Hi everyone,
I thought I would post this simple fix for the door lock actuator grinding noise in my 2011 FD i30. After reading through all the posts and YouTube videos I decided to pull it apart and see what the matter was. Also I was not buying a Hyundai part for $500 AUD.
Everything internally seemed fine which another user had also found. I connected the mechanism back and actuated it with my key. What I found was there was a lot of force driving the two parts of the housing apart. All the gears and mechanisms are housed in one half and the motors in the other. There are only plastic clips and locators that hold it together. When it is assembled I think the two halves of the housing move and grind the gears as the force drives them apart.
To fix it I ended up drilling 3 of the plastic locators to a M3 and bolted it together nice and tightly. (See attached picture) Now there is no grinding noise.
If anyone else is able to do the same fix I would be interested to know if this solves the problem as well but it certainly worked for me.