Rust Repair for Strength

Update by Per Schroeder to the Saab 99 project car
Apr 24, 2007

We’ve been continuing our rust repair work on the Saab 99. If nothing else, it’s a fun diversion while we wait for the clutch to get the car registered and back on the road.

The trailing edge of the right rear wheel well has several small perforations around the lip. While we could just mud this up with some polyester filler, the repair wouldn’t last long with gravel being thrown from the tires on stage.

We used a wire wheel attachment on an angle grinder to remove paint and previous filler. The paint and most of the rust is gone, but it’s not good enough to weld, yet.

A grinding disk does a better job of getting the metal ready for a weld, then a small piece of 20-gauge steel is tack welded to the area over the hole. The piece is then completely welded down and the welds are ground nearly flush.

The repair continues around the mudflap mounting points. The bottom of the trunk also needs some work.

Before the trunk is repaired, the factory sound deadening and undercoating need to be removed. We used a propane torch to soften up the asphalt based goop. A scraper was then used to scrape everything clean.

Skipping ahead, after the trunk welding, the metal was treated with POR-15s Metal Ready and a coat of POR-15 paint. Next, we’ll be using seam sealer to smooth over the joints and fill any pinholes.

Metal Ready and POR-15 were also used around the fender lips. The metal repair will provide a strong foundation for polyester filler on the outside of the fender and a strong mounting point for rally-strong polyethylene fender liners on the inside.

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