Rotted stringer/engine mount questions

I've drilled all the rotten wood out of the stringers in my '69 Barracuda and I'm ready to fill and drill the new wood/dowel/clear epoxy mixture. A friend suggested using 3/8" stainless threaded rod instead of lag bolts. He said bend about 2" of an 8" rod at ninety degrees and then embed it in the right place when you put the mixture in. Sounds like a great idea to me. Afterward you can remove the mounts by removing stainless nuts on the rods. Kind of like a carb mounts to the top of an engine. Any good reason not to do it this way? I can't think of any, but I'll defer to wiser heads…

But my real question is about re-doing the fiberglass. I wound up with three holes at the back and two at the front on each side about 1"to 1.25" in diameter in the fiberglass. When   I replace this fiberglass, do I just layer new fiberglass over the old with resin? If I do that in large sheets, I will be adding thickness above the old fiberglass and changing the orientation of the motor by the thickness of the fiberglass. Do I adjust the motor mounts to restore the alignment? Or do I cut the existing fiberglass back so I actually add no thickness in the area where the motor mounts will sit? That will mean removing a lot more fiberglass. And how do I join the old with the new? Does the new just butt up against the old? Or does the new need to overlap? How much? And that will change the location of the mounts and engine, won't it?

Also, how many layers of fiberglass do I need? Do I lay multiple layers all at once? Or several layers laid at different times? Or just a single layer with lots of clear resin. As in, is that how I control thickness, and how much is the right amount?

Thomas

Got it. Thank you. But…

How do I know how many layers to use? I didn't look that closely, but I'm not sure I can tell how many layers are in the original. Is that the standard?

Or do I go by the final thickness? In which case doesn't it matter how much I compress the layers as I lay them in?

(My only previous experience with fiberglass was a failed experiment on a rusty Vega with a product that was supposed to cure and harden with the sun. Never really hardened and didn't leave a very good taste in my mouth.)

Thomas

tleed:

Number of layers does not matter as it will vary dependent on the weight of mat or roving you purchase. Just lay-up to equal the original thickness. You need to also get a groove roller to compress the layers and force out all the entraped air bubbles.

You should not have the hardening issues with epoxy as it is almost impossible to make a mistake as it will most likely be 1:1 or 3:1 ratio epoxy.

Visit www.uscomposites.com for materials.

Maybe you can lay a sheet of plywood on the exisiting holes and dril holes in the plywood to make a templet.

Probably all of us share your spirit of adventure. Take some pics along the way showing steps if you can (before, during, and after), and let us know how it works out - I like the idea of having threaded studs to bolt to.

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