Utopia Texas

In the last two weeks since owning my new to me 2008 SL550 my wife and the mechanic who replaced the transmission filter and fluid have driven the car too close to some parking stops and damaged the front end fiberglass underneath the front bumper. This is at the very bottom and one has to almost get on one's knees to see the damage. The mechanic only left scrapes but the second incident has resulted in a crack in the fiberglass that I know will get worse over time. Can I strengthen the back side of this piece with fiberglass tape and some fiberglass or bondo or is this a job for a professional? I have worked on machinery all my life here on the farm and am quite handy at mechanical repairs but have never worked on fiberglass repair. This would all be done on the inside so looks are not important. I would just like to strengthen the area so more damage does not occur. Thanks...

kbob999

Sounds like you just want to stop further damage, not fix the crack so it is invisible.
I had a crack, and plenty of scrapes, on my front air dam when I bought the car. Here's what I did.

To stop the crack from growing you need to first drill an 1/8" hole at the visible end of the crack. This relieves stress at the point.
Next get a sheet of 0.050" to 0.080" aluminum 3" wide X length of the crack. Preferably from an airplane mechanic at your local airport, as it is the preferred grade and strength.
Shape the aluminum to fit, place it inside the air dam, clamp it, then start drilling 3/4" from the crack, at 1" spacing, both sides of the crack.
Drill size will depend on rivets, use 1/8" or 3/16", countersunk rivets will hide better. Rivet the plate in place.
This same airplane mechanic has the correct tools, called Cleco's for this task, as well as the rivets. For a bottle of wine or 6 pack he might fix it for you.
Worked great on my car.