minimise flexing.
The badge of office.
TOP LEFT Steering wheel is cut away to clear driver’s legs. BOTTOM LEFT Hand pump pressurises fuel tank. LEFT Rear brake operates via linkage to rear wheels. ABOVE Aim for the banking! BELOW Garth Thomas with his masterful recreation.