Rumblings

Two Sprints
October will see two more sprint meetings. On the 8th the Bristol M.C. & L.C.C. will hold a meeting at Weston-super-Mare, a repeat of last year's highly successful Two Sprints initial event, along the Marine Parade and Promenade in the best old-style seaside speed trial tradition. There are no specific sports-car classes, but the usual capacity classes, all cars over 2 litres, however, running together. Entries have closed. F.T.D. wins £75, and we shouldn't be surprised to see it go to Butterworth's A.J.B. A slight bend in the 1/2-mile course will render the battle exciting.

On the following day the Vintage Sports Car Club will stage one of its big days, at Luton Hoo, in aid of the National Institute for the Blind. The course is that exciting one of no less than 1.4 miles, cars turning at one end and proceeding back towards the start. Again, no sports-car classes are included, but any age car is eligible, vintage cars competing for special awards. Entries are limited to about 50 cars and unfortunately no Edwardian class is included, so that these cars are deprived of an autumnal outing. The entry list has closed, but marshals may still be needed — offers should be made to G. R. Grigs, 73, Redcliffe Gardens, S.W.10. Improved spectator accommodation is available, and the charge is 3s. each, children 1s. 6d., cars 5s., coaches £5 (with all passengers); profits to go to the blind. V.S.C.C. members go in free if they show their current membership cards. F.T.D. again carries £75, the cash prizes totalling £150, so the struggle should be a keen one. Starting time is 12.30 p.m., practice occupying from 12.30 to 5 p.m. on the Saturday, so presumably those who run at Weston-super-Mare will have to miss Luton.

Both these events are deserving of your support. They would appear to conclude the speed season, after which those who prefer to do other things besides spending the winter before the fire or in the cinema can busy themselves with spectating at trials.

The A.J.B.
There have been few sprint cars so enthralling as Archie Butterworth's four-wheel-drive A.J.B. with redesigned air-cooled V8 Steyr engine. That this car works is proved (a) by watching its acceleration from a standing-start, and (b) by cogitating its f.t.d.s at Weston last season and Brighton this season. Consequently we are glad, and our readers will be glad, that Butterworth, who conceived, constructed and controls this A.J.B., has generously penned some notes for us about his intriguing car. Potent as the car is as a sprint job, Butterworth has some very definite ideas for a future Grand Prix Formula I car, as the data sheets he includes in his notes show; it will be perceived that he has already secured patents on many of the special features he proposes to incorporate.

Butterworth admits that his A.J.B. was the outcome of seeing Sydney Allard at work in his Steyr-engined car, so it is fitting that Motor Sport should not only publish the exclusive data on the A.J.B. which follows, but that in August, 1947, it gave the first detailed description of the Steyr-Allard. It remains only to hand over to A. J. Butterworth, but before giving you his exceedingly interesting data we would like to say that, as befits an ardent member of the Bentley Drivers' Club, the designer/driver of the A.J.B. now uses the original "Speed Six" Bentley, endowed with a vast van body, as his tow-car; his enthusiastic wife accompanies him on all his racing expeditions. Over to "A.J.B.": —

"By way of preamble, the current A.J.B. started life as a retrograde step! Early in 1947 I had on the board an unblown V8 4 1/2-litre engine of 89 by 89 mm., to go in an all-independent chassis incorporating stressed-skin tankage (it seemed to me that to hope to compete in Formula races, blown or unblown, one had to accept the necessity for alcohol and high fuel consumption). At this point I saw at highly exciting debut of Sydney Allard's Steyr-engined car at Prescott. Inquiries suggested that it would be a good plan to adapt my design to use the 92-mm. Steyr crankshaft, and the resulting smaller bore-87.5 mm. — enabled me to machine my cylinder heads from the Steyr castings, but only just! Naturally, new cylinders, pistons, cams, etc., were required.

"Next, an almost complete hold-up of materials for the G.P. chassis and gearbox, in the winter of 1947-48, made me decide to build a more simple car as a short-term, experimental project. I had hoped to adapt a Jeep chassis, but the frame and suspension were found to be quite hopeless for fast work and in the end only six feet odd of the Jeep side-channels were incorporated, in a fully-boxed 7ft. 6 in.-wheelbase frame using semi-elliptic springs with hardened steel slide blocks instead of shackles, underslung tubular torque-arms all round, and a diagonal sway-bar at the back. The Steyr gearbox was retained, although only three of its ratios were any use and these so wide as to require yet another camshaft redesign. (The rather "peaky" camshaft for the G.P. engine was designed for use in conjunction with a very close-ratio five-speed gearbox.)

"This 'quick answer' was built and raced in one day short of six months, being started up at midday at my home in Frimley and 'run-in' up the course at the 1948 Brighton Speed Trials the same afternoon, where it did one slow run and one fast one, mysteriously being given a slower time for the full-throttle run!

"Standard Steyr cams were used for the first two meetings (Brighton and Prescott) and the intermediate cams were ready for Weston in October last year, giving us our first success — f.t.d. in 23.16 sec.

"I was very concerned to get the car finished before the 1948 season was over and so, instead of a properly-designed suspension system, hard springs were thrown at it on the Brooklands principle that even a bad suspension will go straight at speed if it isn't allowed to work! The Editor, having been towed in the car down to Goodwood and back last year, has, I believe, some very bitter memories of this. [Memories, yes, but the bruises have healed. — Ed.) On a fast bumpy corner I found the effect appalling.

"During the winter the front springs were softened as far as they safely could be without danger of shimmy (a wide front spring-base is a great help in this respect on a rigid-axle car), the front and rear frequencies matched up as close as possible, and the axles properly located. Result — the A.J.B. is now comfortable and in my estimation handles well.

"Its main requirement now is a suitable gear-ratio for the slower sprint courses. The following comparative data sheets between the current car (S.2, i.e., S for sprint; S.1 being a long-forgotten dirt-track effort) and the proposed G.P. car may be of interest: —

S.2
Wheelbase ... 7 ft. 6in.
Track ... 4ft.
Weight ... 14 cwt. (plus about 50 lb. in road-racing shape)
Bore and stroke ... 87.5 by 92mm.
Cubic capacity ... 4,425
Design b.h.p. ... Not ascertained. Estimated as 230-250 at 4,700 r.p.m. #
Design max. torque ... 350 lb./ft. at 2,500 r.p.m. (established by skid-torque tests).
Design max. b.m.e.p. ... -
Cylinder arrangement ... V8, air-cooled.
Heat, material ... Alloy
Barrel, material ... Iron Barrels
Lubrication ... Wet sump, radiator
Gears ... Three-speed, dog-engaged, separate transfer box.
Ratios ... .805, 1.24, 2.1-to1.
Equivalent ...1, 1.54, 2.6-to-1
Transfer ... .66-to-1
Final Drive 4.88-to-1, free differentials.
Overall ... 2.58, 3.97, 6.75-to-1
Suspension ... semi-elliptic, slide locks, torque arms all round, rear sway-bar. Newton shock-absorbers all round, additional friction at front.
Roll Centre ... Approx at axle level front and rear.
Frequency, front ... 128 cycles/min. Adjustable in ranges 86 to 100, progressive bump control.
Frequency, rear ... Sprint, 123; road-racing, mean 115. Adjustable in ranges 86 to 100, progressive bump control.
Brakes ... 9 in. by 1 3/4 in. Lockheed 2LS, mechanical, hand, rear.
Castor angle ... 2 deg.
Tyres ... Dunlop racing, 5.50 or 6.00-16
Magneto ... Scintilla Vertex 8.
Plugs ... Lodge R49.
Pistons ... Martlett.
Carburetters ... Eight 1 5/32 in. Type 289 Amals.

G.P.1
Wheelbase ... 8 ft. 0in.
Track ... 4ft. 1 1/4 in.
Weight ... 11 1/2 (dry)
Bore and stroke ... 87.5 by 92mm. or 89 by 89 mm.
Cubic capacity ... 4,425
Design b.h.p. ... 350 at 5,500 r.p.m. @
Design max. torque ... 370 lb./ft. at 3,700 r.p.m.
Design max. b.m.e.p. ... 210 lb/sq. in. at 3,700 r.p.m.
Cylinder arrangement ... V8, air-cooled.
Heat, material ... Alloy
Barrel, material ... Alloy Barrels, iron liners.
Lubrication ... Wet sump, radiator
Gears ... Five-speed, built-in transfer shaft, foot control.#
Ratios ... .5.0, 4.0, 3.0, 2.0, 1.0-to1.
Equivalent ...1, 1.12, 1.37, 1.79, 2.46-to-1
Transfer ... Various
Final Drive -, hydraulic controlled differentials.
Overall ... -
Suspension ... Generated vertial straight-line wheel motion with axles and brakes on frame.# Adjustable torsion springs.
Roll Centre ... Approx at axle level front and rear. Front roll central.
Frequency, front ... 128 cycles/min. Adjustable in ranges 86 to 100, progressive bump control.
Frequency, rear ... Sprint, 123; road-racing, mean 115. Adjustable in ranges 86 to 100, progressive bump control.
Brakes ... Disc, hydraulic, separate hand, rear.
Castor angle ... -
Tyres ... -
Magneto ... -
Plugs ... -
Pistons ... -
Carburetters ... Eight 1 5/16 in. Type 10TT Amals.

@ Differentials: British Patent No. 585736.
Suspension and drive: British Patent No. 618423.
Gears and control: British Patent Application No. 23019.
Valve gear: British Patent Application No. 23018.
# [It will be recalled that Allard claimed 80 b.h.p. at 2,000 r.p.m. and about 140 b.h.p. at 4,000 r.p.m. from his Steyr, but the compression-ratio is lower and it gives away over 700 c.c. — Ed.]

"Finally, the three great bar-room talking points — compression-ratio, fuel consumption and maximum speed. The first is easy and definite: 14.1-to-1. Average measured m.p.g. of fuel is between 5 and 7 according to jets and where I'm consuming it! This fuel being currently 80/12/8 methanol, benzole, petrol. As to speed, I have only rev.-counter readings to go by. Two fairly careful readings on a smooth runway at the end of some s.s. kilometre tests (average time 24.25 sec., by the way) gave 4,850 r.p.m. This x 2.58-to-1 x 5.50-16 racing tyres equalling, I think, 154 m.p.h. A wild and bumpy 4,900 r.p.m. at the V.S.C.C. Silverstone meeting on 6.00-16 tyres I think it safer to discount, but we were certainly going very quickly. I may say that there was no question whatsoever of clutch slip on these occasions — Ferodo and Borg and Beck and I looked after that very drastically last winter."