GOOD MOTORING
The crash grill doesn’t help
H. Kishie Singh

THE accompanying photo shows a crash grill fitted on a car. As the name suggests, the crash grill is a strong steel structure bolted on to the main frame of a car to save it from frontal damage in the case of a collision. Rally cars which have extra lights need this to protect the lights and radiator from damage in case of a head-on crash.

The crash grill has many names. The Australians call them "bull bars". They are very effective in saving the car from kangaroos, which cross highways with the same gay abandon as cows do on our roads. The Europeans call them "nudge bars". They come in handy for nudging! Whatever they may be called, they serve the same purpose, to protect the front-end of the car in case something hits it.

Crash grills could be bolted securely on to the cars of yesteryear, which had a chassis or ladder-frame structure. They, however, should not be welded to the chassis or the frame of the car.

The ladder-shaped frame is independent of the body. Other types of frame structures include the space frame. In this case, pipes are welded to the frame. There is also the perimeter frame. This allows the floor to follow the shape of the frame. In all these cases, the body and the frame or the chassis are two separate components.

In case of a collision, the impact-generated energy is taken by the grill and is passed on to the chassis, which, being strong, absorbs the impact.

And because the body, which housed the occupants, was a separate component, very little of the impact-generated energy was passed to it.

If your car has no chassis or frame, there is no place to fit this grill. The new breed of cars have monocoque structures.

In case of a monocoque structure, the body itself forms the frame. In other words, there is no frame independent of the body. This applies even to a welded frame, or built-in frame structure. One advantage is that it makes a lower floor possible. This lowers the centre of gravity (COG).

The other advantage is that since the frame is also the body, it is stronger, lighter and allows for crumple zones to be built in by the manufacture. This is a tremendous safety factor.

A crumple zone means that portions of the car — both in the front and the rear — will fold up. In a severe collision, the designated portions will collapse as per the design. The passenger compartment, which has been reinforced, will be safe. All this is done at the manufacturing stage.

In the absence of a chassis, there is no place to bolt a huge crash grill on to a car with a monocoque structure. The wayside mechanic bolts it on to the sub-frame and immediately destroys the crumple-ability of the car, thus, endangering the occupants.

The impact energy will be passed on to the main frame. This is where the occupants are enclosed. It is one of the most counter-productive measures you can make. You have spent money to increase the danger factor for you and your family’s safety.

Please be careful about the accessories you fit in your car. Get professional advice. As seen, the crash grill has changed the entire geometry of your carefully designed car. Looks alone should not be a factor in sprucing up your car.

Happy motoring

This feature was published on April 3, 2004