Car Features

The infamously banned 1981 Lotus 88 Formula One car featured a well documented twin-chassis design, but we’ve found another two-chassis car that deserves credit as well – particularly as it emerged back in 1906!

During the USA’s automotive boom of the early 1900s, brothers Howard and Walter Marmon built their first automobile, in Indianapolis.  However, there were hundreds of fledgling auto makers at that time and the Marmon Brothers were determined to build a special type of vehicle.

With Howard as engineer and chief designer, and Walter handling finances and manufacturing, the brothers manufactured a 20bhp, air-cooled, overhead-valve, 90-degree V4 engine and slotted it into their first Model A Marmon touring car, in 1902.  It was priced at a heady A$60,000 in today’s values, but they sold five examples and were urged to continue development and production.

Marmon leapt ahead of its competitors in 1906, with the invention of a patented ‘Double Three-Point Suspension’ system. The idea was to provide wheel travel over rough and undulating surfaces without causing excessive chassis twist.

The design employed two three-point-mounted frames: a lower one carrying the engine, transmission and drive axle and the other carrying the bodywork. 

Each frame was roughly triangular. The bottom frame mounted to the front axle and both front wheels, and also to a central point on the rear-axle’s structural differential case. That structure meant that the engine and differential were always aligned, thus eliminating the need for universal joints on the propeller shaft.

The second triangular frame, which mounted the rear axle, rear wheels and the body, was connected to a central point on the front of the lower frame. 

The system eradicated twisting from the driveline and from the bodywork. However, this was a complex, heavy and expensive solution to ‘twistless’ wheel travel, so touring-bodied Marmons were priced at more than A$90,000 in today’s money and larger, seven-seat versions were 50-percent more than that.

Eventually, as roads and spring technology improved, Marmon dropped its dual-chassis design, but the marque continued to be regarded as one of America’s best. 

Marmon continued manufacturing, after restructuring during the Great Depression, into modifying Ford vehicles to 4WD Marmon-Herringtons and later, producing Marmon-branded heavy trucks, until the late 1990s and, thereafter, truck parts.

Lotus’ twin-chassis

Lotus 88B – Takayuki Suzuki

The Lotus 88 was an innovative Formula One car designed by Colin Chapman, Peter Wright, Tony Rudd and Martin Ogilvie. Like all F1 car makers in the early ‘downforce’ era, Lotus struggled with the necessary compromise between achieving the needed aerodynamic downforce and too-stiff suspension. 

By 1981 the FIA had banned the moveable skirts fitted to the bottom of the cars’ side-pods that were vital for achieving consistent ground effect and regulated a mandatory ground clearance of 60mm, in the interests of driver safety.

Brabham was the first to circumvent the rules by using hydropneumatic suspension which compressed under aerodynamic loading and lowered the Brabham BT49 onto the track surface. This effectively eliminated any suspension deflection, causing the driver to be buffeted even more than before. 

However, the performance gains were such that other teams soon followed suit to lower their cars. Lotus took a totally different path.

The 1981 Lotus 88 used twin chassis, one inside the other, in contrast to the Marmon approach, where one chassis sat on top of the other. The purpose of the Lotus chassis pair was to have the main monocoque chassis – with driver, engine, transmission and suspension – operating with no inherent ground effect or downforce. 

The aerodynamic package that produced downforce was mounted on a separate, outer perimeter chassis that was connected by four, secondary coil/shock suspension units to the main suspension uprights.

Because the central monocoque needed to be slimmer than conventional aluminium tubs, Lotus soon calculated that aluminium sandwich just wouldn’t be stiff enough. So it developed a carbon/kevlar structure that preceded McLaren’s mid-1981 carbon tub by three months.

In operation, the aerodynamic bodywork connected to the outer, perimeter chassis progressively pushed down on the secondary suspension units as speed increased and that pulled the main suspension harder onto the track. 

At lower speeds, in tight corners, the amount of downforce lessened because of reduced airflow and the main suspension functioned with much more suppleness than the very hard suspensions of conventional F1 ground-force cars.

It was a brilliant innovation and seemed to comply with the rules, because there was no mention of twin chassis being prohibited.

However, when the Lotus 88 made its debut at the first practice session of the 1981 season opener, the US Grand Prix West at Long Beach, it was not allowed to race, following protests by its competitors. A subsequent 88B model was also banned.

Like many groundbreaking innovations in racing, the twin-chassis concept was consigned to the scrapheap.

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