With the Z3 doors you will quite easily see that a small section of the front wing mounting bracket needs to be removed. About 3" at the door end. What is not so easily seen is that the leading edge of the door at the top will hit the bonnet hinge. With the bonnet open there looks like plenty of room but when the bonnet is closed the hinge moves backwards so that when the door is opened it hits the bonnet hinge but only when the bonnet is closed. I couldn't work out why the leading edge of my door kept on chipping.
I fitted a hinge packer behind the check strap, this limits the door opening slightly stopping it from catching. You can of course make your own packers but I have seen some where the door opening is so limited that you have to squeeze in.
I have had some laser cut and powder coated for my new build, easy to fit, remove the pin that holds the check strap onto the car and then remove the 2 bolts holding the check strap on. Slide the packer in and bolt back up. A thin x-head screwdriver helps to align the holes. Simple and it works.
I have had a few of the packers made, if anyone wants a pair they are £14 inc UK P+P
