The transition from the 3200 GT to the 4200 GT involved a complete reengineering of weight
distribution and power transmission.
The Transaxle Layout
The most radical change in the chassis engineering was the adoption of the Transaxle layout. In the
previous model (3200 GT), the gearbox was coupled directly behind the engine, at the front of the car. In
the M138, the gearbox was moved to the rear axle, forming an integrated unit with the differential.
The engine at the front and the gearbox at the rear are connected by a rigid torque tube, inside of
which the driveshaft rotates at engine speed. This arrangement is costly and complex, but it offers
unparalleled dynamic benefits. It shifts a significant mass (the transmission) to the rear, counterbalancing
the engine's weight. The result is a near-perfect weight distribution:
- Maserati Coupe: 52% Front / 48% Rear.
- Maserati Spyder: 53% Front / 47% Rear.
This distribution reduces the polar moment of inertia, allowing the car to change direction more
readily and maintain a neutral attitude at the limit of grip, avoiding the excessive understeer typical of
heavy front-engine cars.
Gearbox Options: GT vs. Cambiocorsa
Maserati offered two interfaces for the same 6-speed mechanical transmission manufactured by
Graziano:
- GT (Manual): The purist version, equipped with a clutch pedal and a
traditional gear lever with a metal gate. Due to the rear location of the gearbox, the lever uses long
cables or linkages to engage the gears. Although it offers total involvement, this version represented a
minority of sales and is extremely rare today.
- Cambiocorsa (Sequential Automatic): The standout technology of the time.
"Cambiocorsa" means "Racing Gearbox" in Italian. It is not a conventional automatic transmission with a
fluid torque converter, which "slips" and smooths out shifts. It is the same mechanical gearbox as the
GT version, but robotized. A high-pressure electro-hydraulic system, controlled by a processing unit
(TCU), operates the clutch and gear selection.
The driver commands shifts via paddles mounted on the steering column (not on the steering wheel,
meaning they remain fixed while the steering wheel turns, a preference derived from F1 so the driver always
knows where the upshift and downshift commands are).
Operating Modes: The system offers "Sport" mode (faster and more aggressive shifts), "Auto" (the
computer decides, simulating an automatic), and "Low Grip" (for snow/ice).
Software Evolution: Throughout production, the control software (nicknamed "SOFAST") was updated.
Early versions (2002-2003) could be somewhat jerky in traffic. From 2004/2005 onwards, and especially in the
GranSport, the software became much more refined, smoothing out maneuvers and speeding up shifts under high
load.
Skyhook Suspension: Real-Time Adaptation
The aluminum double-wishbone suspension on all four wheels ensured correct geometry. However, the
technological innovation lay in the Skyhook adaptive damping system, developed in partnership with
Mannesmann-Sachs.
The Skyhook system uses a network of sensors that monitor vertical wheel movements, body
acceleration, and driver inputs (steering, braking, throttle). An electronic control unit processes this
data thousands of times per second and adjusts the fluid viscosity inside each individual shock absorber via
electromagnetic valves.
The theoretical concept is to isolate the body from road imperfections, as if the car were suspended
by a "sky-hook," staying level while the wheels work. The driver can select between "Normal" mode (focus on
absorption comfort) and "Sport" mode (focus on roll control and precision).