Customer grumbles about poor shift quality and difficult cold start gear engagement were behind a revamp of Opel manual transmissions, according to manual gearbox specialist Rolf Kruettgen.
Second generation five and six-speed manuals are claimed to match their best-in-class competition for fast, smooth shifting. There is also a completely new six-speed unit.
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The General Motors Europe unit has spent over EUR50m at its European facilities to improve the gearboxes and is now launching them in Corsa, Meriva, Astra, Zafira Tourer and Insignia models with engines exceeding 135Nm of torque.
Numerous revisions to the transmission internals and shifter mechanisms, as well as their in-vehicle integration, have enabled a significantly reduced shift travel with very low shift lever forces – typically less than required to push in a small drawer at home.
For a smoother engagement, all gearboxes have gears with wider, partly asymmetrically-cut dog teeth. Triple-cone synchronisers for first and second gear have also been re-profiled for five-speed gearboxes, and enlarged by 10% for six-speed units. For third/fourth gear, there are now double cone synchronisers on five-speed gearboxes and triple cones for six-speed units. Reverse gear is synchronised.
Shift quality is improved by the introduction of a more direct external linkage with revised cabling to minimise friction. For the driver, this has reduced gear shift travel and also delivered a more ‘connected’ feel, allowing the shift lever to ‘snap’ easily into position with a minimum of effort.
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By GlobalDataAn additional comfort feature is the installation of an internal vibration absorber to eliminate any vibration in the shift lever. The use of low viscosity oil also improves shifting comfort, particularly in cold-start conditions, as well as contributing to the powertrain’s reduced fuel consumption and CO2 emissions.
A new six-speed gearbox will be introduced in small and sub-compact vehicles with engines rated up to a 220Nm maximum torque. In each application, the new gearbox will be carefully integrated with an available choice of 12 sets of gear ratios and seven final drives.
Whilst the new gearbox incorporates all the improved shift quality measures introduced for the current second generation units, its completely new design has enabled a dry weight of only 37 kilograms, which is up to 15% lighter.
Opel will introduce a new automated manual transmission which uses an electro-hydraulic clutch actuator to eliminate the need for a clutch pedal. Instead of using two electric motors for gear selection and shifting, it now features an all hydraulic operation to give a substantially smoother gear change quality. New control modes between the engine and transmission control units contribute substantially to performance improvement. Other new features, applicable for both automatic and manual modes, include power launch for optimised take-offs, start/stop functionality and vehicle ‘creep’ movement, a useful aid for parking and low speed manoeuvres.
The new automated manual transmission is developed from the second generation five-speed manual gearbox, employing its high precision shift system. The gearshift lever is used to select drive, reverse or neutral mode in full automatic operation, and can be moved across its gate for sequential style, manual gear shifting. This new gearbox, primarily for small cars, supports engines with up to 190Nm of torque. The transmission is tailored to offer customers the comfort of an automatic transmission with even better fuel economy than a manual transmission, at a more affordable price compared to an automatic transmission.
We tried the new gearboxes at Opel’s Dudhofen test centre and were impressed with the quality of shifts although we did have trouble getting into the 5-6 plane on one prototype. The automated manual – in an Adam – was, like othes of its type, very jerky on full throttle starts but much better if driven in a more restrained manner as you would in urban conditions where it should be ideal.
