Guide: How the Humble 131 Replaced the Legendary Stratos - a Historical & Technical Review of the Fiat Abarth 131 Rally
Background
In October 1969, the struggling Lancia concern was purchased by Fiat.
Abarth followed in July 1971 and became Fiat’s competition department.
Despite the fact that both firms were owned by the same parent company, they were initially permitted to compete against one another in rallying. Lancia had the revolutionary Stratos which won the World Championship in 1974, 1975 and 1976 while Abarth campaigned the more conventional Fiat Abarth 124 Rally. Both cars ran in the ultra competitive Group 4 class.
In addition to the 124 programme, Abarth also prepared a couple of highly modified Group 5 specials for the 1974 and 1975 Giro d’Italias. The resultant SE 030 finished second in 1974 while the SE 031 took victory in 1975.
The SE 031 was tenuously based on Fiat’s 131 which was launched at the Turin Motor Show in October 1974. A replacement for the 124, the 131 was available as either a two or four door saloon or a five door estate.
When Fiat decided to retire the Stratos, the 131 became its unlikely successor.
The two models could not have been more different. The Stratos was a mid-engined supercar with dramatic Bertone bodywork and a Ferrari V6 motor. By contrast, the 131 was a small capacity eco-box designed for a post Oil Crisis world. It featured a pressed steel monocoque with a rigid rear axle, discs brakes at the front only and a four-speed gearbox. 1.3 and 1.6-litre pushrod engines mustered between 65bhp and 75bhp.
Although some were incredulous at the idea of such a machine replacing the Stratos, Fiat wanted their competition budget to stimulate sales of showroom models. Additionally, management had decided that Lancia should become the parent company’s sports car racing brand while rallying would be left to Fiat. With Formula 1 Ferrari’s domain, resources would no longer be wasted by one subsidiary trying to beat another.
As the standard 131 was obviously not an out-of-the-box contender to win the World Rally Championship, Fiat had Abarth engineer a Group 4 homologation special.
At the time, Group 4 regulations required a production run of 400 identical vehicles.
As this figure was too small for any of Fiat’s factories but too big for Abarth, Bertone were brought into to handle the bulk of assembly. The Turin firm would also be responsible for styling the heavily modified contender.
Chassis
Abarth’s first task was to uprate the existing rear suspension assembly. As a rigid axle was no good for rallying, an independent multi-link layout was devised. It comprised a MacPherson strut with lower semi-trailing arm and transverse control rod. At the front, the standard MacPherson strut with lower transverse arm was retained. Coil sprung telescopic dampers were installed at each corner and anti-roll bars at either end.
Body shells were modified to this Tipo 131 AR specification at the Bertone works.
227mm brake discs from the Fiat 127 were fitted front and rear along with a separate hydraulic circuit for each axle.
The 7 x 15-inch Cromodora CD68 sand-cast magnesium alloy wheels came shod with Pirelli P7 tyres. Compared to the standard 131, the Abarth variant’s track was 73mm wider at the front and 134mm wider at the rear.
Both models shared an identical 50-litre fuel tank mounted underneath the boot floor.
Bodywork
In addition to modifying the bodyshell to accept independent rear suspension, Bertone also fitted a host of lighter and more aggressively styled exterior panels.
Fibreglass was used for the wings, wheelarch extensions, bonnet, bootlid and spoilers. These panels were supplied by Turin boat builder, Cigala & Bertinetti, and either riveted or bonded in place.
The doors had aluminium skins on standard steel frames. Side windows were Plexiglas.
To enhance the standard 131, Bertone added enormous fender flares. The front arches were connected by a deep front spoiler that housed a pair of brake cooling ducts. Another intake was added to the bonnet along with one down each flank ahead of the rear wheels. A roof-mounted bridge spoiler worked in conjunction with a secondary wing located on the bootlid.
Fiat offered a choice of just three colours: red, yellow and blue.
Interior
Inside, the Abarth 131 came with different instrumentation, a three-spoke steering wheel, lightweight door panels and more heavily bolstered seats. The seats were trimmed in fabric upholstery with a body coloured centre stripe.
Once bodyshells had been painted and trimmed at Bertone, they were delivered to Fiat’s Rivalta plant to be fitted with mechanical parts.
Engine & Gearbox
The standard engine was ditched in favour of an uprated Tipo 131 AR.000 derivative reworked by Aurelio Lampredi.
This inline four used the same cast-iron block as the original but combined it with a new light alloy head that featured dual overhead camshafts and four valves per cylinder. Displacement was taken out to 1995cc by extending the stroke from 71.5mm to 90mm. Bore remained unchanged at 84mm.
Wet-sump lubrication was employed and the compression ratio was 10.0:1. A single Weber 34 ADF downdraught carburettors was installed.
Output figures were 140bhp at 6400rpm and 130lb-ft at 3600rpm.
Instead of the four-speed gearbox used in the standard Fiat 131, a non-synchromesh dogleg five-speed assembly with Colotti cogs was adopted. Transmission was via a single dry plate clutch and bodyshell-mounted differential. A ZF limited-slip differential was the only option.
Weight / Performance
At 980kg, the Abarth 131 had a top speed of 119mph and 0-62mph time of 7.7 seconds.
Production
Production started on October 13th 1975 and homologation was approved on April 1st 1976. The car made its international salon debut at the Geneva Motor Show in March 1976. Fiat advertised a list price of just over 9m Lire which compared to 2.3m Lire for the entry level 1.3-litre variant.
As per the Group 4 regulations, 400 examples were manufactured all of which were left-hand drive. Of these, 50 were sent to Abarth for use as competition cars.
Competition History
The model went on to have an extremely successful career. It most notably secured a trio of Driver and Manufacturer World Championships in 1977 (Sandro Munari), 1978 (Markku Alen) and 1980 (Walter Rohrl).
Text copyright: Supercar Nostalgia
Photo copyright: Fiat - https://www.fiat.com
