Tech-Talk – Understanding Ride Comfort:

Does a hard suspension make a harsh ride? Not always, as TCR Tech Talk explains:
Does a hard suspension make a harsh ride? Not always, as TCR Tech Talk explains:

 

Soft suspension equals comfort, and hard suspension equals a trip to the chiropractor, right?  Not quite.  Soft isn’t always plush, and likewise, hard doesn’t always mean harsh.  It might be tough to understand at first, but TCR Tech Talk is on hand to explain how soft can be harsh and firm can be comfortable.

Understanding ride comfort starts with understanding the basics of suspension, in specific the 2 main components of suspension – springs and dampers:

Springs:

These are coil springs, the most common type of spring found in modern passenger vehicles.
These are coil springs, the most common type of spring found in modern passenger vehicles.

Springs support the weight of the vehicle.  They’re the most easily identifiable piece of a car’s suspension visually (leaf springs aside unless you know what you’re looking for), and are the main controlling component in whether or not a vehicle rides ‘hard’ or ‘soft’.  When you drive over bumps or through dips, the firmness of the springs dictates how easily the wheels recoil towards the body, or how quickly they rebound down into the dip to keep the body of the car level.  Hard springs resist body roll, whereas soft springs result in large amounts of body roll – a trait which can greatly improve, or reduce handling ability, and to an extent, ride comfort.

Springs control the firmness of a ride.

Dampers:

Look familiar? These are common shock absorbers, otherwise known as 'dampers'.
Look familiar? These are common shock absorbers, otherwise known as ‘dampers’.

Dampers are more commonly known to the layman as shock absorbers.  As their more common name suggests, these are responsible for absorbing shocks and bumps.  Where springs control the firmness of a ride, dampers are the main controlling component in the comfort of a ride over anything less than a perfect surface.

Dampers, or shock absorbers, feature a piston housed within a fluid-filled cylinder.  When travelling over corrugated surfaces and small road imperfections, the piston reacts and moves within the cylinder, with the compression of the oil converting vertical movement into other forms of energy (mainly heat) and cushioning the ride.

Dampers, simply put, absorb vibrations and prevent them from permeating into the cabin.

Ride Comfort:

Ride comfort isn’t just about how hard or soft a car feels.  Ride comfort is the culmination of firmness and the way a car’s suspension filters out imperfections on the road surface.  The more comfortable a car is, the less you’ll feel every bump through your seat, and ultimately your body – even if you may feel those changes through the steering wheel in a truly communicative driver’s car.

While a car may be soft or firm thanks to the springs, the quality of the dampers is what dictates the real ride comfort.

Take for example a car with soft springs (generally thought to be comfortable) – this will absorb larger bumps in the road quite easily.  However, if equipped with sub-standard dampers, every single little bump in the road surface would shake its way into the cabin – likely resulting in more visits to the chiropractor’s office than the soft suspension is worth.

On the contrary, a car equipped with firm springs and a sporting inclination will be affected by larger bumps, resulting in the need to take speed bumps slower.  But, if said car is equipped with high performance dampers, every ripple in the road’s surface will be absorbed and cushioned resulting in a smooth ride, free from vibrations through the cabin.

In the second example, a large bump can be pre-empted and planned for, but small imperfections would be effortlessly absorbed – whereas the first example would need constant micro-management to negotiate pockmarked roads in comfort, and even the best driver wouldn’t be able to completely take the edge off a poor road.

Other factors affecting ride comfort:

While suspension, predominantly dampers, plays a massive role in ride comfort, there are other factors that influence how comfortable a car will be.

Tyres can have a relatively big role to play too – some tyres are engineered for comfort and reduced noise, while other are more performance orientated.  Generally, firmer compound tyres will be more uncomfortable.  Low profile tyres also reduce comfort as they reduce the amount of cushioning when the wheel meets imperfections on the road surface.

However, no traditional tyre compromises ride quality more than run-flat tyres (RFTs).  With their rigid side walls, the rubber compound RFTs are made of does a poor job of absorbing bumps.

Improving and adjusting ride comfort:

When developing a car, manufacturers often can’t justify the costs of equipping high-quality dampers to a budget, or mass-production vehicle.  They opt instead for cheaper dampers that improve the affordability and give ample comfort levels for the intended target markets.

Some vehicles – usually performance vehicles – feature dampers that can be adjusted from within the cabin.  Magnetorheological dampers feature a magnetic fluid in the dampers instead of the usual oil.  The viscosity of this fluid can be changed by electro-magnetic currents to make the dampers firmer or softer depending on road conditions.  This is usually controlled via buttons or dials in the cockpit.

Alternatively, ride comfort can be managed and improved in a variety of aftermarket ways.  For example; equipping adjustable dampers that can be tuned for different scenarios – these types of dampers are a great option for cars that need to double up as weekend track cars, and daily drivers.  EVO recently produced a video explaining the virtues of equipping adjustable dampers, which you can watch below:

Another aftermarket option can be simply to equip quality coil over suspension with high quality dampers.  Despite offering greater performance, the increased body control also bleeds out imperfections in the road surface for better road holding, and subsequently, higher levels of comfort.  Buying and equipping these replaces the ‘budget’ suspension components manufactures build a car with, and can be a fairly economical way of improving ride comfort drastically, as well as performance.

This set of Ohlins coilovers can be equipped to firm up the springs, and improve the quality of shock absorption - giving better performance and improved ride comfort.
This set of Ohlins coilovers can be equipped to firm up the springs, and improve the quality of shock absorption – giving better performance and improved ride comfort.

Changing suspension from a spring and damper setup to air suspension can also improve comfort drastically, as air can withstand large amounts of compression, and these suspension systems can be adjusted merely by changing the amount of air in the suspension bellows.

Changing tyres and wheel sizes can also improve or reduce ride comfort, offering more or less cushioning prior to the involvement of the suspension.

Conclusion:

There are many determining factors in a vehicle’s ride comfort, but none has as big a role to play than the dampers.  A firmly sprung vehicle can be made comfortable with dampers that mitigate every undulation in the road, and likewise a soft suspension can be crashy if every pebble on the road reverberates through the cabin like a vibrating phone.  Firm doesn’t necessarily mean uncomfortable!

So next time you read that a Subaru WRX, Porsche 911 GT3, or any other performance car is firm, but comfy, you’ll know the engineers equipped it with high quality dampers to make sporty road-holding partner a smooth ride – and you’ll know that even the softest of cars can still be uncomfortable if the manufacturer cut corners to make it cheaper to build.

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