My wife drives a manual transmission Saturn. When she backs out of the driveway, she does not come to a stop before shifting into 1st gear. Unfortunately, she also does this when she drives my automatic transmission Corolla. Would someone provide me an explanation that will convince her why this is bad for the car? Thank you in advance.
In a manual transmission this will not harm the transmission but it will put additional stress on the clutch and cause it to wear out sooner. In an automatic transmission this is VERY BAD and will cause serious damage to the transmission if it is done repeatedly. Don’t let her drive your Corolla !!!
Doing that is hard on all the driveline components. This includes the engine mounts, transmission, and axle CV-joints. When going in reverse, these components are rotating in one direction. When going forward without allowing these components to come to rest first causes excess torsional stress on these components. Which can cause them to wear out faster.
Tester
In a manual transmission, the 1st gear synchronizer clutch would experience some extra wear as it has to reverse the rotation of the input shaft. Whether that is or is not more severe than a high speed 2nd to 1st downshift, I don’t know. The main abuse is probably the clutch. People who use their clutches as a substitute for brakes are what gives manuals a bad name.
When she drives your car, does she go backward 20 mph and then throw it into drive with the accelerator floored leaving burned rubber on the road as she speeds off, or, does she put it into drive with the car still going backwards at about walking speed with the engine idling and then gently accelerates like a normal person? If it’s the later, I wouldn’t lose any sleep over it. If automatics were that fragile, they would never have gained a reputation for being more trouble free than manuals.