Tuesday, July 25, 2017

Another Porsche 917 "Who Knew?"

One of the fun things about the iconic nature of the Porsche 917 is that it must be one of the most documented race cars in history.  "Stuff" keeps popping up.  Apparently nobody threw anything away. Or maybe by the time they thought to pitch some files the car was already legendary and they thought again.  Thus the blind alleys and "...meh's..." of 917 development have been preserved.  They illustrate the fact that all race cars are constantly being developed.  ("No battle plan survives first contact with the enemy.")  With most race cars, by the time secret tweaks that didn't work out might become public, nobody cares anyway.  The 917 is immune to that indifference.

The story of the Horsman (Wyer) K-tail for the 917 is fairly well-known because it transformed the 917 from a car with diabolical handling into an instant winner.  The story of Ferdinand Piech's development of the LH tail (and indeed, the entire car's shape) over three years are less well-known but available to 917 geeks.  So are accounts of "The Pink Pig," commissioned by Piech from S.E.R.A.  Finally, we know about the Wyer center wing[let] tail, which provided slightly more downforce with an acceptable drag penalty, and Porsche's 1971 fin tail, which provided slightly less drag, with acceptably lower downforce.  (Bonus trivia points for geeks who know about Wyer's "one race only" full-width spoiler tail used at Spa-Francorchamps in 1970.)

And now, the news (at least to me):  Here are three Wyer body configurations got up for testing in the M.I.R.A. wind tunnel, presumably in 1970, probably by John Horsman.  Evidently none of them measured up to the drag/downforce ratio of the center wing tail.  So they were not used, or passed along to Porsche.

This wing is twice the width of the "center wing," mounted on pylons to elevate it away from the body.  If it produced
more downforce (way more seems likely), it likely unsettled the balance of the car without balancing aero mods to
the front end.  obviously, the drag would have been higher.

Here the center "rear visibility slot" is filled in.  The rear edge is similar to the "one race only" full-width spoiler used
at Spa-Francorchamps in 1970 except that it lacks the slight spoiler upsweep.

Conventional rear fenders, added to the conventional ("production version") Porsche refinement of the Horsman tail.
Interestingly, this bite at the apple apparently didn't reduce drag as compared to the "open" production tail.  If it had,
it presumably would have been used.  Freaks for the bad-assed look of the 917 K can be grateful!

Friday, May 5, 2017

Alfa GTZ Racing In The U.S.A.

Vito Witting da Prato says in his mostly OK book Alfa Romeo TZ-TZ 2: Born To Win that the TZ was not raced in the United States (sidebar page, 77).  This is not correct.

The TZ was approved in 1964 for both the SCCA's USRRC U2L class and C Production.  The one in these pictures was the only TZ campaigned in the States in 1964 and 1965.  da Pratto is correct when he says that the TZ was expensive for its class (think: Lotus Elan).  Also, Alfa wanted to sell TZ's to competitors who had a good chance of advancing "brand image" in the States.  TZ's weren't available to someone who wanted to take a flyer at CP in the SCCA's amateur division.

Alfa leaned on, or finessed, the SCCA into approving the TZ as a production car (which was, at best, a reach).  The car featured in this post was sold at a "friendly" price to Chuck Stoddard, a driver with a winning record in Giuliettas in GP and DP, with the understanding that it would be campaigned in the USRRC manufacturer's championship in 1964.  In 1966 and later, a few TZ's (including this one) found their way into the CP class in the SCCA's amateur division.

Here is Stoddard's record with his TZ:

1964: 4th in SCCA Manufacturer's Championship (USRRC) and Central Division C Production Champion.

Sebring: 1st, GT 1600 class (13th overall), with Jim Kaser.  Chassis 750052 (factory car, entered by Scuderia Sant' Ambroeus).  FIA race.

Above: the Sebring class-winning chassis 750052, now in the Revs Institute/Collier Museum in Naples, FL.  It is my
understanding that this car went back into factory inventory in Italy after the race.  Below: Sebring sister car 750051
 at Thompson Raceway in CT for a Regional or National event.  It was DNS at Thompson and I know not what
happened to it after that.  It was not raced in the States in '64, at least not at the national level.  This picture is
from da Pratto's book; his source was George Fogg, who took it and had an association with the car.

SCCA National, Mid-Ohio: 2nd, C Production (I crewed for Stoddard at this race; won by a Porsche 904.  It was a shakedown for the USRRC events.)

USRRC Watkins Glen: 1st, GT 2 (6th overall)

Watkins Glen USRRC.  I crewed for Stoddard at this race.  His GTZ and Mike Gammino's Ferrari GTO (with race
with race number 23) made a fine-looking pair when they ran together, which they did because Gammino lapped
Stoddard at least twice, as did the factory Cobras, which looked squirrely as hell braking for the chicane.

USRRC Greenwood Raceway: (Indianola, IA): 3rd, GT 2 (15th overall)

Above and below: Stoddard's car at the USRRC at Greenwood, IA.  Note the three-eared knock-off hubs.  They were
typical of factory (Autodelta) run cars in Europe, but "never" seen on private-entrant cars (although available as an
option).  The Kaser/Stoddard Sebring car had two-eared hubs.  The car Stoddard raced in '64 and '65 had the three-
eared hubs seen here.  He was told that it was Sanesi's factory test mule, refreshed.  It arrived white; he repainted
it red.

USRRC Mid-Ohio: 3rd, GT2 (8th overall)

USRRC Meadowdale (IL): 1st, GT 2 (6th overall)

Meadowdale, 1964, I believe (this looks like "Serpentine").

USRRC Road America 500: 1st, GT 2, (8th overall, drove solo in the Road America 500)

Road America 500 (USRRC) 1964.  Stoddard also won his class at the Road America 500 in 1965, driving solo!
Although his TZ finished at the sharp end of the small-bore cars in '64, it was not easy to stay out of the way
of big-bore cars.  At this race, all cars ran together, including the big-bore modifieds like the Chaparrals.

Stoddard scored 35 points for Alfa Romeo to take 4th in the Manufacturers' Championship of the USRRC.  He towed to 5 races only in the midwest.  Shelby American's Cobras scored 72 points (contesting all races), Porsche scored 52 points in 7 races (with various 904's), and Ford of England scored 45 points in 9 races (with a two-car factory team of Lotus Cortinas, one of which was often driven by Sir John Whitmore).

Stoddard's bete noir in '64 was John Whitmore, in a Ford of Britain factory entry (one of two cars).  Later "Sir John,"
Whitmore passed away at the end of April, 2017.  "He raced me hard, but clean," Stoddard told me, "a good guy."
"They used to fly him over, with a fresh engine, for every race.  The Cortinas themselves stayed in the States."
This picture is one of the best I could find of a Lotus Cortina, at a recent Goodwood event.

1965: National Champion, Central Division, C Production

Sebring: DNF, accident (factory car, not the one pictured here).  FIA race.

Meadowdale (SCCA National): 2nd in C & D Production race

Road America June Sprints (SCCA National): 82.7 m.p.h. (no finishing position listed)

I don't know where this picture was taken; I just like it.  My note (pulled, like the pic, from the internet) says it was
Mid-Ohio.  But Bill Green does not place Stoddard and his TZ at Mid-Ohio in 1965.  I am sure that it was '65,
because Chuck didn't run the "Stoddard Racing Team" logo in 1964.  He is 6'-3" tall and the TZ was a tight fit.
He always drove "head down" in this car.  More chassis trivia: only "factory cars" had extractors for cockpit
ventilation, in the rear quarter windows.  Most TZ race cars had sliding panels in the side windows.  Some
factory cars had fixed plastic side windows, like the ones in Stoddard's car.  No configuration worked
well for driver comfort.  Stoddard raced with the vent wings held "full open" with rubber bands.

USRRC Road America 500: 1st, GT 2 (15th overall)

Road America 500, 1965.

Indianapolis Raceway Park (SCCA National): 2nd, C Production

Daytona Beach (SCCA Runoffs): 4th, C Production  (This was the first year of the Runoffs; it was possible to be one of several National Champions, by Region, as it had been in previous years.  In later years, a driver's finishing position in the Runoffs determined his national class championship rank.)

NOTE: Many thanks to Bill Green of the International Motor Racing Research Library in Watkins Glen, NY, for compiling Stoddard's racing record for me in 2007.  Bill's sources were periodicals from the 1950's and 1960's, principally the SCCA's magazine Sport Car.

Monday, May 1, 2017

Alfa Romeo GTZ's at Sebring, 1964-1966

I backed into this post partly because of my amusement (with the distance of years) at Chuck Stoddard's reversal of fortunes at Sebring, and partly because I hadn't realized that Alfa TZ 2's raced at Sebring in 1966.  Three class wins in three years: not bad.

In 1964, three cars were entered by the (Italian team) Scuderia Sant Ambroseus, but were, in fact, the factory team.  For the drivers of one car, Alfa chose three Italian mainstays including Consalvo Sanesi, its long-time race and go-to test driver.  The other two cars were offered to American drivers with successful SCCA records in Giulietta Veloces.

Chuck Stoddard behind the wheel of the class-winning '64 car here.  His co-driver was Jim Kaser.  The primary
competition at Sebring in '64 was the factory Lotus-Cortina team, led by Jim Clark, which failed to last the
distance.  Knock-off wheels on GTZ's were seen almost exclusively on factory-entered cars, although
they were a customer purchase option.  Cockpit ventilation was almost nonexistent in TZ's and the
extractor vents in the rear quarter windows didn't help.  Stoddard raced his own TZ in the States in
'64 and '65 with the vent windows held "full open" by rubber bands.

The American-driven sister car in 1964, by Bill Wuesthoff and Chuck Dietrich, who, like Stoddard, had stellar careers in
small-bore cars in the SCCA.  The exhaust shown here was the factory 4-2-1 race system, with a flattened final pipe,
exiting in front of the rear wheel.  Note the "New Jersey Manufacturer" plate.  This car was DNF, gearbox. 

The third car in '64 was driven by Alfa's factory driver European "regulars," Consalvo Sanesi, Roberto Bussinello, and
Giampiero Biscaldi.  Sanesi was driving a wounded, lightless, car slowly past the pits when hit by Bob Johnson's
Cobra, which was going a ton.  Sanesi might have been broiled alive but for the heroic effort of a driver
standing in the pits, Jocko Maggiocomo (an American).  He was painfully but not seriously burned.
Sanesi was by now a  middle-aged guy; unsurprisingly,  he ended his racing career after this shunt.

Alfa upped the ante in 1965 with four GTZ's, now entered by an undisguised factory team, Autodelta. This was the famous "gullywasher" Sebring rain race--the one of the iconic motorboating pictures, although, surprisingly, rain did not hamper Alfa's 1-2-3 class-winning results: Rolland/Consten (both French), Bussinello/de Adamich (Italian), and Deserti/Zeccoli (also Italian; Zeccoli was another regular FIA European driver).  In a role reversal from 1964, the only American drivers, Gaston Andrey/Chuck Stoddard were DNF.

Above and below: minor inconveniences for Roberto Bussinello and Andrea de Adamich (who went on to a career in
big-bore sports cars and Formula One) on their way to 2nd in the GT 1600 class in 1965's "gullywasher" race.

The Rolland/Costen GTZ follows the Maglioli/Baghetti Ferrari 275 P through the Hairpin en-route to a trouble-free
class win in GT 1600.  GTZ's typically ran with their Ferrari GTO-like supplementary radiator nose vents fully or
partially open, even in moderate ambient temperatures, except at high-speed circuits like LeMans and Monza. 

Above: the Reed/Gerber Cobra, already with nose damage, on its way to a three car DNF.  Below: the remains of the
Riley/Cone Volvo P-1800 after the three-car accident.  I've not found a picture of the Andrey/Stoddard GTZ.  The
Volvo blew it's engine in the Webster Turns and spun in its own oil.  The Cobra punted it, bigtime, into the infield
of the circuit and spun to the outside (the Cobra is barely visible in the picture below).  Chuck Stoddard in his
GTZ hit the oil, collected the wreckage, and was out.  From Hero ('64) to Zero ('65) in the Alfa team.

In 1966, Alfa again entered 4 cars, with consecutive race numbers, although one car was allegedly a private entry, driven by Americans Sam Posey and Teddy Theodoracopulos.  The factory cars were driven by Russo/Andrey, Ziccoli/Russo, and Bianchi/Casten.

Unlike other homologation specials of this era, the TZ 2 was actually a true "evolution:" a lower, wider, lighter, fiberglass-bodied version of the TZ on the same frame.  But time had passed it by.  Nobody was doing front engine, rear drive GT cars with tubular space frames any more, even in the small-bore classes.

As in 1964, but unlike the sweep in 1965, Alfa won the GT 1600 class (Russo/Andrey)--with the last car standing.  The other three cars were pfffffftt.  One blew its engine at 16 laps.  Another retired with an "oil leak" 6 laps later.  Let's call that a blown engine as well.  The last non-finisher ate its gearbox before quarter distance.

Above: the 1966 Russo/Andrey class-winner.  Below: remember suspension?  Body roll?  Theoretically streetable GT
cars?  The # 61 car was out early with an "oil leak" probably caused by a rod through the block.

Wednesday, April 19, 2017

The Mini (And Me)

Alexander, later Sir Alec, Issigonis.  After the Suez oil crisis of 1957, Austin's management
green-lighted the revolutionary small car experimental design he had been working on.  It
wasn't, and hadn't been, developed as a successor to the Morris Minor.  Instead, it was
intended to be the smallest, most fuel-efficient "real" car that could carry four adults.
The Mini's small size forced some innovative packaging and technical solutions.
A sporty ginat-killer with brilliant handling was the last thing on Sir Alec's mind.

Here's a link to the Wikipedia piece on Alex Issigonis:


Automotive design history, as it pertains to compact cars, can be divided into Before Mini and After Mini.  Cars had existed for over 60 years until someone did a front, transverse engine, front-wheel-drive car.  After the Mini, for 60 years, there has one way to do a compact car: that way.  When Volkswagen and Honda did their first new "clean sheet" subcompacts in the early 1970's, they copied the Mini's architecture.  And so on.  The Mini was the prototype of today's World Car.

I was dimly aware of the Mini when it was introduced here in 1960, and completely missed its point. It struck me as an anti-Beetle: water-cooled, overly-complicated front drive "just to be different."  The Mini abandoned the body-on-frame construction of its conventional predecessor, the Morris Minor, for the unit-body construction of the Beetle.  But it retained the Minor's cast-iron engine, which was heavier and far less reliable than the Beetle's aluminum air-cooled unit.  The Mini's 10-inch wheels seemed ridiculous (which they were, for American Interstates).  It did not occur to me that the Mini was a "clean sheet" design.  I completely missed the point of the Mini's ability to carry 4 adults (and very little else) in a car weighing only 1400 lbs., with innovative and superb fully-independent rubber suspension, designed for Issigonis by Alex Moulton.  So I missed its sporting potential too.

It was all about the packaging or, if you prefer, shrink-wrapping four adults into a car.  The U.K. did not have many
motorways when the Mini was designed, so "B Road" capability was fine.  (In the early 1960's, European car firms
were still exporting whatever they had designed for their domestic markets, with no modifications, let alone doing
a car for the U.S.--or each other.)  Ten-inch wheels provided more cabin space and less weight.  Sliding windows
required no window-winding mechanisms and made room in the doors for storage pockets.  The original Mini
had an 850 c.c. engine when the V.W. Beetle had just been upsized from 1.1 to 1.3 liters: 50% larger.  The Mini
was, at bottom, a response to the very real possibility of petroleum shortages in the U.K.  And spartan.

The scales fell from my eyes at Mid-Ohio in 1961.  A brand-new Mini-Cooper (with more power from a 1.3 liter engine and front disc brakes) showed up at an SCCA Regional race.  It ran against the G & H Production Sprites (&c.) and won.  So the Stewards let it run against the F & E Production MGA's (&c.).  It won.  So the Stewards let it run in the C & D Production race against aging Jaguar XK 120's and Alfa Veloces (&c.).  It finished respectably.  Shortly thereafter, the Mini-Cooper scored several overall wins in the Monte Carlo Rally.  Having a lifelong weakness for giant-killers, I was enchanted.

When I was thinking about my first car--which had to be a cheap used car--I stumbled across a 6-year-old Mini that a young imported car mechanic had been starting to prepare for racing, but decided to sell to finance the purchase of a new Hillman Imp.  (I don't know how he did road racing the Imp, but it was a better bet than a well-worn 850 c.c. Mini with tiny front drum brakes.)  He had stripped out the Mini's interior (except for the passenger seat) and painted it battleship grey with a brush.  He had installed a racing seat belt and a big chrome Sun tach--just like the drag racers used.  He had installed twin S.U. carbs, and a big Alfa Romeo resonator at the end of the Mini's straight exhaust pipe.  Best of all, he'd mounted Dunlop SP 41 high performance radial tires on the 10-inch wheels.  I loved that car.  It felt fast, and it was fast--around tight corners.  I drove it for two years, until it burned an exhaust valve and I left for graduate school 600 miles from home.

This is Mini #1 off the assembly line, now in a museum.  Mine looked just like it--except for a red grille and silver wheels
with fatter high performance tires on them.  With a stripped-out interior, mine was surprisingly roomy: enough to haul
my stuff back and forth to and from college.  And noisy.  Which didn't bother me then and doesn't much now.  The car
was huge fun on back roads.  It's maximum cruising speed was a bit north of 60 m.p.h.  So it didn't see Interstates.

Since my those days, I've owned some interesting cars (and some real duds).  But none that I enjoyed more than the Mini.   I love to watch them race: 50 years of giant-killing.  Whenever I encounter one in a parking lot (oftener than you might think), it gets a good look-over and a chatted-up owner, if he's around.

The real deal (Mini-Cooper with modern modifications, done in Monte Carlo Rally style and colors.  With a Nordschleiffe
sticker on the trunk.  Seen in St. Hubert, Belgium.  I would have chatted up this owner too, except that he and his pals
spoke only French, and I speak only English.  Mini-mania can be communicated without words, however.  With
pointed fingers, gestures, smiles, and grins.

When I needed a new daily driver in 2009, I didn't consider a New Mini for several reasons, the most important being that it didn't come with four doors.  The Civic Si looked like a good bet because 1) it performed well on my "bang for the buck" spreadsheet 2) my son had had good luck with his Hondas.  I wasn't expecting a Mini feel.  And shouldn't have: the Si weighs twice as much as an Old Mini. Weight is the enemy, as we know.  Air-conditioning, cruise control, electric windows, rorty through-the-gears but quiet cruising...  Any resemblance between Honda's world-class engines and gearboxes, and what B.M.C. did with cast iron back-in-the-day, are purely coincidental.  A real trunk!  Seventeen-inch wheels!  I'd have expected the electric power steering to have far less feel than the Mini's brilliant unassisted rack-and-pinion.

Yet, although the Civic Si is huge compared to a Mini (what isn't?), it feels small and agile.  Steering feel and grip are Mini-like, especially on Michelin Pilot Super Sports.  In a straight line, it goes like a rocket compared to the Mini.  With my limited skills, I've never been comfortable pressing a rear-drive car to or past the limit.  But the Civic Si inspires the same confidence that the Mini did: I've learned to push it into a tight corner hard: slow in, fast out, with the front tires on the limit and a bit more.  Huge fun!  Without fully knowing it, I'd been looking for another Mini for 50 years.  Found one!

1960 Mini: "When I grow up, I want to be a Honda Civic Si."

Monday, February 6, 2017

"Present At The Creation" (Allen Grant's Lola GT Mark 6)

Oh, my... Who knew?  A completely original version of what became the Ford GT!  Single-owner, purchased from Lola Cars in 1965, and it was almost Eric Broadley's personal "keeper" car, converted for road use.  Well... it's restored, but restored to "as original" for the London Motor Show in 1963.

And Allen Grant's interview with Jay Leno is as careful and meticulous as his restoration of the car.  And the provenance trail!  For instance, Grant's correspondence with John Wyer about buying a ZF gearbox when he intended to race this car, to replace the original-spec. Colotti box.

Ford said in 1964 that the Ford GT was a Dearborn design.  And it's certainly true that Ford went through the Lola GT from stem to stern, modifying it extensively in detail.  But still, Ford bought the rights to the Lola GT from Broadley, hired him as a consultant to help with the conversion and the build of the Ford GT, and retained most of the basic design.  Including the troublesome Colotti box and what turned out to be sketchy aero with a full-race 289 pushing the car up to 190 m.p.h.  Ford didn't conceptualize the Ford GT, Broadley did.

Here's the link to Jay Leno's excellent interview with Allen Grant about the car:


Wednesday, December 28, 2016

Inauspicious Beginning

Chassis 102 at the Hotel de France, La Chatre sur-le-Loir, before LeMans, 1964.  This hotel was, and remained, John Wyer's favorite base of operations for LeMans from his earliest Aston Martin days.  This is a rare photo I'd not seen before.

In 2016, the Ford GT dominated LeMans from qualifying on and won the race in its maiden outing.

In 1964, the situation was precisely opposite.  The build of the first GT 40 was frantically completed at the end of March.  Instead of being endurance tested prior to LeMans Test Days (three weeks away), to John Wyer's disgust, Dearborn insisted that the car be flown to New York City for the Auto Show.  The only two GT 40's in existence did only four short test sessions at Goodwood.  Chassis 102 did only 25 miles.

At LeMans Test Days (April 18-19), Chassis 102 was damaged when Jo Schlesser discovered aero lift at only 150 m.p.h. (he was uninjured).  So much for small scale models "extensively wind-tunnel tested."  A rear deck spoiler was added, which solved the rear end problem for good, and was used on all GT 40's thereafter.  Fiddling with the front end began too, with "Version 1.1" shown in the pictures here.  The front was fixed permanently only with the complete revision by the "Len Terry Nose" in 1965.  Terry's revision became the standard (iconic) GT 40 nose for both factory and customer cars.

Chassis 102 in the LeMans race, 1964.  Note the modification of the nose and radiator intake from the picture above.

LeMans itself in 1964 was a disaster.  Chassis 104 (Richard Attwood/Jo Schlesser) burned to the ground when a fuel line broke.  Chassis 102 and 103 (#10, Phil Hill/ Bruce McLaren, and #11, Richie Ginther/Masten Gregory) retired early when their Colotti gearboxes failed.  The Colotti had been specified by Eric Broadley in 1963 for the GT 40's mother, the Lola GT.  Adequate endurance testing would have exposed its weakness.

Wyer immediately commissioned ZF to design a gearbox that could handle the torque of Ford's 289.  And he recommended that the GT 40 be withdrawn from competition until systematic endurance testing could be completed.  Instead, Ford entered the Reims 12 Hour race (July 4).  The cars again failed.  Wyer was removed from race team management and told to get on with the GT 40 production build.  Carroll Shelby managed the factory race team in '65, '66 and '67.  With the ZF gearbox and Len Terry nose, the GT 40 became all-conquering (on longer circuits with longer straights).

This was the car Wyer wanted to race.  But Ford blew by it with the Mk. II (7 liters) and the Mk. IV (a new chassis/body), which were Dearborn-developed.  Ford factory teams contested only at LeMans in '65, '66', and '67.  (Daytona and Sebring were used as tune-ups, but no European races were entered.)  This resulted in failure again (in '65) and then complete dominance (in '66 and '67).  Meanwhile,  Wyer had reasonable success in supporting customer cars at LeMans and other FIA races.

And he had the last laugh, when it came to the small block GT 40.  When Ford bailed on LeMans (in particular) and sports car racing (in general), it sold the rights to the car and everything that went with it to Wyer at a very attractive price.  This included the design, tooling, parts, spares and the Ford Advanced Vehicles building.  He would be responsible for continuing support of customer race cars.
Wyer updated the GT 40 with wider tires and a more powerful engine that featured Gurney-Weslake heads atop a full 5 liters.  He won a championship (something Ford had not attempted or accomplished) and LeMans twice more, in '68 and '69.  Pretty good "proof of concept" for a design that was six years old (a lifetime in race car years) at the time of its last major win.  Makes me wonder what might have been achieved in late '64 and '65 if the GT 40 had been thoroughly developed and tested in early to mid '64.

The '68-'69 Wyer-Gulf GT 40: essentially the 1964 car with wider tires and the Len Terry nose.

Wednesday, November 23, 2016

Rolling Art: Jaguar XKSS "Continuation" Video (Jay Leno)

Above: Ecurie Ecosse Jaguar D-Type Short Nose; Below: Jaguar D-Type chassis (model)

Jaguar D-Type central (aluminum) monocoque and front (tubular steel) subframe.

Here's a link to the Jay Leno video on the new "continuation" Jaguar XKSS:


Return with me, now, to those thrilling days of yesteryear...

For much of its history, LeMans was a unique race.  The rules were written by the Automobile Club de l'Ouest (and still are).  Sometimes they accommodated cars built for the FIA's sports car championship, sometimes not.  After World War Two, the LeMans circuit was a special case too: smooth and flat with long straights and (mostly) tight corners.  Jaguar's solid rear axle worked perfectly fine there.  At longer, bumpier, circuits,  Jags were less competitive.

Doubtless because of Bentley's success at LeMans in the years around 1930, British sports car manufacturers were always more interested in LeMans than the FIA championship.  Before racing sports cars had bullet-proof reliability, the drama of a "last man standing" win in a 24-hour race gave British sports car manufacturers something to crow about when they (often) lacked the outright pace of continental race cars.

One reason I love postwar racing sports cars is that they were "freestyle," and so different from each other.  Ferrari (and Maserati) attacked LeMans with powah: 4 to 5 liter engines.  The Mercedes 300 SLR attacked it with technical sophistication and reliability.  Jaguar (and Aston Martin) attacked it with what they had in the parts bins for their road-going sports cars.

When the LeMans-winning C-Type became long in the tooth, Jaguar decided to put its proven (but underpowered) 6-cylinder engine into a radical new car: the D-Type.  The car's advantage would be light weight, a low-drag body, and improved disc brakes.  Malcolm Sayer, the designer, had a background in aircraft.

Sayer insisted on minimal frontal area and used an aircraft-style aluminum monocoque body/chassis center "tub"--an automotive first.  Tubular steel subframes hung from its front and rear to support the engine and suspension.  While this was no more rigid than the 300 SLR's fully-triangulated tubular space frame, it produced a lighter car.  The D-Type was both lighter and more rigid than Ferrari's twin-tube ladder frame.  Working with Jaguar, Dunlop developed a new (improved) brake/hub/wheel package that eliminated the brake fade of Mercedes and Ferrari drums while saving weight compared to the wire wheels customarily used.

The D-Type won LeMans in '55, '56, and '57.  Boom!  In fairness, it must be said that Mercedes probably would have won in '55 had it not withdrawn its team after the terrible accident: the 300 SLR swept the board except for LeMans.  When Jaguar decided to withdraw factory-entered cars from competition at the end of 1956, it had surplus chassis lying about.  What to do?  The XKSS.