JPB77

I'm looking to repair both wheel archs which have bubbling surface rust. Having done a bit of searching it appears there's are no kit available to
make it easy to replace part of the arch with a new piece of metal. Does anyone know of a kit or has anyone used a kit for another car?

WarrenW

I don't know of a kit but there's something I heard about that is supposed to change the molecular structure of rust back to metal. I don't know the name or if it works. Maybe someone here knows. There's also Navel Jelly I don't know if either one of them will prevent the rust from getting worse.

zeroptzero

Any good auto body shop could replace with new metal. Some small bubbles can be ground smooth without being rust-through, you don't really know until you take a grinder to them. On my integra I ground the bubbles down to shiny metal , then used rust converter on them, then primer paint and it was ready for top coat.

Slowcrash_101

It's really hard to repair fenders. I'm planning to replace mine.

JPB77

Yes have tried a few things - zinc amalgam spray seem to be working but had to put on alot then primer and a top coat.
So was left with a ridge of paint. When used 2500 grit and compound to flat the rust came back. So it was a case of
leaving it very thick or cutting it out and replacing with new metal. Alot of cars have kits but looks like there
isn't anything we can use for the S2000. Garage said it would be easier if we had a kit to start with.

Slowcrash_101

Like I said the front fenders are really hard to repair. You can pick up brand new unpainted fenders from the dealership for ~$350. But then you have to get them painted along with the front end of the car.

engifineer

I am guessing he is referring to the rear quarter panels, not the front fenders. The rear quarters are a lot more involved to remove and replace (they are connected and overlap a large portion of the rocker panels). Possible to remove rusted area and patch in sheetmetal and refinish if you really know what you are doing. Not aware of a kit. I assume a shop good with sheetmetal would cut out and patch (really good body folks I have talked to prefer this on most cars over buying patch panels .. but only if they are good with sheetmetal work) or buy an entire quarter panel. Like I said, you cant just unbolt that one and replace it like a front fender though so there is still a decent amount of work there.

Spoon Fed

You could always cut out the rust and run mild over fenders ...

B serious

You could buy a rear half cut from a wrecked S2000 and cut/weld panels you need.

Repairing rust from the outside is futile. It probably didn't rust from the outside. It probably rusted from inside the water channel.

Unfortunately, I've studied this process pretty thoroughly.

Most cars rust at the seams...from the inside. The seam sealer is like a sponge and it holds water against each panel.

You'd need to cut out the panel. Repair all the rust on the internal surfaces of the chassis.

Coat everything. Then re-weld. Hopefully, you're using spot welds as much as possible, to minimize coating loss.

Unfortunately, this will rust again. In the same environment, it will rust faster than the factory panel did. The welding necessitates bare metal. And the heat from welding removes the surrounding coating. This bare metal is on the inside, where paint won't reach. But you can always try to spray some in there. It will help to some extent.

When cars are manufactured, the chassis and metal body panels are individually welded up first. Then cleaned like crazy. Then phosphated. Then dipped in a bath of epoxy that gets into every internal crevice. Then the whole thing is baked at like 300F. Then its painted.

If you're going thru this, I'll tell you that epoxy paints like rust bullet and POR 15 are excellent to use in the right spots. Just prep the surface well.

Sorry bruv.

B serious

This way works well since theres no welding involved. You just gotta coat that mother up from the inside before attaching the over fenders. And be intelligent about how you're attaching everything.

Think like an OEM.