Enduring Racer

Its two decades old, but it’s still racing, we peak under the skirts of the Aston Martin Nimrod  group c endurance race. 

The world endurance championship rules were formulated to group c regulation in 1982 and a classic era for long distance sports car race cars was thus born. Even today the genetic shape of those cars is  uppermost in many motor sports fans minds when you mentioned Le man GTP class, in which the Bentley was the sole runner  in the last two races, caters for outwardly similar machines in a nutshell closed sports prototype. In essence what the group c rules require was for manufacturers to construct their own chassis, But engines had to be production based. This allowed independent constructors  like March, Lola, Nimrod, Grid, Rondeau and WM to fit such as Chevrolet, Ford, Aston Martin Tickford and Peugeot engines and compete against the major established manufacturers like Porsche and Lancia. by the mid 1980’s more manufacturers had joined the fray , including  Spice, Harrierit’s, Ecosse, ADA, and EMKA, and of course Jaguar which won le mans and the world championship  with a series of cars from the XJ-R6 through to the XJ-R15. Heady days indeed. But it’s not all just a dim and distant memory as many cars form the period not only survive but are also still fit to race. Enter Heritage Racing Support, the motor sport arm of a well known Stratton motor company, an Aston Martin and Lotus dealership run by arch-enthusiast and race car pilot Roger Bennington. Heritage racing support was set up to provide preparation and racing support services to Aston Martin’s and their owners, and in conjunction with the Aston Martin owners club the company runs the Aston Martin championship and the Lotus road sports series. It has also created the Historic Grand Touring challenge, and the world sports car invitation trophy. The latter is the new arena where these superb  group  C and similar machines can come out to  entertain their drivers, and the trackside spectators, not surprisingly Aston Martin powered cars feature prominently in this series.

Aston Martin Nimrod was one of the earlier machines to be built to group C regulations and it’s a brute, looming large around that Aston Martin Tickford V8, with a classic race car layout but sturdily built to withstand the rigors of high-speed endurance racing. But first of all here is a little bit of history to put the car in context. Robin Hamilton, an Aston Martin dealer from Staffordshire, formed Nimrod Racing Automobiles (NRA) in 1981 with  Victor Gauntlett, then the new chairman of Aston Martin and. Petroleum. Eric Broadly and his Lola concern were contracted to design the chassis and running gear, while engines were prepared by Aston Martin Tickford, then an Aston Martin subsidiary. Five cars were built, one as a development car and the other four to either group c or the USA equivalent of group C regulations and were raced extensively in the USA and Europe. Ray Mallock and his late father Arthur were responsible for the suspension preparation of the cars, and Ray made his Le man debut with Drake Olson in 1982 aboard chassis number 003. We were running well but during the night we had an engine problem and limped home on 6 or 7 cylinders But we still managed to finish seventh overall." Ray recollected.

NRA ceased trading in August 198:3, and Ray Mallock Ltd basically carried on with the project, financed by Victor Gauntlett. RML produced an 'evolution' bodywork kit, as you see on chassis number 005 before you, for the 1984 season, but tragedAston Martin ample issue of engine, needy struck at that year's Le Mans, as Ray recalled. "it was about 11 o'clock on Sunday, John Sheldon was driving 004 and I was sharing 005 with Drake(OIson).

John had a slow puncture in his left rear b/re, but it was being kept up at speed by centrifugal force. This was pre Mulsanne chicane days, and as he went into the Mulsanne kink the b/re collapsed. The car hit the barriers and broke in two. A marshal was killed, and John was very badly injured and burned. He subsequently made an excellent recovery and is racing again. But ironically the next car on the scene of John's accident was our Nimrod and Drake hit the debris and crashed out:' 004 was totally destroyed, but 005 was rebuilt by RML, and now resides in the tender loving care of Roger Bennington at Stratton Motor Company who have restored it to its former glory. Nimrod is, apparently, an old Hebrew word for valiant, but its modern meaning is 'great hunter, or sportsman,' a well-chosen tag for such a machine then.

Simple construction. This particular Nimrod - type 01 and chassis number 005, the last to be built - was constructed for the 1984 season of the World Endurance Championship, as it was then known. Although many constructors were beginning to take advantage of composite construction at this time, the monocoque of Nimrod 005 is basically comprised of folded and riveted thin aluminum sheet with a few panels of aluminum skinned aluminum honeycomb sandwich, such as the central divider between the driver's seat and the 'passenger space', and at the front either side of the radiators. When Nimrod ceased its business activities it was actually designing an advanced carbon composite chassis, but the credit for the first composite sports prototype ended up going to TWR for its Jaguar XJR-6 in 1985. The Nimrod's chassis structure is essentially comprised of two large box sections, one on each side, linked by the floor and the bulkheads behind the cockpit, over the driver's legs and ahead of the pedals. Twin roll-hoops, one over the rear bulkhead and one under the top of the windscreen add some more stiffness and afford driver protection. Compared to today's race cars you can't help observe that the chassis sides are low, and frontal protection is a bit minimal.

Suspension and wheel systems. Lola did the basic design of the suspension, but the task of making it work fell to Ray and his father Arthur Mallock, as was mentioned earlier. The layout is fairly conventional for its time at the front, with cast magnesium uprights held on by double unequal length wishbones, the upper of which is also a rocker that actuates the inboard mounted spring damper units. The rear leg of the lower wishbone is fitted with a rubber gaiter to prevent muck and rain getting in the cockpit. The inboard mounting point of that same wishbone is just under the driver's legs, by the way, again a location you probably wouldn't see these days for safety reasons. The long steering rack connects to steering arms that offer a choice of outboard locations for varying steering rate (and weight), while the anti-roll bar is actuated from the inboard ends of the top rocker, and resides behind the radiators. The rear layout is even more traditional, with the cast magnesium uprights located by a short single top link, twin lower links and twin radius rods, and the springs and dampers are outboard. A long anti-roll bar, adjustable by sliding top links, runs across the top of the rear suspension, actuated by drop links connected to the bottom of the rear uprights. The forward radius rod connections offer a choice of location so that anti-squat and anti-lift characteristics could be played around with. Koni double adjustable, alloy- bodied dampers are used front and rear. The Nimrod's 18-inch BBS split rims accommodate pretty hefty-Looking brakes with four-piston AP Lockheed callipers and :5:30mm diameter, :35mm thick ventilated discs. Ducting from the front end to the front and the rear discs provided additional cooling, of which more shortly. The hydraulic fluid reservoirs are voluminous too, ensuring a copious supply should any weeps or leaks develop. Ray Mallock recounted his feelings about the car's handling both from those days in the 80s and again in 2002 when he has shared the Nimrod with son Michael in WSCIT events. "It was lovely to get back in the car," he said. "It was underpowered compared to the turbocharged cars of its day, and overweight too. But it has super handling, with a good balance and good brakes. We certainly got the suspension to work well! It was great to drive it again, and it was the first time I've been able to share a car with Michael which was good too."

Drive train. The big V8 nestling in the back of the Nimrod has its origins dating back to 1969 when it appeared in the beautiful DBS VS. In standard form and on carburettors it produced around :375bhp, and by the time the car had evolved into the Vantage it was turning out 4:38bhp. So when Ray Mallock recalled that it turned out 'just' 540bhp at 6250rpm in the Nimrod, you can understand what he meant earlier when he said it was a bit underpowered. Originally on Lucas mechanical fuel injection with slide throttles, the all-alloy, double overhead cam, two valve per cylinder engine would rev to 7000rpm, compared to the road car's 5800rpm peak power speed. Some of the race engine's power hike came from the usual balancing and lightening which, together with forged pistons and H-beam conrods, enabled somewhat higher revs. Cylinder head potting and full race cams provided improved breathing, as did enlarging the valves, which were already the size of dinner plates. But remember, endurance racing is not necessarily about ultimate speed, rather it's a balance between speed and durability, and so an overstressed engine isn't what's needed. The big capacity of the Aston Martin V8 was what fundamentally produced the power and torque, enough to propel the Nimrod to pretty competitive performance at Le Mans and in other endurance races in its day. That it came third in the World Championship in 1983 proves the point. Aston Engineering look after engine preparation nowadays, and the induction system has now been converted to an MBE engine management system with electronic fuel injection, which, Ray Mallock observed, makes the engine more flexible and easier to start and warm up. Twin four-into-one exhaust systems pipe waste gasses into those huge silencers, which then merge into that gas main-sized tail pipe. Lubrication is by a dry sump system as you might expect, with that massive oil tank located on the right hand side of the engine bay. Twin oil coolers connected together reside behind the single, large water radiator at the front of the car. The transmission, fed through an AP Racing 12-bolt triple plate clutch, is one of Mr Hewland's sturdier models, the five-speed H-gate magnesium-cased DG300 transaxle unit with Salisbury plate-type limited slip dill. This 'box had an integral oil pump for efficient lubrication, and an external oil cooler, located on the left hand side of the casing, another essential for endurance racing. Notice those enormous universal driveshaft joints too - they didn't want one of those to break, did they...

Reworked body. You'd think that a body as curvaceous and intuitively 'streamlined' as a closed top Group C cat's would have inherently good aerodynamics - well, at least low drag anyway. And you wouldn't necessarily be wrong. But in the quest for all-important aerodynamic efficiency (especially true of endurance racecars where fuel efficiency is vital) this car actually became Ray Mallock's first wind tunnel project. And it was the same for one Willem Toet, known to some as an extremely fleet hill climb driver and to others as the BAR F1 team's chief aerodynamicist these days (having previously also served in that role at Benetton and Ferrari). Ray recalled "we ran a quarter scale model at MIRA and we found three times the downforce while reducing the drag by 10 per cent. The gains contributed to an 11 seconds per lap gain around Le Mans." Willem also strolled down memory lane to recollect some of the details: "Having had the model built we only had two or three days testing with time in between those days to re-think and make more bits to test. I remember being dismayed with our first day's testing. It took too long to make the changes we needed to make. The next time we went we were better prepared and, for example, for bodywork changes we built the model to the smallest configuration that we wanted to test and built up layers (of clay generally) over the base shape on cling film so that we could carefully remove one layer at a time to expose the next shape. The next day's testing went much better... "Some of the key things we found included cooling. The size of the inlet duct, its expansion rate, the angle of entry, and the angle of the radiator had a dramatic effect not only on cooling but also on down-force. The side view of the nose near the front wheels had a big effect on down-force and drag. The splitter was the big down-force producer loads of down-force for no drag. And even without ground effects the underbody made a difference too. "The plan view of the windscreen bubble was important, and the detail shape of the wheel arches made quite a difference. The slot behind the front wheel was designed to extract pressure from the wheel arches (most cars use Louvres on the top arch surface now). Clearly the rear wing made a difference, and the relationship between the wing and the bodywork was important. We had a longer, more swoopy tail than the previous Nimrods, and we also tried to keep the back end of the car open to atmosphere to use the Arthur Mallock 'shoe box' effect - rip the back out of the box, push it forwards fast and the base drag suction also sucks it down. "The rear wing and the tail both had Gurneys [no longer fitted to the rear wing as photographed] and the one on the body was very efficient. We even built driver-cooling exits into the car. The engine was fed by an airbox from NACA ducts in the roof. They fed into aluminum expanders that continued to expand the air and hence convert dynamic to static pressure. This made a difference to power and kept the engine supplied with nice cold air. "Then there was brake and driver cooling. The base design had the 50mm by lOOm oval ducts at the front (either side of the radiator aperture), but initially we fed two 50mm flexible hoses, one on each side to the brakes and one to the driver. Both the brakes and the driver cooked! Then we made some expanding ducts to slow the air down a bit and split the air into two tubes for the brakes and one for the driver (entering the cockpit via Ford swiveling ducts). Ray was pleased when he tested them because he was nearly blown out of the cockpit!    "Happily it wasn't obvious to competitors which of the changes we made were cosmetic and which were important aero wise," says Willem. "On the Ray Mallock car none of the changes were cosmetic." Which, as Willem says, is why he loves aerodynamics, and is what makes it as much an art as it is a science - as I’m sure he won't mind me pointing out.

View from the cockpit. You'd need a bit of practice to slide in and out of this car swiftly at a pit stop, but once installed the view is panoramic. The seat is little more than a couple of plastic bags of expanded PU foam strategically located to grasp the nether regions, but your buttocks are in firm contact with the chassis floor. Talk about driving by the seat of your pants. Being about three feet shorter than Ray Mallock I could barely reach the pedals, and though this compromised my ability to sense what the car was doing it didn't jeopardise our entirely static photo shoot in any way. Mind you, snapper Harmer reckoned he was on the limit as he reversed it (under the power of gravity) out of the transporter in the morning. The instruments are tellingly primitive by today's standards, the big one in the middle being a Jones chronometric tacho. In case you're too young to remember those, they were driven by cable off the end of a handy camshaft or such like, and told you what rays you'd been doing half a minute ago. Oil pressure, water temperature, battery volts and fuel pressure are also displayed on good old-fashioned analogue dials. In the passenger space is the obligatory pair of Firefighter extinguishers, just in case...

Performance and cost. As some sort of performance comparison guide it's interesting to look at the lap times from the event at Silverstone in early June this year. The best lap put up by our Aston Martin Nimrod in the two races was l-minute 22.1 79secs. The best lap set by the winning Saleen GT in the British GT Championship race at the same meeting was lm21.207secs. Eighteen-years and less than a second between the cars then. But a valid comparison is not really possible, especially when you consider the Nimrod is a rare, valuable and cherished part of Roger Bennington's inventory and no doubt the drivers kept this in mind while they were racing it. In fact Roger tells me that if you and I wanted to buy one we'd need around £200,O00. Looks like I'm going to be on that street corner near Rave Talker's place for a few more nights yet then...