Re: removing a 5k windshield...help!

["Fred Munro" <munrof@isys.ca>]

Hi Chris;

    The stainless steel trim strips are usually replaced with a new
windshield, but you may be able to save it with careful removal. I've never
tried to save one.
    The Extend is not a great basecoat to use under primer if you have
already removed the rust. Extend is a latex-based product designed to be
used on rust to stabilize the rust. The latex base is probably not all that
compatible with the solvent-based auto primers and paints, but then I've
never tried to paint over Extend.
    If you have removed the rust, treat the bare metal with a phosphoric
acid metal treatment (I use Dupont's Metalprep, but there are lots of
choices out there). This chemically dissolves remaining rust, etches the
metal for better paint adhesion, and passivates the metal surface to resist
corrosion. I like epoxy base primers because they have excellent chemical
and mechanical adhesion to the metal and are very tough - some of the better
ones are difficult to remove by sandblasting. A two-part polyurethane primer
on top of the epoxy builds up film thickness and is itself a tough,
corrosion resistant paint. The corrosion resistance of the paint job is in
the primer, not in the coloured topcoat.
    These primers and metalprep chemicals should be available at autobody
supply shops.

HTH

Fred Munro
'91 200q  272k km

----- Original Message -----
From: <JordanVw@aol.com>
To: FRED MUNRO <munrof@isys.ca>; <quattro@coimbra.ans.net>
Sent: Tuesday, April 13, 1999 12:54 AM
Subject: Re: removing a 5k windshield...help!


> In a message dated 4/12/99 10:36:07 PM Eastern Daylight Time,
munrof@isys.ca
> writes:
>
> <<
>  These windshields have an outer trim seal but are structurally bonded to
the
>  car with urethane adhesive. They are a real PITA to remove. When I went
back
>  to Standard Auto Glass after my last windshield replacement to gentley
>  admonish them for installing the windshield wipers in the "park" position
>  with the arms stopped in the "up" position, the tech told me they
absolutely
>  hated working on Audis - said the windshields were the hardest to R&R of
any
>  make they worked on. I would suggest paying one of the "do it in the
>  driveway" shops to R&R your windshield (usually $100 or so).
>   >>
>
> i removed all the caulk, and sanded (w/ rotary sander) all the rust down
to
> shiny metal around the windshield, on the body. I then painted it with
> "extend"..  and then just brushed on some primer over that. i will have to
> build up a few layers of primer to get the level near the existing topcoat
> level.. i will do a better job once the windshield is pulled, after i
attack
> the rust in the groove around the windshield..
> a few questions - can the stainless trim strip be saved? or will it get
bent
> up during windshield removal?   i was going to remove the windshield
myself -
> but i think i'll have someone do it, (my luck i'll break it taking it out)
> but i will probably use a rotary wire brush to remove the rust from the
> windshield channel..
> whats a good paint ot paint the windshield channel with? POR 15?  or is
the
> epoxy primer better?
>
> chris
> '86 5k TQ