Ralph Watson New Zealand Legend

My Years of Motor Racing Engineering
By Ralph Watson
Note: This article appeared in the January 1997 edition of ‘Front Wheels’, the official magazine of the BSAFWD club.


Some pictures of the Watson special, supplied by Ray Waters


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Extra spring leaves

Front Assembly

Racing at Ohakea

After the rebuild

After the rebuild

Lowered chassis

Racing at Wigram

Front Assembly


Although I had competed in Club events with a Singer Le Mans my introduction to racing on a larger scale occurred in 1949 at the first race on the Wigram airfield circuit.
I was asked to help in the pit crew of the Austin 7 run by Ron Roycroft and Harry Chatteris. This was one of the 1931 single seater Brooklands racing cars with an offset drive low seating position and strengthened and supercharged motor producing about 56bhp.
The clutch had cast iron linings and suffered from slip when Ron tried a practice lap, so we carried out the usual cure of pouring petrol into the clutch housing through a funnel held alongside the exhaust pipe while Ron revved the motor and Harry lay on the road holding a plug in the hole in the bottom of the housing. This procedure seemed to add to the excitement and sense of danger. Other troubles prevented Ron doing any worthwhile practice and when Halsey Logan with whom I had become friendly asked me how I thought the Austin would go my reply was that it was in trouble and would not do any good-a poor prediction!
On race day, Ron started from the back of the grid and was well through the field by the first corner A battle developed between him and Hec Green, both having pit stops en route.
Ron’s first stop was to change a wheel his outside rear tyre had lasted only 75 miles. On restarting a plug oiled so he came in again and we changed them all. He eventually finished 6th.
Interesting specials at this meeting were Hec Green’s Wolseley a single seater with a modified 6 cylinder OHC motor (from an English police car) in a quarter-elliptic sprung chassis. It was quite quick and was to win the race the following year.
Halsey Logan’s entry was a 1936 Singer Le Mans motor in a Fiat Mouse chassis and Pat Hoare had a similar car.
When seen again in 1952, both of these cars were supercharged. Pat’s having a Vauxhall motor.
On returning home, full of enthusiasm, many ideas for building specials were considered. One of these was an aero-engined car using the small radial Pobjoy motor, and although with the help of friends one was located, it could not be obtained. Another interesting scheme was to use 2 Triumph Thunderbird motors, each driving one pair of wheels, the throttles being coupled to twin pedals so that the proportion of power front or back could be controlled by rocking the foot. It was as well that these ‘problem’ schemes came to naught, particularly the latter, which may have been more suited to Stirling Moss as driver!
Many other possible motors were listed, among them being the 1930- 36 BSA air-cooled V twin used in their 3 wheelers, and finally a 4 wheel 1931 chassis with this motor was obtained from under a hedge. These are a 1021 c.c. 90° V twin with a wet cork clutch, 3 speed gearbox and worm drive unit mounted in front of the engine and driving the front wheels. Suspension was independent at the front with 4 quarter elliptic springs each side. When building the special, the chassis was cut and lowered behind the motor, and new rear spring mountings made. Body framework was made from duralumin angle cut from aircraft wings, and the aluminium panels were riveted on, forming a stressed-skin construction. Plywood was used for the floor and top of the scuttle.
As the car was front drive, every effort was made to keep the weight forward, the tail being very light and just used as luggage space when touring.
The original brakes were one 8″ drum mounted on the differential cage for the front, and 7″ drums on the rear wheels. These were retained, but with a new fully compensated operating system of rods and cables fitted. Braking through the differential gave even braking action on the front wheels in all conditions, and the system proved fairly satisfactory though the front drum did suffer from fade when the brakes were used hard. Engine development went on over a period of 4 years. It was found possible to bore out the valve seats about 1/4″ and fit Speedway J.A.P. valves and springs, which with 1 5/32″ Amal carburettors greatly improved the breathing. Lack of lubrication at the exposed pushrod ends caused rapid wear of the top ball joint ends, so these were replaced by a flat top acting against a radiused adjusting screw on the rocker giving a rolling instead of rubbing motion, and lighter pushrods and tappets were made at the same time.
The original big end had loose rollers without cages and as these needed replacing the crankpin was ground to take standard roller [bearings. This was a bad mistake as the bronze cages wore rapidly due to the centrifugal load, and the whole assembly seized up while testing the car before what would have been its first race. It was obvious the job had to be done according to the best engineering practices as one seldom gets away with less in a racing motor! A new crankpin was made and cages cut from an aircraft propeller blade to take 1/4 x s/s rollers. The lubrication was altered from jets into the cylinders to a feed through the crankshaft to the big end. A small crack, possibly due to the seize-up was found in one rod so 2 more of improved design were made from Nickel Chrome steel. The use of a milling machine to do the job was much appreciated. Except for normal wear this big end gave no trouble but the life of these bearings is not long, only about 8000 miles from this one. Later standard roller bearings were again used but with the bronze cages replaced with duralumin ones. It is interesting to note that if the inner race creeps around a little on the crankpin (but not enough to cause it to wear) the life will be increased, as the load is distributed around the race instead of being concentrated in one place where the case hardening eventually fatigues and breaks up. At this stage of development the car was run for the 1952 season, beginning with a standing 1/4 mile time of 19.1 sec and a handicap win at Seagrove airstrip, most of the opposition being from Ford 10 Specials, notably Don Tisley, whose car was faster.
Next came an enjoyable tour to Ohakea and Waikanae as pit crew for Ron Roy croft who was racing his Type 35 Bugatti. On the way down the Desert Road Ron passed me laughing and pointing behind. Arthur Cowper in a Ford 10 Special had been following him closely and found the sun in his eyes at a critical moment, the tail of the Bug vanished and a wall of rock appeared in its place, so he spun the car. Ron had made a quick left- hand turn over a bridge! At Waikanae, having some 400 miles to drive home, I had not intended to race an unproved and possibly fragile BSA, but the Club persuaded me to enter the 2 supporting handicaps to the main event. The first was won at touring speed with no stress on the motor.
On the start line for the second race George Smith, who had just won the Championship, must have had an idea of how things might go as he came over and enquired about my handicap. I took it easy again but about 1/2 distance got a wave from the pit and had to hurry a bit as a V8 Coupe was catching up. About this time too George took me by surprise, his GCS (V8 Special) coming past about 40mph faster with a shower of sand. However, he was still a lap behind which he could not make up, but I should not have forgotten about him. Home again and feeling more confident of the BSA’s ability to keep going, I entered for the North Island Championship Beach Race at Muriwai and finished the 50 miles in 3rd place, behind Ron Sutherland with a Willys Special and Fred Zambucka with a De So to Special, and ahead of some Ford V8s. George Smith and Ron Roycroft were not at this meeting. As usual when racing I ran with the silencers removed, the exhaust pipes terminating about level with the back of the seat. My ears -were painful for a week afterwards and I resolved never to do this again. As the correct length pipe would have finished level with the front of the seat and may have been even worse on the driver’s ears, all ideas of exhaust tuning were abandoned and a set of stub pipes about 4″ long were made, which resulted in much less exhaust noise and so were used in future. The next event was the North Island Championship Sprint at Napier, where the BSA managed a time of 35.4 sec for the standing kilometre. Other interesting times were Herb Gilroy’s 33.6 in the Brooklands Austin single seater/ George Smith’s FTD of 29.4 with the V8 Special and Ron Roycroft’s 33.4 with the Type 35 Bugatti.
When Ron suggested returning via Lake Waikaremoana and staying at the Tourist Lodge, I mentioned having been turned away for arriving in a dusty condition in a Singer Le Mans. Ron overcame this problem with a telephone reservation, so that on arrival, covered in dust, we were met by a disapproving porter waiting to carry our bags. Ron, perhaps because of speedway experience, seemed to accept driving in a cloud of dust, and I remember him saying that when flying stones appeared among the dust it meant you were dose enough to get past!
By the time we reached home again the BSA had done many miles trying to keep that blue Bugatti tail in sight in the distance.
Not long after, when driving back from Orewa one hot day, a head came off one exhaust valve and of course went through the piston. The pieces seemed to be safely out of the way in the sump, so the 2 pushrods were removed and the BSA driven home on the other cylinder and then this motor was retired! During the Ohakea tour I had acquired another BSA motor, the owner having fitted a s.v. Hillman in its place. Later inspection revealed that the cylinders had cracked off around the base flange at one time, and had been welded on again and sleeved, so this was not a very good motor but became useful for town running in the winter time. I later managed to get a 3-wheeler chassis with motor and gearbox, so now had a reasonable amount of spare parts.
For the next season a much improved motor was prepared. Long holes were drilled through the cylinder fins and long holding down studs fitted to avoid any possibility of the cylinders breaking off at the bottom flange. Rockers were enclosed and oil feed fitted to them at the same time. It was now possible to bore out the cylinders 3mm to give a capacity of 1095cc and fit pistons of 8 to 1 compression ratio. The inlet cams were altered by welding up and grinding off to the same shape as the exhaust ones. New valves with 1/32 ” larger dia stems were made from Rolls Royce Merlin ones and bronze guides and triple valve springs giving 169 Ib fitted. A Bradford distributor with reground cam was used, to take advantage of the centrifugal advance mechanism. All these changes increased the torque so much that the clutch slipped. This was cured by fitting twice the number of springs and increasing the pedal leverage to cope.
The small cooling fins and high cylinder temperatures made alcohol fuel desirable but the cost was a limitation. Checking the specifications of racing fuels from all the companies and comparing the latent heat values per $, resulted in making a mixture of blends from Shell and Mobil giving 44 Ethanol/18 Benzole/37 Petrol at 67c per gallon compared to the current price of petrol at 45c. With the calculated jets in the carbs, and plenty of spares, I set off to do some testing at Muriwai beach on this brew one Thursday. This turned out to be one of those wonderful days when every adjustment made resulted in the car going faster and I came home really thrilled with the BSA having reached 80mph on 1/2 mile straights.
Winning the NSC Club’s 1500cc scratch race the following Saturday against the Ford 10 Specials was almost an anti-climax to the best day’s testing ever. The BSA went on to win this 10-mile race 3 years in succession, the last time in the hands of a new owner, Dave Long.
Another interesting event was a Sprint where 16.6 sec for the standing 1/4 mile was recorded and 10.2 for the flying 1/4 – (88mph). An effort to race at Ohakea aerodrome was not so successful. After driving 300 miles to the meeting on normal compression, the 8 to 1 pistons were fitted by the roadside and alcohol added to the fuel. During practice a mixture check by the spark plug colour seemed to show too rich on one cylinder, so this was leaned down 2 sizes on the jet. At the beginning of the race the BSA was lapping comfortably with a supercharged MG TD for 11 laps but then one cylinder cut out. Inspection showed the plug points (platinum type) had fused together. As the only spare plugs were the touring ones, the car was nursed along at slightly slower speed for the 12 laps to the finish.
In hindsight it seems that, as much of the circuit around the curves by the Hangars was done on part throttle, the appearance of the plugs may not have been an indication of full throttle mixture, and a check down the straight by partly closing the air slides would have been more reliable. The platinum point plugs were not used again, a cooler type. Champion Rl, being substituted.
Many miles were done, the BSA being in almost daily use during the 4 years I owned it, with either pistons or motor being changed for competition events. The front wheel drive was suited to a car of its performance and made it very easy and safe to drive. With driver only, the weight distribution was 58 on the front, and the reasonably light small section tyres and wheels with no brake drums made for a good “sprung to unsprung” weight ratio, and gave excellent front wheel adhesion on sealed surfaces. Conditions at the rear were not nearly so good, the beam axle being rather heavy and having little sprung weight over it except when the luggage space was full.
Best speed through the comers was obtained with just a little power on, using most of the tyre adhesion for cornering force. If more power was applied the tyres would lose some of their cornering power and the radius of the turn become larger. Reducing power immediately tightened the turn, there normally being no possibility of spinning up. However, the car would spin up on a bumpy road if the rear broke away, the cure being to quickly apply plenty of power, which if the bump was in the right place could result in a very fast comer indeed!
Traction in mud was poor, it being of little use to attempt any slippery sections in trials. As the power of the motor was increased, it became easier to spin the front wheels till finally they would spin in top gear on a metal road, all steering control being lost and feeling almost as if it was disconnected.
The BSA was a good town car, as the front tyres could act as a soft bumper, and the rear was so light it could be lifted into a small parking space. Driving an open car in the rain is usually not too bad if the correct speed can be maintained. At 45 to 50mph the screen deflects most of the water over one’s head, but a cap with a good peak is essential. At higher speeds, heavier drops get through and at 30mph much water thrown forward from the top of the rear wheels can come into the cockpit if no mudguards are fitted, as I was later to find out with the Lycoming Special.
Plans were made for further improvements, such as a lighter rear axle to improve roadholding and a higher gear ratio for both touring and the longer circuits. The performance had been increased so much that the standard 5.25 ratio was now only ideal for sprints, and its continued use on mile straights would greatly increase the risk of a blow-up.
As making a worm and wheel would be a very expensive job, it appeared that the car had now reached the end of its economic development. Also by this time I had been test driving some much faster cars and had acquired 2 Lycoming aircraft motors, so the BSA was sold, though not without some regrets.
The new owner, Dave Long, required a spare engine modified for racing, and it was only when doing this that I realised how many hours had gone into the first one. This proved a wise move, however, as one engine later blew up in a big way when being raced at Ardmore.
In 1950, when building the special, new front axles were made of 4340 heat treated steel because the keyways in the originals were badly worn, due to the failure of previous owners to tighten the hub nuts sufficiently. One of these broke through fatigue when Dave was racing at Ohakea (a concrete track which generates high cornering loads). While the car slid to a stop on the steering arm the wheel took off across the track and, bouncing over the head of a Maori spectator who was sitting on a box, embedded itself in the wall of a shed behind him. Dave quickly ran over and retrieved his wheel while the spectator was still recovering from the shock. ‘Pi gorry you might have killed me!’ he exclaimed. This was an unlucky meeting for Dave, for the BSA had broken a valve rocker in practice, and he had only been able to get a spare by ringing a friend who took one off the spare motor and found some RNZAF aircrew who were flying down to see the race to take it with them.
The BSA valve clearances needed to be checked often to make sure they were right as the setting increased by 0.012″ when the cylinders warmed up. Two new front axles were later made, 1/16″ larger in diameter with splined instead of tapered ends and having taper roller bearings.
The BSA went on racing for about 2 years after I sold it, being driven by Bob Hugill and Mal Roberts as well as Dave Long. After this it seemed to disappear.
In the early 1950s another BSA was being used in competition in Christchurch by the Stanton brothers. This was a 3-wheeler to which a tubular rear axle with a transverse spring had been fitted, to convert it to 4 wheels. The Stantons also modified the front suspension by replacing the 8 quarter elliptic springs with wishbones and one transverse spring. When first meeting the Stantons in 1953, I was a little secretive about my performance times, but need not have been as the opportunity to race the 2 cars together never occurred.
At the time the Stantons were working on an aircraft-engined special, as I was to do later, so perhaps it is natural to graduate from aircooled BSAs to aeroengines 30 years later the 2 BSAs were found together in Wellington, where they had been stored for a considerable time. My car was in bad condition, the body having been removed and much of it lost. The best motor, however, was there and showed little wear, but had suffered from rust through being left partly dismantled.
After some negotiation and sorting of parts, the remains of my car came back to me. Examining it again after all this time, the lightness of the body construction was a surprise and even after bringing out my old notebook it took some time to remember all the important details.
Restoration work took nearly 2 years, a complete new body being required, the workmanship being of a much higher quality this time.
The concept and shape were kept the same as the original Special, but it was now possible to incorporate some improvements based on the sketches and calculations I found in my old notebook. The rear axle weight was greatly reduced and a new worm and wheel made to replace the worn one and raise the gear ratio from 5.25 to 4.4 This higher ratio would reduce stress on the engine and enable the car to be driven longer distances at modern motorway speeds, and also on racing circuits with long straights, with much less fear of blowing it up.
The first drive with the restored car along city streets felt so bumpy that I had doubts whether I would be using the car much. A second try early one morning along the motorway was much different and at 60mph the ride smoothed out, all the old sensations came back, and there was promise that it may yet become a delight to drive after all. The fitting of thinner front spring leaves brought the frequency down from 160 to 124, and this after many road tests to adjust shock absorber settings brought about an improvement in the ride.
During the 1985 summer the BSA attended some historic car meetings and hillclimbs but I drove cautiously being troubled by the thought that the early model connecting rods could come apart. They had some stress risers near the small end (these had been improved on later (1934) BSA rods) but worse than this, it had been impossible to polish out the rust marks which penetrated right into the steel (intergranular corrosion?), Also the tappets, although built up with hard welding, were wearing rapidly and the cams having lost their correct shape were giving the valve gear a rough time.
During the winter a suitable cam profile was designed with help from textbooks by Ricardo and Mackerle, and a new camshaft and tappets were made.
The connecting rods I had previously made were in the motor that blew up at Ardmore when Dave Long had the car, and unfortunately I had never examined the remains and do not know what became of them. Reports were that there was little left unbroken and no one could really say what gave way first. The pistons were New Zealand made Y alloy castings of light section, the piston pins were 3/4″ instead of the usual 7/8″, and the connecting rods had a stress riser where the shank joined the small end (though not as bad as the BSA rods from which they were copied) and from memory were cut from across a bar of steel so the grain would have been running the wrong way.
Hardness tests to find the strength of the steel used for the BSA rod and calculations showed that the would be stressed to their fatigue limit in the modified engine. Although I had 6 rods to choose from none was free from damage, corrosion, or manufacturing faults so it was decided to make new ones from 4340 steel, trying to avoid all faults this time.
New big end bearings were fitted, these being standard RHP 30 x 62 x 16 roller races but with dural cages made up to be guided on the outside (where the oil is) instead of on the inside as before. For safety the clearance to allow for expansion at an ’emergency’ 300°C was calculated and came to a surprising 0.018″. Another part found to be overstressed was the differential cage which holds the single front brake drum the spline which it fits on being twisted. No doubt improvements to the brake system and modem linings were responsible.
Tests showed the part to be made from soft steel, so it was easy to choose some twice as strong to make a new one.
After this there was sufficient time left to make 4 new gears for the gearbox to replace the worn ones and endeavour to reduce the scream when in second gear, something which was only partly successful. A greater benefit was the choice of closer ratios, which along with a lighter flywheel, made gearchanging faster and easier on the gears as they were no longer being used as synchro cones to the same extent when in a hurry.
At the same time needle rollers were fitted to the mainshaft spigot bearing, replacing the original bronze bush that at some time had become hot enough to soften the surrounding gear and its ball bearing. My guess would be during a climb on the 70-sec Wairamarama hill.
After all this work, 1,000 miles of local running with no real problems gave me enough confidence to drive the BSA on a nostalgic 2,500-mile tour to Dunedin and back to attend historic race meetings and visit old friends. The last occasion I had been this far south was nearly 30 years before in a rather similar car but of 4 times the power, so there were some interesting memories along the way. I A few laps were done at Wigram and Dunedin, but it was only after being back home that an attempt was made at Pukckohe using 50 alcohol fuel to find out what the top performance was.
No accurate times could be taken, but the BSA pulled its higher gear ratio and the top speed appeared to be higher than before, although the revs were 850rpm lower which showed how undergeared the car was originally. Acceleration was not as good as before. The most useful result of the change was the increase in touring speed from 50mph to 60mph and increase in engine life.

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