Actually, there are many types of materials used for exhaust donuts. I have even seen wire wound gaskets. In most cars, exhaust donuts are used for flexible connections. Instead of being bolted solid, shoulder bolts and springs are used so that the joint is actually under a spring load allowing the joint to move while in use. The fiber and wire donuts work well for these. VW went to the steel donuts for many applications. These need to installed tightly to seal and will often come loose shortly after installation. Stainless bolts seem to make the loosening worse, mostly due to bolt stretch and the washers crushing. Maybe a good fix is to use the spring loaded exhaust bolts used on other cars.

Dennis

----- Original Message -----
From: Frank Condelli <RAlanen@AOL.COM>
Date: Friday, August 12, 2005 6:48 am
Subject: Re: Broken Stebro Muffler Bracket / Malcolm's trip + FIBER EXHAUST

> In a message dated 12/08/2005 12:03:19 AM Eastern Daylight Time,
> LISTSERV@GERRY.VANAGON.COM writes:
>
> Fiber
> gaskets were (are?) recommended for any SS  joint.
>
>
>    Tabe, Pascal and all other interested parties, the  doughnut
> gasket joint
> in an exhaust system is used to allow placement of the  components
> so that
> there is no undue stress.  A solid flat joint allows no
> repositioning of the
> components to the best position.  That said there are  two types
> of doughnut
> gaskets available on the market today.  Asbestos  fibre ones and
> solid steel
> ones.  It was though that the fibre ones were  better for the
> stainless steel
> flange connections due to stainless steel being  susceptible to
> cracking from
> vibration.  The fibre ones were though to  reduce this problem.
> This now after
> many years of testing may not be  true.  Many of the stainless
> steel joints I
> encounter in my shop have  been fitted with the steel gasket and
> no flange
> cracking has show up thus  far.  The steel gasket will definitely
> give a longer
> life over the fibre  ones.  The fibre ones will eventually burn
> out from exposure
> to the hot  exhaust gases.  So what to do ?  I have begun using
> the steel
> ones in  most all applications and I am checking these connections
> as often as I
> can to  see how the joint is surviving.  So far I see no problems.
> So, I
> would therefore recommend using the steel gasket in all
> connections.  See  my
> _STEBRO/Vanagon Stainless  Steel Exhaust System_
> (http://members.aol.com/Fkc43/stebro.htm)  webpage for a list of
> part numbers of these two  gaskets.  They are
> widely available from most good automotive parts  supply.
> Contrary to
> popular belief they are not made or supplied by  STEBRO.  I
> included them with the
> STEBRO/Vanagon Stainless Steel Muffler  and J-pipe as a
> convenience to the
> customer.
>
> Cheers,
>
> Frank  Condelli
> Almonte, Ontario, Canada
> '87 Westy, '90 Carat & Lionel  Trains
> Vanagon/Vanagon Westfalia Service in the Ottawa Valley
> _Frank Condelli &  Associates_
> (http://members.aol.com/Fkc43/busindex.html)or
> http://frankcondelli.com_STEBRO/Vanagon Stainless Steel  Mufflers_
> (http://members.aol.com/Fkc43/stebro.htm)
> _BusFusion_ (http://members.aol.com/BusFusion/bfhome.htm)  a VW Camper
> camping event, Almonte, ON, June 09 ~ 12,  2005
>