Hilicoil ate aluminum thread! Need help.

[Fred Munro]

Hi Konstantin;

It depends on the thread length. If the thread is long enough, aluminium
will support enough torque to twist off a bolt. IME, bolts usually fail on
overtorquing by twisting off rather than by stripping threads unless the
thread is damaged in the first place.

Fred
----- Original Message -----
From: "Konstantin Bogach" <konstantin.bogach at morganstanley.com>
To: "Fred Munro" <munrof at sympatico.ca>
Cc: "Jim Green" <jeg1976 at yahoo.com>; <quattro at audifans.com>
Sent: Friday, January 11, 2002 1:46 PM
Subject: Re: Hilicoil ate aluminum thread! Need help.


> Fred,
>
> I thought that the soft aluminum alloy is stipped fist, not a bolt.
>
> Konstantin.
>
> Fred Munro wrote:
>
> > Hi Konstantin;
> >
> > The torque depends on the bolt class. The generic torque spec for a
standard
> > class 4T 6mm bolt is 5 Nm. Even a class 7T  6mm bolt only takes 10.5 Nm
> > torque. A class 8T can take 29 Nm.
> >
> > It sounds like you may have overtorqued the bolt and stripped the
helicoil.
> > You may want to double-check your 25 Nm torque spec - I sold my beloved
> > Bentley manuals for your model Audi to Geo, so I can't check it out for
you.
> > If it is 25 Nm, those are darn good 6mm Allen bolts!
> >
> > Fred Munro
> > '94 S4
>