That was obviously a worn-out or incorrect clamp.  Replacing it is the
only proper fix. Your 'shim' is not a good idea, but it did work for you.
That doesn't make it 'right' or even a good idea to recommend to others as a
good way to make a quick fix.  Positive and negative terminals are different
sizes to match the battery posts.
  Using a larger terminal on a smaller post will cause the bolt to close the
terminal all the way up until the 'tabs' meet, before it tightens against
the post.  Use of a post and terminal scraper tool will make this situation
even worse, as the post is made smaller, while the terminal hole is
enlarged.
  If you purchase a new battery cable with crimped-on terminal, be sure to
select the right size for the application; not just cable length, but also
negative or positive-sized terminal end.  Some times the right one is not
available, and you have to 'make do' with the wrong one.  The later-model,
stamped-steel, stock VW battery terminals are famous for being
over-tightened, cracking, deforming and becoming loose, as well as being
unable to be tightened properly.  They're fine when they're new, but I
replace them when they're older.

Mike B.

----- Original Message -----
From: "Mike Collum" <collum@VERIZON.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, August 08, 2008 4:38 PM
Subject: Re: Can a battery terminal clamp cause a battery to discharge?

> That certainly wouldn't cause a "Short".
>
> I once had a battery clamp that was still a tad loose after tightening
> it to the point where the tabs were touching.  On that one, I simply
> split a short piece of thin walled copper pipe, which I slipped over the
> battery terminal before putting the clamp on, and I used it that way for
> over four years without any problems.
>
> Mike