Window and light cover attachment

[Steve C]

Thanks all! If I upgrade from the screws only I think Brian and Marks helicoil solution will be best for me as the car is painted and I don't want to mod the fiberglass or worry about the rubber well nuts bottoming out too early....I have used helicoils B4 in metal but, good to know will work in Fglass ( have you guys had long term experience w/ this use??)....So if I use the tool...add a little quick set epoxy to the helicoil B4 insert should be OK; ...no Fglass cracks????Prob a good idea to oversize the holes in the plexi to let it float a bit (better for temp cycles to prevent cracking of the plexi)?????If I start w/ holes already drilled in the plexi and Fglass I assume I can just open them up to the proper dia and all should align???What w/b the best machine screw head to use ( I think I perfer ss vs a plastic screw although the plastic prob is less likely to crack the plexi????). Thanks for any further input.....Steve

 

[Peter Delaney]

I went the same way as Mark & Brian - helicoils (4mm dia & 4mm deep). I used a smear of POR-15 clear 1-part epoxy in the threaded holes before running in the helicoils & it seems to have worked fine so far after quite a few R&R's.

As a seal under the edges of the rear window & light covers, I used a very soft 1/2" wide closed-cell rubber strip (available in rolls with a peel-off backing) & just punched holes for the bolts with a leather punch.

I made the mistake of using c/s bolts - whilst I reckon that they look the nicest, there is definitely a risk of splitting the perspex due to the "wedge effect" - pan-heads thru straight holes would have been a safer bet.

The only problems that I have encountered are :

- Some of the bolts do work loose after a while - I run over them all about once a month (I am a bit wary of using thread-lock in case I end up removing the bolt & helicoil together).

- I had a couple come out around the rear vent over the exhaust with the extreme heat - solved that by using nyloc nuts, washers & bolts.

If I was doing the whole thing again, I would go for c/s nutserts or well-nuts where there was sufficient depth, & helicoils for the shallow spots.

Kind Regards,

Peter D.

 

[Mark Clapp]

I've had mine in for over 4 years now with no cracks in the body or paint. I did not use any adhesive to set the coils and none have moved as they are essentially a spring that is stretched a little as they thread in. I use #6 counter-sunk phillips head ss screws and counter sunk the plastic for a flush fit of the screw heads. The thing is to just snug to hold the pieces in place. If you over tighten, the plastic will dimple around the screws over time, which looks like crap to me. My pieces have never star-cracked around the holes because again they are not too tight. To align the pieces, first tape down the piece then drill both the piece and the body. Then install a coil in the body and screw down the piece as a first anchor spot. Move across the piece and do it again and again. It will be tedious but if you try to just eye-spy the spots, you will be off due to drill "walk".

 

[Steve C]

Mark...Do you find the screws loosen over time? If so have you found a way to minimize or prevent it from happening? Do you recall the size helicoils you used? Tx Steve

 

[Mark Clapp]

Steve a very few of the screws have loosened a bit since I'm very careful to just lightly snug them down. I just check them periodically as Peter said although none have ever fallen out. I used 6-32 internal thread in the 0.207 inch length. I use the regular coils with the tang. Go to www.mcmastercarr.com and put heli coils in the search and they come right up. The insertion tool grabs the tang which is used to run the coils in and then you break off the tang since they are scored to detach. I flattened the point off of a nail that was small enough to slide into the coils. After installing the coil, you then push and sort of bounce on the tang and it breaks right off. I threaded the coils in to just under the surface of the body so once the plastic piece is installed you see nothing.