eatonm90

Assuming you have a roadster it's a counter weight, think there is also a weight in the boot as well.

I had the same problem, I thought it was where the outer side trim seal meets the windsreen because it was slightly off the screen in the lower 6". Tried pouring water down the screen on this side and didn't leak bu when I poured water on the roof section of the trim it leaked. Found it was coming in where the trim comes off the roof and down the screen right by the top screen trim there is a gap. Basically the water comes in rolls down behind the trim and gathers in the rubber at the bottom, this then leaks down the door rubber and into the car. I used some dum dum putty in the gap and it stopped most of it. But my plastic trim lifts away from the roof very slightly depending on temperature, going to remove the trim when I have time to find a complete fix.

While doing my normal summer arch clean up I found my first bit of actual perforation rust behind the plastic trim on the passenger side rear.

Didn't expect to be welding it already, but I suppose it is 11 years old now.

Had to cut it out and make up a patch, seems like water gets into the box section behind and runs inbetween the panels.

section cut out and repair section ready

All welded and done, had to cut the stud out the old section and weld it onto the new panel from behind before it was welded in. Also drilled a hole into the box section to spray in water dispersant then wax then blanking grommet to seal, so I can now keep an eye on it.

Also took the front of the arch back to bare metal round the water drain/back of sill. This had corroded to almost the point of me thinking of cutting it out. Decided to use Fe123 rust coating followed by primer and seam sealer. Will stonechip and wax when dry.

Well worth checking these areas out.