Quick question for you gents,

What size and strength are the larger bolts on a cortina ball joint?

Cheers Dan.

Standard M12s, 30mm long, i.e. 8.8 grade

Cheers Westie, thought they were higher strength for some reason.

Dan.

Hi,
The large ones are 8.8 and the smaller ones are 10.9 in the kit I got from Lolocost. I'm not sure if this is standard or not but may explain why you though they were higher grade.
Cheers,
Craig.

That could well explain it.

Cheers Gents

Dan.

I bought 10.9 for both sizes, for the extra 30p for 4 bolts, it gives a little extra peace of mind

If you can keep your head, whilst all others around you are losing theirs, you are probably using 10.9's.