I've got an update, I removed the three bars (needed to remove the roof rack to get access), and removed the headliner to check out underneath.
Turns out these things are just directly screwed into the roof, with no nuts or extra attachments. It looks like the factory put some sealant around the screw to prevent moisture from getting in, but those seals were all damaged, so all six of the holes had some amount of rust --- minimal on four of them, but pretty bad on two (see attached picture).
I sanded down the paint and some of the rust. I was about to fix it with some bondo, but the metal was pretty damaged by the rust (there were penny sized holes), so I decided to pay the price and have it professionally repaired (welded, refinished and painted).
If the holes were not rusted, it would have been possible to re-install the bars, using some sort of aftermarket sealing agent, but I decided to have the body shop fill in all the holes and remove the bars altogether.
My suggestion: It's a pretty big job to do by oneself, unless you have experience with body work and rust repairs. If you're looking to keep the car for a long time it can be worth it, but if you don't actually have a hole in the roof yet it's probably better to leave it be.
As a reference, the body shop gave me a quote for $1500 to remove all the rust, weld the holes, sand the surface and repaint the entire roof (roof had bad sun damage anyway, so it's good to have it painted again). I live in the Bay Area in California: I think it's about the market price around here for this sort of repair, body work is expensive.
Turns out these things are just directly screwed into the roof, with no nuts or extra attachments. It looks like the factory put some sealant around the screw to prevent moisture from getting in, but those seals were all damaged, so all six of the holes had some amount of rust --- minimal on four of them, but pretty bad on two (see attached picture).
I sanded down the paint and some of the rust. I was about to fix it with some bondo, but the metal was pretty damaged by the rust (there were penny sized holes), so I decided to pay the price and have it professionally repaired (welded, refinished and painted).
If the holes were not rusted, it would have been possible to re-install the bars, using some sort of aftermarket sealing agent, but I decided to have the body shop fill in all the holes and remove the bars altogether.
My suggestion: It's a pretty big job to do by oneself, unless you have experience with body work and rust repairs. If you're looking to keep the car for a long time it can be worth it, but if you don't actually have a hole in the roof yet it's probably better to leave it be.
As a reference, the body shop gave me a quote for $1500 to remove all the rust, weld the holes, sand the surface and repaint the entire roof (roof had bad sun damage anyway, so it's good to have it painted again). I live in the Bay Area in California: I think it's about the market price around here for this sort of repair, body work is expensive.
