Guide: Ferrari 308 GT Bertone Rainbow
Background
As Ferrari's coachbuilding partner since 1953, Pininfarina had created all officially sanctioned show cars that wore the prancing horse. However, after Bertone were commissioned to clothe the Dino 308 GT4, they were also given the opportunity to present a styling concept on a special 308 chassis.
What emerged was the 308 GT Rainbow that debuted at the Turin Motor Show in November 1976.
Bertone had been at the forefront of wedge design and created several pioneering concepts between 1968 and 1972. These had included the 1968 Alfa Romeo Carabo, the 1971 Lamborghini Countach and the 1970 Lancia Zero (that ultimately became the Stratos).
Prior to the wedge era, Bertone had also designed a couple of masterful one-off Ferrari 250 GT Berlinettas as well as the ground-breaking Lamborghini Miura and Espada. All things considered, it was easy to understand why Ferrari sought a collaboration with Pininfarina's arch-rival.
A healthy supply of obsolete prototype racing chassis from Ferrari and Alfa Romeo had seen a proliferation of cutting edge concepts by Italian coachbuilders during the late 1960s. However, by the mid 1970s, Ferrari had abandoned sports car racing to focus on Formula 1 and the cache of old chassis had dried up.
Chassis
What Bertone received instead was a special 308-based chassis. It was numbered 12788 and had an unusual 2450mm wheelbase. By contrast, the 308 GTB had a 2340mm wheelbase while the 308 GT4 (which had a 2+2 layout) was 2550mm.
Ferrari's much later 288 GTO did have a 2450mm wheelbase, but was otherwise completely different and used a longitudinally rather than transversely mounted engine.
Like production 308s, the Rainbow chassis was tubular steel. Fibreglass was used for the floorpan, inner arches and front bulkhead.
Suspension was fully independent via unequal length wishbones, coil springs and telescopic Koni dampers. Anti-roll bars were fitted at both ends.
Ventilated disc brakes ran off a hydraulic twin-circuit with a separate system for each axle.
Rather than fit standard Cromodora or Campagnolo wheels, Bertone installed custom split rim components with a unique five-bar grille pattern.
Bodywork
The bodywork was a mix of flat surfaces and practically devoid of any soft edges: even the wheelarches were angular in profile.
The Rainbow's most notable feature was its retractable targa-style roof. This innovative fixture was hinged at the trailing edge and, once raised into a vertical position, slid down behind the seats.
The nose featured pop-up headlights located above a full-width slatted bumper that housed simple rectangular indicators and a chrome prancing horse emblem.
A body coloured roll-over hoop had a faux air scoop mounted on the top and a bank of slatted vents down each sail panel.
Aside from a louvred central airbox above the engine, the rear deck was completely flat.
At the back, the tail fascia incorporated boxed light clusters connected by a slim full width reflective strip. Above this was a stylised model designation and another bank of cooling slats.
The wraparound rear bumper mimicked the slatted effect used at the front and was mounted above a deep body-coloured apron.
Bertone opted for a white colour scheme with two black coachlines down each flank.
Interior
Flush door release catches gave access to the cockpit which was trimmed in black leather with beige carpet. Custom seats had fixed backs and a white vertical insert. The same colour scheme was repeated for the door panels.
Bertone fitted the Rainbow with a body-coloured flat panel dash fascia. It housed the instrumentation and some of the ventilation controls. The rest of the switchgear was located behind the gear lever on the central console.
A conventional steering wheel had a black leather rim with three matching spokes.
Engine / Gearbox
The engine was quoted as a dry-sumped Tipo F106 AB unit from the 308 GTB / GT4.
These three-litre all-alloy 90° V8s displaced 2926cc thanks to a bore and stroke of 81mm and 71mm respectively. They came with belt-driven dual overhead camshafts, two valves per cylinder, an 8.8:1 compression ratio and four Weber 40 DCNF downdraught carburettors.
In this configuration, peak output was 255bhp at 7700rpm and 210lb-ft at 5000rpm.
Transmission was via a five-speed gearbox with a single plate clutch and limited-slip differential. As usual, the gearbox was located below the transversely mounted engine and to the rear of the sump.
Subsequent History
The Rainbow proved to be the last collaboration between Ferrari and Bertone. The contract for the next new Ferrari (the Mondial) was handed to Pininfarina.
As for the Rainbow, it was later re-painted light metallic blue with matching blue carpet.
For many years, it remained part of the Bertone factory collection.
Text copyright: Supercar Nostalgia
Photo copyright: Bertone - https://www.bertone.it
