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Last modified: 21.4.2025
The Jumbo Story
A summary of the short life of the Jumbo
1.6.1973 The Steinmetz Automobiltechnik competes for the first time in the 36-hour race at the Nürburgring with a Commodore B. Opel introduced the new model in spring 1972.
Initially – unusual for Steinmetz – it white. A special crankshaft was cast for the engine, giving it a displacement of 3.6 litres. Werner Christmann, Rudi Eberhardt and Klaus Miersch were hired as drivers.
The race was quite successful for the new Commodore. As expected, of course, they also had to struggle with problems of the brand new car. For example, oil sprayed through the torn seam of an oil line directly onto the brake on the front left. In addition, there was continuous rain. A spin followed by a crash into the crash barrier was therefore almost inevitable. The resulting damage could be provisionally repaired. At the front, the Commodore was given a headlight from an Ascona A, at the rear a truck taillight.
As a result, the race had to be abandoned.
This was followed by only one more race in the DRM in Mainz-Finthen in July 1973.
In the course of 1973, Bernie Ecclestone lobbied the International Sports Commission for the "Silhouette Car" series, which had been under discussion for two years. Klaus Steinmetz Steinmetz saw the Commodore B in Group 2 as uncompetitive after only two appearances and decided to be prepared for this series. He took the Commodore out of active action and began to convert it. Klaus Steinmetz was able to reach an agreement with Opel that they would bear part of the development costs.
The Commodore then became the legendary Jumbo with its distinctive front and rear wings, 5.3 liter V8 engine from the Diplomat, whose displacement was changed to 6 liters by a special crankshaft from the american company "Hank the Crank" , equipped with Mahle forged pistons, 4 x 48 Weber twin carburettors (later replaced by 52 from Morand) as well as a compression ratio increased to 11.4:1 and a ZF 5-speed transmission. The power output was stated to be 510 hp at 7100 rpm. 0 to 100 km/h in 4.3 seconds. For 1973 these figures are very remarkable, even if they would probably be hardly achievable under normal conditions. The torque was 56 mkg / 5600 rpm. 12x15 rims at the front and 15x15 at the rear. On each side, hand-bent 4-in-1 elbows made of 60mm pipes that ended in sidepipes. The curb weight was about 1,020 kg. This corresponds to a power-to-weight ratio of 2 kg/hp. The doors and hoods were made of plastic. When the car was realized, Hans Herrman was responsible for the engine (the engine was supplied by CanAm driver Lothar Motschenbacher), and Klaus Schuppener responsible for the chassis. By the way, the fender flares, the front wing and the "OPEL COMMODORE" lettering as well as the choice of colors were not developed and manufactured by Steinmetz, but by the OPEL Styling Center. The rear wing was developed and manufactured by GRP specialist Willy Deppert in Ramstein. Willy Deppert was the responsible head of model making at Irmscher for 25 years and was a good friend of Volker Steinmetz. The V8 engine was probably chosen - at least at the suggestion - by GM.
At the customer's request, the jumbo was also to be supplied with a five-liter engine (Formula 5000) with about 485 hp. Injection is also said to have been possible.
The jumbo was the first car on the continent to be created according to the idea of "silhouette cars", but did not fit into any official vehicle group for the time being. He was not allowed to start in Group 5 because the displacement was limited to 3 liters. Nor in touring car races, because there was no number of units. Thus, only the CanAm or Interserie remained, where there were no restrictions.
The British Super Saloon series was also considered as a possible area of application. No major changes to the vehicle would have been necessary for its regulations. However, no further efforts are currently known in this regard.
Das erste Mal tauchte der Jumbo Ende 1973 beim "Akademischen" in Hockenheim mit der Startnummer 10 auf. Erste Probefahrten, von Klaus Steinmetz selbst durchgeführt, ergaben eine Zeit von 1,13 Min für den kleinen Kurs. Danach hatte er seinen ersten Interserie-Auftritt in der Saison 1974 in Mainz-Finthen mit der #2. Er startete in der für 1974 neuen Super Stock-Klasse. Es folgten noch wenige Interserie-Auftritte. Eine Schwachstelle des Jumbo war die Hinterachse und das Getriebe, die der Leistung des V8 nicht gewachsen waren. Vermutlich deshalb taucht ab etwa Mitte 74 ein Ölkühler am Heck auf. Ein weiteres Problem war der massive Hitzestau unter der Haube, verursacht durch die nach oben gebogenen Auspuffrohre.
Between July and August 1974, the front wing was significantly modified and then had a rather blunt shape. Presumably, the downforce on the front axle had to be reduced, as there was enough weight on the front axle anyway due to the heavy V8. A completely closed version was shown at the season finale Hockenheim on 30.11.1974. However, this may have been a temporary repair (see also here). At the Jim Clark race on 13.4.75 the jumbo appeared with closed headlights. Further modifications are currently unknown.
The original Front Wing
New form - since Kassel Calden 18,8,1974
Even before the jumbo could compete in the series for which it was actually built, Steinmetz Autosport GmbH went bankrupt at the beginning of September 1974 (certainly not least due to the energy crisis).
OPEL had already seen the cooperation as "interrupted" due to the lack of prospects of success of the jumbo and stopped the V8 project. Steinmetz himself stuck to it until the end. After Steinmetz's insolvency, the car was taken over by Peter Hoffmann, who had already been used by Steinmetz as a driver, and continued to be used in the Interseries. He replaced the vulnerable rear axle with a Camaro axle. However, there are very few races known under Hoffmann's application. After four races (if you assume Hoffman and no longer Steinmetz application for the Redlefsen Super Sprint on 08.09.1974), Hoffman ́'s new car - the McLaren M8F - already appears in the databases.
The following events with Jumbo participation are known:
01.06.1973 - #1 - 36-hour race Nürburgring - Steinmetz Automobiltechnik - Cancelled
01.07.1973 - #16 - DRM Mainz-Finthen Div.1 - Steinmetz Autosport GmbH - Retired
0 3.11.1973 - #10 Academic Hockenheimring AMS - Steinmetz Autosport GmbH
??.??.1974 - #65 test day in Hockenheim. Driven by Klaus Steinmetz
02.06.1974 - #2 Int. AvD/HMSC Airfield Race Mainz-Finthen - Steinmetz Autosport GmbH -Cancelled
17.06.1974 - #101 Int. ADAC 300 km race for the Goodyear Cup Nürburgring - Steinmetz Autosport GmbH - 27th place
14.07.1974 - #93 Reisdorf Hill Climb (Artur Blank) - Steinmetz Autosport GmbH
21.07.1974 - #26 Int. 4th ADAC Circuit Race Hockenheim, Prize of the City of Karlsruhe - Steinmetz Autosport GmbH - retired
18.08.1974 - #9 Kassel-Calden Airfield Race - Steinmetz Autosport GmbH - 10th place
24.08.1974 - #46 AvD Prize of Nations – Steinmetz Autosport GmbH – Entered (probably did not start)
08.09.1974 - #5 International Redlefsen Super Sprint - Steinmetz/Hoffmann – Entered (probably did not start)
30.11.1974 - #15 Int. Season Finale Hockenheim - Peter Hoffmann Racing
13.04.1975 - #16 - Jim Clark Race, AvD Germany Trophy Hockenheim - Reter Hoffmann Racing - Retired
15.06.1975 - #19 - Int. AvD/HMSC Airfield Race Mainz-Finthen - Peter Hoffmann Racing - Retired
The starting number 126 could not yet be assigned.
The distinctive black hood is probably the result of an incident in Kassel-Calden.
A photo from this event shows the car without the hood (see also here ).
Presumably the original hood was lost during this race. On this occasion, an attempt was made to dissipate the enormous heat radiated by the upwardly curved exhaust pipes through openings in the hood.
The rear wing could also have been damaged in Kassel-Calden, because in the next known photos the middle section of the wing is also black.
It is also conceivable that Peter Hoffmann wanted to adjust the changed overall appearance (through the black hood) at the rear.
Last known development stage of the Jumbo (Hockenheim 1975)
The rear view has hardly changed until the end
The Jumbo made no further appearances in 1975 and the Super Stock class was dropped from the Interserie. After that it disappeared from the race track and was supposedly sold by Peter Hoffmann. However, Peter Hoffmann was still in possession of the vehicle registration document and the ONS car passport long after the car disappeared.
After the sale (?), it was apparently exhibited in the showroom of Opel dealer Georg von Opel (Opel-Rondell) in Frankfurt. Peter Hoffmann is quoted in an interview as saying "...when this was demolished, all trace of the Jumbo was lost." The demolition took place in 1997. Could the Jumbo really have still existed at that time?
It seems certain that the car ended up in an Opel car dealership (Gräf?). The is said to have been stripped down there. The original rear wing and a rear rim are proven to still exist. These parts surfaced in the early 1990s.
A rumour about its whereabouts persists. According to this, the Jumbo was sold to four motorsport enthusiasts and parked by them in a kind of allotment or back yard. After complaints from neighbours, it was eventually dismantled and scrapped. However, there is no evidence to support this story.
The OPEL Rondell in Frankfurt
The Jumbo is said to have been standing in the shop window here before it disappeared.
Sad remainder: The rear wing of the Jumbo (Photo: Marco Wolf)
The Jumbo in model
In addition to the real models #101 (Int. ADAC 300km race) and #10 (Akademisches Hockenheimring) by NEO, there are two other designs "Tabac" and "Pan Am" but these are purely fantasy products. The Jumbo was only built once and the paintwork remained the same until it disappeared.
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