Shock Absorbers and Struts
The function, types and troubleshooting of Shock Absorbers
Dampers, or better known as shock absorbers and struts, are vehicle components that many vehicle owners under valuate. The only way to realize the full value of shock absorbers and struts is when they start to malfunction.
In this article, we will take you on a short journey through the land of dampers and on the way, we will acquaint you with what shock absorbers and struts are. You will also see what the different types of absorbers in use are and how to troubleshoot shock absorber and strut faults.
What are Shock Absorbers?
On a physical level, shock absorbers are basically oil pumps; a piston is attached to the end of a piston rod and works against hydraulic fluid in the pressure tube. As the suspension goes up and down, the hydraulic fluid is forced through tiny holes inside the piston. Only a small amount of fluid is passed through these holes, so the piston is slowed which in turn slows down spring and suspension movement. Shock absorbers automatically adjust to road conditions because the faster the suspension moves, the more resistance they provide – this is why they are also referred to as velocity sensitive hydraulic damping devices.
On a scientific level, shock absorbers take the kinetic energy (movement) of your suspension and converts it to thermal energy (heat) that is then dispersed into the atmosphere through the process of heat exchange.
On a practical level, shock absorbers sustain a comfortable ride by (a) absorbing any vibrations, jolts or bounces while driving, and (b) keeping all of your tyres in contact with the road at all times.
Types of Shock Absorbers
There are three common types of dampers:
Telescopic shock absorbers
This is your most basic type of shock absorber and when it becomes damaged or reached the end of its lifespan, it is replaced rather than repaired. It can be fitted to both the rear and front suspensions and is not expensive.
Strut type shock absorbers
This type of shock absorber replace part of the suspension system, which means they are built stronger in order to handle larger loads and forces. The strut type shock absorbers can be replaced or repaired, that is why they are available in both sealed and repairable units. They are also more expensive than your common shock absorber.
Spring seat shock absorbers
This type of shock absorber shares qualities from both the telescopic and strut type dampers. Much like struts, a spring seat shock is both a suspension unit and a damping device, all in one. They are not built to sustain large loads (as in the case of the strut type), and once damaged, you will have to replace the entire unit.
What is the difference between Shocks and Struts?
In this article, the terms shock absorber and strut are used together because many people refer to them in the same way, as if they were interchangeable. These two parts do indeed serve a similar purpose, but they work in different ways, so let me quickly explain the difference between the two components. Image 1 will serve as an illustration in this regard.
To lean on shockwarehouse, the major differences between struts (left side of the image) and shock absorbers (right side of the image) are that struts are a structural part of a vehicle’s suspension system, while shock absorbers are not. You cannot use a shock absorber to replace a strut and you cannot use a strut to replace a shock absorber. A strut is a crucial part of the vehicles steering system because it greatly affects alignment angles; because of this, an alignment must always be done when a strut is replaced. Furthermore, a vehicle will have either a shock absorber or a strut at each wheel, never both. Every vehicle was also designed with either shock absorbers or struts and your vehicle’s suspension cannot be changed to use the other.
This then is the major differences between these two components. As any other component, so are these prone to failure; let us therefore have a look at how to identify problems related to failing shock absorbers and struts.
It is important to be aware of failing shock absorbers and struts. Pay attention to the following warning signs and have them addressed if ever they cross your path.
Nosedives & Squats
When you apply the brakes and the front end of your vehicle dips forward (nosedives), there might be a problem with the shock absorbers or struts. When you accelerate and the entire backside of your vehicle sinks down (squat), then there might be a problem with your vehicle’s shock absorbers or struts.
Bouncing on rough roads is perfectly normal, but when it is excessive, for example when it causes you to be bounced off your seat, then you may have difficulties with the shock absorbers or the struts.
Make sure to inspect your tyres regularly. Shock absorbers and struts keep your vehicle’s tyres on the road, and the moment it cannot do this anymore, there will be irregular road contact, which will result in uneven tyre wear.
Piston and hydraulic fluid within the shock absorbers may leak. If you notice any leaks in this area, have it checked and rectified.
When you drive under normal conditions (no winds or surface water throwing your vehicle off course) and you experience your vehicle shifting from side to side, it is highly likely that there is something wrong with the shock absorbers and struts. Have these and the entire suspension system checked.
Delayed stopping distances
Worn shock absorbers can increase your braking distance considerably, thereby decreasing your ability to execute a safe stop and avoiding an accident. There may be other causes for a delay in braking that is not related to shock absorbers. If you experience delayed stopping then have it checked and corrected immediately.
Excessive steering wheel vibration
Normal vibration when driving over an uneven surface is okay, but if the vibration remains while driving over a smoother surface, then it may be something you need to address. There are a few possibilities why this may be the case, and one of these are shock absorber or strut issues. Be safe and have your vehicle inspected for the origin of the vibration.
At each end of the shock absorber, there is a point where the shock absorber is bolted to the vehicle. These points have rubber bushings and if the bushings crack or break, you may hear a tapping when you drive over a bump. If this is the case, have the bushings replaced.
This concludes our discussion on the troubleshooting of the shock absorbers and struts. If you are still not sure about the presence of a faulty shock absorber or strut component, then you may consider doing the bounce test. Simply push down on the front or the rear end of the vehicle as hard as you can. When you remove your hands and there is no bounce, then your damper components are fine, but if there is a bounce, then you should consider having those components checked.
If you are unsure about when to have the shock absorbers and struts replaced, then simply have them checked during normal service sessions, and do not forget the bounce test. Also, do keep in mind that your driving conditions and driving style will play an important role in determining when to change shock absorbers and struts.
Feel free at any time to bring your vehicle to one of Steves Auto Clinic’s branches and have your shock absorbers and struts inspected. We have the expertise and the equipment to handle any damper-related issue. Prevention, at the end of the day, is far better than cure. Safe driving!
Sources consulted during the writing of this article:
- Firestone. 2017. Is your car “cursed?” 6 Noticeable symptoms of worn shocks.
- Online available at: https://blog.firestonecompleteautocare.com/alignment/symptoms-of-worn-shocks/ Accessed on 4 August 2018.
- Shockwarehouse. (Undated). What is the difference between shocks and struts? Online available at: https://www.shockwarehouse.com/news/differenceshocksstruts.cfm Accessed on 4 August 2018.
- Sunautoservice. (Undated). The difference between shocks and struts. Online available at: https://www.sunautoservice.com/about-us/shop-talk/2017/march/16/the-difference-between-shocks-and-struts Accessed on 4 August 2018.
- Tlmotors. 2015. The difference between shocks and struts, and when do we need to replace them? Online available at: https://www.tlmotors.com/blog/the-difference-between-shocks-and-struts-2c-and-when-do-we-need-to-replace-them-3f Accessed on 4 August 2018.
Images used in this article:
- Image 1. – Ford Racing Strut/Shock Kit. Online available at https://www.levittownfordparts.com/ford-racing-strutshock-cobra-p-1753.html Accessed on 23 Aug 2018