Mounting E-Speed hangers.
 

Tried a search but can't find anything on this really simple question, what's the screw size I need to fit the hangers and do I need a nyloc nut too?

Ta.

Standard 4/40" screw just like the rest of the car. No need for a nut unless you strip the thread... I did.

You need a nut to secure the ball stud.

Oh you're right I forgot about this one.

Thew nut does not secure the ball stud. It is used to spread stress on the bottom of the ball stud land. Even better with a washer above the nut. This helps keep the bulkhead brom breaking where the stud is.

When you put the hangers on, especially if you use two screws, you probably don't need the nuts or washers. It would be stronger with them, but I would save weight and not put them on unless I broke a bulkhead.

On the hangers I had, I needed 2x 4-40 screws to mount it to the bulkhead and a nyloc to secure the ball stud to the hanger. My hangers weren't threaded so the nyloc was a mandatory requirement.

I'm with Toby, a nut is needed for the hangers to hold the ball stud, also needs to be a relativley long ball stud.