Managed to fit a 4tb hard drive in my 15 R3

Didn't think it was possible but it kinda fits, drive thickness is 15mm, the back case of the laptop bends out slightly, see images.

I have since taken it out as i'm not sure if it's good for long term, but it does work in Windows. Really wish there was a 12.5mm 4tb.

 

Can't imagine smashing your HDD pcb against the magnesium chasis like that is good for it.

That being said, you could potentially buy space by carving out the area that's specifically partitioned for the HDD. The laptop has three layers. Top (Palmrest), Mid Chassis (Main support) and bottom (The part that's bowing out in your images) ...

But with a dremel you could probably cut the mid chassis and remove the spot they give for the hdd. The flex would likely not completely disappear, but it would be dramatically less. I have no idea what this would do the over all stability and structure of the laptop though. It's been a long time since I took my 15 R4 apart and they had very similar chassis. Probably not a good idea to do. I definitely wouldn't do it, but it's an idea.

 

Didn't actually think of that, but yeah like you said it's not something to recommend, especially as i don't want to modify the laptop, may sell it in future.

 

I would've taken a grinder to the bottom lid to lessen the pressure, and applied some electronic tape or a thin piece of plastic to the PCB to protect it.

 

That got me thinking, i could actually remove the whole bottom lid and replace it with a thin piece of flexible plastic, drill some holes for airflow and attach it somehow. Maybe even cut out the hard drive section and use a slightly raised section there. Will post pics if i attempt it.