FORD'S 230-MPH J-CAR, DESPITE ITS 21ST CENTURY APPEARANCE, IS SUPPOSED TO BE A LIGHTER, MORE STREAMLINED VERSION OF THE LE MANS-WINNING MK, II. TROUBLE IS, IT'S SLOWER.
After you've won the world's most prestigious road race, what do you do for an encore? Well, for the team that created the Le Mans-winning Ford Mk. lIs, you think about next year because there is nothing more obsolete than last year's race car.
Or is there?
To date, Ford's J-car. successor to the Mk. II, is a qualified success at best. It has shown occasional flashes of brilliance, but it has never been entered in a race. It is a year late in emerging as a potent weapon in Ford's arsenal, and it has yet to demonstrate any reliable superiority over the Mk, II.
Contrary to some reports, the J -car is not the fastest car ever to lap Le Mans. A J - car was the fastest during last April's open practice session - run in intermittent rain when Bruce McLaren clocked a 3: 33.0. During the race last June, Dan Gurney's Mk. II set the fastest laps in both qualifying and the 24 hour, with a pair of 3: 30.6s (142,9 mph), but the "record" is a 3: 30 flat (147,2 mph), turned by Phil Hill in the 475-hp, 2375-1b, prototype of the Mk. lIs, unofficially timed during practice for the '65 race.
The Mk. II was over a year old when it took the first three places at Le Mans last year. Its basic design was more than two years old, and something of a hand-me-down at that, being descended from the Lola GT of 1963, The Mk. II is the most thoroughly engineered and tested race car ever made, and it would have been folly for Ford to throw all that away in favor of a completely new design. So the J -car is an evolution of the Mk. II, not a radical departure from the tried and true.
In 1964, Ford fielded unsuccessfully a team of the Mk. II's ancestors, the GT 40s, with their 289 cu. in. engines, and came away from the defeat determined to win the 24-hour classic the following year. However, in 1965, Ford split its effort between the GT 40s and the new Mk. lIs, with their NASCAR derived 427 cu. in. engines. Confusion reigned, and Ferrari won again. In the post-mortems, it was decided that the big-engined car was the only way to go, but that the Mk. II was too heavy. A new car would be designed-learning from the mistakes of the GT 40s and the Mk, lIs, but not basically different a car with less weight and better aerodynamics. Thus, the J -car was conceived as a Le Mans winner when the Mk, II would be made obsolete by its competition.
This year's Daytona Continental has come and gone and no one is sure if the Mk. II has met its match, The Ferraris won the race, to be sure, but at a slower average speed than last year's record (set by the Ken Miles/ Lloyd Ruby Mk. II), The Fords qualified faster than the Ferraris, but in the early laps of the race, the Ferrari P4s easily out-gunned the Mk. lIs. Both Ford and Ferrari planned to run a 24-hour pace, but a batch of faulty transmission parts decimated the Ford ranks before the issue could be settled, And the dark horse Chaparral was much faster than either the Fords or the Ferraris. Daytona wasn't a race, it was a rout, but the results are anything but conclusive.
The air of uncertainty following Daytona may have panicked some Ford officials. Ford's attitude toward the sport of auto racing the attitude of Henry Ford II himself is win at any cost, win "or else." Before the Continental, it was generally believed that, even though the Fords were getting heavier and the Ferraris lighter, the Mk. II could hold its own. In a win-or-else atmosphere, that isn't good enough.
The men who work for Henry Ford II want to make sure, so the J -car will finally be rolled out to meet the opposition.
Some say prematurely.
Ken Miles was killed at Riverside when the lightened, modified J -car he was driving apparently came apart. "Apparently," because the car was smashed beyond recognition, and despite intensive FAA type investigation, the cause of the accident remains a mystery. It's unlikely that it was driver error; Miles had more experience in the J - car and the Mk. II than anyone else, and was a phenomenally talented driver as well. For lack of any evidence to the contrary, Ford engineers were forced to presume that something went wrong with the car. And because nobody could pin-point the flaw, virtually every suspicious part had to be beefed up.
The Miles tragedy had a three fold effect on the J -car program. One, he was the best development driver Ford had, alone in his ability to test cars to the limit of their potential, accurately assess their characteristics, and communicate his evaluation to the engineers. Two, as a result of the beefing-up process, the J -car gained a few hundred pounds, not only making it slower but also placing a greater strain on its components. The point of diminishing return is reached when the weight of the extra beef'in a component causes another to fail-and some say the J -car is perilously close to this limit. Finally, the post accident investigation and subsequent modifications to the other J - cars consumed valuable time, time that was earmarked for vital development work. The J-car project may be as much as six months behind schedule.
The current J-car is a somewhat different machine than the J-car last seen in public at the '66 Le Mans trials. It is not a whole new creation, but it is different enough that problems that didn't seem to exist before have cropped up only as recently as February. The turbine-spoke wheels, for instance, cracked in mid-winter tests on the banking at Daytona. The automatic transmission has temporarily been shelved in favor of a conventional 4-speed manual. Engine output has been raised, and may be raised again. The car is heavier. And, to Ford's horror, it isn't as fast in a straight line all other factors being equal-as the Mk. II.
The J -car's body has evolved slowly, because aerodynamic development proceeds on a cut and try basis. The organic-looking "mandibles" on either side of the radiator inlet have disappeared. The air scoops behind the doors were first enlarged, then eliminated in favor of a faired-in fender line, with air being drawn in through slots on either side of the rear window. Trim tabs have been tried on the tail, which was supposed to work without spoilers. The latest bodywork looks somewhat like a Porsche Carrera 6. Meanwhile, the Chaparrals get slipperier and slipperier.
Ironically, it was aerodynamics that gave, indirectly, the J -car its nickname. A change in Appendix J, the rulebook of international racing, allowed smaller interior dimensions, and the J -car's shape was formed around a narrower cockpit that, hopefully, was to improve on the streamlining of the Mk. II. The official name of the J -car is the GT-P, for GT Prototype, the class in which it, the Mk. II, the Ferrari P4 and the Chaparral 2D/2F compete. The J -car nickname comes from the car's compliance with Appendix J.
The J -car is built at Kar Kraft in Dearborn. The outfit sounds like a hot rod shop, but it is, in fact, a supplier of tooling parts to Ford. When Ford's Advanced Concepts department was looking around for an outside shop where they could build their wild creations, Kar . Kraft stepped forward, and the facility has become the construction site of the GT prototypes.
Roy Lunn, Advanced Concepts Manager for Ford Division, occasionally occupies a large, walnut paneled office off the Kar Kraft drafting room. The walls are festooned with photos of GT 40s and Mk. lIs, and every corner is cluttered with a great assortment of broken or rejected J -car bits and pieces. Fractured J -car wheels are used as wastebaskets.
Most of the men who brought the GT 40 and Mk. II projects to fruition have been involved with the J -car effort. Lunn acts as the overall supervisor and coordinator, Ed Hull designed the chassis, and Chuck Mountain is the project supervisor. Track testing, design consultation and race preparation are provided by the Shelby American organization. Most of the actual engineering work is done by Ford people from the various divisions of the company, an arrangement Ford feels raises employee initiative and general morale.
Lunn explains the switch from sheet steel in the GT 40 and Mk. II chassis to the J -car's unique honeycomb aluminum panel construction in terms of the time involved.
"With the GT 40," Lunn says, "we were faced .with a one-year deadline from the beginning of the project until the date we were to be racing. We felt there were so many new areas and problems to be investigated and solved that we should use the simplest monocoque chassis structural material possible. Therefore, we chose sheet steel, a material with which Ford people had had a great deal of experience. We did J-car, so we decided to learn to use the strongest, lightest structural technique known. This is, of course, aircraft aluminum honeycomb-panel construction."
The J-car chassis is made entirely of an expanded aluminum honeycomb material sandwiched between .016-inch aluminum sheets, bonded together with epoxy resin and riveted in areas of highest stress. All major chassis pieces are bonded at the Brunswick. Corporation's Defense Products Division in Detroit, to take advantage of that firm's experience with sandwich panel construction for the aircraft industry.
Construction of the first J -car chassis presented one problem the designers had not anticipated: a maximum working time of less than an hour from the time the hardener and resin were mixed until it set up solid. A second, but related problem was obtaining the proper glue thickness with hand-trowel application methods. The situation was resolved by the adoption of sheet adhesives, which look and work like wax paper. A piece approximately the proper size is cut, positioned where desired, trimmed, and placed under pressure, with no working timelimit and no mess.
Both sheet adhesives and two part mixtures require a three-hour, 2500 F. cure and give approximately the same tensile and shear strength, but Lunn says the peel strength of the sheet adhesive is very high. If a suspension bracket or similar piece has to be modified after assembly, the work must be done on the chassis. Any attempts to peel or pry the piece off inevitably result in tearing the thin honeycomb panel, or breaking the offending item in half.
Suspension brackets, suspension arms, roll cages and other miscellaneous items are made at Kar Kraft, hardened and X-rayed if necessary at Ford, and shipped back to Kar Kraft for final inspection and installation. Many of the scrap items cluttering up Lunn's office are rejects that failed to meet anyone of the many inspection standards.
The J - car's original engine was a 427 cu. in. V -8, identical in specification to those used in last year's Mk. lIs. This powerplant is basically a NASCAR wedge engine with aluminum heads, modified porting, a lower compression ratio, and a single four-barrel carburetor. During most of the '66. season, these edItions are capable or ouu np J. uetail refinements to the Mk. II engines raised peak power to 505 hp, also at 6200 rpm. But less than a week before Daytona, Ford decided to switch to the cast iron NASCAR heads, with their larger ports and valves, and the two four-barrel carburetion, raising horsepower to 525 hp and engine weight to a whopping 660 Ibs.
In going to the 2 x 4-bbl. carburetion, Ford traded a small horsepower gain for a huge drop in fuel economy. The Le Mans Mk. lis were getting almost seven miles per gallon, while the '67 Daytona cars were only getting about four. Transposed to Le Mans, this mileage-or lack of it-could prove disastrous. As Holman-Moody has recently become U.s. distributor for the English Tecalemit-Jackson fuel injection system, there has been considerable speculation that f.i. will be tried.
Holman-Moody claims that the Tecalemit-Jackson system, developed in 1964 but only recently gaining acceptance in the racing fraternity, can deliver more power on less fuel than carburetors. We would estimate that a fuel-injected 427 could produce 550 hp and get almost six mpg in the J-car. At Le Mans, this could add up to six more laps over the 24-hour period, minus one lap for an extra gas stop-or a net gain of about 1.4%; not much to stave off a determined attack by the gas-miserly Ferraris.
Several transmissions are available, both manual and automatic. The only manual box is the two year-old four-speed developed for the Mk. lis. It uses production gearsets, continuous synchronization, and a 10-inch hydraulically actuated clutch. The automatic transmissions are still under development, but both Lunn and Jacques Passino, chief of Ford Advanced Concepts, believe that a power-shift two-speed unit will ultimately be selected. The alternative is a two-speed dog-shift box. Both types use the same torque converter.
Overall, the J -car is 164 inches long, 69.3 inches wide, 38.5 inches high, with a curb weight of less than 2300 Ibs. (still some 600 Ibs. over the legal minimum). The wheelbase is 95.0 inches, the same as the Mk. II's. Front and rear tracks are 55.6 and 54.8 inches, respectively. The wheels are made of cast aluminum magnesium alloy with knock-off hubs. Wheel sizes are 8 x 15 or 8 x 16 inches in front, and 12 x 15 or 12 x 16 inches rear-a far cry from the 6 x 15 front and 8 x 15 rear, 60spoke wire wheels used on the original GT 40. Thirteen-inch-wide rear rims are also in the works, but have not yet been tested.
When the Ford GT was designed, the minimum weight specified in Appendix J for under-305 cu. in. GT prototypes was 2035 Ibs., or 2310 Ibs. if over 305 cu. in. The 289 cu. in. GT 40s weighed in at about 2200 Ibs., or 165. Ibs. more than necessary. In going to the Mk. lI's 427 cu. in. engine, Ford added 100 hp at a 275-lb. weight penalty. The first 427 engined car weighed only 65 lbs. over the minimum, and Ford was pleased. Then the mercurial Appendix J rules changed, reducing minimum cockpit dimensions, as mentioned, and also dropping the minimum weight for over305 cu. in. GT prototypes to 1650 Ibs. (or 15401bs. for the under-305 cu. in. class), and suddenly the Mk. II was 750 lbs. over the minimum.
When the J -car was conceived, no one at Ford imagined that it could weigh 1650 Ibs.; that would mean throwing out all the Mk. II's hardware. The target weight was 2200 Ibs. Ford decided to retain the 580-1b. 427 engine because it was more powerful, more reliable, and considerably less expensive than an all-out racing engine would be. The weight of the Mk. II's other components had been pared as much as possible, and you can't eliminate items like seats and transmissions. This left the 370-lb. chassis of the Mk. II as primary target for weight saving measures.
Here, designer Ed Hull achieved his goal-the J -car chassis has exactly the same stiffness as the Mk. II, and it weighs only 180 Ibs, including roof, suspension brackets, steel-reinforced transmission hoop and all tube hangers.
The minimum stiffness of both chassis is 10,000 Ibs-ft per degree of flex. This is a stiffness per pound of weight ratio of 27.0 for the Mk. II, and 55.6 for the J -car. By comparison, the Chaparral 2C (sports/ racing) plastic chassis weighs approximately 98 Ibs. and has slightly over 4000 Ibs-ft per degree of stiffness a ratio of 41 lbs-ft per degree of flex per pound of weight. No exact figures are available for the Ferrari P4 chassis, but it's assumed that the latest Italian product is not as stiff as either the Chaparral or the Ford.
Ferraris have won a lot of races despite their relative lack of chassis. rigidity. This year's 330/P4 is fast because its shape is small and clean, because it has about 20 more horsepower than last year's 330/P3, and because it's 200 lbs. lighter than the P3. In fact, Ferrari is the only contender this year to add power while shedding weight.
Both this year and last, the Chaparrals have had an edge in power-to-weight ratios, and their aerodynamics are probably the most advanced in racing. In 1966, however, Chaparral lacked the raw horsepower to propel the 2D at speeds high enough to win a race like Le Mans. For 1967, the Chaparrals have picked up 150 Ibs. and an estimated 100 horsepower.
The Ford Mk. lIs have added 120 Ibs. and 20-25 horsepower. The cast iron heads-and 2 x 4-bbl. carburetion added 80 lbs., plus about 120 Ibs. for the roll cages and internal fire control systems. (Lastditch lightening efforts winnowed a further 80 Ibs.). With fuel injection and the aluminum heads, the J -cars could have more sheer horsepower and flat-out speed than anything else on the track. They won't have the power-to-weight ratios of the competition, but the Mk. lIs were in the same boat last year, and made up for it in other respects.
Aside from dimensional and material changes, the J -car's structural layout is the same as for the Mk. II and GT '40. Twin side tanks form the main load-carrying structures, connecting the rigid engine bay and front toe board sections: All" structural sections are made of 0.5 inch thick honeycomb panels, except the cowl and seat-back bulkheads, which are one inch thick due to their function as the primary transverse stiffeners. Additional strength is provided at the transmission hoop bulkhead with steel reinforcements bolted and bonded to 0.5 inch aluminum closure panels. The only other steel pieces in the chassis are the suspension arms, the tubular spare tire support frame above the exhaust pipes, and the roll cage. "
The floor panel extends fuIl length in a single honeycomb pIece from the front suspension bulkhead to the transmission hoop. A radiused edge at the rocker panel curves into the door sill and forms the only curved honeycomb panel section on the car. The longitudinal torque boxes measure 15.5 inches wide by 10.5 inches deep, with space inside for 42 gallons of fuel in rubber cells.
A three-inch diameter aluminum pipe runs transversely along the cockpit floor behind the seats to equalize fuel levels. The filler neck is located at the base of the righthand windshield post, with another equalizer tube running ahead of the cowl to the lefthand tanks. Condensation tubes from both tanks vent into - the tubular steel roll cage behind the seats.Corner bonding presented the second major problem in the honeycomb construction. To join honeycomb material together at an angle through a mitered joint is useless since the stresses are carried by the aluminum sheeting, not the honeycomb inside. Under ideal conditions, one sheet is in tension and the other in compression at all times, with the honeycomb simply transferring minor local loads and acting as a fixed dimension divider. To solve the problem, all major joints on the J -car are bracketed with two- or three-inch wide, .016-inch thick aluminum clip angles, bonded and triple-riveted to the aluminum panels. A flat aluminum plate is then bent twice and bonded to both panels about an inch from the inside edge of the joint to form a triangulating gusset. Double or triple rivets in staggered rows and varying sizes complete the joint. This transfers the main loads from the joint to the panel surface at the edge of the gusset plate, where the panel will break if the aluminum's elastic limit is exceeded.
The J -car's suspension looks like Son-of-Mk. II, as well it might, as computer-oriented suspension engineer Klaus Arnung is primarily responsible for the design of both. Unequal-length (and fairly short) wishbones, concentric coil spring/ shock absorber units, and an antisway bar are used at the front. The rear uses trailing radius rods, single transverse upper links, reversed lower wishbones and concentric coil spring/shock absorber units.
Two alternate inboard mounting points are provided for the leading link of each front upper wishbone, giving .40 and .80 of camber change for each inch of wheel - travel. Threaded links provide for static camber and toe changes. Thirty percent anti-dive is incorporated through the angle of the upper trailing link. The steering rack mounts ahead of the forward bulkhead, with the tie rods in the same plane as the upper wishbone to prevent toesteer on jounce and rebound.
Both upper and lower front trailing links attach to a single vertical fabricated-aluminum channel mounted on the flat side-surface of the footwell box. It would obviously be more consistent with. good structural design to take the suspension forces into the chassis nearer the cowl, but Lunn says the resulting long, wide-based arms would occupy space needed to clear the tires on full steering lock. A total of 27° of lock is provided in both directions, and all of it is needed to comply with the FIA minimum curb-to-curb turning circle of 44.4 feet.
The rear suspension has antisquat and anti-lift built into the geometry of the trailing links to keep the chassis stable on acceleration and braking. There are three alternate mounting points for the inboard end of the transverse upper links, giving approximately .4 0, .80. and 1.20 of camber change per inch of wheel travel. As at the front, five inches of wheel travel are allowed, and - Lunn is convinced that Ford's computer has accurately described what happens on every inch of it under all conditions.
Static camber at the rear may be changed by altering the length of the threaded upper links. Static toe adjustment is provided by threaded links at the rear wheel-mounts of the reversed wishbones.
The J -car's brakes are similar to the Mk. II's, using cast austenitic iron rotors with quick-change hat section mounts and forced-air internal ventilation. The similarity ends in the amount of work required of them. At Le Mans, the J -car is expected to approach 230 mph on the Mulsanne straight, followed by a 35-mph hairpin turn. This means that 4,142,559 Ibs-ft of kinetic energy must be dissipated by the brakes (ignoring engine braking and aerodynamic drag) in less than 15 seconds, figured at a deceleration rate of .62 G. (Braking rates much higher than .62 G would not only severely shorten the estimated 12hour rotor life, but also place undue stresses on both car and driver.)
To handle these loads, Ford engineers have collaborated with Kelsey-Hayes to design 12.0 x 1.25-inch rotors, a great step up in mass from the 11.56 x .'75-inch rotors used on the Mk. II. But that's about as far as Ford can go, for both rotor diameter and thickness are now at their practical maximums.
The original wheel design, cast in an aluminum-magnesium alloy, featured turbine-like spokes, not to blow air in, but to draw warm air away from the brakes and expel it to the outside. These were the wheels that fractured in the Daytona tests, and have been replaced by conventional spoked wheels, at least for the time being.
Only three J -cars have been completed as of this writing, although three more will be ready in time for Le Mans. Chassis Number 1 was completed in January, 1966, only five months after the first idea sketches and preliminary drawings were begun. It was taken to Le Mans last April, then returned to the test tracks for further development. Meanwhile, Ford was considering the J -car as a possible competitor in the Group 7 sports/racing car category, and Number 2 was built to these specifications, and later wrecked at Riverside in September. Number 3 was then completed but "grounded" until the results of the Riverside. crash were analyzed. Suitably strengthened, Numbers 1 and 3 resumed development work in the hands of the Shelby American organization and Ford Advanced Concepts. One of these two will probably have been raced at Sebring, while the other will have been" at the Le Mans trials the following weekend by the time this is published. It is expected that Shelby American will prepare and operate Numbers 4, 5 and 6 at Le Mans, while their friendly rivals at Holman-Moody will field three Mk. lIs.
The consensus among veteran observers is that the J -car has the durability and the handling to win Le Mans, but that if the aerodynamics aren't sorted out by the April trials, there won't be enough time between then and the 24-hour race to guarantee success for the J -car. And, like Deuce says (Deuce is what the crews call Henry Ford II, "win. . . or else."
