Much the same as Mark, I used 4mm dia / 10mm long s/s c/s bolts to hold all the perspex panels in - all mounted into helicoils in the f/glass.
Just before installing the helicoils, I wetted the newly tapped threads in the glass with a tiny dab of urethane clear paint (POR-15 Clear) to seal the raw glass against moisture & to help glue the helicoils in place.
I have seen the results of moisture getting into raw f/glass where self-tapers had been used on my Vette - not pretty - even in areas where there were no consequential cracks from the water-weakened glass, each hole had to be ground out to about 2" & re-glassed.
I have had the panels off & on a number of times, & the only problem I have had is with one helicoil for the aly vent panel on the rear clip directly above the exhaust system.
(The fact that I ran the car for a couple of kms with 2 cyls missing & got the CAT on that side to glow red hot might just have had something to do with that) !!
With all the ins & outs, I have managed to split the rear window from the c/s bolt hole to the edge in one place. On reflection, if I was doing it all again, I would not do c/s holes in the perspex - I would use flat pan-head bolts to avoid the tendency of the c/s ones to split the perspex when tightened down.
The only downside of using helicoils that I can see is the fact that the bolts tend to loosen up after a while. I haven't resorted to thread-lock as I suspect that this might provide a stronger bond between the bolt & the helicoil than that between the helicoil & the f/glass. So all I do is check the bolts every month or so - finger tight, & usually less than a 1/4 turn is enough.
For the seal under the edges of the perspex panels, I used a very soft self-adhesive closed-cell foam (about 1/2" wide), stuck to the f/glass lip in the edge of the recess for the panels, & with holes punched for the bolts.
I have now done this twice ! The first time, I just laid down the foam & bolted the panels in place. Problem : when it came time to remove a panel or two, I found that in most places, the foam stuck to the perspex better than its adhesive stuck to the f/glass lip ! (particularly with the heat around the rear clip). The net result was that the foam was not re-usable & it was a bitch to get off.
The next installation involved meticulously cleaning the f/glass lip, laying down the self-adhesive foam, then running a good coat of silicon spray (applied with a clean cloth) over the top of the foam. I was a bit worried that the silicon might squeeze out when the panels were tightened down - but no, not a hint of it. (I guess that is because the closed-cell foam doesn't absorb anything). The net result this time was that I can now R&R the panels with no problems at all.
If you lay the foam tape down nice and accurately, then use the silicon, the finished effect is almost indistinguishable from a perspex panel that has been painted with satin black under the edges (& a whole lot less trouble).
Kind Regards,
Peter D.
