McLaren Graziano Gearbox Explained: How the Seven-Speed SSG Works

The Gearbox Behind a Generation of McLaren Supercars

When McLaren Automotive launched the MP4-12C in 2011, the company needed a transmission capable of combining supercar performance with the refinement expected from a modern road car. The solution was a seven-speed dual-clutch transaxle produced by Graziano, the specialist transmission manufacturer now operating under Dana Incorporated.

Dana describes the Graziano unit as a seven-speed dual-clutch transmission designed specifically for mid-engined, high-performance cars. It combines the gearbox, final-drive arrangement, clutches, hydraulic control system and shifting hardware into a compact rear transaxle.

The Graziano brand became part of Dana when Dana completed its acquisition of Oerlikon Drive Systems in 2019. However, many McLaren owners and technicians still refer to the transmission simply as the Graziano gearbox.

Which McLaren Models Use the Graziano Gearbox?

Dana’s technical documentation identifies Graziano seven-speed dual-clutch transaxles in numerous McLaren models, including:

• McLaren MP4-12C

• McLaren 650S

• McLaren 675LT

• McLaren 720S

• McLaren 765LT

• McLaren 540C

• McLaren 570S and 570GT

• McLaren 600LT

• McLaren GT

These cars do not necessarily use an identical gearbox specification. Gear ratios, final-drive ratios, clutch control, software calibration, cooling requirements and torque limits differ according to the model. Dana’s published data, for example, shows different overall ratios for the 765LT compared with the earlier Sports Series and Super Series applications.

The current McLaren 750S and GTS continue to use a seven-speed Seamless Shift Gearbox, while the hybrid Artura uses a different eight-speed SSG with electric reverse. The term McLaren SSG therefore describes McLaren’s transmission concept, but it should not be assumed that every SSG has the same internal design or interchangeable components.

What Does SSG Mean?

SSG stands for Seamless Shift Gearbox, McLaren’s name for its electronically controlled dual-clutch transmission.

Despite the name, it is not a literal Formula 1 seamless-shift gearbox. It is a road-car dual-clutch transaxle engineered to minimise interruption in drive during a gear change.

The transmission contains two clutch circuits. One clutch controls one group of gears, while the second clutch controls the alternate group. While the car is accelerating in one gear, the control system can prepare the next anticipated gear on the other side of the transmission.

During the shift, torque is progressively transferred from one wet clutch to the other. The outgoing clutch opens while the incoming clutch closes. When the pressures, engine torque and shaft speeds are coordinated correctly, the result is an extremely fast change with very little interruption in acceleration.

Dana confirms that the McLaren transmission incorporates a dual wet-clutch module, mechatronic control, clutch-control hydraulics, gear-selection hydraulics and auxiliary hydraulic functions.

Why Use Wet Clutches?

A wet clutch operates while immersed in fluid. This provides cooling and helps the clutch cope with repeated engagement under high torque.

This is particularly important in a McLaren because the clutches must perform several different jobs. They must launch the car from stationary, provide controlled low-speed movement, execute fast full-throttle shifts and remain smooth enough for normal road use.

The disadvantage is increased complexity. Clutch operation depends heavily on the condition of the fluid, hydraulic pressure, temperature control, electronic calibration and accurate clutch adaptations.

A wet dual-clutch transmission should therefore never be treated as a conventional manual gearbox with an automatic gear selector.

McLaren Pre-Cog: Preparing the Next Shift

One of the most interesting features introduced with the 12C was Pre-Cog.

Under acceleration, the gearbox will normally prepare the next higher gear because an upshift is the most likely request. Under deceleration, it may prepare a lower gear.

However, the driver may want the opposite. A driver could accelerate towards a corner and then require an immediate downshift, or decelerate briefly before accelerating and selecting a higher gear.

McLaren’s two-stage paddle movement allows the driver to lightly load the required paddle into the Pre-Cog position. This tells the gearbox which direction the next shift is expected to take. A full pull of the paddle then commands the change.

McLaren’s official handbook explains that the system anticipates and preselects the required gear. It also confirms that the driver can lightly hold the downshift paddle after acceleration, or the upshift paddle during deceleration, to alter the gearbox’s normal prediction.

The original 12C technical specification officially described the car as using a seven-speed McLaren dual-clutch SSG with Pre-Cog functionality.

Automatic and Manual Operation

The Graziano SSG can operate in automatic mode or through the steering-wheel-mounted paddles.

In automatic operation, the transmission controller considers factors such as vehicle speed, accelerator position, engine load, braking, selected powertrain mode and driving style. It then determines both the shift timing and the clutch pressure required.

In manual operation, the driver requests shifts using the paddles, but the system still protects the powertrain. It can refuse a downshift that would over-rev the engine and may intervene when necessary to prevent the engine from operating outside its permitted range.

The driver does not need to lift the accelerator during an upshift. Engine and gearbox controllers communicate during the change, modifying engine torque while the clutch handover takes place. This coordination is one of the reasons correct engine and gearbox software is so important.

Why It Can Feel Different at Low Speed

A dual-clutch gearbox has no conventional torque converter. At parking speed, the car moves by progressively engaging and slipping one of its clutches.

This can make the transmission feel more mechanical than a traditional automatic when manoeuvring, reversing or moving slowly on an incline. A small amount of clutch engagement sensation is not automatically evidence of a fault.

However, violent shuddering, excessive delay, repeated banging into gear, significant RPM flare or persistent warning messages are not characteristics that should simply be accepted as normal.

Low-speed operation places considerable demand on the clutches because they cannot remain fully locked. Continually creeping forward in traffic or holding the car on a slope with the accelerator creates unnecessary clutch slip and heat.

Clutch Temperature and Driving Technique

McLaren specifically warns that repeated hard acceleration, excessive hill starts and driving slowly up steep gradients for extended periods can cause high clutch temperatures. Under these conditions, the gearbox may limit engine torque to protect itself.

When a clutch-temperature warning appears, McLaren instructs the driver to stop the vehicle and allow the engine to idle in neutral for several minutes.

Owners can reduce unnecessary heat by using the brake rather than the accelerator to hold the car stationary, avoiding prolonged creeping and allowing the transmission to cool after repeated launches or demanding track use.

Launch control is an engineered vehicle function, but that does not mean it creates no wear. A standing launch requires the clutch system to transmit very high torque while the vehicle is initially stationary. Frequent launches will inevitably place more thermal and mechanical load on the clutch system than conventional driving.

Maintenance Is Essential

The McLaren Graziano gearbox is a strong and sophisticated unit, but it is not maintenance-free.

McLaren’s owner documentation states that the clutch and gearbox oil have mileage-related service intervals. It also advises that oil loss or gear-selection problems require professional inspection.

The exact fluid specification, quantity and replacement interval must be confirmed for the particular model, production year and VIN. A fluid that is suitable for one McLaren transmission variant must not automatically be assumed correct for another.

Correct servicing may involve more than simply draining and refilling the transmission.

Depending on the model and work performed, the process can require:

• Controlled fluid-temperature conditions

• Correct filling and level-setting procedure

• Diagnostic activation of hydraulic functions

• Clutch adaptation or relearning

• Gear-position calibration

• Inspection for leaks and fluid contamination

• Verification of software and fault-code status

Using an incorrect fluid, setting the level incorrectly or ignoring the required diagnostic procedure can create shift problems even when the gearbox itself has no internal mechanical damage.

Warning Signs That Require Diagnosis

A transmission should be professionally checked when it displays persistent symptoms such as delayed engagement of Drive or Reverse, clutch-temperature warnings during ordinary driving, abnormal noises, visible fluid leakage, repeated gear-selection faults or a sudden deterioration in shift quality.

RPM increasing without a corresponding increase in vehicle acceleration may indicate clutch slip, but this must be confirmed with diagnostic data rather than assumed from road behaviour alone.

A correct investigation should include a complete fault-code scan, live hydraulic and temperature data, clutch adaptation values, commanded and actual gear positions, software status and a physical inspection for leaks.

Replacing parts without first analysing the control data is an expensive and unreliable approach.

Gearbox Considerations on Tuned McLarens

Engine tuning increases the torque that the gearbox and clutches must transmit. The peak power figure alone does not determine gearbox load; the shape of the torque curve, the RPM at which torque arrives and how aggressively it is introduced are equally important.

A calibration that delivers a sudden torque spike at low engine speed can be more demanding on the clutches, input shafts and gear teeth than a smoother calibration producing similar peak power at higher RPM.

Dana’s published McLaren applications demonstrate that the Graziano transmission family was produced with different ratios and vehicle torque requirements, including documented 630 Nm and 800 Nm applications. These figures describe specific original-equipment configurations and must not be interpreted as universal tuning limits for every McLaren gearbox.

A properly developed tuned McLaren should therefore consider:

• Engine torque delivery

• Gear-dependent torque management

• Clutch pressure and adaptation condition

• Transmission temperature

• Shift intervention and torque reduction

• Vehicle mileage and previous use

• Track, road and launch-control demands

• 
  

Simply increasing engine torque without understanding how the gearbox controller manages that torque is not professional calibration.

A Highly Capable Gearbox—When Correctly Maintained

The Graziano seven-speed SSG helped define the character of the modern McLaren. It combines the direct response of a manual transmission with rapid electronic shifting and sufficient refinement for normal road use.

Its speed comes from mechanical preselection, wet-clutch control, hydraulic pressure and precise communication between the engine and transmission controllers. That same sophistication means that servicing, diagnosis and tuning must be performed correctly.

A healthy McLaren SSG should shift quickly, consistently and predictably. When its behaviour changes, the correct response is not guesswork or unnecessary parts replacement. The car should be diagnosed using accurate data, the correct procedures and a proper understanding of how the complete McLaren powertrain operates.

At Torque Tuning, we approach McLaren gearbox diagnosis and performance work as an integrated powertrain system. Engine calibration, transmission behaviour, clutch condition and thermal management must all be considered together—particularly on modified or heavily used cars.