I’m an engineer by training. I also grew up with a father who was an engineer, and did his own car work when possible, so I always do my own car work when possible. In the past three years I’ve rebuilt heads, replaced valves, drive-shafts, and bodywork. Car repairs can be dangerous though, even with simple jobs, and every now and then, That danger aspect needs to be reinforced.
Even simple jobs like a brake replacement can end in disaster. When putting a wheel back on, after replacing brakes, despite being chocked, and on axle-stands (or jack-stands, depending on where you’re from) the car still fell. Luckily I was untouched. At the time, I was jacking up the drivers side to remove one of the stands, but because there was a jack involved, I had no body parts under the car. The stand did fall, and the wheel roll on it. This is the result. This is a 2-ton stand, and you can see what a mess was made of it when a 3300lb (1500kg) car lands on something. Imagine if it was your leg, or foot.
When working under a car, NEVER have your body under it with just the jack. Don’t even remove the stands by hand, use a pole, or long tool – I use a long wheel brace. Sure, working without proper support might save you ten minutes, but if the jack collapses, or the car rolls, is that ten minutes worth a leg, an arm, your life? What’s more, you never know what else you might find needs doing.