I'm replacing floorboards upstairs due to excessive movement/noise, background in:

 

Adding noggins between the joists is simple enough and is having the desired effect but I'm unsure how best to approach the joists in the hangers. It would appear that the hangers aren't the proper size for the timber which is 44x220, have had a suggestion of pulling the nails out, packing with shims and securing with screws. My research though seems to state that only the fixings supplied with the hangers can be used.

 

I'll be adding a row of noggins by these hangers but I'd still like to tighten these hangers up if possible.

 

You can use screws, look for connector screws as these are made for the job, or you can use connector nails (these are very good in shear and have a twist in them, very tough nails) no problem packing the side gaps but it won’t make much difference to noise or deflection. Adding noggins will help if the joists are twisting. Replacing floor with 22mm boards fully glued and screwed will make a big difference

Hardboard or shim, plenty of foaming glue then replace nails with something like a Tie connector screw (not a run of mill wood screw) 

And the nails are

 

Thanks both, been searching for the appropriate screws and somehow never came across those!

I second the sheradised twist nails - tough as anything on hangers/plates etc.

 

Having said that, I think gluing and screwing 22mm eggerboard to the joists will make more of a difference than anything else!