Machine Skeletal Mesh with Physics Asset, how to drop it with gravity ON without breaking the bones/physics assets?

I added a constraint, to keep the crank attached to the body of the machine:

I have an animation to spin the machine:

I set the Crank bone to Kinematic, so the animation can drive the physics asset:
imagen

But then this happens, the crank and handle turn extremely tiny while animating + simulating physics. I tried tweaking every possible value, but I can’t find any way to fix this. Any idea?