What did I do to my car's transmission

I drive a SmartCar - engine is in car’s rear. Last night, I switched from Reverse to Drive, and BAM, something feeling just like I backed into an object. (there were no such objects.) Did I do something to the transmission or engine?

Was the car in motion when you changed from R to D?

You should be fine.

Yeah, a couple MPH.

Do NOT do that.

Nothing good can happen. The odds on something expensive happening if you do that once are low. Make a habit of it and you’re asking for a problem. The kind spelled with lots of these: $.

If you felt a bang and a jolt you were tickling the dragon.

Thanks - everything still *seems *to run smoothly, so… hopefully it’s just minor damage.

This. I absentmindedly did the same thing to my wife’s CR-V a few years ago, and it did not respond well. There was much chattering/shuddering that shook the whole car; my guess is that there are clutch surfaces in there somewhere that don’t like to engage with any speed differential at all. No apparent damage, but I’m not doing that again.

A friend and I had a working car with an automatic transmission that we wanted to ruin. Never mind why. One of the ploys we tried was to hold the gas on the floor while we went back and forth between D and R, accelerating to a good speed in each direction before moving the selector again. It felt kind of violent, but the car still wasn’t working any differently by the time we got bored of this strategy.

Then we took get roof off with chisels and removed the doors, so it looked like one of those shoe store gages for measuring feet…