I have a 2009 RX 350 I'm getting a hard down shift going from 3rd to 2nd gear, This usually is happenings going over 60 MPH and coming to a fast stop. When tooling around 45 MPH and below really no issue. I have seen some post with similar problems but just trying to figure what my first approach should be. I know the transmission fluid was changed at 87,000 miles, 120,000 miles. the car has 133,000 miles now.

 

I take it , your not manual shifting? Do you change the trans filter & clean the two pan magnets? Or did a drain 'n fill?

 

I'd start by looking at the motor and transmission mounts. They are usually the cause for such a knock (but not always).

Bob

 

I had the same issue and it went away when I got my motor mounts replaced, so id suggest starting there.