2022 marked 50 years of BMW’s M division and to celebrate BMW released a number of new M cars including this: the BMW M4 CSL.
Limited to 1000 units worldwide with 100 cars supplied to the UK, the M4 CSL marks the return of the ‘CSL’ moniker which was last used on the celebrated E46 generation M3 CSL in 2004.
For those that are not so familiar with the ‘CSL’ badge, it stands for “Coupe Sport Lightweight”, and it’s that last word ‘lightweight’ that is the biggest focus. BMW has managed to strip approximately 90 kg (200lbs) of dead weight from the M4’s chassis. Weight saving measures include: lighter bucket seats; titanium exhaust system; carbon ceramic brakes; a basic-spec air conditioning system; lightweight front grille; the removal of the rear seats; a carbon fibre bonnet; lighter wheels and a carbon fibre boot lid with an integrated ducktail rear spoiler.
Whilst the BMW M4 CSL is hardly a true lightweight (it’s not exactly Caterham light at 1625kg) the reduction in weight versus a standard G82-generation M4 xDrive (1775kg) is admirable. BMW’s willingness to strip so much weight out of, what is essentially, a big coupe is impressive, and less weight is always a good thing when it comes to performance; the M4 CSL managed to lap the Nürburgring 13 seconds faster than an M4 xDrive.
Other changes made by BMW to boost the M4 CSL’s dynamic performance include revised suspension geometry and hardware. This CSL was fitted with a re-tuned version of the Adaptive M Suspension, with three selectable suspension modes: COMFORT, SPORT and SPORT+ with each mode making the dampers progressively stiffer. Whilst the Adaptive M Suspension is not a new feature for the M4 CSL, the CSL does benefit from unique damper settings that have been specifically tuned for the car’s more focused character.
We were eager to take a look under the M4 CSL to see what changes BMW had made for the ultimate M car. The front axle was much the same as the standard G82-generation M4, save for a more aggressive front camber setting. This camber increase is built in to wheel hubs that are unique to the M4 CSL.
The rear axle is where we were expecting the most amount of changes. The G80 M3 and G82 M4 both use subframes that are nearly identical to those used on the previous generation F80 / F82 M3 / M4. This is not necessarily a bad thing, as the rear subframe on the previous generation F80 and F82 are already solidly-mounted to the chassis, and the five-link rear suspension gives excellent rear axle kinematics.
So, how different is the rear axle of the super-focused CSL? Not much, as it turns out.
There are some differences; the rear toe arms are now mono-balled at both the wheel hub and the subframe. On the standard G80 / G82 M3 / M4 the toe arms are only mono-balled where the arm meets the subframe, with rubber-bushes where the arm meets the wheel hub. By solidly-mounting the rear toe arms there is less flex during cornering, which ensures the toe angles remain consistent during cornering, increasing stability.
The rear subframe of the G82 M4 features two rear upper camber arms per wheel, and on the standard M4 both of these arms are rubber-bushed at the subframe. On the M4 CSL, the forward-most camber arm still features a rubber subframe bush, but the perpendicular camber arm features mono-balls on both the wheel hub and subframe. Much like solidly-mounting the toe arms, this is done in order to reduce flex during heavy cornering, and to ensure the car remains stable and predictable.
After our inspection, we came up with an idea that would benefit M4 CSL owners.
The idea is to take the solidly-mounted M4 CSL toe arms and to use them to replace the standard rubber-bushed traction arms to improve traction and acceleration. The next step would be to fit our Suspension Secrets G8X Adjustable Rear Toe Arms where the original M4 CSL toe arms were originally fitted. Our fully-adjustable toe arms increased traction, grip and feedback. The final change would be to replace each of the rubber bushes in the camber arms with Suspension Secrets solid bushes. These bushes improve handling by ensuring the rear camber angle does not change during heavy cornering.
These changes would make the M4 CSL’s rear end entirely solidly mounted. The result? Greatly improved handling, traction and stability and a transformation for the handling of your M4 CSL.
Not lucky enough to get one of the 100 UK supplied M4 CSLs? All is not lost…
The standard G80 M3 and G82 M4s can be made to handle as well as or even better than an M4 CSL with our range of BMW G8X upgrades.
We make the following upgraded suspension components for the G80 M3 and G82 M4 that all improve handling substantially over the standard components:
- Suspension Secrets Adjustable Toe Arms
- Our toe arms give improved cornering stability and corner exit traction. They give you full control over the rear toe settings of your BMW allowing for more advanced geometry setups to be applied.
- Suspension Secrets Rear Camber Arms
- Our fully adjustable rear toe arms give you full control over rear camber settings, making them perfect for more the more aggressive camber settings required for track days.
- Suspension Secrets Rear Traction Arms
- These fully-adjustable arms allow you to modify the kinematics of the rear axle in order to improve traction. These arms allow the rear axle to rotate slightly during acceleration which digs the tyres into the tarmac and develops much more grip. These are ideal for drag racing or big power builds.
- Suspension Secrets Front and Rear Drop Links
- Our drop links allow your to fine-tune the position of your anti-roll bars to ensure even handling, making them ideal if you have lowered your M3 or M4 on lowering springs or coilovers.
- Suspension Secrets Front Solid Control Arm Bushes
- Our solid control arm bushes ensure your steering remains accurate and communicative during heavy cornering. As they do not flex, our control arm bushes also improve braking stability and help to reduce understeer.
If you would like any help or advice on upgrading and improving your G8X BMW then feel free to get in touch with us directly!