www.QV500.com - BMW (E26) M1 Part 2: M1 Group 4
 

Winkelhock/Mignot/Poulain, 1979 Le Mans 24 Hours

Having initially conceived the entire M1 project as a means to compete head-on with Porsche in the premier Group 5 'Silhouette' class of the World Manufacturers Championship, BMW's plans were scuppered right at the last moment. An FIA ruling that 400 identical road-going examples had to be constructed before homologation into Group 5 would be granted instantly killed any chance of the M1 racing competitively and forced BMW to make some big decisions to ensure their glorious new road car would not become a white elephant.
   
With no immediate openings for the M1 other than maybe the ACO's Invitational class at Le Mans and a handful of non-championship race's, BMW Motorsport supremo, Jochen Neerspach, cut a deal to run Group 4 cars in a one-make series that would support many of the European Formula 1 rounds. Known as the Procar Championship, this high profile league ran between 1979 and 80, bridging the gap between the FIA homologating the M1 into Group 4 on December 1st 1980 and providing BMW Motorsport with a couple of years in which to perfect their new machine. 50% more expensive than the standard road car, Group 4 M1's initially weighed in at 1005kg for the Procar series although those that went onto run in IMSA and the World Manufacturers Championship were generally 70kg or so lighter, thus coming in right on the minimum weight for Group 4. Set up changes saw Unibal joint suspension instead of the road cars rubber bushed components whilst custom springs and dampers, fully adjustable anti-roll bars and a quicker steering rack were other notable changes. All servo-assistance was removed from the brakes and an adjustable brake balance set up installed. Replica road wheels of 11 and 12.5-inches were fitted at the front and rear respectively. Mechanically, the Group 4 M1's featured a heavily modified engine with a race tuned alloy block, these 3.5-litre motors developing 470bhp at 9000rpm – an amazing 193bhp up on the production car. Slide or guillotine type throttle slides were used in place of individual butterflies whilst the five-speed gearbox boasted a separate oil cooler and a choice of alternative ratios.
 

Stuck/Hobbs, 1980 Watkins Glen 6 Hours		 There was also an uprated Fichtel & Sachs clutch and a high-lock limited slip diff, all of which helped endow the Group 4 M1 with a 193mph top speed and 4.3 second 0-60 time. Aesthetically, BMW were forced to retain much more of a resemblance to the production M1 than would have been the case for Group 5, just bulbous wheelarch extensions, a deep front spoiler and high rise rear wing being fitted. Meanwhile, the cabin was totally stripped of all luxuries, the side and rear glass being replaced with lightweight plastic windows.
   

The press got their first look at the Group 4 M1 in spring 1978 at Munich’s Olympic Stadium, BMW displaying a Motorsport-liveried example in anticipation of the Procar series for 1979. Interestingly, this prototype was still lacking the distinctive rear aerofoil that wasn't fitted until January 1979 after conclusive tests at Paul Ricard. Group 4 M1's did go onto race in a handful of open events that year, Le Mans governing body, the ACO, gifting an entry for the invitiational class at their 1979 24 Hour race (a couple of weeks after Marc Surer had driven one in a German Group 5 support event at the Nurburgring). This Le Mans car was no ordinary Group 4 M1 as it had been painted by none other than Andy Warhol at a reputed cost of £5000. It went onto finish an amazing sixth overall. Although the FIA allowed the Group 4 M1 into an appropriate class for 1980, North America's IMSA governing body forced it to run in their prototype category which meant M1's were penalised in the overlapping WMC events held in the US (like the Daytona 24 Hours and Mosport 1000km, for example). Nevertheless, Group 4 M1's went on to score three notable successes on European soil that year, class wins coming at the Nurburgring and Dijon 1000km race's as well as the Mugello 6 Hours. Officially homologated into Group 4 on December 1st 1980, subsequent seasons at last allowed the M1 to show its true potential with these cars winning 22 of the 33 World Manufacturers Championship race's they contested between 1981 and 84. Just 49 were constructed, most of which were used at one time or another in the highly entertaining Procar series.

 

Ferrier/Servanin, 1980 Mugello 6 Hours