Ford Focus ST MK4 Clutch & Flywheel Upgrades

MK4 Focus ST clutch and flywheel buying guide

The manual MK4 Focus ST responds extremely well to tuning, but the standard clutch is one of the areas that can begin to struggle as torque increases.

How long the original clutch survives depends heavily on its mileage, previous driving style and general condition. Some cars will cope with Stage 1 without any problems, while others can begin slipping as soon as the extra torque is introduced.

Our preferred upgrade is the Genuine Ford MK3 Focus RS clutch, which gives considerably more torque capacity while retaining excellent road manners.

For our complete tuning stages and expected power figures, read our MK4 Focus ST tuning guide.

What is the best clutch upgrade for the MK4 Focus ST?

For the majority of tuned manual MK4 Focus STs, we recommend the Genuine Ford MK3 Focus RS clutch kit.

It provides a significant improvement in torque capacity without turning the car into something unpleasant to use every day.

In our experience, the Genuine RS clutch has proven capable of handling approximately 450–460 lb-ft in real-world tuned applications.

That makes it comfortably suitable for normal Stage 1, Stage 1+ and Stage 2 MK4 Focus ST builds.

Does the RS clutch fit the MK4 Focus ST?

Yes.

The Genuine Ford Focus RS clutch is a proven upgrade for the manual MK4 Focus ST and works with the MK4 ST dual-mass flywheel.

There is no need to convert the car to a single-mass flywheel for normal road or tuned use.

Does Stage 1 need a clutch upgrade?

Not necessarily.

Some healthy standard MK4 ST clutches will cope with Stage 1 without slipping.

Others will struggle almost immediately.

The biggest factors are:

• Mileage
• Previous driving style
• How often the car has been launched
• Previous clutch overheating or abuse
• Existing wear before the remap

If the clutch is relatively fresh and has had an easy life, you may be able to run Stage 1 successfully on the original clutch.

If the car already has considerable mileage or the clutch feels marginal, we would budget for the RS upgrade.

What happens as the clutch wears?

A clutch that copes when new may begin slipping later as the friction material wears.

The extra torque from a tuned 2.3 EcoBoost exposes a marginal clutch much more quickly than the standard engine output.

That is why two otherwise identical Stage 1 cars can behave completely differently.

How do I know if my MK4 Focus ST clutch is slipping?

Clutch slip often becomes obvious in the higher gears where the engine is producing high torque against a heavy load.

A simple symptom is:

• Accelerate hard in a high gear from relatively low rpm.
• Engine revs suddenly rise.
• Vehicle speed does not increase at the same rate.

Other symptoms can include:

• Burning clutch smell after hard acceleration
• Reduced drive under full boost
• Increasingly high engagement point
• Judder when pulling away

If the revs flare without a corresponding increase in road speed, the clutch is slipping.

How does the Focus RS clutch feel?

The RS clutch has a slightly heavier pedal than the standard MK4 ST clutch, but the difference is not excessive.

Importantly, it still behaves like an OEM clutch.

You retain:

• Smooth engagement
• Good low-speed control
• Normal road drivability
• No aggressive on/off bite
• No unnecessary judder

For a fast road car, this is one of the main reasons we prefer the Genuine Ford RS setup over a more aggressive aftermarket clutch.

How much torque can the Focus RS clutch handle?

In our experience, approximately 450–460 lb-ft is a sensible real-world figure.

That is more than enough for our normal Stage 1, Stage 1+ and Stage 2 MK4 Focus ST packages.

As with any clutch, actual life depends on how the vehicle is driven. Repeated hard launches and poor clutch technique will shorten its life even if engine torque remains within its normal working range.

2-piece or 3-piece RS clutch?

We offer both configurations.

2-piece RS clutch

The Genuine Ford RS 2-piece clutch contains the clutch friction plate and pressure plate.

This can be useful where you already have a new or known-good slave cylinder.

3-piece RS clutch

The Genuine Ford RS 3-piece clutch kit also includes the slave cylinder.

Because removing the gearbox is a significant part of the labour involved, our preference is to replace the slave cylinder at the same time rather than reuse an older unit.

Should I replace the slave cylinder?

Yes.

We strongly advise replacing the slave cylinder whenever the gearbox is removed for a clutch replacement.

The labour involved in accessing it is substantial compared with the cost of fitting a new slave while everything is already apart.

We prefer the Genuine Ford Focus RS slave cylinder because it uses a more robust metal construction compared with the standard ST plastic unit.

What happens if the slave cylinder fails later?

A failed slave cylinder normally means the gearbox has to come back out again.

That means paying for a large amount of the same labour twice simply because an older component was reused.

For that reason, replacing it during the original clutch job makes much more sense.

Do I need to replace the flywheel?

Not every clutch replacement automatically requires a new flywheel.

If the existing MK4 Focus ST dual-mass flywheel is genuinely healthy and the clutch has not been slipping, it may be possible to reuse it.

However, we would replace it if:

• The old clutch has been slipping
• There is excessive dual-mass movement
• The flywheel has developed judder
• There is vibration or rough engagement
• The friction surface is damaged or heavily glazed

Why replace the flywheel after clutch slip?

When a clutch slips, it generates a significant amount of heat against the flywheel surface.

This can glaze or damage the friction face.

Installing a new clutch against a badly glazed flywheel can prevent the new friction material bedding in correctly and potentially reduce clutch life.

If the old clutch has been slipping noticeably, we would normally fit a fresh flywheel rather than take the risk.

Complete MK4 Focus ST clutch and flywheel kit

For a complete job, the Wayside MK4 Focus ST Clutch & Flywheel Upgrade Kit combines the parts we would normally use together:

• Genuine Ford Focus RS clutch plate
• Genuine Ford Focus RS pressure plate
• Genuine Ford Focus RS metal slave cylinder
• New MK4 Focus ST dual-mass flywheel
• New flywheel bolts

This is the straightforward option where you want to replace everything while the gearbox is removed and start with a completely fresh clutch and flywheel assembly.

Should I retain the dual-mass flywheel?

Yes.

For a normal fast-road MK4 Focus ST, we recommend retaining a dual-mass flywheel.

It helps preserve:

• Refinement
• Smooth low-speed driving
• Reduced gearbox noise
• OEM-like clutch behaviour

There is no need to introduce the additional noise and harshness of a single-mass conversion for a normal Stage 1 or Stage 2 road car.

Do the flywheel bolts need replacing?

Yes.

The flywheel bolts are single-use stretch bolts.

They must be replaced once removed rather than reused.

This is a small cost compared with the labour involved in a clutch replacement and is an important part of doing the job correctly.

Should the gearbox oil be changed?

We recommend it.

The gearbox already needs to be removed for the clutch replacement, so it is a sensible opportunity to refill it with fresh oil.

It is inexpensive preventative maintenance compared with the overall clutch job.

Should the driveshaft seals be replaced?

We recommend replacing them while the driveshafts are removed.

Driveshaft seals can begin leaking after the shafts have been removed and refitted, particularly if the seals have already covered considerable mileage.

Replacing them during the clutch job helps reduce the chance of having to revisit the area later for a gearbox-oil leak.

What would we replace during a complete clutch job?

For a car where we want to do the job properly once, we would consider:

• Focus RS clutch
• Focus RS metal slave cylinder
• MK4 ST dual-mass flywheel where required
• New flywheel bolts
• Fresh gearbox oil
• New driveshaft seals

The majority of the cost is in getting the gearbox in and out, so it makes sense to address inexpensive wear items while access is available.

Best clutch setup by tuning stage

Standard car

The standard clutch is perfectly adequate when healthy.

Stage 1

A healthy standard clutch may cope.

If the car has higher mileage, has been driven hard previously or already shows any sign of clutch slip, we would upgrade to the RS clutch.

Stage 1+

The increased torque makes the RS clutch a very worthwhile upgrade.

Even where the standard clutch initially holds, its remaining life may be significantly reduced.

Stage 2

We recommend the RS clutch setup.

Its proven 450–460 lb-ft real-world capacity is well suited to our normal Stage 2 power and torque levels while retaining excellent everyday drivability.

Does the RS clutch fit the hatchback and estate?

Yes.

The clutch setup is the same across manual MK4 Focus ST hatchback and estate models.

Does it fit facelift MK4.5 cars?

Yes.

The clutch setup covered here applies across the relevant MK4 and MK4.5 manual 2.3 EcoBoost Focus ST models.

Does this fit the automatic Focus ST?

No.

These clutch and flywheel components are for manual gearbox cars only.

Frequently asked questions

What is the best clutch upgrade for the MK4 Focus ST?

Our preferred option is the Genuine Ford MK3 Focus RS clutch.

How much torque can the RS clutch handle?

In our experience, around 450–460 lb-ft is a sensible real-world figure.

Will my standard clutch hold Stage 1?

Possibly. Some do and some do not. Mileage, existing wear and previous driving style make a significant difference.

Should I upgrade the clutch before Stage 1?

Not automatically. If the original clutch is healthy you may choose to retain it, but we would budget for an RS clutch upgrade if it begins slipping.

Does Stage 2 need an uprated clutch?

We recommend one. The Genuine Ford RS clutch is our preferred solution.

Is the RS clutch difficult to drive?

No. The pedal is slightly heavier, but engagement remains smooth and OEM-like with no aggressive on/off feel.

Does the RS clutch work with the standard MK4 ST flywheel?

Yes. Our normal setup pairs the RS clutch with the MK4 Focus ST dual-mass flywheel.

Should I replace the flywheel?

If the existing flywheel is healthy and the clutch has never slipped, it may be reusable. If the clutch has slipped, the flywheel is worn or there is excessive movement, judder or vibration, we recommend replacement.

Why does clutch slip damage the flywheel?

The slipping clutch generates heat against the friction surface and can glaze or damage the flywheel, making it a poor surface for the new clutch to bed against.

Should I replace the slave cylinder?

Yes. We recommend replacing it whenever the gearbox is removed.

Why use the RS slave cylinder?

The RS unit uses a metal construction and is our preferred replacement over the standard ST plastic slave cylinder.

Can flywheel bolts be reused?

No. They are single-use stretch bolts and must be replaced.

Should I change the gearbox oil at the same time?

Yes. It is a sensible opportunity to refill the gearbox with fresh oil while everything is apart.

Should I replace the driveshaft seals?

We recommend it. They can begin leaking after driveshaft removal and refitting, so replacing them during the clutch job is inexpensive preventative maintenance.

Does this clutch fit the estate?

Yes. The same clutch setup is used across manual hatchback and estate models.

Does it fit facelift cars?

Yes. It is suitable for the relevant MK4 and MK4.5 manual Focus ST.

Does it fit automatic cars?

No. This collection applies to manual gearbox models.

MK4 Focus ST tuning guide

For Stage 1, Stage 1+ and Stage 2 power figures and supporting hardware recommendations, read our MK4 Focus ST tuning guide.

More MK4 Focus ST performance parts

Browse our complete range of MK4 Focus ST performance parts for induction, cooling, exhaust, brakes, suspension, servicing and styling upgrades.