E30 Zone

Pic is of the inside of the left rear arch, looking forward. I'm not sure whether to fabricate a piece, buy an 'outer inner arch' (?) panel, or clean it, seal it with rustproofer and fibreglass it
I'm looking to keep the car for a few years and apart from a small part of the rear valance, this is the only bit that needs repair.

I would buy an outer panel and fabricate an inner one. Wouldn't go near Fiberglass if you plan to keep it for a while.

just done this myself on all 4 corners, fabricated all of it.

not a quick or easy job, and doesnt look very pretty but its a bit of a slag alround so wasnt bothered.

if you want it looking minty buy the panels.

Chop it back to clean metal and blend it in with fiber glass.Id like to know why people think its such a bad idea. IO would have fiber glassed mine instead of welding them if i had the idea at the time. My holes werent quite as big as that though

The problem with fibreglassing an area that big it that the fibreglass tends to collapse into the hole unless you use some sort of reinforcement. AKA CHICKEN WIRE!

I replaced the outer wheelwell £70 ish from bmw you will have to cut the lip off the rear quarter/wing to fit it but that looks rusty anyway, the repair panel for the arch lip is about £30 for a late model and £15 for an early model hadrian panels are the only ones that sell the late style don't believe anybody who tells you different.

fiber glass it from the inside first. or use some sort of platic to mould it on. not chicken wire. dont want more rust now do we.