The clutch: signs of wear and what replacing it involves

How a clutch works#

On a car with a manual gearbox, the clutch connects the engine to the gearbox. The friction plate, with friction material on both faces, is clamped by the pressure plate against the engine's flywheel. When you press the pedal, the release bearing frees the clamp and the engine is disconnected, so you can pull away and change gear. When you lift the pedal, the plate is clamped again and drive is passed on.

The friction material wears every time the clutch engages, especially when pulling away, in traffic and on hills. How long it lasts depends heavily on the car and on how you drive, so there's no mileage that fits everyone.

Signs of a worn clutch#

• It slips: when you accelerate, especially in a high gear or uphill, the engine revs rise but the speed doesn't follow. This is the classic sign of a worn friction plate.
• It bites very high: the car only moves once the pedal is almost fully up. The bite point rises as the plate gets thinner.
• Gears are hard to select or go in with a crunch, especially first and reverse: the clutch no longer disengages fully.
• Noises: a whine or squeak when you press the pedal can come from the release bearing; a rumble at idle that goes when you press the pedal can have other causes, which the mechanic will pin down.
• Judder or jerking when pulling away.
• A burning smell after a hard hill start or after slipping the clutch for a while: the friction material is overheating.
• The pedal is much heavier, softer or doesn't return properly; on hydraulic clutches it may also be a fluid or cylinder problem.

A slipping clutch doesn't fix itself; it wears faster and faster. Book it in while the car still drives normally, so you aren't left stuck on a hill start.

The dual-mass flywheel, in brief#

Many modern cars, especially diesels, have a dual-mass flywheel instead of a conventional one: two masses linked by springs that absorb engine vibration before it reaches the gearbox and the body. It wears over time too.

• Possible signs: knocking or rattling at idle, strong vibration when the engine starts or stops, jerking at low revs.
• Why it comes up with a clutch change: it sits right behind the clutch, so it's reached with the same labour. The mechanic measures it and tells you whether it's still within the manufacturer's limits.
• Don't replace it "on principle", but don't refuse without asking why either: a worn flywheel can ruin a new clutch.

What replacing the clutch involves#

To reach the clutch, the mechanic removes the gearbox. That's why labour is a big part of the cost, and the parts in the same area are worth checking then rather than separately later.

• The clutch kit: friction plate, pressure plate and release bearing, replaced together.
• The flywheel, conventional or dual-mass, if it's worn.
• The release system: the cable or, on hydraulic clutches, the slave cylinder and the fluid.
• The oil seals between engine and gearbox: an oil leak onto the clutch ruins it quickly, so they're worth checking while the gearbox is off.
• Gearbox oil: some gearboxes have a change interval, others are filled "for life", depending on the manufacturer. Ask what the service book says for yours.

Dual-clutch automatic gearboxes have clutches that wear too, but diagnosing and repairing them is a job for a garage that works on that type of gearbox. Some faults in the release system also show up in a diagnostic check.

How to drive so the clutch lasts longer#

• Don't rest your foot on the pedal while driving: even light pressure makes it slip a little.
• Don't hold the car on a hill with the clutch: use the brake, and for pulling away the handbrake or hill-start assist if you have it.
• Pull away in first gear with moderate revs, without slipping the clutch for long.
• At the lights, for a long stop, select neutral and take your foot off the pedal.
• Change gear decisively, with the pedal fully down.
• Don't load the car beyond the limit in the registration certificate, and don't tow trailers heavier than the manufacturer allows.

What to ask the garage#

1. What they found: worn plate, bearing, flywheel or release system, and how they checked.
2. What the quote includes: the kit, flywheel, slave cylinder, oil seals, gearbox oil.
3. Which parts they fit: from which maker, matched exactly to your engine and gearbox.
4. Whether they'll call you before fitting any extra part found once things are apart.
5. What warranty they give on parts and labour, in months or kilometres (see what a repair warranty covers).

How CariX helps#

In the free driver account, a big repair like a clutch stays documented and tracked.

• "Is the price fair?" shows an indicative price range for clutch work in your city, from the prices garages list on CariX on their pages and quotes; the real price depends on the car, the gearbox and the parts.
• The PDF quote: with garages on CariX, you receive the quote and approve it online before the work starts.
• Warranties: the warranty the garage records on the job, in months and/or kilometres, appears under "Active warranties" on the car, with an email 30 days before it ends (for a warranty in months), so you can go back to the same garage if something goes wrong.
• Costs: you log the repair under costs and see what the car costs you each month, with charts.