by H. G. Dobbs
(In an Interview with the Editor)
One of the most successful of pre-war amateur racing drivers, Hector G. Dobbs specialised in making Riley cars go very rapidly indeed. Curious to know how it was done, I called at the Riley House in Southampton, where Comdr. (E.) Dobbs, O.B.E., R.N. (RTD.). A.M.I.MECH.E., has his automobile and marine business, and Riley and Fiat distributorships, to find out.
Dobbs started with motorcycles, winning the Amateur T.T. on a Norton in 1925, at 59.98 m.p.h. The following year, also on a Norton, fog obscured the course, and he crashed. After this, racing activities gave way to marriage and a spell at sea with the Royal Navy.
When, invalided out, Dobbs returned to civilian life his former sport was resumed, this time at the wheel of Riley cars, for which he was an agent at Hedge End Motors, then at Botley.
A Riley Imp was entered for an M.C.C. London-Exeter Trial with considerable success and when the Light Car Club ran its 1932 Riley Race at Brooklands, Dobbs teamed up with H. J. Ripley and another Riley enthusiast. His car was outwardly a humble Riley Gamecock but it had been considerably tuned, and averaged 92 m.p.h. for 45 laps, which was considerably over its safe rev. limit. Ripley was called in after 15 laps, so Dobbs had to complete these 45 laps of the Relay Race before it was the turn of their third team-member.
For the 1933 season Dobbs acquired a blue “Brooklands” model Riley Nine, which was fairly standard and not particularly successful, although he was third in a Sprint Handicap at the Opening B.A.R.C. Meeting, averaging 69.87 m.p.h. For the Easter 1933 Meeting at Brooklands Dobbs had a highly-tuned, rather home-made Riley Nine, which suffered from being too heavy. It proved able to lap the Track at nearly 103 m.p.h. but never won a race.
The next venture was a 1933 Riley Lynx 4-Seater, so effectively tuned that it could lap at better than 100 m.p.h.! Entered as Riley I to distinguish it from the outer circuit car, this one was intended for races over the Brooklands Mountain circuit. For this it proved well suited. Painted black, with ivory wheels, in 1934 it won the First Ripley Mountain Handicap at the Easter Brooklands Meeting, from Geoffrey Taylor’s Alta, and then came out again to win the Fourth Ripley Mountain Handicap, in spite of being re-handicapped, lapping in this race at 63.25 m.p.h. round the 1.2-mile circuit with its two difficult corners. The engine of this 9-h.p. Lynx had a c.r. of 13 to 1 and was taken up to 7,000 r.p.m. The body was drastically lightened, even to hollowing out the wooden formers of the frame, the only seat was one from an aeroplane, and a small fuel tank was installed above the engine. Eventually the crankshaft broke!
During 1934 Dobbs also raced his white Riley II single-seater, which now had a carefully streamlined body with neck-level cockpit and cowled chassis and radiator. The body was made by a small coachworks in Netley. This Riley. was placed third in the Ripley Senior Long Handicap, then, its lap speed gradually improving, it was second behind Mike Cooper’s Talbot in the First Kingston Senior Long Handicap, lapping at 106.19 m.p.h., and, although not placed again, lapped at 108.74 m.p.h. at the Autumn Meeting. At the Inter-Club Meeting it won the Third Short Handicap from Rayson’s blown 2.3 Bugatti, to which it had given 8 sec. start.
These results were very creditable but many other Rileys were being raged at this time, a few faster, most of them much slower, so for 1935 Dobbs decided to do something really interesting! Taking a Riley M.P.H. chassis, it was endowed with the first of Dobbs’ famous offset single-seater bodies. He had decided that streamlining, as on his previous Riley II, merely added weight without any advantage, a hard decision to face, as this earlier body had been evolved after a week spent in the City & Guilds’ laboratory doing wind-tunnel tests.
However, a mere shell it was to be, with virtually no cockpit sides, to afford plenty of elbow-room, the back axle also being exposed. This body, of 20 g. magnesium sheet, weighed a mere 30 lb. The 6-cylinder engine was not tuned to anywhere near its limit, but had six Amal carburetters, while all Dobbs’ Rileys had an exhaust camshaft substituted for the inlet camshaft to give greater overlap, in the fashion then current in circles where these power units were prepared for racing.
So successful was the M.P.H. single-seater that it was followed by a similar car, using a Sprite chassis, and with the engine “stretched” to 1,808 c.c.
Driving the 1½-litre car, then painted blue, at the Opening B.A.R.C. Meeting of 1935., H. G. Dobbs won the First New Haw Mountain Handicap at 66.4 m.p.h. The next engagement was the opening Donington Meeting, where the white Riley won two 5-lap races, averaging 63.68 m.p.h. in the up-to-3-litre event, followed home by the Hon. Jock Leith’s supercharged 2.3 Bugatti.
At the Brooklands Easter Meeting the Riley was third in its heat and finished in the same position in the Final of the British Mountain Championship. Dobbs also drove his old white Riley Nine in an outer-circuit race, lapping at 110.68 m.p.h.
Dixon had been using a 1.8-litre engine, which capacity Dobbs resorted to before essaying a long-distance race, the J.C.C. International Trophy Race at Brooklands (for which Dixon had a 1,986-c.c. engine). Dobbs found his light car very suited to the course but seven pit-stops, mainly to adjust the front brakes, pulled down his average to 79.87 m.p.h., and he finished ninth, ahead of Mays’ 2-litre E.R.A.
At Donington in May 1935 the Dobbs’ formula of good braking and low weight paid dividends, for his Riley won three 5-lap races in succession, one of them open to cars of up to 3½-litres. His average speeds were 64.20, 64.46 and 65.69 m.p.h., respectively, and the Riley also took second place in another 3,500-c.c. race, behind Maclure’s Riley, which started 45 sec. earlier.
The offset single-seater Riley was by now an extremely famous car and it, and the Nine, ran at the B.A.R.C. Whitsun Meeting. The latter won the Whitsun Long Handicap at 104.58 m.p.h. lapping at 109.22 m.p.h., leaving Ian Connell’s s/c. 1½-litre Vale Special 300 yards behind, although it had an advantage of 14 sec. at the start of the race. The other Riley was unplaced in its Mountain races.
Dobbs’ next race was another long-distance classic, the B.R.D.C. British Empire Trophy Race over a 240-mile artificial road course at Brooklands. Using the 1,808-c.c. engine, he finished eighth, at 72.72 m.p.h., in spite of a spin which stalled his engine and other “excursions” during some particularly rapid cornering—the advantage of his skeleton bodywork was evident when, extending one leg, he paddled the car away, to restart its engine.
In the Nuffield Trophy Race at Donington the Riley experienced one of its few retirements, when a dural bush tightened up, making the steering impossible, although the official reason was given as a split fuel tank.
Amends were made at the next Club Meeting at that circuit, the Dobbs’ Riley taking two second-places, and winning the 3½-litre race at 67 m.p.h. On this occasion Dobbs drove the 1½-litre car.
For 1936 the Riley Company, now disposed to be quite helpful although Dixon had first call on racing parts, supplied a 2-litre racing engine, which went into the drilled Sprite chassis, the residue of the parts from the 1,485-c.c. and 1,808-c.c. cars being assembled into a third single-seater. The 2-litre car was Hector Dobbs’ greatest achievement. Bodied like his other Rileys, the engine was carefully built up (but never bench tested) in Dobbs’ workshop. A lighter crankshaft and no dynamo made it possible to dispense with the vibration damper, although speeds of over 6,000 r.p.m. were habitually indulged in. The six motorcycle Amal carburetters were retained, operated by Bowden cables from an overhead shaft, and their synchronisation was simplicity itself. Moreover, these carburetters were not sensitive to jet variations. “Tuning, in those days,” says Dobbs, “using methanol fuel, was really quite straightforward. We hadn’t heard of `tuning’ inlet pipes to match extractor exhausts, although Dixon may have had the idea.” The big engine had a c.r. of 11 to 1, and was not taken above 6,500 r.p.m., reliability being more important than sheer power, although as the normal 2-litre Riley engine gave 145 b.h.p. it is pretty certain that Dobbs was getting well over 150 b.h.p., in a car weighing well below 11 cwt.
Every effort was made to reduce weight. An elektron gearbox casing was obtained from the factory, and the gears, drilled and hardened, had straight-cut teeth. Reverse gear was just a duralumin cog revolving on a dural tube! Wet sump lubrication was retained but different-size sumps of 20 g. elektron sheet were fabricated for different races—thus for a 5-lap race ¾-of-a-gallon of oil sufficed, such a sump weighing some 3 lb., compared to 17/18 lb. of the standard sump. The flange of the cylinder block was laboriously cut back 1/16 in. all round, another weight-reducing gambit.
The Riley “endless cable” brake actuation was scrapped in favour of a simple dural cross-tube on ball-bearings, from which hung the operating levers, coupled to the brake cams by separate cables. By altering the height at which the cables were anchored to the drop-levers Dobbs could obtain any bias he required—very cunning! It is a fact that he ran with more braking on one side of the car than the other, not only to compensate for the offset seating position and therefore weight unbalance, but also to suit the direction of a given circuit. The drums remained normal M.P.H. elektron drums with cast-steel liners, which distorted like nobody’s business, yet without any ill effects, while the linings survived splendidly.
It is largely to this ingenious retardation of a lightweight car that Dobbs attributes his successes. Not only did his brake layout save another 20/27 lb., but he told me he could easily outbrake E.R.A.s and Maseratis, passing them at 30 m.p.h. higher speed and gaining up to 100 yards on a circuit like the International Trophy, for instance, before they re-passed, with the advantage of supercharged engines, on the Byfleet banking.
Dural shock-absorbers, a light-alloy gearbox layshaft, elektron steering box and a dural steering column tube contributed to the low weight implied by the minimal bodywork. Suspension was rendered suitable by removal of a few spring leaves. An attempt to shorten the torque-tube and set the engine back 3 in. in the chassis resulted in such loss of control that it was hastily restored to its former position.
Wheelspin was obviated by deleting the differential, but in Dobbs’ time twin-rear-wheels were not used. Ignition was normally by a Scintilla Vertex magneto, replaced by 4 perfectly satisfactory Lucas vertical magneto on one occasion when a prize was offered for the best performance by an all-British car.
So to the 1936 racing season, during which the offset Riley fully vindicated Dobbs’ tuning methods and the excellence of the Riley high-camshaft, light-push-rod valve gear and hemispherical heads. Incidentally, the car was taken from Botley to Brooklands on a trailer behind Dobbs’ 8-litre Bentley—”you couldn’t drive it on the road,” he explains, “because to lighten it a bit more we had removed the handbrake. . . .”
The season opened with the British Empire Trophy Race, now at Donington, but after 37 laps engine trouble intervened. However, at the Brooklands Easter Meeting the 1,986-c.c. Riley was back on form, winning the second heat of the British Mountain Handicap, in which it started level with Rayson’s blown Maserati and Powys-Lybbe’s blown 2.3 Alfa Romeo, at 71.88 m.p.h., and finishing third in the Final, in which it was required to give Rayson 3 sec. and Scribbans’ E.R.A. 7 sec. start!
Perhaps the Riley’s greatest success came in the 1936 J.C.C. International Trophy Race, when Dobbs finished third, averaging 89.38 m.p.h., behind the E.R.A.s of Bira and Mays.
At the Club Donington Meeting at which Seaman tried out his rebuilt 1927 Delage, Dobbs won a 5-lap Handicap for cars up to 5-litres, at 64.24 m.p.h.
At the Whitsun B.A.R.C. Meeting, Dobbs again in black overalls (in 1935 he wore white attire) and the Riley if anything even more lightly clothed, two Mountain races were won in succession, respectively at 73.13 and 76.03 m.p.h., the two fastest laps being at 77.72 m.p.h. This is thought to be the fastest lap of the Mountain circuit by a non-supercharged car. At Shelsley Walsh hill-climb Dobbs won the Garvagh Cup, in spite of ending up amongst the sand-bags on one ascent. Another speed hill-climb at which the Riley performed well was the Riley M.C. event at Lullingstone Park, where it was third in its class (25.36 sec.), behind Scribbans’ E.R.A. (24.1 sec.) and Dixon’s blown Riley Special (24.13 sec.).
In the French G.P. Dobbs partnered Von der Becke in one of the four “works” Rileys which dominated the 2-litre class, finishing 15th overall.
Back in the single-seater, Dobbs drove a magnificent race at Donington in the Nuffield Trophy Race, the Riley finishing fourth, at 65.61 m.p.h., behind the E.R.A.s of Martin, Dobson and Whitehead.
I asked Dobbs if he felt tired driving the very fast Riley in long-distance races, or when winning a couple of hard-fought Mountain handicaps or three short Donington races in succession. “Not a bit,” he replied promptly, “not at that age.” Nostalgic, these memories of Brooklands, Donington, the white Riley arriving behind the massive Bentley. . . .
But all good things end eventually and when, in 1936, the Riley Company ceased to support racing Dobbs realised that he possessed three famous and successful cars for which, if they blew-up, no spares would be forthcoming. So he sagely sold them.
The 2-litre car went to Eric Fernihough, who intended to supercharge it, when about 190 b.h.p. would have been developed. He was killed before he could do this, but Roy Salvadori drove the car, with a wire-mesh grille over the radiator, in 1946. It has appeared at V.S.C.C. Meetings looking very non-original but is, I hear, being rebuilt to look more as it did in Dobbs’ time, for this year’s Historic Racing Car events. Billy Cotton had the 1½-litre car, which was also driven in 1937 by “Wilkie” Wilkinson and later won a S. African G.P., driven by Meyer. Dobbs had acquired some scrap T.T. bodies from the factory and, using one of these and a 4-cylinder 1½-litre engine, he built up a car for Davies, which made car f.t.d. in a Ceylon speed hill-climb in 1940, driven by Vincent Cox.
Today, at the Riley House in Southampton, Comdr. H. G. Dobbs concentrates on sailing and business, but his foreman of the old days, S. Hanslip, is still with him. He has lost touch with Bull, his racing mechanic, however.—W. B.