So the rear wheel arches are a rust spot on these. The main reason i can see for this is the poor design of the plastic wheel arch liner. It tucks up behind the wheel arch return, rather than fitting to the edge of it (my old Fiat Sceicento runabout even had this sorted!). This means there is a ledge here for all the mud to collect into and it's difficult to wash out. The area is also prone to stone chips.

On mine at least it looks like they fitted a rubber to the rear part of the arch, but it still leaves a gap between the plastic liner and the arch for mud and water to get into.

As a solution i bought a roll of rubber edging with an extra rubber lip on it.



This is the profile i bought, you could probably use an old door seal and cut part of the seal part away.



Fitted to the rear part of the arch



Fitted to the front part you can see the extra lip doing it's job more clearly. (i need to clean off that over spray i know)

1.5 metres is more than enough for both rear arches. There the little bit in the middle of the arch at the top where you have to leave a gap, but this is still better than leaving the whole thing open to trap mud, salt and moisture.

I bought mine from a local trim supplies (East Kent Trim Supplies), but i expect there are others that will do it.

I think that is a great fix to a rust prone area, great job will be doing something along those lines to mine asap, mine is showing signs of minor rust in the same area so will sort that and then add a rubber strip.

Personally I think that will trap water, and salt in the winter, and make it worse..... Hope I'm wrong though... Pete
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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
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Salt and water will always get up there to an extent, but this should reduce the amount that gets to it. I'll also spray Dinitrol up behind it, the rubber should stop the dinitrol from being washed off. Ideally the plastic liner should have come right out flush with the wheel arch, not tucked up behind the lip - tucking it up behind it is just lazy design.

I used to hear the same about plastic wheel arch liners traping water and mud, but all cars have them now and you rarely see wheel wells rotted out.

The worst part is mud as it holds damp and salt for long periods. So where as water might sit behind the rubber seal, it'll dry out overnight, whereas without it the gap fills with mud and that stays damp for days, given our climate, where we might only go a couple of days without rain in winter so it stays damp for months.

The rear half of the arches had a bit of of plain rubber edging pushed over it, presumably from the factory that has barely any rust on it at all, whereas the front half, which was left bare was pretty bad.

But if it rusts again in a few years then i've not really lost anything.

I had my liner out for another reason, cleaned out behind it and it was rust free... the rust seems to stem from chipping of the paint on the outside of the arch lip, as you say, they used a trim on the rear part but not the front.... and a small redesign would have prevented that as well...

I've just cleaned mine up and given it a good dose of stone chip but mines not a shiney and will get some abuse off road...



While you are there you should take the sill covers off and have a check of the sills, Mr Tee had a shock when he checked his.....



This is his thread about it...

http://www.fullfatrr.com/forum/topic27383.html?

I also had some rust but luckily nothing like his...

http://www.fullfatrr.com/forum/topic24817.html?

Plenty of holes in the sill to shove some Dinitrol in...





Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated  Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Yeah i checked the passenger side when i replaced the rotten running board, I was expecting to see some rust but it's pretty clean behind there. I'll dose it up with 3125 anyway.

The original passenger side running board was completely rotten. Although the drivers side seems pretty sound, i'll replace that seeing as i have a new one.

Incidentally the cheap pattern/Britpart side steps are a good match, the front mudflaps they supply aren't the same, but once i chopped off a small bit of box section that sticks out from the front of the new steps they fit into the factory mudflaps perfectly.