Chassis Stiffening

These days we read a lot of about how car manufacturers are stiffening the chassis for every new model that they develop. Each replacement model seems to be increasing chassis stiffness by 30% to 50% on the previous model. What this basically means is to improve structural rigidity of the car. This has a direct impact on handling and safety. With reduced chassis flex the car will have better cornering stability and also better crash protection for the driver and occupants.

You may also notice that some car manufacturers seem to have cars that appear a lot stiffen in construction than others. A good example is Porsche, it has one of the stiffest chassis for any production car in the market, and with the opposite end of the scale being Proton and some China brands. Naturally Porsche being a performance car manufacturer they would be using stiffer chassis compared to a mass market passenger car manufacture that is more concerned about profits. European car manufacturers adopt a different approach when designing their cars and have made their car chassis stiffer than most Japanese cars. This is very evident in the NCAAP crash test results. Making cars with stiffer chassis is more expensive and heavier.

For older cars that have less stiff chassis there are many aftermarket solutions available. There are strut bars, fender brace bars and other chassis stiffening bars. These add weight to the car but also significantly increases the chassis rigidity. The key thing is that the brace or bars are made to high standard and will not break off easily under load. There have been incidences where a car fitted with several chassis stiffening braces have helped the driver survive big accidents. The chassis stiffening braces were able to absorb and defect the energy from the crash and channel is away from the cabin. In some cases the chassis stiffening braces kept the cabin's structural integrity intact.

The other alternative is the Chassis Foam. This special foam is injected directly into the chassis cavities and allowed to expand to fill the hollow sections of the chassis. Once cured the foam will improve chassis rigidity significantly. It will also reduce the road noise and vibration. The foam will reduce the sound waves traveling through the chassis. One of the other benefits of using chassis foam over strut braces and other bars is the chassis foam only adds less than 2 kg of extra weight compared to 1 strut bar alone will weight 4 to 6 kg.

For cars designed and build in the 1990s and the early 2000s, I would recommend installing some chassis stiffening braces or having the chassis foam treated.