A few months ago, I was going to drop a friend off at work and hit the curb a little too hard with my front right tire. A week after that, I was going down a garage to my workshop which had a very steep "hill", which resulted in scrapping the underside of my car twice (since I had to exit the garage somehow too). After these two incidents, I noticed that my car shakes/wobbles/vibrates ONLY when I drive around 40 kmh (25 mph), especially in curved downhill streets. The feeling is almost like the car has a smaller tire on the right front side, and wobbles up and down. Under and above the speed 40 kmh, the shake/wobble disappears.

Summer was around the corner, and it was time to change for summer tires, so I thought I'd do that along with a wheel balance to see if it goes away.
After the change, the shake is still there.

I went to my local mechanic, to have all the relevant parts looked at (rods, bushings, cross bars, control arm etc etc), and after paying him 800 SEK (around 80 dollars) he finally said that he found out that........

Nothing. He found nothing. All looked good.

So I was left confused and been living with this shake since then. I read some online that it could be the engine mounts, so I ordered them but haven't found the time to do it, also due to lack of competence for the job. But before I do, I wanted to check if anybody here has had a similar experience or might have a clue of what it is? I am a little suspicious of the local mechanic too, because he didn't seem to be interested in finding what it could be. So I am open to the idea that he might not have looked properly.

2001 V6 3.0 btw.

 

Has the wheel balance been checked for the wheel in question?

 

Yes all of them were checked and balanced when the tires were changed to summer tires.