Automatic bone weighting with character with multiple objects

Hey Guys!
See I have this problem, I converted a Halo 4 Spartan Amour over from SFM to Blender. The model works great but the Armature itself is not so I decided to use Rigify to make a new one to replace it. The model is made of 7 Parts for customization:

  • The Body itself minus head
  • A helmet
  • A chest piece of Armour
  • Two shoulders (these are both separate)
  • Arm Armour
  • Leg Armour

I got the rigify armature acurate to the models body position and was able to parent the body as well with automatic weights but i do have some problems.
I can Parent with automatic weights with everything except two, the torso and leg armour. I receive the “bone heat weighting” error when I try to pair these objects to its respected bones.
I have linked the blend file for whoever wants to help try and fix this issue.
blenderartisthelp.blend (4.08 MB)