As a teen I replaced a clutch disc in a 54 Ford while parked in the garage. It wouldn't have been a problem except the parts guy gave me a disc too large. Luckily when I started the car I had it in reverse or it would have blasted through the back of the garage. As it was, it just shot back out the garage and petrified my young, know-it-all, behind. Then I had to drive it across town without a clutch, a major piece of hair-raising experience. Experience is the best teacher, if you can live through it.