Type 44: corrosion of side impact beam

[Paul Meyers]

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
--
--
[ Picked text/plain from multipart/alternative ]
The passenger rear side molding on the Gray '87 5K acted like it was coming
"unstuck" at the rear. I thought it was failing adhesive. It turns out that
the side molding is held on by two bolts that screw into an embedded side
impact beam. The beam is an incredibly robust affair that looks to be made
of forged aluminum in a modified I-beam configuration. To accommodate the
impact beam, there is a deep groove at the midline of the door, neatly
covered by the side molding. The bolts are modestly covered by rubber caps,
making them look like bumpers of some sort. They are readily visible with
the door open, one on the front and one on the rear of the door abut midway
between roofline and floor pan. Anyway, I found out that something was amiss
when I found the bolt laying in the gutter after a child had exited the car
(slammed the door).

To my utter amazement, on disassembly I found what looked like flakes of
paper or cardboard or some other material embedded in this pristine forging.
The flakes just crumbled in my hand. On further investigation, I concluded
that the flakes were what was left of the forging after years of sacrificial
anodic corrosion had eaten away massive amounts the impact beam, starting at
the original rear threaded bolt hole. Wow! The front bolt and bolt hole were
pristine, as was the forward half of the forging. But no rust on the car!

Since maybe 20% of the original cross section of the beam was left, it's
safe to say that the beam would not have exhibited its intended performance
in a side impact crash. Since Audi wants over $100 for a new beam, I will
try to find a used one.

If your car exhibits a rear molding that seems to be lifting at the rear,
remove the bolts and inspect it for corrosion. The life you save could be
...

Paul Meyers
'88 5KCSTQ Pearl, 128K Mi, 2pc EM, Fuchs, K24, 1.8 bar, Bilsteins
'87 5KCSTQ Gray, 154K Mi, Fuchs, SJM chip, 1.8 bar, Boges
'87 5KCSTQA White, 208K Mi, Replica TT wheels, Adjustable WG, 1.8 bar,
Bilsteins, no roof rack

--