E21 316: Big job broke out - Time to do the N/S/R Wheel-Arch...

This is the first wheel-arch I pulled to fit the 16s and it's the only one now still needing a tidy-up, to say the least. I cut too much of the lip off trying to wedge some balloon-like 45% profile tyres and left it in a right mess. The newer 40% profile tyres fit perfectly and only needed minor cutting to the other arches, leaving this one miles from the rim and totally out of shape. The bit I cut off is the line used to form the arch on the rest, so this one was missing an edge to build the filler up to and totally sculpting the new arch-line by hand with hanging bits of mesh and filler was never going to happen. The easiest method would be a plastic arch cover, hiding the cut area completely and easily smoothed into the wing, but all four would have to match and the Group 2 ones are just too big to consider. It seems my only options are -

A. Buy a new pressed-steel wheel-arch from eBay for £25. Trim it, grind the wing away in the right shape, weld it in place, grind the welds down flat and smooth it all off. Only then could I pull the new arch-lip out and fill it to match the other three. [http://www.ebay.co.uk/itm/BMW-E21-316-323i-1977-1983-REAR-PASSENGER-SIDE-WHEEL-ARCH-NEW-CLEARANCE-PRICE-/190865619545?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2c707a3a59]

B. Spot-weld the piece I cut off back into place and secure it with fibre-glass filler. Fill the lip to match the others and build up and re-shape the arch up to where it meets the wing almost.

No doubt B involves a lot less time and effort, but it's still going to be a lot of rubbing down.

The chewed up scrap of metal, good job I saved it. It didn't just slot back into position, there was quite a bit of grinding and filing.

I had wanted to tack-weld the metal on and fill the gaps with fibre-glass, but I couldn't get hold of one so masking-tape did the job. I caked on plenty of P40 fibre-glass filler in between the tape, waited for it to go off, removed the tape and filled in the gaps.

Well sealed behind with more P40. You can see the sliver of metal in position as the light shines through, showing just how much arch got cut off originally.

It was then ground down with a rotary-file on the drill, mainly inside so nothing rubs on the tyre, but a bit to give the lip some shape. All that's left now is the arduous task of filling all that arch.