Krrrch – a crunching sound breaks through the usual sounds when switching. Such a switch has probably happened to almost every motorist. Is it ruining the gearbox? Our guide outlines how damage occurs and how to change gears without damaging the transmission.
Change gears without damaging the transmission
How dangerous is it to get the changes wrong while driving? Can gears break off, or does the vehicle even cause damage elsewhere? “Few people know that it is not only the gearbox that can be seriously affected by a switch. In extreme cases, even engine damage can be the result,” says automotive engineer Achmed Leser.
According to readers’ experience, the most common cause of the crunching transmission noise is incorrect coupling or uncoupling. Depending on the severity of the fault, the transmission parts are subjected to extreme loads. In case of frequent switching, this can lead to premature wear of synchronous rings, seals or the needle bearings up to the switching sleeve. So in the end, you will save on repairs bills if you change gears without damaging the transmission.
Too small a gear: What happens?
If motorists insert too small a gear when switching, for example when switching accidentally from the fourth to the first gear, the engine gets into an overspeed when coupled. The increased rolling speed of the vehicle is transferred from the high gear with full force to the too small gear. “The engine is really jawing up, the vehicle is heavily slowed down. This is where the manufacturer’s speed limiters reach their limits,” says Leser. “To avoid this happening, drivers should make their changes smooth and cam. You shouldn’t change down more than one gear, and (off the racetrack) make sure the revs are strong but not too high.”
However, this greatly increased speed range not only harms the gearbox, it can also lead to a capital engine damage. Because inside the engine, the extremely high speed causes the pistons to move faster than the valves can open and close. If the pistons hit the valves with force, they can be bent or even penetrate the piston. The result is also often a buckling of the connecting rod.
Automatic drivers can’t do anything wrong, can they?
But it’s not just drivers of cars with manual transmissions who can make expensive mistakes: some automatic drivers like to change from driving level D to R in a hasty way when manoeuvring in order to be able to drive backwards. If the speed step change is still carried out on a rolling vehicle, the automatic system will be unduly charged. Even such incorrect operations inevitably lead to increased wear of the transmission components.
“However, early gearbox damage can also occur due to a lack of maintenance,” explains Leser. Thus, too little oil is just as harmful to the gearbox as to the engine. If the oil film breaks off, the gear gears are no longer optimally lubricated, there is increased friction and material abrasion up to breaking gears. But also sneaked-in habits such as placing your hand on the shift knob during the entire ride are not exactly conducive to the service life of the gearbox.
Each switch increases wear
Be careful with clutch and gearbox and strictly adhere to all your car maintenance intervals. In fact, engine and transmission components are designed by the manufacturers for high mileage. However, poor operation, lack of maintenance or bad habits can greatly reduce the service life. And: Every switching increases wear.