TORINO: The McLaren MP4-12C’s new Sequential Shift Gearbox (SSG) is not only the lightest and most compact in its class but supplier Oerlikon Graziano says it also sets new standards for the refinement and durability of a Dual Clutch Transmission (DCT).
“As well as being immensely fast and dynamically capable, the cars must be comfortable, refined, efficient and a pleasure to drive every day," said Oerlikon Graziano head of automotive transmissions Paolo Mantelli.
"We worked closely with McLaren Automotive’s engineers to develop a new transmission that would help them meet these targets.”
|The McLaren MP4-12C’s new Sequential Shift Gearbox.
A DCT-type transmission combines smoothness and refinement with the possibility to change gear quickly with no torque interruption and therefore no reduction in acceleration.
It also allowed a highly sophisticated control system, developed in conjunction with DCT controls specialist Vocis (a subsidiary of Oerlikon Graziano), whose British-based team has managed some of the world’s most challenging and prestigious DCT programmes.
The compact dimensions were driven by McLaren’s desire to maximise passenger space without compromising dynamics.
A three shaft architecture was chosen because the parallel secondary shafts help to minimise gearbox length, allowing the engine to be mounted further back.
All eight ratios use Oerlikon Graziano’s high-performance synchronisers, optimised to allow substantially faster changes without compromising durability.
“We wanted to achieve genuinely fast, smooth shifting without any of the ‘tricks’ that can be employed to make a DCT feel fast,” said Vocis managing director Mike Everitt, whose team also calibrated the transmission.
“The secret is to get the very best out of the whole control system with a highly-optimised interaction between the software and the hardware. This ensures that the responses are not just quick and accurate but are also consistent and progressive.
"That means rigorous attention to the fluid dynamics and to the design and calibration of the control algorithms, which are constructed using our proprietary architecture.”
An unusual feature of the McLaren transmission is a ‘pre-cog’ facility that can make the already class-leading change time feel almost instantaneous.
The driver can pull the gear up/down paddle to the first detent position, commanding the transmission to engage the next gear and preparing the oncoming clutch.
When the paddle is pulled to the second detent, the gear shift is completed in a fraction of the time required by a conventional DCT. The system also makes the shift more engaging than typical DCTs with single-pull paddle shifts.
The new transmission is manufactured at Oerlikon Graziano’s plant in Luserna, Italy, using a combination of precision automation and traditional craft skills to allow consistently high-quality manufacture in low volumes.
Comprehensive end-of-line functional testing, using custom-built automated systems, ensures that every transmission delivered to McLaren meets their demanding requirements for Britain’s newest supercar.
Oerlikon Graziano has also recently started production of transmissions for the new Lamborghini Aventador and for the new Aston Martin Vantage S.