I've had quite a few people ask about installing there posts to the helmet so I've decided to put a quick tutorial up. I'm not sure if one already exists or not but here is another. I don't take credit for this method, I'm sure its widely used as I've seen other helmets with the same thing.
I used a 1/4" FLAT HEAD BOLT with a LOCK WASHER & LOCK NUT
It is important to use a flat head bolt so that you can countersink it to the stalk. The bolt I used was way too long, your going to want to use a 3/4" or a 1" long bolt. All I had was a 1 1/2"
To begin I alligned the stalk and the cradle it sits in and drilled my hole for the bolt using a 1/4" drill bit.
Then I scooped out the connecting the end of the stalk where the bolt will attach using a 1/4" tapered drill bit.
If you don't have tapered drill bits I suggest you use a #10 bolt and nut which is smaller, there about 3/16" Then you can use your regular drill bits to countersink the bolt by drilling half way though with a larger size.
Your bolt will now sit flush and not interfere with the top cap. You now thread the lock washer and the lock nut on from the inside and tighten them up. Your post will travel up and down and will hold on any position without falling.
Very easy to do should take less than half and hour.