This all started when shifting from R to D and hearing a quick metallic sound for a split second (more pronounced if the slightest movement forward or backward without a complete stop from R to D).

Years ago with some detroit iron I had a broken motor mount and the fan would hit the shroud with a similar sound. Now the FIT obviously has an electric fan but this brought up a concern.

I opened the hood with the car in P (no parking brake on) and with my knees rocked the car forward and backward. I am not exaggerating when I say the motor rocks forward and backward 1 inch. Now this makes me wonder if they all rock that much (I know the motor mounts are rubber) or if I've got something wrong and the rocking from R to D twists the motor and something hits causing this mysterious split second grind?

I know I've read one other post regarding this grind on the AT trans, perhaps we have a problem here?

 

Well I dont have a AT Fit so I cant completely relate to your exact problem but as far as the motor mounts, in the MT I can tell there pretty soft mainly to stop engine vibration in the cabin. I havent looked in my service manual but its possible that the AT can lack a mount that is present on the MT because that is the case on my other car.

At the least both AT and MT configuration drivetrains are gonna be 3 mounts if not 4. The most visible of these mounts is the passenger mount when you open up the hood. They sell polyurethane material if you want to fill the mounts to make them solid but the center's will still be rubber but it will make them much firmer. Only bad side effect is more engine vibration in the cabin.

 

I will let u know when I get mine in