So I just got a 07 mazda3 s sport 2.3 and noticed something.
If the engine is not at prime operating temperature just yet, even after it kicks down, she shifts hard (jolts) when it shifts from 1st to 2nd. The tranny (A) is new when I got it a few weeks ago. What could be the cause?

 

I don't know. I have the same issue if it is one. I just changed the fluid and filter with synthetic as well. No change. So, I'll live with it until ....