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Random Quote: I do what the voices in my tackle box tell me
I am installing a set of Lenco trim tabs and am having a hell of a time screwing the self tappers into the fiberglass. Any recommendations. At the current rate it will take me 2 weeks to screw in all 16 screws. I am tempted to drill the holes slightly larger to make the job easier but I am afraid that the screws won't seal the holes. Anybody have any tips?
The Lenco instructions indicate the exact drill bit size to use if you look. Ater drilling use 3M 4200 or 5200 under the waterline sealer, and you are done. It is better iff you do not pierce the inner side of the transom, so that bilge water will not soak the hole from the other side.
Use a small conical stone to widen the gel coat a bit at each drill hole to avoid craking same when the screws are inserted with a driver bit on the same drill. 1/2-1 hour job, at most..
All screws need 4200 to seal, so save your transom before its too late.
If you have vernier calipers, you can measure the root diameter of the screw threads. Keeping in mind that fiberglass/gelcoat is relatively brittle, and prone to chipping/flaking, I would drill a pilot hole slightly larger than this root dia. If you can't measure the root dia. then hold the screw up to a light source and then hold a drill bit up aginst the screw to find a drill size slightly larger the root dia. Drill the hole. Then use a countersink, or a drill slightly larger than the O.D. of the screw thread and countersink or drill to a depth that equals the thickness of the gelcoat. This will prevent chipping of the gelcoat when you install the screw. Try the first screw for fit. It should be snug, but not tight enough to threaten chipping the fiberglass. If you sense it too tight, back off and go to a slightly large pilot drill. Try again. If the screw works well, you have the right combination for the rest of the holes. If you want to use a lubricant on the screws, try smearing liquid soap, or bar soap onto the threads. if you want to seal the holes, try OMC 4200 on the threads. This is not as permanent as OMC 5200.
I just installed Lenco's last week. If you don't use the EXACT drill bit size, you'll have difficulties. Also, I used an power screw driver which helped. Important: find a screw driver that is perfectly sized. Too small, and you'll strip the heads. You will likely drill through the transom. Don't worry. Place a small amount of 5200 on the screws and it'll seal right up.
Follow the instructions exactly, and you won't have a problem.
Next, put masking tape other the area you are going to drill. This helps reduce gel coat chipping while drilling (it also makes for a nice way to mark your holes and measurements).
Next, if you got a dremel tool with a metal cutting wafer disc, make a little v-shaped groove on both sides of the fip of the screw, 180 degrees apart from each other. This makes the screws self tapping and really makes a noticeable difference in how easily and cleanily the screws go in. Once I tried this technique for the first time, I have used it everytime I install screws in fiberglass. I make the V by applying the cutting disc straight down onto the screw (disc is parrallel to root of the screw), cutting the screw threads from point of screw tip, to where the screw has reached it's widest diameter. Then make another cut at an angle to meet the first cut. I hold the screws in a vise (or large vise grips) while doing this and always wear goggles. I heard you can achieve a similar effect by flattening opposite sides of the screw tip with a file.
__________________ Grady White SeaFarer 226 w/Yamaha F225 - SOLD
Thanks for the replies. I am following the directions and I used the exact drill bit size listed. The screw goes in about half way with my drill and then stops. I screwed it in the rest of the way by hand but it took me about 20 minutes. I am not that strong a guy, but that is ridiculous. There has to be a better way. I might try lubing up the screws or flatening the tips, anything to make it easier.
If you have to torque the screw that hard to install it, back it out and drill a slightly larger pilot hole!!! Otherwise you'll risk breaking the screw and leaving part of it imbedded in the fiberglass (not good), or stripping the threads in the fiberglass or screw. You don't want any of these results.Good ideas by Brad1. You can also grind a "self-tapping" point on a bench grinder.
I'm an idiot. I didn't realize the drill had a torque adjuster on it. Screws went right in on the higher setting. Thanks for all the help anyway. Sometimes its the most obvious thing that you overlook.
I'm an idiot. I didn't realize the drill had a torque adjuster on it. Screws went right in on the higher setting. Thanks for all the help anyway. Sometimes its the most obvious thing that you overlook.
Good thing the drill wasn't in reverse!
Seriously, I like to run the threads, remove the screw, fill the hole and coat the screw with sealant, and then reinsert the screw. An easy way to do this is to use a hex head screw of the same size and pitch and a hex driver bit in the drill. It won't tend to "cam out" as phillips screws often do. After chasing the threads with the hex screw I substitute the original screws for the final installation.
Screwing into fiberglass 
