AC Frua
1971 AC 428 Convertible
Overview
ManufacturerAC Cars
Also calledAC 427[1]
AC 428[1]
Production1965–1973
81 made
DesignerPietro Frua
Body and chassis
ClassSports car
Powertrain
Engine
Transmission4-speed manual
3 speed automatic
Dimensions
Wheelbase95 in (2,413 mm)
Length176 in (4,470 mm)
Width68 in (1,727 mm)
Height49 in (1,245 mm)
Curb weight3,150 lb (1,430 kg)

The AC Frua or AC 428 is a British GT built by AC Cars from 1965 to 1973. Production was 81 cars built in total: 49 coupés (known as fastbacks), 29 convertibles, and 3 special bodied.

History

The Frua is built on an AC Cobra 427 Mark III chassis extended by 6 inches (150 mm). Chassis were built at the AC plant in England then shipped to Frua's workshop in Italy where the body was fitted and then sent back to England to have the power train and trim added. Production costs were high and the cars could not be sold at a competitive price. Unlike similar cars such as the Iso Grifo, Iso Rivolta, Monteverdi, and De Tomaso models of the period, the AC Frua features fully independent racing based coil spring suspension.

The AC Frua was never fully developed because AC Cars lacked the financial means. The car's main drawback is a tendency of the V8's heat to bleed into the cabin.

Chassis

1971 AC Frua convertible

Chassis construction was similar to most Italian supercars of that era, with square and rectangular tubing connecting the steel body to the frame. Though the 4-inch (100 mm) tubular chassis allowed both coupé and convertible versions to be rigid, the design was intricate and prone to rust. The bonnets and boot lids were fabricated from aluminum.

Performance

1968 AC Frua coupé, quarter
1968 AC Frua coupé, rear

The AC Frua competed with Ferrari, Lamborghini, and Maserati models. Built over a stretched AC Cobra 427 chassis, the car had immense performance; the big-block Ford FE engine had larger capacity, more torque and more power than similar Italian cars, but in a car of similar weight.

John Mclellan wrote in his book "Classic ACs, Auto Carrier to Cobra" that Derek Hurlock once said to journalist Mike Tailor: "I like the 428 because it fits my image of a true GT Car". He is quoted in Autocar "Like anything exclusive, especially from craftsmen, it costs a lot of money. For this you get one of the fastest cars on the road, guaranteed to make an impression anywhere, and backed by a small company that cares. This one AC that joined that select company of very fast, very luxurious touring automobiles which moved effortlessly from current model to collector's piece". The magazine published a road test report in 1968 of a 428 coupé, and recorded a maximum speed of 141 mph (227 km/h) along with a 0 - 60 mph (97 km/h) time of 6.2 seconds.[2] The acceleration time was fractionally better than the magazine's testers had achieved with an Aston Martin DB6, but the Aston Martin was comfortably ahead on top speed.[2] The AC's overall fuel consumption for the test came in at 15.6 mpg (18.1 L/100 km), roughly 15% better than the heavy Aston Martin.[2] The AC 428 coupé sported a recommended UK retail price of £5,573 (including automatic transmission), to the manual transmission Aston Martin DB6's £4,460 - itself roughly twice that of a 4.2 litre Jaguar E-Type roadster at £2,225.[2]

Towards the end of the production run a couple of prototypes for an extended range were produced. There was a four-door version of the coupe and a more streamlined version of the convertible that included electrically operated "pop-up" headlamps. Neither was developed due to the precarious state of the company finances.

The AC Frua may be confused with the very similar looking Pietro Frua-designed Maserati Mistral. However, only the front quarter windows and door handles are shared.

AC Frua Technical Data
Chassis "AC Cobra 427 Mark III" four inch (100 mm) tube frame extended by 6 inches (150 mm). Front engine, rear drive.
Engine Iron "big block" Ford FE 428, some models fitted with higher performance cross bolted main Ford 427 engine (side oiler). Hydraulic lifter, Autolite or Holley four barrel carburetor. (Specifications can vary substantially with each car).
Bore & stroke 104.9 X 101.2 mm, 10, 5:1 compression.
Capacity 428: 7,016 cc (428.1 cu in), 427: 6,997 cc (427.0 cu in).
Power 428: 345 hp (257 kW) @ 4,600 rpm, 427: 385 hp (287 kW) @ 5600 rpm
Torque 428: 642 N⋅m (474 ft⋅lbf) @ 2,800 rpm, 427: 624 N⋅m (460 ft⋅lbf) @ 3200 rpm
Transmission Fully synchronized 4-speed Ford Toploader transmission (close-ratio) or 3 speed automatic Ford C6 transmission.
Steering Rack & Pinion.
Front suspension Fully adjustable independent suspension with double triangular wishbones, coil spring hydraulic telescopic shock absorbers.
Rear suspension Adjustable independent suspension with double triangular wishbones, coil spring hydraulic telescopic shock absorbers.
Differential Salisbury, limited slip. Ratio: Automatic 2.88, Manual 3.08.
Brakes Four discs power assisted "Girling" 3 pistons, dual remote servo assistance.
Body Coach-built steel body over extruded rectangular and square tubing.
Measurements 4,470 mm (176.0 in) X 1,727 mm (68.0 in) X 1,245 mm (49.0 in); Wheelbase 2,413 mm (95.0 in).
Unloaded weight 1,430 kg (3,153 lb)
Maximum speed Manual Transmission: More than 245 km/h (152.2 mph), 0 to 100 km/h (0-62 mph): 5.4 s (Autosport Magazine); Automatic Transmission: 220 km/h (136.7 mph), 0 to 100 km/h (0-62 mph) 5.7 s.
Fuel consumption 17.2 L/100 km (16.4 mpg‑imp; 13.7 mpg‑US)
Production life 1965 to 1973
Number of cars built 49 coupes (31 of which had right-hand drive),[3] 29 convertibles and 3 special bodied cars.

See also

References

  1. 1 2 AC 427, www.motorbase.com Archived 12 November 2014 at the Wayback Machine Retrieved on 12 November 2014
  2. 1 2 3 4 "Autocar Road Test A.C. 428 fastback: All-independent Cobra chassis with Ford 7-litre V8 and Frua body". Autocar. 129 (3777): 11–16. 4 July 1968. Extremely fast and not too heavy on fuel. Plenty of adhesion; little roll, no dive or squat. Firm ride, comfortable seats. Positive steering, too much kick-back. High price for hand-built exclusive GT from small manufacturer.
  3. ↑ http://hexagonclassics.com/cars/ac-428-frua-coupe-automatic-1971/ Archived 6 April 2016 at the Wayback Machine Hexagon Classics 1971 AC 428 Frua Coupé
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