knocking sound

Give me a little more info about the car--engine--tranny type mileage etc. Without more info it sounds like it might be a motor mount issue. Probably from driving on the wrong side of the road Ha! Ha!

Let me know

My car is a Honda Civic, automatic transmission, 1991 make, mileage 118550. We recently replaced battery as well. HAHA! Wrong side of the road!
Hope this helps!

That makes it a little clearer with an automatic. The Honda doesn't like to be put in reverse unless you are at a dead stop.

Do you hear the knocking sounds when you are in park or neutral? Do you hear them when you are accelerating slowly? Because the engine and tranny are bolted together under the bonnet. I am trying to isolate if the sound is engine or tranny.

Do one test for me. Open the hood, and watch the engine as you slowly rev it in neutral. Does it tend to shift or stay still?

Have someone in the car and put it in Drive. With the foot on the brake, increase the engine RPM and see if the engine "picks up." Do the same in Reverse. I am trying to determine if there is a broken motor mount.

If the engine "picks up" then there is a broken motor mount. They can make a nasty knocking noise as the engine/tranny bounce along on a broken support.

Let me know

PS I will be out of town from 5 Apr to 10 April visiting siblings.

could be loose muffler clamps. check it out.