Guide: Ford GTX1
Background
During November 2005, Ford unveiled a surprise addition to the GT range when the wraps came off an open top version dubbed the GTX1 at the Specialty Equipment Market Association show (SEMA) in Las Vegas.
In addition to having offered GT buyers wind in the hair Roadster motoring, the GTX1 could also be configured as a T-top or Coupe by virtue of its innovative roof system.
The GTX1 came about as the latest product of Ford’s SEMA initiative which started back in 1999 when technical drawings of the ‘New Edge’ fourth generation Mustang were shared with aftermarket companies that wanted to develop parts and accessories.
Since then, the programme had been expanded to include the provision of 3D CAD data for the majority of Ford and Lincoln Mercury vehicles. Ford had also supported the creation of several vehicles for the SEMA show every year.
The GTX1 was just such a machine.
Work began when Kip Ewing who had served as an engineer on the original project GT created a series of topless scale models. These were then shown to Ford’s Special Vehicle Team (SVT) and a budget was signed off to bring the project to fruition.
As the GT was nearing the end of its production cycle and neither Ford nor production partner Saleen had any spare capacity, the Genaddi Design Group of Green Bay, Wisconsin, was brought in to collaborate on the project.
Run by Mark Gerish, the Genaddi Design Group had a history of high end open top conversions. Importantly, the company was able to bring the GTX1 to market much quicker than if Ford had produced it in-house.
The new car and it’s GTX1 moniker were inspired by Ford’s original X1 Roadster of late 1965 when another outside company, Bruce McLaren Motor Racing in Feltham, Middlesex, were commissioned to produce a super lightweight GT40 that could push the existing platform to its limit.
The McLaren-built X1 was based around an experimental GT40 tub uniquely fashioned from aluminium instead of steel. It also featured a hitherto unseen cut-down body, a special Hewland gearbox and weighed 250kg less than a conventional GT40 Mk2 Prototype. Chris Amon did a handful of late season races in the X1 Roadster before it was converted to a more conventional appearance (effectively a Mk2 Roadster) for the 1966 season.
Famously, Ken Miles and Lloyd Ruby went on to drive the now Mk2 Roadster-bodied X1 to victory in that year’s Sebring 12 Hours, after which it was deliberately destroyed owing to a disagreement over customs duties with the American authorities.
The new GTX1 was offered through the official North American Ford dealer network at a 15% premium over the standard GT. Three to four cars per week were expected to undergo the factory-sanctioned conversion for a period of six to twelve months.
Bodywork
The GTX1 most obviously differed from a standard Gen.1 Ford GT on account of its new roof architecture and custom rear clamshell.
The roof system comprised four individual body coloured panels that allowed the driver to choose from one of three alternative configurations: Coupe, T-top or Roadster.
In Roadster trim, all four roof panels lifted off Targa-style.
In T-top trim, the GT’s trademark door panels that cut into the roof detached separately which left a retro-style central spine.
In Coupe trim, the GTX1 looked, from the front at least, identical to a standard Ford GT.
All four roof panels could be stowed within the car for added practicality.
The GTX1’s redesigned rear clamshell featured two buttresses that swept backwards to give a streamlined effect in a similar fashion to Porsche’s Carrera GT. In between was a flattened rear deck with a clear glass screen that meant the supercharged V8 engine was still on display. There was also a vertical glass screen between that buttresses that could be electronically raised and lowered for additional cockpit ventilation.
Otherwise, the rest of the GTX1’s predominantly aluminium panels were retained in standard trim.
Adhesive sill and centre stripes (the former with Ford GTX1 script) were fitted as standard.
Chassis
To compensate for the lack of a roof, Ford came up with an array of chassis reinforcements for the GTX1’s aluminium spaceframe.
Each car also came with forged 6061 Alloy Corporation five-spoke wheels that were an inch bigger than standard (19 x 9-inches front and 20 x 11.5-inches rear). Pirelli P Zero Rosso tyres replaced the original Goodyear Eagle F1s.
The Brembo brake system was left alone. It comprised cross-drilled and vented discs all round (355mm front and 335mm rear) along with monobloc four-piston aluminium calipers.
ABS was standard along with power steering.
A 66.3-litre fuel tank was housed within the central tunnel.
Engine / Gearbox
In the engine bay was a 90° V8 imported from the standard GT which was itself loosely based on the unit found in the F150 SVT Lightning (albeit much modified by Roush Engineering in Livonia, Michigan).
Instead of the SVT Lightning’s wet-sump cast-iron block, Roush created a brand new dry-sumped aluminium block for the GT. There were also new dual instead of single overhead camshaft heads with four as opposed to just two valves per cylinder.
Other Roush enhancements included high-lift camshafts, forged alloy pistons, high-strength connecting rods and a forged steel crankshaft. There was a new supercharger too - the Roots-type unit found in the F150 was replaced with a more efficient intercooled Lysholm screw-type Eaton 2300 compressor that ran at 0.83 bar.
Engine management was courtesy of Ford’s EEC-V OBD II software and fuel delivery via a sequential multi-port electronic system with dual injectors per cylinder.
As per the SVT Lightning, displacement was kept at 5409cc thanks to a bore and stroke of 90.2mm and 105.8mm respectively. Similarly, the compression ratio was an unchanged 8.4:1.
Peak output was 550bhp at 6500rpm and 500lb-ft at 4500rpm.
For comparison, the SVT Lightning produced 380bhp at 4750rpm and 450lb-ft at 3250rpm.
Engines were assembled at Ford’s Romeo plant in Michigan and hooked up to a six-speed manual transaxle developed by Ricardo in the UK. Transmission was through a single-plate AP Racing clutch and helical limited-slip differential.
Interior
Inside, the GTX1 was, roof aside, identical to any other Gen. 1 GT which Ford’s designers had copied from the original 1960’s GT40.
Housed in a wide oval binnacle was a cluster of seven horizontally laid out gauges. Directly behind the three-spoke steering wheel was a large 8000rpm rev counter flanked to the left by a water temperature read out. Off to the right was an oil pressure gauge, a voltmeter, a vacuum boost dial and fuel meter. Angled towards the driver at the far right-hand side was a 220mph / 360kmh speedometer.
In addition to a bank of warning lights, the instrument binnacle housed a quintet of large toggle switches.
Carbonfibre Sparco seats with vented portholes were another nod to the GT’s heritage. In between was a chunky magnesium transmission tunnel complete with polished aluminium gear lever.
The seats, dash, door panels, header trim, centre console armrest, centre bulkhead panel, A and B pillars and cowl trim were all upholstered in black leather. The rest of the interior was a mix of natural aluminium and hard black plastic.
Air-conditioning, a two-speaker audio system, remote central locking, electric windows and driver and passenger airbags were fitted as standard.
Weight / Performance
As a consequence of the various chassis reinforcements, the GTX1 weighed 50kg more than a standard GT of the time (1588kg as opposed to 1538kg).
Top speed was unaffacted (205mph) as was the 0-62mph time (3.7 seconds).
End of Production
Ford officially offered the GTX1 conversion via the Genaddi Design Group until production of the GT was discontinued in September 2006. However, the Wisconsin firm is understood to have retroactively carried out conversions for a year or two after.
In total, around 30 to 40 Gen. 1 Ford GTs are believed to have been subject to the GTX1 conversion.
Text copyright: Supercar Nostalgia
Photo copyright: Ford - https://www.ford.com
