Although the historic Mini Cooper marque is now wholly owned by BMW, the Mini is marketed as a completely separate brand. The manufacturer is referred to as 'Mini' and the models are Cooper, Cooper Convertible, Cooper S, and Cooper S Convertible.

Mini clutches and transaxle assemblies have several design/performance details of which owners and repair professionals should be aware:

Clutch:

For the average driver, stock Mini clutches tend to last just short of 100,000 miles. Even the Cooper S clutch will usually last more than 70,000 miles. Aggressive performance drivers and inexperienced drivers should not be surprised to get considerably lower mileage.

Hydraulics:

Mini clutches are operated by a master and slave hydraulic system (two separate cylinders, one on the firewall, one mounted on the transmission). Layout and design is quite conventional. Components look and operate as do many other vehicles. The unusual feature is that the clutch hydraulic system shares fluid and reservoir with the brake system. Although not exclusive to Mini, this is not a common configuration.

The brake fluid reservoir is larger than most of those used on clutch systems. When a small leak occurs in one of the clutch cylinders, additional brake fluid feeds into the system to replace what is lost. The large volume of available fluid tends to obscure symptoms that are usually expected from a leaking clutch cylinder. The system continues to work as long as fluid is available. The clutch pedal probably seems a little soft and shifting the transmission may feel a bit sticky. There will be some brake fluid loss.

Be sure to check the entire hydraulic system (clutch and brake) when diagnosing clutch or brake fluid loss.

Flywheel:

Mini uses a dual-mass flywheel. Dual-mass flywheels act as momentary impact/thrust absorption implements (absorbing the initial shock of clutch engagement) while transferring torque efficiently to the transmission. By placing the absorption mechanism in the flywheel rather than in the clutch disc (as has been done for decades), a great amount of shock can be absorbed. This helps prevent clutch chatter and engagement 'jump' while protecting transmission and differential parts from damage under aggressive driving.

But, dual-mass flywheels do not last forever, and they are expensive. A Mini flywheel is likely to cost $700 or more!

During most clutch replacement operations, the flywheel should be replaced. Their life expectancy is not much greater than the clutch itself.

When doing a clutch job, replace the entire clutch kit (plate, disc, release bearing, and pilot bearing), Check motor mounts and transmission mount for breakage and/or sagging.

Transaxle:

Minis are equipped with conventional transverse-mounted, forward placed transaxle assemblies. The one unusual feature in the Mini is in the differential portion of the transaxle. The differential ringgear in the Mini is not bolted to the carrier. Instead, the ringgear is pressed onto the housing. With heat expansion, aggressive clutch engagement, and hard cornering under acceleration, the ringgear can fail by coming completely off the carrier!

When repaired, this problem is solved. All replacement parts have been redesigned include a bolt-on mounting kit. However, until recently (and perhaps to some extent still), replacement parts were extremely scarce. Some vehicles were inoperative for 3 - 4 months, waiting for parts. The delays have been so prolonged that some enterprising repair professionals have resorted to drilling, tapping and fitting aftermarket bolts to the old parts.

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