[NOT A TA]

Most 2nd gen F bodies need rear window channel repairs at some point because of a lousy drainage design. I never knew until taking the car apart this time but mine was repaired by the previous owner with fiberglass in the 70's. I didn't remove the rear window the first time I painted my car 25 years ago but with it out this time I noticed the fiberglass matting and started digging with wire wheels and grinder discs exposing some areas that had rusted through and thin metal with pitting in surrounding sections.Luckily the rusted parts had not extended beyond the part covered by the trim before the previous owner had glassed it over preserving it.

Welding in new metal would require welding over the headliner and risking warping the exterior sheet metal so I chose to add new metal by bonding it in with panel bond. I DO NOT recommend this type of repair if the rust extends to the exterior surface because there is a high probability of ghosting and other surface anomalies occurring after painting the car. This happens because of the different expansion/contraction rates of single thickness sheet metal vs. double thickness sheet metal, and the panel bond itself. If the rust extended to the exterior I would have made a new channel and butt welded it in place.

For this repair I wire wheeled the window channel to remove all rust and cut out the thin rusted sections of the channel with a cut off wheel. Removed paint on the backside with sandpaper rolls on a tapered mandrel attached to a long reach die grinder to get up in the little channel inside the quarter. Welded trim studs in sheet metal measured to line up in the centers of the holes I'd made, then cut and ground the patch panels to fit. Dimpled the panels where the trim rivets that will be used for trim clips are being retained after panel install (extras are used to hold patch panels while drying). Bend twist panels to fit tight to the back of the original window channel. Finger smear panel bond on backside of channel and locate panel into position. Pull the panel tight using the trim rivets to pull on. Used old bondo spreaders with a slot cut and additional spreaders used as a wedge to keep panels tight while drying. Used carbide grinding tip on die grinder to remove unneeded trim rivets. Ground off excess panel bond and then added a layer of panel bond over the repaired section including all pitted areas. Ground down panel bond with 36 grit wheel and hand sanded to make sure the panel bond was slightly lower than the metal. Finger smear bondo over the whole section. Sanded bondo smooth and epoxy primed, ready for high build primer and finish sanding. Backside will be brush painted with epoxy primer to cover any bare metal of the sanded metal and patches.