The future of Clutches & Transmissions
Alistair Mason, Schaeffler REPXPERT
Tuesday, November 12, 2019
With engine design having seen some radical design changes in recent years, clutch and transmission technology is also in a period of transition. Alistair first explained the changes currently taking place; “Manual gearbox cars are still very popular, so there is still a high demand for clutch repairs and replacements. The number of vehicles using self-adjusting clutches continues to increase, as they give the benefits of a lighter clutch operation with a consistent bite point and clamp load. We are now seeing the use of hydro-electric clutches in semi-automatic transmissions, where an electrical actuator controls hydraulic pressure to the concentric slave cylinder to operate the clutch. A position sensor is fitted to the slave cylinder to give feedback on the clutch position.”
Looking to the years ahead
Looking to the years ahead Alistair said, “The future is in electrically-controlled clutches, which will also help reduce vehicle emissions, allowing the car to coast wherever possible. Double clutch systems are also now being used by most vehicle manufacturers. The main advantage is the gear change speed, which can be as quick as 0.08 seconds! Because of this, when accelerating, drivers tend to hold the throttle in one position until the desired speed is reached, and then they lift slightly to maintain that speed. As a result, it is lot easier for the vehicle to run at Lambda 1 to aid emissions control and, because the gearbox is controlled by an ECU, it is always in the correct gear. The dry double clutch system is the most efficient as there is no drag on the clutch.”
Clutch and transmission system maintenance
Alistair was then asked about clutch and transmission system maintenance. He said, “Generally, the only maintenance required on the transmission system is to change the oil on automatic, wet double clutch and constantly variable gearboxes. This is because the oil becomes contaminated as the clutch wears. It loses its lubricating properties as it deteriorates, causing premature wear on associated components, which can mean expensive repair bills.” He added, “Another area to look at, to ensure gearboxes are maintained properly, is control unit software updates.”
Guidance on parts choice
Alistair then offered guidance on parts choice; “My first piece of advice would be to fit quality parts from a known manufacturer, not simply choose on price. It is the workshop’s reputation at the end of the day, and if rectification work is required due to faulty parts, who’s going to pay? There’s also going to be an unhappy customer. I’d also recommend not ‘mixing and matching’ parts during a clutch replacement. Use all components from just one brand, as they will be optimised to work together. We have seen many problems arising from mixing different branded components.” He added, “I would also use a reputable and trusted supplier so if there are any problems they can then be quickly and easily resolved.”
Practical tips for working on clutches and transmissions
Alistair then offered some practical tips for garages working on clutch and transmission systems. He said, “It is a good idea to spend 10 minutes researching the job. Special processes are becoming more common and mistakes can be costly. Software updates can resolve a lot of faults, so these are always worth checking before removing major components.” He added, “Secondly always use the correct tools. Tolerances are a lot finer these days and components are more sensitive. A special tool will pay for itself against a job having to be done again.”
Alistair concluded, “Always check for the latest technical information. Bulletins are becoming more widely available on manufacturers’ websites, so it is always worth checking if there is one for your job, as this could save a lot of time and effort.
Information on Schaeffler products, fitting instructions, labour times and much more can be found on the REPXPERT garage portal at www.repxpert.co.uk and also in the REPXPERT app. You can also call the Schaeffler REPXPERT hotline on 0044 1432-264264.