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The latest BMW M2 to be unleashed from the M Power division at BMW is definitely a performance machine ready to go toe to toe with many other sports cars currently on the market. It comes as standard with electronic dampers, 6 piston front brake calipers, electronically controlled limited slip differential, 460BHP and a top speed of 177 MPH. However, despite these headline grabbing statements and figures; as soon as you start to drive your G87 M2 hard either out on the roads or the track, the limits of the chassis will be found quite quickly.
The majority of feedback we have heard from owners, further confirmed by our own test drives, is a serious lack of steering feel, a very wallowy boat like chassis through the bends and a lack of front end bite mid corner. Finally, when pushing out on track or in damp conditions on the road, instability and a lack of trust in the rear end on corner exit is a frequent comment too. Of course none of this is helped by the increased kerb weight when compared to the F87 M2 which now sits at over 1700Kg.
With the driver feedback rolling in we got straight to work developing suspension upgrades that would improve these areas to make the G87 M2 handle like it should and get the maximum potential from this great chassis. The combination of the highly tune-able power plant and the near perfect weight distribution means that this car has the potential to be a fantastic sports car with exponential potential to go toe to toe with supercars out on track and the roads.
The first area to address, due to it being the most common grievance with the chassis, is the lack of steering feel. When we refer to steering feel we are referring to a couple of things. Firstly, the physical effort it takes to turn the steering wheel. A weighted steering wheel that requires some effort to turn when driving fast adds a lot of confidence for the driver as steering inputs can be more accurately dialed in. This then means that feedback can be felt from the wheels more. It is often described as “knowing where the front wheels are” which refers to the feeling that when you turn the steering you can feel the front wheels move through the wheel so you know as a driver where the car is placed and the amount of steering angle that is required for the corner. With cars with less steering feedback and a light steering feel, it can sometime feel like guesswork when turning into a corner where the driver becomes stuck in a feedback loop of turning the steering wheel, waiting for the car to turn and then seeing if more or less steering input is required. This can feel very detaching for the driver and ruins the experience.
The key ingredient to bring steering feel and feedback back to life is caster. Therefore we designed a solid front offset control arm bush that can replace the original rubber bush in the front lower control arm. This not only adds caster into the system but removes the flex that the original bush suffers from under heavy braking. This caster bush has three major benefits; improving steering feel by introducing more self centering torque; reducing understeer by increasing dynamic camber gain as the wheels are turned through the corner and improved braking stability due to the lack of movement under heavy braking.
With these improvements installed we took some inspiration from the BMW M4 GT4 cars that we have worked with so much this year to see if there were any other components where we could increase caster to figures closer to that of the racing cars whilst still retaining the OEM suspension and maintaining clearance for all parts. With a detailed look over the components and data of the GT4 cars, we identified the OEM top mounts as a major area of improvement for the chassis.
As the front suspension system is MacPhereson Strut on the G87 M2, a lot of the geometry can be set using the top mounts which are not adjustable at all and are completely fixed on the G87 M2. Therefore, we 3D scanned the OEM top mounts in and increased the caster offset in the design. The caster offset is a fixed machined amount so no gauges are required to set the caster, we have done all the work for you so all that is required is their installation to benefit from this geometry alteration.
With the caster now improved significantly over standard by around 4 degrees with the combination of caster bushes and top mounts, we had massively improved steering feedback and feel with better turn in response and braking stability already making for a much better fast road/track car. With steering feel and feedback improved the feedback loop is removed and the driver intuitively knows how much steering lock to dial in to position the car perfectly for the corner, making for a much more enjoyable and intuitive drive.
Despite steering feel being improved, as we started to push harder through the corners due to the improvement in driver confidence, we noticed that the mid corner understeer was still very present at the limit of grip. The largest contributor to removing mid corner understeer is camber. Therefore, we engineered our top mounts to be camber adjustable too. With experience working with other styles of camber plates we needed to also include our signature anti-slip feature into our design to ensure that once camber was set, it would remain and not shift when being driven hard. After development was complete we had a camber plate for the G87 that increased caster, allowed for adjustable camber up to -3.5 degrees and had anti slip features whilst still working with the OEM spring and damper assembly as well as multiple other coilover options.
With the camber plates fitted the mid corner understeer was completely removed and the front end became much more direct and pointy. Following professional driver feedback at Circuit of Spa-Francorchamps not only had we eliminated the front end understeer, but we had made the front axle so direct and grippy that it was now the rear axle that required some attention to help it keep up with the front through the corners and maintain the 50/50 balance that the BMW M chassis’ are so well known for.
To get the rear back in shape and generating much more grip we had two key components ready to fit to increase both traction and corner entry stability. The first component is the Suspension Secrets Adjustable Rear Toe Arm. The adjustable rear toe arm unlocks the ability to set the rear camber and caster to a position that provides the most grip available without having to compromise on one area of geometry alone. The rear toe arm also replaces the OEM rubber bushes in the standard arm. During heavy cornering, the rubber bushes in the toe arm flex and alter the rear toe angle through the corner. As G load increases, the amount of deflection increases, leading to a car that feels different to drive through fast corners than it does through slow corners. With the rear toe arms installed and setup, the rear axle became much more stable on corner entry and through the mid corner section with the increased rear camber to lean onto matched with more toe in at the rear to compensate for the now positive front end.
The last area of the corner to keep the rear axle under control is on corner exit. As throttle is being re-applied, the oversteer tendencies were still quite high as all of the power was being put down through the rear loaded tyre causing the grip to become overwhelmed and break away. This is where the installation of the rear traction arm comes into play to keep the rear axle locked into the ground as throttle is being applied on corner exit. The rear traction arms can be set at a specific length longer than standard that we have developed to produce the maximum amount of traction from the rear axle. This alteration in length alters the arc pattern of the rear traction arm under compression and rotates the hub forwards and down slightly as the throttle is being applied. This means that as the car accelerates down the circuit, the front edge of the tyre is being physically forced into the ground generating much more mechanical grip and improving rear axle traction substantially. The Suspension Secrets Rear Adjustable Traction Arms were the final piece to restoring the balance back into the chassis to improve the whole car’s level of grip when being driven hard.
With the major areas of concern addressed and the whole car now performing much better out on track we could turn our attention to some more incremental changes in the chassis to fine tune the handling further. Similar to the deflection in the standard rear toe arms, the standard rear control arm bushes are also made of rubber and deflect in the same way through the corners. This leads to alterations in camber through the corner, which again slightly alters grip level through fast and slow corners. With the installation of the Suspension Secrets Solid Rear Control Arm Bushes this deflection is removed and the rear camber setting is stabilised as the tyre is loaded during cornering, leading to a more consistent and reliable chassis allowing you as the driver to push even harder with confidence.
With all of these chassis mods fitted and the car behaving much better than before it was time to address the ride height which is very high on the standard chassis. The stock dampers on the G87 M2 are electronic, and for mixture of road and track use, offer a nice compromise. Therefore we looked at keeping the OEM dampers in use and addressed the ride height and soft springs with a HAS (Height Adjustable Springs) kit instead. Brands such as KW or AST manufacture great HAS kits for the G87 chassis and the threaded platforms press over the standard shock absorber allowing for height adjustment so that the car can be lowered, corner weighted and have its rake angle set too. This combination lowers the centre of gravity, reducing body roll and also offers more chassis support through the use of the stiffer springs supplied with the kit. The spring rate is still comfortable enough for road use but firms the car to a point where the chassis is much more under control and has much less body roll when cornering hard. Not only does this improve temperature distribution on the tyres through the corners but it also provides much more driver confidence in the chassis.
With the G87 M2 now much lower, firmer and with the perfect geometry settings dialled into it we only had one final component to fit to turn this chassis into the perfect clubsport spec car. We installed a set of Suspension Secrets adjustable front and rear drop links (sway bar end links) that allowed us to remove the tension from the anti roll bar at the new lower ride height. The main reason for fitting adjustable drop links is so that the chassis can be corner weighted without introducing additional anti roll bar tension as a result. To corner weight a car, the ride heights are set slightly differently at each corner of the car by a few millimetres. This adds tension into the anti roll bar (sway bar) when the car is static which can make the car feel stiff in one direction and immediately soft and then stiff in another as the bar unloads and then re-loads quickly.
The adjustable drop links (end links) allow the tension to be removed as each link is set to a slightly different length to match the imbalance in ride heights. This restores the balance of left to right cornering, improving handling even further to finish off the whole recipe of components that make this car so much better out on circuit.
With all of these parts fitted, we headed back to track one more time to see how the whole car performed out on circuit. The balance of the car was perfect with a front to rear shift available just by slightly tuning throttle input throughout the corner. Understeer was entirely removed with a much more neutral wash at the limit of traction with lateral forces increased substantially as the whole car now had much more stable and consistent levels of grip throughout the corner.
So what would the next steps be?
Well if you were looking to go even further and turn your G87 into a more track focused machine then options such as Suspension Secrets adjustable rear camber arms and 3 way adjustable coilovers would take the chassis up to the next level and provide even more grip out on track and would introduce the ability to fine tune the damper settings to improve the corner entry and exit behavior as well as controlling dive and squat under heavy braking and acceleration.
If you would like any advise on upgrading your G87 or would like to see some more information about the products that we have mentioned in this article then head to the link below to head to our shop.
