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      03-25-2019, 10:00 PM   #136
Second Lieutenant

Drives: 2007 Z4 M Coupe
Join Date: Oct 2012
Location: Woodstock, GA

iTrader: (0)

Carbon fiber quarter window panels

Finally got around to replacing the quarter window glass with carbon fiber panels. These windows provide zero visibility for me on track with my halo seat so why not replace them with carbon fiber instead of Lexan?

My first thought was to remove the glass from the window rubber, make the CF panels and glue them back onto the old rubber and reinstall the assembly to the car. But then I thought why reuse the old rubber. It's old and rubber is dense (ie, heavy). Why not mold the window assembly with carbon fiber vacuum bagged to shape.

Removing the quarter window from the car is pretty basic. I used a large break away blade to cut the adhesive around the window.

Quarter window assembly weighs 2lb 5oz.

I prepared the window for the mold with clay. To make it easier for the carbon fiber to mold into the inside corners, I used modeling clay to bevel these edges. First roughing them in and then smoothing the clay with a blade. This should also make for a more aero looking art as well.

I covered the clay with aluminum foil then waxed all for easy mold release.

I laid three layers of 3k twill fabric and vacuum bagged it. This forces the fabric into the shape. Let it sit for 12 hours at 25 inches of vacuum.

The raw piece weighed 3.4 ounces! Nice!

Trimmed to fit...

A couple coats of epoxy, sand, rub, buff, and polish and the finished result looks pretty good. Finished panel weighs 4 ounces.

I used clay to gauge how much adhesive I would need around the perimeter of the window opening. I used 3M Window Weld to mount the panel.

The finished product looks pretty good. A bit of time and effort, but very little cost compared to the roof. These quarter window panels removed over 4 pounds. while this might not seem like much, consider the roof removes 10 pounds. The large rear window removed 11 pounds. So these little panels were really a pretty good bang for the buck, IMHO. And they definitely look custom!