New Meriva FlexDoors: Opel rear-hinged doors, past and present

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New Meriva FlexDoors:
Rear-hinged doors at Opel... since the twenties

FlexDoors with full-sized doors which open independently.

FlexDoors with full-sized doors which open independently.

20 Jan. 2010 - Scheduled to go on sale this summer, the new Opel Meriva brings many attractive and clever solutions.

One of the most evident signs of distinction of this small monospace (minivan) can be quickly seen in the FlexDoors, the rear-hinged rear doors which can offer comfort and safety advantages over the regular front-hinged ones.

First, Opel says that unlike many rear-hinged doors systems, FlexDoors feature full-sized doors which open independently without the need for a clamshell overlap by the front doors. A conventional B-pillar makes this independent opening possible, while ensuring good body rigidity and side impact protection. In addition, a handle further facilitates entry and exit.

Options

FlexDoors open up to 84 degrees, wider than conventional doors.

FlexDoors open up to 84 degrees, wider than conventional doors.

From the beginning, two options were quickly rejected. Making the rear doors wider would necessarily mean reducing the size of the front doors, skewing the proportions of the new monocab design. Slide doors, too, were axed because it would have meant increasing the rear length of the vehicle to accommodate the travel of the door and it would have increased vehicle weight.

FlexDoors make it easy to get into and out of the rear seat. Locating the door hinges on the C-pillar also allows more clearance for passengers’ feet to swing past the B-pillar flange. The FlexDoors open up to 84 degrees, much wider than conventional doors, for which 68-70 degrees is the usual standard.

FlexDoors: Parents can reach into the rear seat more easily to help kids.

Parents can reach into the rear seat more easily to help kids.

Entry and exit space is wider and higher because entry access is adjacent to the B-pillar where there is more space between the roof and floor. Stepping in and out of the vehicle feels also more natural. It’s no longer necessary to twist or slide out of the rear seat. Accessing the rear cabin is also easier in narrow car spaces.

Front passengers, who benefit from the same 84 degrees opening angle, can find the FlexDoors also convenient to open the rear doors when stowing a jacket, a briefcase or an umbrella behind the front seat.

From B to C

Meriva FlexDoors: engineers added a raised metal plate to the upper face of the B-pillar which wedges between the closed edges of the doors.

To minimize any lateral door movement in the event of a crash, engineers added a raised metal plate to the upper face of the B-pillar which wedges between the closed edges of the doors. An added benefit is that the plate, which is covered by a black trim panel that sits flush with the window frames, gives a smooth finish that contributes to good aerodynamics and low wind noise.

While door technology is generally a routine thing with front-hinged doors, the rear-hinged type presented some engineering challenges.

On a front-hinged door, the hinges are secured on the B-pillar. On the FlexDoors, though, the hinges had to be moved to the C-pillar. But here was the challenge: on a C-pillar the rear wheel arch takes up too much space to mount a door properly. On the Meriva, hinges must be at least 360 mm apart for the door to be stable.

To solve that challenge, engineers had to move the C-pillar of the FlexDoors aperture 70 - 80 mm forward of the wheel-arch. But door stability involves more than simply relocating the fixing points. To withstand the door loadings on the C-pillar, engineers reinforced the inner body panel down into the rocker. The opening and closing action of the door is also ergonomically engineered so that the door is easy to open and shut.

Safety

Opel Admiral sedan (1937) with rear-hinged rear doors.

Opel Admiral sedan (1937) with rear-hinged rear doors.

Opel adds that from the safety angle, parents can reach into the rear seat more easily to help with buckling up, and children can be more safely guided when getting in and out of the vehicle. For example, when both the front and rear doors are open at the same time, a safety zone is created between the two doors, as both child and parent can get out of the car without any door separating them, reducing the risk of children stepping out into traffic.

Opel Admiral 4-door cabriolet with rear-hinged rear doors.

Opel Admiral 4-door cabriolet with rear-hinged rear doors.

Speedlock

Opel engineers have developed a fail-safe system that ensures the doors are always latched and locked whenever the vehicle is in motion at speeds above four kilometres per hour (2.5 mph).

Opel Kapitan sedan with rear-hinged doors (1938 and 1953).

Opel Kapitän sedan with rear-hinged doors (1938 and 1953).

Electric locks (speedlock function) are automatically triggered at this speed, and FlexDoors cannot then be opened from inside, but they automatically release again after stopping. In that case the doors have to be unlocked before entering. However, in the event of a crash - when in-car restraint systems have been deployed - the doors unlock automatically.

Coach doors

Interestingly, Opel notes that rear-hinged doors are not that exceptional in transportation. They were a common sight in horse-drawn carriages, when personal transportation was the preserve of a privileged few, and getting in and out with grace and decorum was a necessity. Back then, doors with a wide front opening were a natural solution.

Opel Regent Luxus Limousine, 8-cylinder in-line engine (1928) with rear coach doors.

Opel Regent Luxus Limousine (1928) with rear coach doors.

Even when engines replaced horses, early automobiles keep much of the same design as their forbearers, including the way the doors opened. Ladies wearing long dresses, for instance, could get in and out without fear of getting them soiled by brushing against the bodywork. When there was a chauffeur, he was able to quickly alight and open the rear door while standing by to help his occupants out.

As far as Opel is concerned, it started building cars with rear-hinged doors around the turn of the century, in the early days of the horseless carriage.

Opel-Motorwagen 16/18 System Darracq of 1904.

Opel-Motorwagen 16/18 System Darracq of 1904.

An example is the Opel-Motorwagen 16/18 System Darracq of 1904. This had a high-riding, wooden body with two rear-hinged doors, allowing passengers to step up onto the running board and get straight in and out without twisting or bending. For the chauffeur up front, there were no doors at all.

The first four-door Opel with its rear doors rear-hinged was the 1925 Opel 10/45 sedan. The Opel Admiral, a larger luxury car produced in limited numbers between 1937 and 1939, had rear coach doors in both four-door cabriolet and sedan body styles.

Opel's long-running Kapitän sedan had a unitary body construction, an advanced feature for the time, as well as the more traditional rear coach doors. More than 100,000 Kapitäns with rear-hinged doors were produced between 1938 and 1953.

Rolls Royce Phantom: rear-hinged rear doors at the top luxury segment.

Rolls Royce Phantom with rear-hinged doors.

Even today, Rolls Royce limousines still feature rear-hinged, or coach doors, as they are commonly known. Traditional London black cabs are famous for them - cabbies can reach back and open the rear door without leaving their seat. Passengers can step out to pay their fares without having to first walk around an open door. Those models, like the Meriva, have a central B-pillar.

There are other vehicles on the market with rear-hinged doors, but they are asymmetrical: The front doors are larger than those in the rear. In these cases, the rear doors can only be opened when the front doors are already open.

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So, the new Opel Meriva did not invent the rear-hinged doors. It simply brings them up-to-date, with modern engineering and useful technology for everyday use... in a small economic car.

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