Is it bad if a truck takes off into third gear instead of the first gear? Will it damage something?

We talk about a truck with 12 gears.

It depends on the type of truck, (Pickup? 18-wheeler?) the gear ratios, and the loading - the grade could also be a factor.

Perhaps an 18-wheeler with many forward gears could start from a dead stop in third gear and experience no ill effects. A pickup or other light truck - probably causing undue wear and tear on your clutch, flywheel, and pressure plate. Perhaps you *can* do it, but probably not a good idea.

You know your truck better than anybody. We would say it's perfectly fine to start out in third gear IF the truck is unloaded.

If the truck is unloaded the driver often will start in second or third gear with no harm to the clutch or gearbox.

Only if the gear is so high that excessive slippage of the clutch is necessary. In other words, probably.

Is it bad if a truck takes off into third gear instead of the first gear? Will it damage something?

We talk about a truck with 12 gears.