LEATHER FETISH PART2:SHOCKS
EVERY time we enjoy our favourite back roads in our favourite car, we have to thank one of the key technologies that made high-speed modern-day motoring possible and safe - the dampers or more commonly known as shock absorbers.
As the name suggests, this part puts a damper on the oscillation of the springs, otherwise cars would not stop bouncing from departure to arrival.
Today’s dampers are tubular types. They usually consist of a shaft that slides inside an oil-filled tube. In most cars, the dampers sit inside the coil spring or next to the leaf spring.
Within that damper is a series of metal washers with holes in them.
The number of holes, their sizes and positions are determined by the specifications set by the manufacturer, and are selected to achieve certain characteristics.
A damper that acts quickly on compression will have a different set of washers compared to one that is designed to work more on the rebound.
There are dampers that react differently to wheel movement, depending on the speed of movement, while others may maintain a constant resistance level either way.
At the end of the day, the damper has to rein in the spring oscillation so that the car absorbs road imperfections while maintaining composure and consistent tyre contact with the tarmac.
When the car was being born, there were those who believed that highspeed may be detrimental to health, not in the sense that it could result in FailArmy videos on Youtube, but rather that speed itself could induce blindness or cause mental disruption.
In the beginning, cars were not allowed to exceed 15km per hour and had to have a flag bearer running in front of it.
As you can imagine, Messrs Sachs or Bilstein were not particularly worried about the performance of their dampers. In fact, the top damper brands at that time were Hartfords, Luvax, Girling and Armstrong.
Shock absorbers or dampers that were used in the early days of motoring had no resemblance to the sliding tubular variant that has become ubiquitous today.
While the rest of the car may be doing its best to overcome energy wastage or resistance, the damper relies on entropy, friction and dissipation of energy to rob the spring some of its potential energy.
If the damper doesn’t rob the spring of potential energy, then the spring will oscillate a few hundred times before dissipating the energy.
Andre Hartford came up with the idea of using friction plates that could be compressed to adjust the damping force. In the beginning, they used treated leather as the friction plate and later, wood.
The main problem with leather was a phenomenon called stiction, where it took a considerable amount of force to ‘unstick’ the leather, which meant that the dampers would be very stiff in the initial movement until the stiction is overcome.
Wood has a more controllable friction quality but, as you can imagine, they were about as durable as wooden dentures.
Most cars used this type of dampers until World War 2. A few companies, like Bugatti, designed their own dampers or they used Georges de Ram’s design which involved friction plates. But this time, the design used more than one and they were arranged inside a cylinder.
The design was usually quite heavy and the entire assembly was mounted on the chassis and acted on by the wheels through a lever system.
Since WW2, single tube and dual tube dampers have dominated the market with their simplicity and general ability to control suspension movement at low and medium speed. It was also suitable for use with coil springs.
Only cars that use air suspension or electronically-controlled suspension systems do not need dampers.
While friction plate dampers seem crude, they have the benefit of being easy to fix. If you have worn-out friction pads, all you have to do is loosen a few nuts and bolts, find some leather and, voila!, you have a new set of dampers.
I like the look of those friction dampers. They are definitely more hipster and steampunk than our current tubular shock absorbers.