Contents
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Why does a convertible need a roll bar?
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What is a roll bar on a convertible?
- Do all modern convertibles have a roll bar?
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Can a roll bar be retrofitted in the convertible
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How high does the roll bar or roll cage have to be?
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How dangerous is a car accident with a convertible without a roll bar?
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Are the roll bar and roll cage identical?
- Conclusion: How important are roll bars in a convertible?
Why does a convertible need a roll bar?
When a vehicle is involved in an accident, the airbags, seat belt and cabin protect the occupants from the consequences. So that the vehicle cabin cannot be distorted by the driving dynamics, the centrifugal forces and the wind, the manufacturers are forced to stiffen this structure sufficiently. To do this, columns are used that rise up vertically from the chassis, like the supporting pillars in architecture. Frame components are attached to this, which hold the glazing and the roof. In this way, the occupants adequate rollover protection necessary, because extremely massive forces are required to press in such a cabin.
It’s different with the convertible, because here the pillars are missing from the upper edge of the door line. In addition, there are no frames, because the windows can be completely sunk into the body. The exception is the windscreen, which in a vehicle without rollover protection can only withstand the wind. If a convertible lands on the roof without a roll bar, the windscreen breaks off and the occupants are trapped between the floor and the body. The consequences are mostly massive injuries – also of the head – as the ADAC found out in crash tests. The automobile club’s accident experts state that in the case of a rollover in a convertible without a bar, head injuries are significantly more common and are significantly more serious.
What is a roll bar on a convertible?
Roll bars are the stripped down version of the roll cages used in racing cars. In particular in rallying and touring cars, but also in Formula 1, cages – mostly with steel tubes – are used to protect drivers in an accident. These cages are firmly connected to the chassis or body at four to twelve points.
The Roll bars in the convertible are the lightweight construction of these roll cages. When it comes to the hanger, the manufacturers restrict themselves to an absolute minimum of struts in order to create maximum safety with as little material as possible. This is why the roll bars are not visible in a modern convertible, because they are part of the frame construction of the windshield, for example. Removable hard tops are not considered structural and are therefore not adequate as rollover protection.
Roll bar in the convertible for passengers in the rear
The driver and front passenger in a convertible can be well protected by integrated roll bars in the frame construction of the windscreen. This is different for the passengers on the rear seat bench, because the usually frameless and fully retractable side windows do not give this an opportunity.
That is why the convertible manufacturers have developed foldable brackets. Register with this security system Sensors detect an impact and react as soon as the vehicle rolls past a certain level. In these cases, these sensors trigger the folding out of the roll bars, which takes place as quickly as with an airbag. This technique allows occupants in a convertible to be protected with a roll bar, although there is no way to hide it in the bodywork.
Do all modern convertibles have a roll bar?
By far not all convertibles on the market have a roll bar.
We have one below Compiled a list of the most common convertibles with roll bars. This list does not claim to be complete. Examples of convertibles with a roll bar are:
- Audi A4
- Audi S4
- Audi A5
- Audi S5
- Audi TT
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BMW 3 Series including M3 from 1999 onwards
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BMW 6 series including M6 from year of construction 2003
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BMW Z3, however, only with factory-fitted optional roll bars for an extra charge
- BMW Z4
- Chrysler Crossfire
- dodge viper
- Honda S2000
- Jaguar XK8
- Jaguar XKR
- Jaguar F TYPE
- Lamborghini Murcielago
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Mazda Miata from the 3rd generation and there from year of construction 2006
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Mercedes C class
- Mercedes CLK
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Mercedes S class
- Mercedes SLK
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Mercedes SL, however, only the current models since year of construction 2020
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MINI from year of construction 2009
- Nissan 350Z
- Nissan 370Z Roadster
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Porsche Boxster
- Porsche 996
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Porsche 997
- Porsche 991
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Saab 9-3 from year of construction 2004
- Volvo C70
- VW New Beetle
Can a roll bar be retrofitted in a convertible?
Some manufacturers stayed for their convertibles Roll bar as a retrofit kit at. These either have a general operating permit or must be registered as individual approval by the TÜV. If you drive a convertible without a roll bar and the vehicle manufacturer does not offer a retrofit kit, you can contact an auto tuner. These car extras specialists almost always find a way to fit a rollover protection.
The construction of a convertible is usually very helpful. In open vehicles, neither the pillars nor the roof can be used to stiffen the body. To ensure that the convertible is stiff enough and does not warp, the flanks, including the doors, are usually designed to be stronger. This is exactly where there are points where the tuner can attach a roll bar. The costs for such a one-off production including TÜV acceptance amount to depending on the model and design around 2,500 to 5,000 euros.
How high does the roll bar or roll cage have to be?
A roll bar in a convertible only offers adequate protection if it is high enough to The heads of the occupants do not protrude above it. This is particularly important if racing belts are installed in the vehicle.
If 4, 5 or 6-point racing belts are used, these ensure that the driver and passenger remain seated upright in the event of a rollover. The top of the helmets of all occupants must fall below the line between the top of the windscreen and the top of the roll bar. Only then can the roll bar offer full protection.
In motorsport, this is known as the “broomstick test” because it is common to place a broomstick over the top of the windscreen and roll bar while the occupants are seated in the vehicle. This is a simple way of determining whether the roll bar is high enough. If the top of an occupant’s helmet is above this level, the roll bar will not provide adequate protection.
Adequate height of the roll bar in the convertible can be a problem for tall drivers. Also because the roll bar is designed by the manufacturer for road traffic, i.e. for driving without the additional height of a helmet. It is the occupant’s responsibility to ensure that there is adequate roll bar height. However, the manufacturers usually already take precautions. In most convertibles, the driver and front passenger sit lower than in models of the same series with a hard top. In this way, the car manufacturers ensure that most tall people can drive a convertible without any worries.
How dangerous is a car accident with a convertible without a roll bar?
The The risk of a rollover in a convertible is minimal and also significantly lower than in a coupe, SUV or sedan. The reason for this is that most convertibles are designed as sports cars and therefore have a very low center of gravity. So it’s not that easy to turn a convertible upside down. Still, any car can roll over under the right circumstances. And that’s exactly when the chances of survival are significantly lower than in a vehicle with a real roof and roll cage.
For this reason, a special rollover protection was developed for the Mini Cooper S, for example. In the event of a rollover, the roll bars behind the front seats fold up on this model to provide the occupants with a survival space. Other cars feature Technologies that minimize the risk of a rollover – like the electronic stability program. The numerous airbags in modern cars also help to protect the occupants.
In addition, many vehicles have anti-roll bars, but these are not directly related to the rollover protection. Instead, they connect opposite sides of a vehicle’s suspension across the axles to improve handling. A stabilizer bar prevents the bank, which can cause a rollover. But they are not actually a safety device, but primarily improve the performance of a car.
However is no convertible is as safe as its hardtop counterpart. The added rigidity of a non-moving roof provides much stronger protection and adds extra strength to the bodywork in the event of an accident. However, the driving pleasure and the feeling of freedom when driving in the open air is an unforgettable experience that no hard top can offer, even with a panoramic roof.
Are the roll bar and roll cage identical?
At its simplest, a roll bar is just that: a single bar. It can have loops and consist of several welded tubes, but basically it’s still a staff. His main task is to be the first thing to hit the ground when the car rolls over.
In contrast, has a roll cage has multiple subsections that extend rearward and often forward as well. So-called 4-point roll cages are sometimes referred to as 4-point roll bars because they do not have tubes extending forward and over the doors. This blurs the line between roll bars and roll cages. However, their triangular shape makes them stronger than simple poles.
In addition, roll cages provide solid roll protection and also absorb other impacts, including from the side. Instead of just focusing on the overhead area, protects a cage from all sides and thus offers a larger survival space than a roll bar.
Conclusion: How important are roll bars in a convertible?
A roll cage in a convertible would probably be out of place unless the driver intends to participate in a rally with the top down. However, the roll bar should be part of the equipment in every convertible, because it creates a survival space for the occupants, which is crucial for the outcome of a rollover. If you want to buy a convertible without an integrated or hidden roll bar, you should check the possibility of retrofitting before making a purchase decision. Driving slowly and particularly carefully and even wearing a helmet voluntarily are no alternative to the solid protection provided by the roll bar in a convertible.
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