Old 12-21-2006, 03:17 AM
  #5  
kerno
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Default Re: T-Top floor mount repair advice requested

A couple things to consider......When you put a self taping screw into fiberglass, you start by drilling a hole the size of the minor diameter of the screw. You then force the screw threads down into the fiberglass, which breaks a lot of the fibers by forcing them out of the way. Some fibers remain intact and serve to hold the screw in. Wood is not much different, except the fibers are more flexible and most of them push out of the road instead of breaking. But, If you put enough load on it, the fibers do eventually break and the screw pulls out. If you make the holes bigger and fill them with a resin and fiber mix and install the screws while it is wet, that matrix is made up of unbroken fibers and should hold better. I don't know if you filled and re-drilled the holes or put the screws into wet material. The key is to put longer screws than you are going to use into the wet material, so threads are molded into the material. If the hole is big enough, you'll have to find a way to hold the screws in place, since you cannot tighten them into a hole full of liquid. Once the resin is almost hard, remove the long screws and install the shorter ones. Don't tighten them completely until the resin is hard. You use longer screws so you have more threads than you need. That way, the screw does not bottom out in the hole. If the screw is longer than the hole is deep, it will hit the bottom of the hole and cannot go any deeper, so it strips its own threads.
Another thing you can do is to make the mounting feet bigger with more holes so you spread the load out over a larger area. If I am driving screws into glass that will need to withstand a load, I'll put them in, then take 'em right back out and wet the hole with epoxy, like West 105. I then put the screws back in a tighten them up on the theory that the epoxy will restore the strength of the broken fibers in the hole.
Oh, after you wet the hole, put 5200 on the bottom of the t-top feet and screw it down. The 5200 really adds a lot of bonding strength. I recently removed a leaning post that had 5200 under the feet and two of the feet pulled off gelcoat and glass. That 5200 is tough stuff..