I repaired my bumper with grey epoxy from the hardware store.  A teenage
driver rear ended me.  I never got arounds to painting it, just sanded it
smooth.  Tangeled bumpers eight years later with a Ford Tarus. His bumber
was demolished.  It actually fell off the car.  I didn't notice any damage
to my bumper, even where it was epoxied back together, so  guess the
orginal repair was sucessful.  I didn't use any glass reinforcing fibers,
just epoxy. Like JB weld but it comes in putty cans, mix black and white to
make a grey putty.  You might want to paint your's though, it will look
prettier.

----------
> From: JordanVw@AOL.COM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Damaged fiberglass rear bumper... can it be repaired?
> Date: Monday, May 08, 2000 9:56 AM
>
> In a message dated 5/7/00 6:23:51 PM Eastern Daylight Time,
> ktaylor@PREMIER1.NET writes:
>
> << 've got a '91 Westy Multivan with the black fiberglass bumpers.
>  Someone rearended my van.  The replacement cost for a rear bumper at the
>  local VW dealer is nearly $500.  This dealer also maintains a VW
>  'wrecking yard,' and they told me that it's very rare that they ever get
>  these bumpers in on wrecked Vanagons because in an accident, they're
>  typically the first thing to be destroyed.  As it is right now, the
>  bumper is in one piece, but appears to have torn areas in it, none of
>  which are near an edge.  The largest tear is about five inches long.
>  They are not 'holes,' but are long abrasions with a little fiberglass
>  fabric showing. Anyone have any luck removing a damaged bumper of this
>  type and repair it by patching it from the rear for structural purposes
>  and filling in the abrasions on the front for cosmetic purposes?  Also,
>  is the type of black paint needed to paint fiberglass bumpers available
>  in aerosol cans? >>
>
>
> yes, you can fix them..its pretty easy.  remove bumper, massage cracked
areas
> back into place, abrade backside of bumper, and repair w/ fiberglass
resin
> and matting cloth.  repair face of bumper w/ bondo, and sand. repaint.
> chris