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RE: Lower T- Shirt

To: "Dennis Costello" <djc.tr6@worldnet.att.net>,
Subject: RE: Lower T- Shirt
From: "Navarrette, Vance" <vance.navarrette@intel.com>
Date: Mon, 11 Jul 2005 08:21:25 -0700
        Dennis:

        Your car is incorrect. The pipes pass between the upper and
lower cruciform
pressings, at least they do on my 74-1/2.
        I would be reluctant to gusset the frame beyond what the
original designers
had done, as you have no way of knowing where stresses may end up as a
result.
Obviously, if you are finding cracks then you must gusset things to
prevent
recurrence. But if you gusset an otherwise trouble free portion of the
frame
you risk (a small risk admittedly) redistributing stresses such that
another
area might end up cracking. Other than corrosion, there are no stress
related
failure modes that I am aware of for this portion of the frame. Others
on the
list may know differently, however.
        Gusset areas where you will get some real benefit like the diff
mounts
or the front suspension mounts on the older frames. There is a proven
bang for
your buck there.
        The additional boxing might be helpful, but it will move your
fuel and
brake lines closer to the exhaust pipes, as they currently nest inside
the
lips currently formed by the frame. Additional boxing would mean that
these
lines would need to be relocated (unless you intend to box them in). If
you box them in future maintenance would be problematic, I *think*.  I
like
the idea of being able to inspect the lines when the car is on a lift.
        Just tossing my ravings into the pot, as always. Take with the
usual
grain of salt, YMMV, advice offered "as is", etc, etc.

        Vance


-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Dennis Costello
Sent: July 10, 2005 12:59 PM
To: Six Pack
Subject: Lower T- Shirt

Don Malling and Aaron Cropley replied to my question regarding
reinforcing
the T - Shirt area of my frame and mentioned their concerns of excessive
temperatures in the area due to the exhaust passing through the area
occupied by the fuel line.  My feeble mind then was not sure, but
remembered
my exhaust (twin pipe) not being within the space between the frame
rails
and the T - Shirts.  So, I went to the garage and looked, and it is
true, my
exhaust goes under the lower pressing.  In fact, it seems to have a
slight
bend in the two intermediate pipes to accommodate the slight jog under
the
area of the pressing.  Hmm, no wonder I can see the pipes from the side
of
the car!  Is mine incorrect?  As a further clarification of what I was
attempting to suggest originally, if you look at photo 5-8 in the Roger
Williams book, you can see the two flanges of the channels are open to
the
inside of the frame rails.  I was wondering about filling this in at the
outboard end with a strip, giving a second "boxed section" of lesser
size
than the original.  My curiosity about closing in the cruciform area is
shown in the same book in photo 5-32-12.  This photo shows small gussets
in
the corners, and is suggestive of what I had envisioned.  So, what do
you
think?
Thanks Don and Aaron!
-Dennis
CF8659U




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