What is the best clutch upgrade for the Focus ST225?
Our preferred clutch upgrade for the MK2 Focus ST225 is the LUK MK2 Focus RS clutch.
It retains a similar driving character to the standard ST clutch while providing significantly greater holding capacity. Based on our own experience, we have run these clutches at up to approximately 450 lb-ft of torque without issues.
This should be treated as real-world experience rather than a guaranteed torque rating, as clutch life also depends on vehicle condition, driving style, installation quality and how the car is used.
Do I need the clutch kit or the complete clutch and flywheel kit?
If the existing clutch has been slipping, we recommend replacing both the clutch and dual-mass flywheel.
Once a clutch slips, excessive heat can glaze or damage the flywheel friction surface. Installing a new clutch against a compromised flywheel may prevent it bedding in correctly and can shorten the life of the new components.
If the vehicle is low mileage, the clutch has not slipped and the flywheel is confirmed to be in good condition, it may sometimes be possible to fit only the three-piece clutch kit.
When there is any doubt, the complete clutch and flywheel kit is the safer option.
Should the slave cylinder be replaced?
Yes. We always recommend fitting a new concentric slave cylinder while the gearbox is removed.
The majority of the cost involved is the labour required to remove and refit the gearbox. Reusing an old slave cylinder risks having to repeat the entire job if it begins leaking or fails shortly afterwards.
Do the flywheel bolts need replacing?
Yes. The flywheel bolts are single-use stretch bolts and should be replaced whenever the flywheel is removed.
Do not reuse the old bolts.
Should the driveshaft seals be replaced?
We recommend replacing the gearbox driveshaft seals while the gearbox is removed.
The seals themselves are relatively inexpensive, and replacing them during the clutch installation helps avoid another labour-intensive strip-down if an older seal subsequently starts leaking.
What does the RS clutch feel like?
The MK2 Focus RS clutch has a slightly heavier pedal than the original ST225 clutch, but it remains progressive and comfortable enough for normal road use.
It does not have the harsh engagement often associated with more aggressive paddle clutches or motorsport-focused setups.
Is the RS clutch suitable for Stage 1 and Stage 2 cars?
Yes. The LUK Focus RS clutch is our normal recommendation for Stage 1 and Stage 2 ST225 builds, as well as many higher-powered road cars.
It provides substantially more torque capacity than the standard ST clutch without making the vehicle unpleasant to drive.
Should I fit a single-mass flywheel?
We do not normally recommend a single-mass flywheel conversion for a road-going ST225.
A dual-mass flywheel provides smoother operation and helps control gearbox noise and vibration. A single-mass setup can introduce additional rattling, vibration and harsher engagement.
We would generally reserve a single-mass conversion for very high-powered, competition or specialist builds where outright capacity and weight reduction are more important than refinement.
Our recommendation
For a clutch that has already slipped, choose the complete LUK Focus RS clutch and dual-mass flywheel kit.
For a low-mileage car with an unslipped clutch and a flywheel confirmed to be in good condition, the three-piece RS clutch kit may be sufficient.
In either case, fit a new slave cylinder, flywheel bolts and driveshaft seals while the gearbox is removed.