While the motorcar is undergoing transformative changes at an increasingly fast rate, steering and suspension consumables remain relatively unchanged. Yet, Rob Marshall looks at whether, or not, garages are grasping current opportunities with both hands.
We all need time away occasionally. While hurtling down the M5, bound for the English Riviera for what only be described as a “lads’ weekend”, the conversation drifted inevitably onto cars. One friend was worried, because he feared that his garage was ‘ripping him off’ – a common accusation that is banded around our trade far too much by the public and, very often, unfairly. The issue revolved around his abused V50, which had suffered a broken nearside coil spring. The garage advised and quoted for two front replacements, leaving my friend concerned that he would have to throw more beer tokens than absolutely necessary into the direction of his battered Volvo. Naturally, I responded that his garage was acting in his best interest and I recommend that he authorise the repair. Suitably reassured, the chat moved on to topics that I dare not share this magazine but it left me concerned that advice from a competent and well-respected garage was still questioned by someone who should know better.
Don’t just listen to me…
I am not the only one who thinks this. KYB may be well-known for its dampers but it also is a major spring manufacturer for the car manufacturers and aftermarket. KYB recommends that replacing in pairs is essential to ensuring that a vehicle performs safely as its maker intended. If only a single spring were changed, it could harm vehicle handling and stability. The company also stresses that replacing one coil spring could lead to an uneven ride height. This creates an imbalance and exerts more stress on the spring that was not renewed. Furthermore, if the part has failed, then the opposing part is likely not far behind, especially if they have been on the vehicle for the same amount of time and exposed to the same conditions. In the case of shock absorbers (‘dampers’), when damping rates are significantly different on either side of the vehicle, the vehicle body and wheel movement variations can cause handling abnormalities.
Delphi also advises garages to think of their customers, who rely on you to get the job done right, first time. Additionally, stress and wear affect the entire steering and suspension system, whether the problem came from a collision, a pothole, or simply ageing parts. That is why Delphi says is
so important for garages to complete the task properly, by replacing in pairs. MOOG recommends that, should any technician find any uneven wear, or damage, identify the underlying cause and address the issue appropriately, first. Even so, MOOG says that it remains best practice to replace parts on both sides of the axle, especially as consistent and balanced performance could be compromised, should there be any difference in part design, through either supersession, or manufacturing variation.
Meyle says that the same principle applies to bushes. Since bushing properties change over time, pairing a new bushing with a worn-out one, can impact the vehicle’s driving performance. So, replacing a pair is the better and, above all, the safer option.
Air suspension works in a very different way from traditional metal sprung systems. Therefore, the springs cannot sag physically. Even so, replacing in pairs is still a recommendation that you can make. Arnott explains that replacing in pairs is not strictly necessary from a safety point of view, especially when you are replacing an air suspension unit because of normal wear and tear. Yet, it makes sense
to at least inspect the unit on the other side. The rubber of the air spring has most likely been exposed to the same conditions and mileage as the one that failed, meaning the likelihood of it needing replacement shortly is high. If you are replacing the air suspension unit because of normal wear and tear of the physical conventional damper, then renew them in axle sets.
Is it all about axle sets?
When dismantling either the steering or suspension system, you may have to replace associated components as you work. Typical examples include nuts, bolts and washers.
The bilstein group advises that it is best practice to replace any single-use fixings, including stretch bolts, any locking nut, or fixing, including Nyloc types. This is why the company supplies them either separately, or as part of its febi ProKit range. While Comline also supplies associated fixings, it reminds technicians to follow manufacturer guidance.
When replacing dampers, KYB recommends replacing the top mounts, too. KYB reasons that, should the struts be worn, the mounts are likely to be as well, because they have been subject to the same conditions. Even on a car that has covered 50,000 miles, the rubber component would have been moved around 75 million times. Naturally, the rubber components would have deteriorated within this time, which would prejudice ride control and safety. Therefore, reusing the old mounts to save costs will mean that the replacement dampers will not be performing at their best.
Naturally, things are more complicated with air suspension. If the owner has brought the car to you as soon as a leaking, or otherwise faulty, air spring has been noticed, there might not be any consequential damage to other parts. Arnott advises that catching a leak early makes a big difference to the lifespan of associated parts. If the leak has been long-standing, it is possible that the compressor may have overheated, or might have even burnt out. In addition to the compressor and relay, Arnott recommends that you check the valve block, right height sensors and air lines for their integrity and advise the customer that these might need changing, especially if they have ignored a leaky spring for some time.
Especially where suspension is concerned, there is a multitude of choices available to customise vehicle dynamics. Yet, do not forget the changes that quality companies, including those that supply the OEMs, make to improve their products based on experience over time.
MOOG reports on a common OEM trend of using lighter materials for spare parts to reduce vehicle weight and cut all-important CO2 emissions. This includes sway/anti-roll bar links, which can even be made from plastic, or a hybrid metal/plastic combination. For 2024, MOOG is launching steel-reinforced alternatives for vehicles thus fitted. MOOG says that these upgraded parts possess higher mechanical strength, reducing the risk of breakage during challenging driving situations. They also allow for the integration of a larger ball diameter, within the joint, providing another reason why durability is enhanced. Yet, the company offers these upgraded steel parts (denoted by the suffix ‘M’ in the part number) alongside the original replacement part, which gives technicians, garages and customers the luxury of choice.
MOOG also reminds us of its Hybrid Core technology, which is its patented technology of induction-hardened studs, combined with carbon fibre-reinforced bearings. MOOG says that its Hybrid Core parts have double the strength and the ball joint is up to 42% more durable. Last year, the company introduced new dust gaiters, produced from TPU (thermoplastic polyurethane), which it claims is longer-lasting and more resistant to chemicals, compared with conventional chloroprene rubber. This is why TPU gaiters are fitted to the brand’s ball joints, link stabilisers, tie rod ends and assemblies, and track control arms.
Yet, MOOG is not the only supplier of upgraded components. Comline is another, which has redesigned the wishbone bushes fitted to the Vauxhall Corsa, one of the most popular cars on UK roads. These bushes feature a swaged shape, which allows more rubber to bond, thus extending their lifespans. The swaged bushes are upgrades from the original equipment specification but there is no need to disclose it to an insurance company. They are available under part numbers CCA1011 and CCA2011.
ADAS: The mandatory ‘extra’
Delphi reminds technicians not to forget the importance of wheel geometry and ADAS calibration. ADAS relies on a combination of cameras and radars. Therefore, anything that affects their position, such as steering or suspension work, can be detrimental to ADAS performance. One degree of change in the camera, or radar, position could mean a 1.7-metre deviation 100 metres down the road. Inevitably, the vehicle may fail to detect oncoming hazards, because inaccurate information is being sent to the Electronic Control Unit (ECU). For this reason, it is essential to recalibrate ADAS following any steering and suspension repairs and post-wheel alignment.