Tuning suspension for Australian conditions with the new Hyundai Elantra SR
We spent a day with Hyundai’s engineering team as it tuned the new 2017 Hyundai Elantra SR, and discovered that good suspension is science, art and a lot of a teamwork.
TO GET AN IDEA of a car’s performance most people will fixate on the engine’s power and torque. That’s because those are clear, absolute values which means they are simple to compare. Unlike suspension, where all you get is jargon – McPherson struts, trailing arms, monotube dampers, Watts linkages, roll centres – a lot of copy-paste complexity in a press release designed to impress but not inform the journalist and reader in succession.
Yet suspension is critical to every aspect of a car’s performance, because as the saying goes, power is nothing without control. Suspension makes or breaks a car’s ride comfort, handling around corners, towing ability, braking, acceleration and even has an effect on noise and resistance to punctures. Poor suspension is felt every time the car moves, a weak engine is noticed only under stress. Taken to extremes, you’d always want a car that feels as if it can handle more power than one which feels overpowered for its abilities.
Suspension tune is also country-specific, which reflects not only the typical roads in a country and their frequency of use but also the preferences of the local market, as well as the most common uses of the vehicle. That’s why some, but not all manufacturers tune their cars and suspension for local conditions, whereas others just run with either a worldwide specification or one close to Australian needs.
Hyundai has been developing Australia-specific suspension tunes since 2008, initially only in Korea, then since 2010 in Australia for selected models, and from 2013 onwards every Hyundai received a local tune. Australia is a tiny market for Hyundai – out of the 5 million cars Hyundai sells per year, only around 2% or 100,000 are sold in Australia. As an example, Aussies buy around 8000 Elantras per year, compared to the USA which is good for about 220,000 per year. Yet Hyundai Australia still does its own tuning, and we spent a day with its team in Sydney to find out what they do, how they do it, and why they do it as they tuned the suspension on the new Elantra SR sports sedan.
But before we talk tuning, we need define that oft-used term itself, suspension.
What is suspension and how does it work?
The suspension is the components of the car between the wheels and the rest of the vehicle that allow relative movement between the two.
The reason you want that relative movement is because the car never travels over perfectly flat and level ground…especially in Australia. Even if it did, then it would also change both direction and speed which means the car’s weight shifts to the front or rear and from side to side.
For example, when a vehicle goes over a bump its wheel will rise and force the vehicle as a whole to tip. Similarly, there is a natural weight shift from side to side when cornering which means greater force is placed on the outside wheels. If the vehicle is to perform well then all these forces must be smoothed and evened by the suspension, and the job there is split into two; ride and handling.
Ride is how comfortable the car is as it moves. Handling is how responsive, predictable and even pleasing it is to control input. To some extent the ride and handling are conflicting objectives; we’ve all been in silky-smooth cars that flow over bumps yet are saggily unresponsive to the driver’s inputs.
So the job suspension has to do is easily defined, but the solution is complex. Yet at the heart of all suspension there are just two main components; springs and dampers. In Australia for reasons unknown we insist on calling dampers shock absorbers or just shocks, but that’s wrong because it’s actually the springs that do the shock absorption.
- Springs – the spring is, literally, a spring, just like what you’d find inside the average Biro pen, but larger. Mostly these springs are metal coils, but they can be rods or even bags of air, commonly now found on buses and other heavy vehicles as well as top-end 4WDs. Springs are there to set the ride height of the vehicle, and absorb the bumps and forces generated when wheels move relative to the body. Hyundai cars, like most modern vehicles, tend to be fairly equally well balanced left and right. This removes the need for ‘handed’ springs, where say the right side of the car is heavier than the left.
- Dampers – you know what happens to a spring when it’s compressed and then released; it bounces up and down and up and down, like a rubber ball dropped on concrete. That’s where the shocks come in, which damp out what would be the resulting oscillation. The dampers work in the same way as a coffee plunger – there’s cylinder of fluid, inside which is a rod connected a disc full of holes. The rod/disc moves up and down inside the cylinder of fluid, damping out the bouncing of the springs, which is why they are more correctly known as dampers so that’s the term we’ll use from now on.
Aside from the two fundamentals, there’s a textbook full of other suspension components. A few of these are:
- Swaybars – when a vehicle corners it rolls and transfers weight transfer to the outside of the vehicle. The inside wheels are loaded up, compressing the suspension, and the weight on the outside wheels is reduced, extending the suspension. This rolling is not entirely desirable, so a swaybar is used to control it. A swaybar is a simple metal rod connecting the two wheels on an axle, so the ability of one wheel to move up or down relative to the other is reduced as there’s a limit to how far the swaybar can twist. Because it’s just too simple to have just the one name for any given component swaybars are also known as ARBs, or anti-roll bars.
- Control arms – these are components that connect the wheels to the chassis, all set in complex geometry to allow the wheel to move relative to the car. This movement is not a simple up-and-down motion, as it’s best for the wheel to change angle slightly as it moves to assist with accommodating the changing dynamics from the weight transfer you get when cornering, braking or accelerating.
- Bushes – the dampers and other components are connected to the chassis via mounts typically made of rubber which allow relative movement between the component and the chassis. As the bushes are soft they can also compress and extend, forming part of the impact-absorbing properties of suspension.
- Bumpstops – the suspension’s spring will compress, but only up to a point after which it can’t compress any further and then it doesn’t behave like a spring. When that happens the car needs to absorb the shock by itself. The last chance for the car is the bumpstop, which is typically a little bit of pyramid-shaped rubber that the control arms touch when the spring is fully compressed. If you hit the bumpstops hard you’ll know about it!
- Tyres – even the tyres are part of the suspension, as they are filled with air which is compressible, and that means they can absorb impacts as well as rebound like a spring. The grip of the tyre has an effect on how much weight shift there will be around a corner; high-grip tyres mean higher cornering speeds and more weight transfer and thus suspension compression.
Aside from meeting the complex objectives of ride and handling, the suspension must also allow drive to be transmitted to the appropriate wheels, make allowance for steering, be as light as possible, make minimal noise, cost as little as possible and take up as little space as can be managed. So as with most car components, suspension has to meet many important demands, most of which are in direct conflict with each other, and given all the potential parameters that could be changed the number of potential combinations of tune is as near to infinity as makes no difference. Hence, the science and art of suspension tuning.
What needs to be tuned?
Fundamentally, the end result of suspension tuning is a car that has to feel good across both ride and handling as well as perform by the numbers. But unlike engines, which have clear goals such as fuel efficiency and power, a term like ‘good’ is not so easily defined. That’s why our first question for Hyundai’s team was to ask what they’re trying to achieve, and why.
The answer is not surprising – “compliance and control”, which means a comfortable onroad ride across all surfaces, yet with controllable, agile handling. That mix changes from car to car, for example Elantra SR sports sedan I’m here to observe development on will be more focused on handling and the Sonata sedan will be more focused on ride comfort.
The next obvious question is why the car needs local tuning at all, when the factory has done so much work in the first place. The reason is that while Australia has more or less the same extremes of surface as other countries, from dead-smooth bitumen (apparently there is some in Australia) to rough roads, cars in Australia see those extremes more often than in other countries. There’s also a bit of local driver preference built into each tune. The Korean tune is fairly firm over low-speed bumps, but becomes less firm over higher-speed bumps like corrugations. This is to some extent the opposite of what Australia needs and prefers.
The local team can’t fundamentally re-engineer the car, and don’t need to, so their changes are limited to a few components. They can change the spring compression/rebound rates, but the ride height is left as-is. Sometimes the factory also supplies different control arm options, and that means the team needs to choose between them. But the main focus is on damper calibration, which controls the compression and extension of the springs. Here the team has full control over the complex arrangement of valves and shims that control the speed, and nature, of how the piston moves up and down.
So where do you start with this tuning business? An easy place to begin is the force required to compress the spring for a given distance. Most springs are linear, which means that double the force, double the compression, but some are progressive where you need increasing amounts of force to compress the spring for a given distance. Hyundai tend to use linear springs in their cars, as progressives make more sense for load-carrying vehicles where you want a smooth ride when unloaded, but not much spring compression when you add heavy cargo. As an example, a spring might take 3.3kg of weight to compress it 1mm, and the increments the team works in are 1/10th of a kilogram.
Then there’s the dampers, which are much more complex to tune than springs because there’s far more variables. Their rate of compression and extension can be changed, but with far finer control than springs. There are an almost infinite number of parameters – sizes of the holes in the valves and shims, arrangement of shims, fluid used in the damper (although the team doesn’t change that) and much more. Dampers can be tuned across different ‘rod speeds’ which are how fast the suspension compresses or extends; a slow rod speed is for example a speedbump at 10km/h, and a fast rod speed may be corrugations at 100km/h, which will also generate a lot of heat that needs to be dissipated effectively otherwise the damper will overheat, fade and lose effectiveness.
The car and the test routes
The car itself is standard, but with the disguising cladding and a considerable amount of test equipment. At each wheel there’s a potentiometer, which measures how far and fast the wheel is moving up or down. There’s a Motec sensor system that measures speed, yaw and pitch at each end of the car and a sensitive GPS receiver. All this data goes into the model for analysis, both to refine and model and measure the effects of changes.
The initial test routes are just normal Sydney streets, but a carefully chosen route to encompass a variety of terrains. The team knows the streets in minute detail, down to each tiny imperfection, and will ensure that for example the left wheel of the car is always placed in the centre of a given pothole, and that a given speedbump is hit at 50km/h, plus or minus one km/h. Like me, they don’t appreciate the council making “improvements” to their test route! Even changes in road surface are noted and known, and road joins, so what to normal people is just a street is to Hyundai’s suspension team a rich ocean of potential information. But even for experts it can be hard to pick exactly what’s happening. Noisy suspension may feel harsher than it is, and wet roads create sounds that mask suspension noise.
Most mechanical components on a car need to be warmed up before they work to best effect, and suspension is no different. However, the fluid in the dampers warms up quickly as the suspension starts working immediately as the car is driven, and there’s not much fluid to warm up. Similarly, tyres need a little bit of time to heat up and work to best effect, so the assessment runs don’t formally start until the car has been driven a short distance.
Later in the cycle longer distances are run, and these include high-speed sections as well as dirt roads. Yes, even Hyundai roadcars are suspension-tuned for dirt. The team tell a story of being out on test and nearly being taken out by a young lady sliding around a dirt-road corner in her Excel, one hand on the wheel, the other applying makeup! The degree to which cars are run on dirt varies from model to model, with the likes of the Santa Fe and Tucson spending more time on rougher roads than the likes of the i30. That said, there was a recent test of a Sonata in the outback for 100,000km and 30% of that was on unsealed roads.
The team and the work
The local tuning process starts well ahead of the car’s Australian launch with data. Specifically, all the parameters needed to model the car’s suspension such as weight, weight distribution, dimensions, suspension geometry and tyres. In the case of the tyres the engineers are looking for resistance to deformation – how much the tyre compresses with a given load. This is more important than overall grip, as the ability of the tyre to act as a spring is an important part of the suspension. Taking it to extremes, the springs in Formula 1 cars are extremely stiff as the tyres provide much of the shock absorption.
All the data is loaded into a sophisticated simulation model that tells the team how the suspension will react to given situations, for example speedbumps, hard braking, dirt roads and more. Immediately, the initial modifications required for Australia conditions will be apparent and the first changes are made to springs, dampers and the like. Then key members of the technical team fly out to Korea, where Hyundai have a massive research and development base at their headquarters. Here they drive the stock car, and try their first set of changes. The results are fed back into the simulation model and refined, ready for the intensive Australian development cycle.
Then the first cars arrive in Australia as engineering evaluation models, and these are run on public roads disguised with cladding to hide styling changes. This is where the work really starts, and Hyundai’s experienced team swings into action. There’s Hee Loong Wong (aka ‘Wongy’), who is in overall charge of the process, coordinating everything, able to take a step back and look at the bigger picture. Andrew Tuitahi is the product planner at Hyundai, which means he helps decide which cars are sold and does the detailed work on their specification. That’s normal for a product planner, but what’s not normal is his hands-on development role as a skilled and sensitive test driver, able to pick up nuances humans with normal senses miss.
Assisting the core team are a range of engineering specialists from suppliers, such as a research engineer with a background in suspension.
Out in the workshop are a team of techs, and it is their job to pull the car apart after a run, hand over the components for a rebuild and then reassemble the car ready for the next run. Time is of the essence.
Everywhere and anywhere is Phil, who seems to know a bit about everything. Helping behind the scenes are other members of the wider team such as Hyundai PR boss Bill Thomas, a experienced ex-journalist whose test input is valued. Finally, there’s David Potter, an internationally renowned suspension specialist who Hyundai contracts to work on its local tuning. David owns and develops the simulation models, and uses his vast experience to quickly arrive at the optimal settings. David has worked on everything from Colin McRae’s rally cars to the suspension on downhill skis, so to say he knows his suspension is kind of like saying Stephen Hawking might know a bit about physics.
Having worked in, and observed many technical teams in my time I can say that this group is one of the better teams I’ve seen. It was clear from my interviewing that each team member is good at their job, and knows their role so there’s no issues with tasks slipping between the cracks, problems with responsibility wars and minimal management direction is needed. Each member spoke of the others with genuine respect, and it’s a highly impressive operation – the team can get through several complete cycles of test drive, observe, decide changes and make changes in a day which simply couldn’t happen without skilled and smooth running. Continuity and consistency is important when testing as the only thing which should change is the suspension, not the testing process or environment – that’s how the effect of changes can be clearly identified.
I was also allowed completely unrestricted access to the team, which is unusual and appreciated, as normally information is filtered through PR people after which it somehow seems to be refracted and diluted.
An intensive development cycle
The development process follows a series of cycles, starting with noting the current settings. Every time something is changed, for example dampers, it’s given a build number. The exact details of what’s in each build are noted in a log, but for managing the cycle all the team need to know is which build number is on the car.
Next up are observations on the test run. These are minutely detailed, not vague terms like “nice” or “firm” but precise notes on rebound or compression over specific terrains, whether it was the front or rear of the car, effect on body control such as fore/aft pitching, noise and more. Then the actions are noted, which are things that need to be done, perhaps smoothing out the rebound when the car hits a pothole, or working on the noise over uneven roads. Finally, the priority list, which is are a couple of actions that must be focused on. This process gives the team the clarity they need to make targeted changes – the “subjective is quantified by the objective”, in David’s words, not unlike tuning a piano.
Rear seat ride quality is assessed, and again this is dependent on the vehicle, for example there will be more attention paid to the rear-seat ride of a Sonata than a Veloster. The suspension is also assessed from both the driver’s seat and front passenger seat. The passenger side typically has to deal with harsher bumps as that side of the road is often rougher, and there’s slightly more weight on the passenger side due to the camber in Australian roads. There is also an element of psychology to deal with, as there is in any work that involves humans assessing either subjective or objective criteria. For example, we all know that drivers are less prone to carsickness than passengers, and that means what the driver feels and doesn’t feel is different to the passenger. That’s one reason why tests are run two-up, and the other is that it reflects a typical car load.
There are also test runs at the maximum the vehicle can legally weigh (the GVM, or Gross Vehicle Mass) which are achieved with the maximum number of car occupants, plus a boot load. Towing characteristics are considered, but there are no specific tow tests in this cycle.
The development cycle is fast-paced, and that means many more component changes than would be normal for any roadcar. The standard dampers are not designed to be taken apart, re-valved and put back together again many times in a day for a couple of weeks on end so instead the team use a special development damper, but it doesn’t have exactly the same compression/rebound characteristics as the production damper. This is modeled and accounted for during testing. The simulation can tell the team a lot about how the car will behave, but ultimately it’s really just a way to show what’s happening and narrow down the range of options for the next tuning decisions.
The challenges…and solutions
The biggest challenges the team face are the conflicting requirements of suspension – for example, balancing an idealised handling model against ride comfort, and both against noise. Then there’s the volume of work to be done, because it’s not just one tune for every variant of a car. Diesel engines are heavier than petrol engines, so they need a different tune and it’s not just a case of stiffer springs in the front as changes to the front affect the rear too. Then there’s all-wheel-drive (AWD) and two-wheel-drive, or in the case of Hyundais, front-wheel-drive. That’s a challenge for a couple of reasons – first the AWDs models weigh a bit more, but they also handle slightly differently. That’s due to the weight difference and the extra set of driven wheels, but also differences in the way suspension reacts depending whether the wheel is driven or not driven.
Any driven wheel on any car is always, ever so slightly and undetectable to the human eye, wheelspinning – known technically as ‘slipping’. In other words, the wheel is turning slightly faster than the car’s roadspeed would suggest. When that wheel goes over a bump more weight will be placed on the wheel which means it initially gains traction as the suspension compresses, which ever so slightly reduces slip. Then when the spring extends there’s less weight on the wheel so traction is reduced, and the wheel slips a bit more than usual. This dynamic grip change affects the way the suspension has to be tuned – essentially, it’s more important to keep driven wheels firmly on the ground than non-driven. With an all-wheel-drive it’s easier to some degree as there’s now four driven wheels to consider and each wheel has 25% of the torque, not two with 50% each. Except of course the likes of the Santa Fe and Tucson which are on-demand AWD, which means they’re primarily front-wheel-drive with the rear wheels being driven when front traction is lost…suspension tuning is definitely complicated!
One example of the complication in suspension tuning is the fine detail on damping. When the car’s spring is compressed, for example by the wheel going over a bump, then the spring will absorb the shock, then extend. The damper’s job is to control the spring so it returns only back to its normal length, and the car doesn’t pogo-stick down the road.
If the spring extends just once and immediately resumes its normal length then that’s called critical damping, and you can see this on top rally cars as they land from a jump, there’s compression and then instantly they’re back on the level, no bouncing. You might think that’s desirable for roadcars, but life’s not that simple. Race cars are all about performance, with factors such as comfort and noise not being of any concern at all, as would be apparent if you ever rode in one. So the ride in a rallycar might be quite rough, and noisy, yet offer superb control.
A related problem is the speed at which the damper’s piston moves in its cylinder – this is a source of noise as the faster the piston moves through the fluid the noisier it is, so a slower damping may be chosen, sacrificing speed of damping control for noise. Noisy suspension can fool people into thinking it’s harsh.
Another example challenge – let’s say that when cornering the car rolls too much. This can be fixed in several ways. The obvious is stiffer springs, but that would make the ride harsher. The dampers could also be stiffened. Their resistance to either compression or extension could be increased, but again that has an effect on ride. So if the ride is acceptable but corner body roll is too great, one option is to stiffen the anti-roll bar (swaybar) which to a great extent reduces body roll but doesn’t much affect the ride. But that needs to be done carefully front to rear, otherwise oversteer or understeer will be the result, and stiffening the bar too much won’t allow inexperienced drivers to gently load the weight up on the outside of the car as it corners, causing the car to slide rather than slightly roll and grip.
Cause and effect isn’t always apparent either. For example, if the rear end feels too loose, that might actually be the fault of the front end being too firm and causing a pitching movement onto the rear.
The options for tuning are immense, especially so considering all the sub-models of cars in a range. When there are a lot of car variants to work through the team focus on what will be the highest seller and start with it first. Then they work their way through the rest of the range in an order that allows them to maximise the work already done. Product decisions like the type and dimensions of the tyre play their part too – some models may have a 17″ rim or a 19″ (but always the same diameter tyre) and the bigger rim with the smaller tyre may have a stiffer sidewall, which translates into less shock absorption and therefore a different suspension tune. With all of this work the simulation model is refined and improved, so as the team work through the cars it becomes a quicker and quicker process.
The team also factor in a range of driving styles. Experts are smooth, so the weight transfer from side to side and front to rear is gradual. Untrained drivers are harsher, and might do things like jump off the brakes then turn. The tune has to account for all sorts of driving styles and skills.
Yet another complication is the modern set of electronic driving aids. Every new car sold in Australia has stability control fitted (explanation here), as well as ABS and a variety of other computer-controlled subsystems. These aids are specifically calibrated for each car, and therefore for each suspension. However, there’s no recalibration done as part of the suspension tune as the changes are kept within the limits set by the factory. For example, the tyres are the same, as is the ride height. The electronic systems are a closed-loop anyway which means they will detect a problem – for example understeer – then make corrections until the problem is resolved, so that means there’s a fair bit of latitude for suspension tuning.
The final signoff
During the development process the team might arrive quite early at a setup they’re happy with, but if time permits they’ll continue to explore and refine, perhaps coming back to a previous setup. The entire process takes around two to three weeks, and directly involves eight or so personnel.
So when is the work complete? When the two leaders, Wongy and Andrew, consider the car has met the required standards, when they have “exhausted every possible avenue, done everything we can”. That might be at 2am in the morning, or development might get finished early.
After the tuning is done and the car is signed off the next feedback the team gets is the press launch, when 30 to 40 of the finest drivers in Australia (also known as “journalists”) deliver their expert opinions. The team says that there’s never anything they didn’t already know – which is what you’d expect, as the journos will have only a few hours in unfamiliar cars on unfamiliar roads they don’t get to drive multiple times (I think that works as an excuse). Nevertheless, feedback is monitored for the life of the car, but good suspension is in some ways a typical engineering success story – if it’s done well, few people notice.
So even today, suspension tuning is labour-intensive, albeit a process supported by sophisticated computer models, something that won’t change for the foreseeable future. For example, it took until 2000 for a computer to defeat a grandmaster at chess, and it was only in 2016 that computers bettered the world champion at the far more complex game of Go. Yet compared to Go, suspension tuning has many, many more combinations to choose from, and it is not bound by rules or outcomes as precise as those of Chess or Go. The humans will be doing this job for a while yet!
Related links
- Santa Fe offroad test
- i30 long term test
- What revs should you change up at for maximum acceleration?
- Why doesn’t it exist for my car?
- How stability control and traction control work
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8 Comments
Can you follow up with what happens next?
For example – So they fine tune the shocks and then pass that configuration onto Monroe for a standard product offering?
Australian cars are then built to that specification, or rather the suspension is and fitted to the car on the production line.The exact spec of most cars varies according to the country of sale due to marketing and legislation reasons.
And wiring harness combinaton available in the factory. Tuti is also a good man to do the job. 😀
Thanks it is interesting but just a shame that buying their cars is just propping up the Korean economy at the detriment of our own.
Great article, good to see some in-depth reporting on an Australian automotive website!
Possibly a dumb question – but on the Elantra SR, Hyundai offers the option of an 18-inch wheel package. Wouldn’t that then negate some of the work that the suspension team have done to calibrate the car to our roads?
Yes it would. When the overall diameter of a tyre remains the same but the the rim size increases then that changes the tyre compression characteristics, and therefore the suspension tune. It also changes how the stability control should calibrated for similar but not identical reasons – the tyre’s slip characteristics change. I don’t know if there’s two suspension tunes or they simply chose one that is a median.
Thanks for the reply, sorry I missed it earlier. Your comments make total sense.
I’ve started looking at the SR as a possible purchase, and tossing up whether to upgrade to the 18-inch wheels (mainly for cosmetics) – so I’m thinking about the ramifications for the ride-handling balance.
Worst case scenario is that the suspension tuning program for the SR completely ignored the 18-inch wheel package, and I end up with an overly-harsh ride. (I get the feeling that Hyundai Australia added the 18-inch option as an afterthought.)
Haven’t been able to find any dealer with the 18-inch wheels fitted for a test drive either, which doesn’t help.
So I’m guessing there was zero mention of the 18-inch wheel package during your day with the suspension tuning team?
If only there was a way to confirm this either way.
Just adding to my previous reply – I kinda doubt that there are 2 suspension tunes to cater for the 18-inch wheel package, since it’s a dealer-fitted accessory rather than a factory option.
So my (uneducated) guess is that the 18-inch wheel option was never included in the suspension tuning program. Unless you can tell me otherwise Mr Pepper!