How to drill a leaf spring blade?

Getting closer to fixing the squeak on my RXT pack. The two top leaf blades rub each other without spacers. I want to drill a hole towards the end of each 2nd leaf and put a plastic spacer in there like the other ones have. Have seen it done on YT and need to know what drill bit to use since is spring steel.

 

Drill bits are not created equal, some high speed steel cobalt bits are cheap, others are not.

But fresh steel bits, starting with a small and working up to the size needed will result in less stress on even cheap bits.

Combined with a slow constant speed and lube from oil or a penetrating fluid, you can drill through thick steel.

Try using bits you already have and see how it goes, no sense buying a 150$+ set until you try.

 

Cuntstain tongueglide