Track Series 3: Suspension and Handling

BMW offered a package from factory that feels alert and agile, but the suspension is a compromise as it can feel “crashy” on the road but too soft when on track. This is mainly caused by a mismatch of soft springs and overdamping. The suspension was built to a budget to comply with regulations in different countries with a focus on being used every day with tyre wear and safety being key for even the most inexperienced driver. Thankfully many fast road users find that just a set of lowering springs can heap big improvements such as reducing body roll, lowering the centre of gravity, sharper turn-in and more feel through the steering. However, for those wanting to go on track, a full set of springs and dampers or coilovers are essential to getting more out of the car.

Coilovers

Coilovers will replace the poor OEM dampers and offer much better quality damping and body control. They will help set the ride height and adjust the weight between the front and rear axles, providing a more stable platform, making the car more predicably under braking, accelerating and turning. This adjustment will also allow you to add some rake into the car, which can greatly improve the front end and low-speed turn-in. Coilovers often come with adjustable damping which can help you set the car up for smooth or bumpier tracks. This can also come in handy if you use your car for both road and track as it can quickly be adjusted to be more compliant for the road or stiffened up for track where tighter body control is required. By adjusting both the bound and rebound settings, you can finely tune the oversteer/understeer characteristics of the car, allowing you to find the optimum settings for corner entry and exit.

Some great entry-level options include the Ohlins Road and Track Coilover, KW Clubsport 2-way Coilover, KW Clubsport 3-way Coilover or the Bilstein B16 Clubsport Coilover. For more track-focused variants, you may consider getting the Nitron R3 Suspension Kit or the Ohlins TTX Advanced Trackday Suspension Set

📷: Image from BMW

Camber

Unfortunately, the front camber is not adjustable from factory. So if your coilovers do not come with camber plates, we would recommend adding these on from the likes of Millway or Nitron. During hard cornering, as the car leans, the load on the tyre rolls to the outside edge. This causes the contact patch of the tyre to reduce and creates excessive heat and wear on the outer edge of the tyre which in effect reduces grip and can cause understeer. To counter this, you can use camber plates to apply more negative camber so as the car leans, it rolls onto the full width of the tyre to keep as much of the tyre contact patch on the tarmac as possible, improving mid-corner grip and steering feel. It’s a great way to make the front end bite harder and give confidence whilst cornering. 

Shop Camber Plates - Here

Drop links

Now that the car is lowered, this can place additional pre-load on the Anti-Roll bars, moving them into a position which can foul the chassis and trigger the car to react differently when turning left than it does when turning right. Ensuring load is applied correctly is also important when corner weighting a vehicle as it can skew the results and provide handling traits that aren’t predictable. This can easily be resolved by getting a set of adjustable anti-roll bar drop links. These drop links typically come with upgraded joints for improved durability, and with the adjustment available, they allow for the anti-roll bar to be set to its unloaded factory position giving an even corner balance. SPL Rear Drop Links – Here and Front Drop Links here

By this point, you’ll be able to push the car somewhat harder and may want to increase rear toe-in but will have maximised the OEM settings. A common upgrade is to look at adjustable rear toe arms from Hardrace, Millway or SPL. Hardrace is equipped with a high-quality ball joint to reduce flex as the Millway and SPL come with Spherical bearings. The spherical metal type bearings and bushings help to further remove any deflection and dynamic movement to the alignment. The benefits from this are that you will obtain a better feel and feedback, improved response and handling but at the downside of Noise Vibration and Harshness, therefore more suited to track work.

Tension Struts, Lower Control Arms, Tie Rods

Continuing with this theme, we would then look at the front tension strut bush, front lower control arm bush preferably with caster adjustment and rear control arm bushes. These can be obtained as individual bushes or full replacement arms from either Millway or SPL. Both offer motorsport levels of suspension precision and control. Once done, the next step would be to replace the remaining arms to complete the suspension links.

If running particularly low suspension, we would suggest the adjustable bump steer tie rod ends, also from SPL. When a car is lowered, it can lead the track rods to sit at an angle as they run from the steering rack to the track rod end. This angle causes the arms to shorten as the wheel moves upwards through its travel leading to the arms pulling the back of the wheel in towards the vehicle (giving a temporarily toe-out) and making the car change direction. This is often why lowered cars feel nervous and twitchy on bumpy roads as the wheels travel upwards independently of each other. The SPL tie rod ends realign this angle to its correct position eradicating the bump steer.

When using sticker tyres on track, you will want to make the most of the available grip. At this point, we believe thicker anti-roll bars will be beneficial. These will provide less roll, reducing the dynamic camber change and allow you to fine-tune mid-corner balance. They effectively increase spring rates without the downside of a harder and less compliant ride.

Geometry

As with any suspension changes, it is critically important to ensure that the geometry of the vehicle is checked and aligned after each upgrade. This is one of the most beneficial things you can do to impact how the car drives. Even on the standard suspension, this can have drastic results on its behaviour and road holding. Having this done ensures that the wheels and suspension components are set to the optimum position. It is therefore critical that these are checked to make the most of the upgraded suspension components by preventing premature wear to the tyres and steering, improving the steering feel and ensuring your car handles predictably in a way that suits your driving style.

KW V3 Coilover fitted on F87 M2 at Xatrix

Looking to upgrade your car for track days?

We can now offer fitting services at our workshop Xatrix, based in Lyne, Surrey. Feel free to get in touch with us for any enquiries or quotes HERE.