Veteran types: no. XXI
A 1914 T.T. Sunbeam
Mention has already been made in MOTOR SPORT of the wonderful collection of old cars at Short’s garage in Chelsea, ministered to by Cecil Clutton. It has been mentioned, too, that amongst the vintage and Edwardian cars of varying ages in this collection is a Tourist Trophy Sunbeam. The car in question, having stood out in the open for many years at a garage in Maidenhead, and having been docked long ago of its original, bolster-tank racing body and external exhaust system in favour of clumsy wood-decked sports coachwork and a hastily welded-up inside exhaust manifold, one is apt to pass on to other more imposing veterans, regarding this early British racing car as of only minor interest.
A little thought will show how wrong this attitude is. In 1914 this Sunbeam was amongst the most successful racing cars of the day, at a time when engine design had received great stimulus from the trouncing which the huge Fiat and Lorraine-Dietrich cars had suffered in the 1912 French G.P. at the hands of the Peugeots designed by Ernest Henry. These Peugeots were comparatively small and light, and with motors of approximately half their rivals’ capacity. They achieved victory by reason of higher engine speed and greater controllability, and they had a most noticeable influence on subsequent racing car design. Thus, for the 1914 T.T. Minerva took second and third places with Knight sleeve-valve engined cars, having extra exhaust ports uncovered by the pistons at the bottom of the stroke. Humber favoured a single o.h.c. engine which, to modern eyes, appears to have anticipated the 3-litre Bentley in many ways. Laurence Pomeroy designed a team of Vauxhalls with twin o.h.c. engines, and an original system of crankcase ventilation. All had to give best to the Sunbeams. Owing to their light weight and comparatively short wheelbase, they somewhat lacked directional stability at over 90 m.p.h., but nevertheless attained 100 m.p.h. during the race, although from contemporary accounts they would seem to have snaked a good deal at this velocity. The race was run over the sinuous I.O.M. course, where the light weight and advanced design of the Sunbeams gave very rapid acceleration that was a great advantage. K. Lee Guinness did one practice lap in 37 mins. 45 secs., an average of 60 m.p.h. The roads were rather muddy, so a small mudguard was carried over the off side front wheel to shield the drivers. On the first day, the Sunbeams started with steel-studded Dunlop tyres all round, but on the second day, the then more usual arrangement of two studded and two rubber-treaded tyres on diagonally opposite wheels was adopted. Two spares were carried behind the bolster tanks. The cars were started at minute intervals, and K. Lee Guinness and his brother Algernon immediately went into first and second places and remained there for the first day’s racing of eight laps or 300 miles. Porporato’s Minerva was some 12 mins. behind the second Sunbeam. During the second day, Algernon’s rear universal seized at Hilbury on his 13th lap, and he had to retire, but “K.L.G.” won by 20 mins., at 56.44 m.p.h. for the 600 miles, from Riecken’s Minerva. Resta, on the third Sunbeam, had retired after two laps with a broken big-end bolt.
The years have rolled on, but these Sunbeams have not entirely disappeared. The winning car is in New Zealand, as was described in MOTOR SPORT in April, 1938. Another, the property of B. Dunwell and possibly the reserve car in 1914, carries a four-seater body, and formed the subject of the second article of this series (November, 1930). The car now at Chelsea has been rescued from the scrap collectors by Anthony Heal, who intends to restore it to as near original trim as possible. It is not yet in running order, but technically it is sufficiently advanced in many ways to stand comparison with modern sports-cars, and when restored it should be a truly absorbing possession. Unfortunately, there is no real clue to which car of the team it was, but Anthony inclines to the view that it is the car handled by Resta.
The four-cylinder engine of 81 x160 mm. (3,298 c.c.) has two overhead camshafts, driven by a train of gears at the front of the engine, which operate four valves per cylinder. The cam cases are supported by long studs from the cylinder head; the valve springs being exposed. Light steel fingers are interposed between the cams and the tappets. A good deal of oil escaped from the cam cases down the tappet guides, so that it was found necessary to protect the plugs by means of metal guards.
The counterbalanced crankshaft is made in two parts and supported on three large diameter ball bearings. The steel pistons are drilled for lightness. A tubular member connects the centre of the piston crown to the middle of the gudgeon pin. This not only gives additional support to the piston head, but also helps to conduct away the heat.
Air pressure in the oil tank forces oil to the main bearings and camshafts through visible drip feeds in the dashboard. Lubricant, thrown out from the main bearings, is caught by channel section steel rings attached to the crank webs, whence it is fed centrifugally to the big ends through oil ways drilled in the crank pins. A scavenge pump returns the oil from the sump to the oil tank. The air pump is driven from the front of the inlet camshaft.
A Claudel racing carburetter supplies the mixture through a V-shaped copper induction pipe. Four separate exhaust branches originally projected through the bonnet into a long, straight-through pipe. The oil, air, and petrol pipes were enclosed in rubber tubes to protect them from vibration.
A Ferodo-lined cone clutch transmits the drive through a normal four-speed gearbox and an open propeller shaft with two universal joints. The gear ratios are 11, 7.25, 4.8 and 3.4 to 1. The back axle is fitted with a differential, and although this may seem quite normal to us nowadays, many people at that time thought that the differential had certain disadvantages. A solid axle, it was thought, gave greater steadiness at high speed, but on account of the winding nature of the Isle of Man course it was considered that the differential would render the car easier to handle in the event of tyre failure.
Large, well-ribbed brakes on the rear wheels are operated from the pedal by means of cables. The hand lever takes effect on a transmission brake behind the gearbox, the drum of which is of such size that it projected through the floorboards. The purpose of these large size brakes was to ensure that the linings would endure throughout the whole two days.
Hydraulic shock-absorbers were fitted to both front and back axles, and broad straps, attached to the chassis, passed under the rear axle casing to limit its movement.
Altogether a most interesting design, well representative of 1914 practice. We shall look forward to seeing Heal driving this Sunbeam in pre-1915 class events when war is over, as inspiringly as he has handled his much bigger, though actually less thoroughbred, Fiat in the past. If he elects to use his most recent possession on the road as well, lots of sports-car owners are due for a surprise, for 100 m.p.h. from 3-litres is a good speed, even to-day.