[DeTomaso] Expensive DeTomaso Pantera Gr.3 Prototype on eBay

[MikeLDrew at aol.com]

In a message dated 1/8/12 8 25 55, jjdetrich at gmail.com writes:


> I'm curious as to the differences between a stock car, a GR3, and a GR4. 
> Is
> there someplace that describes these?
> 

I ghost-wrote most of the text for Philippe Olyzyk's De Tomaso racing book. 
  Here is the story behind the Gr3 and Gr4 race cars, as it appears in the 
book.

====

To meet the demands from European racers, the Gr3 Pantera was developed.   
While a Group 4 Pantera is a dedicated, purpose-built race car that used 
Pantera architecture but a unique chassis and suspension, the FIA Group 3 rules 
were far more restrictive, as the FIA intended for this class to consist 
solely of essentially stock, unmodified production sports cars.   Initially, 
modifications from standard, production-car specification were few, mostly 
relating to pure safety issues, but after a few years, as the Pantera became 
less competitive, the FIA relaxed some restrictions and the list of allowable 
modifications grew.
Unlike the Group 4 Panteras which were built on custom-made, non-production 
chassis utilizing special components, all Group 3 Panteras were constructed 
from ordinary, production-line European Panteras.   As they were all built 
to individual customer order, it's difficult to generalize about them.   
Furthermore, the nature of bespoke De Tomaso automobiles makes it even more 
difficult to differentiate between different models, since it was possible for 
any European customer to order each of the components used to create a Gr3 
Pantera directly from the factory, and modify a standard car to that 
specification after the fact.   It was also possible to order a Euro GTS and then 
have it built with all the Gr3 components at the factory.   So there is a very 
fine line between a true, proper Gr3 race car, and a Euro GTS fitted with 
Gr3 components.   While the De Tomaso factory public relations personnel are 
extremely helpful, and are capable of answering a query to determine if a 
specific car was constructed as a Gr3, they don't have a complete list of all 
Gr3 cars made and frankly don't have the time or manpower to conduct the 
necessary research.
The process of building a Gr3 Pantera started in the engine room.   De 
Tomaso certified the Gr3 Pantera with either a standard cast-iron intake 
manifold and Motorcraft carburetor, or an optional aluminum Ford manifold with a 
Holley 650 manual-secondary carburetor.   The stock oil pan was replaced with 
a large (approximately 10-12 quart) pan with an integral windage tray.
European GTS exhaust headers were fitted (consisting of 4-into-2-into-1 
headers with a 2 1/2 inch collector), and the 2 1/2 inch tailpipes fed into 
either low-restriction ANSA GTS mufflers, or the so-called Gr3 mufflers 
(GTS-style muffler cans with no internals, and hence no sound-reduction 
capabilities.)   Finally, the entire muffler assemblies could be deleted and replaced 
by simple straight exhaust pipes.   One would hope the engines were 
thoroughly checked over and received careful blueprinting and hand-assembly at the 
factory, but there is no evidence the De Tomaso engine-builders weren't simply 
affixing these bolt-on parts to otherwise-standard engines.
The chassis received only subtle tweaks initially.   The same Ariston 
adjustable shocks fitted to conventional Panteras were standard on the Gr3 
version, but there were two levels of Koni shock upgrades available.   The first 
featured internal rebound adjustment only, while the top-of-the-line shocks 
had external controls for rebound and preload adjustment, with over 140 
different combinations available.   The expensive shock package cost an 
additional $2,000 back in 1973, quite a serious investment when you consider you 
could buy an entire street Pantera for under $10,000!
The Gr3 Panteras were equipped with the same springs as the European GTS, 
with only one optional spacer listed (presumably for rally cars.)   The 
steering rack was repositioned using spacers to alleviate bump-steer concerns, 
but the control arms and sway bars were the same as those fitted on production 
Panteras.
The brakes consisted of standard Pantera calipers squeezing stock-sized, 
ventilated discs and actuated by a standard master cylinder; this was a common 
option for street GTS Panteras as well.   Standard 7- and 8-inch Campagnolo 
wheels and tires were fitted.
In 1975, the FIA allowed further modifications to the suspension.   The 
rear hub carriers and front spindles were replaced by heavier Group 4 units, 
and the brakes were changed to larger cast-iron three-piston front calipers, 
and cast-iron three-piston rear calipers with heavy-duty vented rotors.   
Although similar in appearance, these were not the same brakes as used on the 
Group 4 Panteras, but this system (initially sourced from the De Tomaso 
Deauville and Longchamp) later became standard issue on the GT5 and GT5-S.   
Small auxiliary rear calipers with their own small pads were used for the 
parking brake.
The stock sway bars were replaced with an adjustable system, 
philosophically similar to, but mechanically different from, the adjustable bars featured 
on the Group 4 Panteras.   Initially they were equipped with standard 8-inch 
and 7-inch wheels, but later the 10-inch Campagnolo Euro GTS wheel was 
allowed for fitment in the rear, and 8-inch wheels were issued for the front.   
The interior of the Gr3 Pantera was surprisingly mundane.   Earlier cars 
had the two-pod dashboard, while later cars received either the one-piece 
molded USA L-model dashboard, or the similar-appearing two-piece upholstered 
Euro GTS dashboard; all were fitted with metric gauges and European switchgear. 
  The stock seat belts were replaced by racing harnesses, and the standard 
Pantera seats were supplanted by one-piece racing bucket seats, the same as 
those in the Group 4 Panteras.
(Interestingly enough, these one-piece racing seats were actually 
constructed from the remains of the prototype Pantera's radical seats.   Those seats 
consisted of a sheetmetal frame, fitted with yellow foam blocks.   Visually 
striking, but judged by Ford as being too weird for the marketplace, they 
never went into production.   As De Tomaso had already produced many of these 
frames, they simply upholstered them with light padding and turned them into 
race car seats.)   
Heavily padded bolsters, as used in the Group 4 cars, were sometimes fitted 
to the door panels on one or both sides
On some cars, the ignition switch was relocated from under the dashboard to 
the middle of the center console, behind the ashtray, and within easy reach 
of the driver while he was belted in.   A fire extinguisher was bolted to 
the floor in front of the passenger seat.
The USA-model steering wheel was standard equipment, but buyers had the 
option of fitting the three-spoke Euro GTS Momo Prototipo instead.   
Interestingly, the Gr3 Panteras were sold with full heating and air conditioning, 
electric windows, an AutoVox radio aerial bolted to the roof, and a pair of 
speakers installed in the center kick panels (one immediately alongside the gas 
pedal, and the other pointing into the passenger footwell), but no radio was 
included.   Air horns were also optional.
The plexiglass rear window and six-point roll cage of the Group 4 Pantera 
were standard issue in the Gr3 cars as well.   Furthermore, the front engine 
cover was modified to allow easy access to the front of the engine without 
requiring the removal of the entire back panel (which would have required 
removal of the roll cage!)
Cosmetically, the Gr3 Panteras slowly changed as the production Panteras 
changed.   Early Gr3 cars carried standard two-piece front and rear 
bumperettes.   After the introduction of the L-model Pantera, some Gr3 cars were 
equipped with early-style front bumperettes incorporating the front turn signals, 
while others had European L-model bumperettes with the turn signals 
residing in the standard L-model pods on the underside of the front fenders.   Some 
cars retained two-piece rear bumperettes while others received the European 
L-model one-piece rear bumper (which was the same as the USA L-model 
bumper, except that instead of being mounted on hydraulic rams, it was mounted on 
solid brackets, considerably closer to the car's body.)
There were various driving and fog light packages issued; some cars 
received Carello fog lights, while others received massive lighting arrays for 
nighttime rally racing.   For the first few years, a simple flat blade front 
spoiler with cooling ducts for the front brakes was installed (same as on the 
Group 4 Pantera) while later cars got a miniature air dam (also a common 
option on the post-1974 European GTS) and small, riveted-on GTS flares.
Apparently most of the Gr3 cars received the Euro GTS paint scheme, with a 
blacked-out front hood and rear decklid (although the Gr3 Pantera shown in 
the factory brochure and postcards is solid yellow.)   In most cases, the 
European GTS rocker panel decal (which said “De Tomaso” in large letters, then 
had the words “Pantera” in smaller script, above the word “GTS”) was 
modified to delete the mention of “GTS.”
As with the Group 4 cars, rubber tie-downs were used to secure the front 
hood and rear decklid, although unlike the Group 4, the sheetmetal was 
standard steel instead of aluminum.   An external battery cut-off switch was fitted 
to the left front fender; the same switch was mounted on the right front 
fender on most Group 4 cars.

=======

While De Tomaso was working on the Pantera road car project, it was 
accompanied by a racing program designed to demonstrate the quality of the car.   
The Gr4 was chosen to go against the “big boys”.   From the beginning, 
former Lamborghini engineer Dallara had decided that the racing Pantera needed to 
be built from a lightweight chassis, and these were built in Torino with 
perforated pressed holes stamped into most of the chassis components.   Only 
14 lightweight chassis were built, and they were delineated by the addition 
of the letter “A”, for Allegerita (light weight) in the chassis number.

Two different models of the lightweight chassis Pantera were built.   
Originally the racing version was going to be called the Gr4 while a street-legal 
lightweight model was to be known as the GT4, but the demand for race 
Pantera was so high that immediately, all the GT4 street cars were upgraded by 
the factory to full race specifications.   In fact, they were even the first 
cars to race, at Monza.   Although the factory officially classified the two 
types of cars as separate models on paper, in reality they were absolutely 
identical by the time they rolled out of the factory doors.

The cars were originally painted an orange-red with satin black hood and 
decklid.   The most obvious difference between them and a standard production 
Pantera was the massive fiberglass flares riveted to the fenders; these 
allowed the fitment of equally massive wheels and tires (15 x 10 inch in front, 
and 15 x 14 inch in the rear).   But in fact the car was substantially 
modified from the standard configuration.

It was much lighter than a production Pantera, due to the use of aluminum 
for the doors, hood and decklid, and the extensive lightening holes stamped 
into most of the main chassis pieces.   The complete car weighted only 2750 
lbs (1250 kg).   The heavy cast-aluminum engine and transaxle mounts were 
replaced by much lighter ones of welded steel, again filled with lightening 
holes.

The suspension was nominally the same (dual wishbone, coil-over shocks, 
with front and rear anti-roll bars) but none of the components were stock.   
Koni shocks were fitted, and shorter, stiffer springs lowered the car (ride 
height is not adjustable however, except by using spacers).   The wishbones 
had solid bronze bushes; some featured heim joints to allow for great 
adjustability in both camber and caster.   The anti-roll bars mounted much more 
rigidly to the chassis, and the center mounts were considerably outboard of the 
standard mounting location.  They were attached to the wishbones with heim 
joints to reduce friction, and the joints at the ends of the anti-roll bars 
were adjustable so that racing teams could make each end of the car softer or 
stiffer in degrees.   The rear uprights were also made much stronger, and 
used much larger bearings.   A quicker ratio was used in the steering rack.

The brakes used four-piston Girling calipers, fully ventilated and drilled 
rotors, and dual independent Girling master cylinders with a balance bar to 
adjust front-to-rear proportioning.   There was no power assist.

The radiator was a standard production piece, but used only a single water 
bottle.   An oil cooler ran the full width of the radiator opening.   The 
front brakes were cooled by air ducted from the simple blade front spoiler, 
while the rear brakes received cooling air from a pair of scoops riveted to 
the underside of the car alongside the engine.   

Originally, the standard steel exhaust manifolds were replaced with “GTS” 
headers, going into 2 1/2 inch straight tailpipes with no mufflers.   In 
1974, the factory homologated 180-degree 'bundle of snakes' exhaust system, 
much like that fitted to the GT40.

The engine was improved, but not radically so.   A solid-lifter camshaft 
was fitted, along with an aluminum intake manifold and 850 cfm Holley 
carburetor.   In 1973, Weber carburetors were homologated.

The interior was mostly stock, although the electric side windows were 
replaced with sliding perspex windows.   Simple aluminum door panels trimmed in 
naugahyde were used, and the driver's panel had a large padded block for the 
driver to brace his leg against.   A six-point roll cage extended through 
the rear window and attached to the inner wheelhouses, above the rear shock 
absorber mount.   The shift gate had a crude reverse lockout welded onto it.  
 Standard gauges were used, along with the two-spoke steering wheel found 
on the earliest production Panteras.   Racing harnesses and supportive bucket 
seats were also installed.

Small turn indicators were attached directly to the front of the fender in 
place of the standard bumperettes, and small spotlights were attached to the 
doors and roof to illuminate the racing number.   The standard Pantera 
taillight (which was shared with several other Italian cars) was replaced with a 
three-bar light (which was shared with different other Italian cars....)

The Gr4 Pantera made a fantastic debut at Monza in 1972, where the overall 
win was virtually locked up until the alternator mounting bracket failed, 
and the car failed to finish.   Throughout the 1972 and 1973 season, the car 
won races in front of a flurry of Porsches.   Unfortunately, De Tomaso failed 
to support the Pantera racing program while Porsche engineers were working 
night and day to improve their cars, so by the end of the 1973 season, the 
Pantera was outclassed in the top ranks of FIA endurance racing, although 
they were still dominant in the hands of privateers at the club level 
(particularly in Italy) and in hillclimbs.

In the USA, the first Gr4 Pantera built, No. 2344, was initially prepared 
at Bill Stroppe's shop and later made the show car circuit and was driven on 
the street by Mario Andretti.   It was then sold to Warren Tope, who was the 
son of the director of the experimental department of Ford USA.   Lee 
Dykstra, a former Andretti mechanic, worked on the car and designed some 
experimental suspension components for it.

In 1974, the car won the first race at the City of Pontiac “Wide Track” 
driven by Tope, but after that, it quickly became obsolete and was reduced to 
competing at the club level, with mediocre results.

And so the Gr4 Pantera's racing career faded.   Had it received even a 
fraction of the development attention that Porsche lavished upon their 911, it 
is probable that the Pantera would have continued to win for quite a few 
years.

====

So there you have it.   I failed to mention (because I didn't know at the 
time) that some Gr3 Panteras had the electric window mechanisms replaced with 
a simply crank system; 1070 has that feature, as can be seen in the 
interior photos.

Mike