Oh, Snap! The Infamous Fabric Retaining Bow

Look on the inside and, chances are, you'll see broken trim.
Look at the inside of the rear window of an A124 Cabriolet, and you'll see a long piece of black plastic that runs the length of the window—MB Part #124-770-02-80, known in the parts book as the "Fabric Retaining Bow." You'll also notice that it's almost always broken on either end. (Yes, add another part to the "they all have that issue" list.)

Mind you, it's not broken from abuse, as with the cross member on the deck lid above the license plate that breaks from slamming the trunk closed. It also doesn't break from the ham-handed work of an installer, as with the overhead courtesy light unit, which is usually mangled by someone looking to replace the windshield. No, this piece breaks from poor design. Perhaps the factory over-torqued the screws as well, but the point is there's very little you can do to forestall this piece from snapping at either end. You're just as likely to see it broken on a low-mileage garage queen as you are on a Cabriolet that's been driven hundreds of thousands of miles and parked in the sun. It's an equal-opportunity annoyance.

Unavailable from Mercedes for years now, the fabric retaining bow was last priced around $200. For owners looking to replace this part today, options are limited:

Option #1 is to cross your fingers and hope to find a parts car with this trim intact.

Option #2 is to re-manufacture the part from ABS plastic using a 3-D printer, as this enterprising ebay seller did. He is selling his bow (sans factory rubber seal) for $600.
Note longer screw used in 1993 on left

Option #3 is you can do what most owners do—you can accept it and live with it broken.

I was fortunate to find a good used replacement part, so you can imagine my excitement to study the still-intact bow that was from a car that was actually two years older than mine. I was very interested to find any differences that could explain what helped to preserve this piece.

What I found was that the actual black plastic bow was identical in every way. Same ABS plastic. Same thickness. Same rubber gasket. The difference was the length of the 6 phillips-head screws used to hold the bow in place. The older bow from late 1993 used screws that were significantly longer from the ones on my Cabriolet that was manufactured in late 1995.

Will the longer retaining screws continue to save this bow after I re-install it? We shall see. For added measure though, I strengthened the backside of the screw hole openings on either end with a layer of JB Weld epoxy to help resist stress cracks.

I'd also be interested to hear from other owners about the state of their bows and to see if we can draw any further conclusions.

Fixed . . . but for how long?