Short story - I had to steal the negative battery terminal screw and nut from my Z to use on my other car. Now I need to replace the square-head screw and nut for the Z. Advanced Auto only had larger diameter screws that don;t fit in the terminal. Can anyone suggest where I might get those items? I don't really want to buy the whole terminal. Thanks in advance,

 

Pep Boys, O'Really, Autozone.... or just get the closest thing from Home Despot/Lowes. There's nothing particularly special about it other than the squared head - and you really don't need that either. Nice to have but not critical.

 

Thanks for the advice. That's what I thought too....but the shape of the terminal clamp where the screw head and nut sit prevent you front getting a socket around them. Hard to explain but take a look and you will see. In fact the nut is special in that half of its length is cylindrical while the other half has a hex. The cylindrical part fits down into the recess of the clamp (where you can't engage a standard nut with a socket) while the hex part sits out belong th clamp so you can get a socket on there.
So I would argue it is necessary to have the "right" parts for this!

TL;DR- I already tried using a standard M6 screw and nut but could not tighten them due to the design of the terminal clamp.

 

Interesting, don't recall having any issue with a pair of 10mm (IIRC) wrenches but maybe I wasn't paying much attention. Just did it...

Well, new clamps aren't expensive so guess that's your next remedy.

 

Yep I was using 10mm sockets but there isn't enough clearance for the socket to fit within the clamp. It's hard for me to explain.
The original hardware is a square head bolt which bottoms out in the clamp (i.e. cannot turn), and the nut is about twice as long as a standard M6 nut where one half of its length is cylindrical and the other half, which sits out beyond the recess of the clamp, is a hex.

If I knew what to call that style of nut, I might be onto something.

 

Why don't you find something that will fit the other car and have that car give the Z its hardware back?