Working one side of the car at a time, I applied some gaffer tape to the car’s wing with the top aligned with the top of the spoiler. I then applied a strip of black insulation tape just touching the top of the gaffer tape. The tape is to release the filler I am going to apply from the paintwork and to provide a guide.
I then applied some Plasticene in a line about 10 mm below the gaffer / insulation tape boundary and a little wider than I estimated the gap between the body and the spoiler to be..
I then installed the spoiler which squeezed the Plasticene slightly to prove a seal for the filler that I was about to apply.
I then applied some filler and smoothed it off flush to the top of the spoiler.
Above shows the filler applied to the left and right sides of the spoiler. Left is the spoiler after a can of Halford’s best matt black paint.
Next I construct an under tray and fit this and the spoiler to the car…