Dampers or ‘shock absorbers’ give control of wheels and car body over bumps and undulations and manoeuvres. Control over the energy put into the suspension springs. Simple, without damping the wheels and car would oscillate affecting control of the wheel and its grip and the car body’s stability and heave. Dampers strength is set by auto engineers carefully to match spring stiffness and ride quality.
Dampers health and efficiency directly affect the rate of turning, braking distance, control over bumpy surfaces and have a direct effect on ride quality.
In early days of our vehicle health checking damping was evaluated by driving the car on specific roads at speed to assess wheel and body control. In some cases the drive would be scary as a damper had failed leading to out of control resonance of body wheels or both.
Dampers are mostly supplied as fixed damping, however most aftermarket performance dampers as coil overs have single, dual, triple or 4 way adjustments.
The key is different car types have different strength dampers to suit the role of the car. Prestige passenger cars will have damper strength defined as the ratio 0.2 to 0.3 of critical damping (very stiff). Sports cars are typically 0.3 to 0.4. Aero LMP cars between 0.7 to 1! So if we test Mercedes ML we expect 0.2to 0.25. If we get 0.15 we have trouble. 0.12 is a fail from mot man! If he could measure it.
Usually the damper strength (damper curve force velocity) is set in the laboratory and measured on a test machine called a damper dynomometer. This requires the dampers if fitted to be removed.
Center gravity invested in a floor mounted drive over machine (Maha Beissbarth Lehr principle) that does a similar job to the bench dyno, however with the wheels on the car and dampers fitted. This has reduced the scary driving test and consequences.
There’s no point in selling car perfect control setup without testing the the dampers that have the monopoly on control.
We have 8 years of baseline data for all prestige and sport car makes, emphasis on Porsche all model years. This data gives us the experience to see the damper health and efficiency. We can even identify a damper type from its test report damper curve!
So we offer the service to test damper health, pairing on axle, correct damping for the chassis and it’s intended role as passenger, sport or track. There’s a report that we can then use to drive repair if possible or replace.
This service is included in the healthcheck package in our other services, or can be exclusively booked.
We recommend that if your dampers are more than 20,000miles old, to get them checked as their efficiency drops with wear. We don’t want control waining when you are out on your next eventful drive.