Vintage fiberglass repair and much conflicting information

I've doing research on fiberglass repairs, specifically stress cracks. Very interesting because I have the book "How to restore fiberglass bodywork" by Miles Wilkins. Considered the bible by early Lotus restores he is very specific when saying never grind/route out a stress crack and then fill it in. Yet I read a short story from a fiberglass expert (35 years) who says that's exactly what you do. Miles Wilkins approach appears to be much more robust in my opinion, but I'm no expert.

Another article right here on this site that deals with restoring the fiberglass body of the Berkeley says to remove all the gelcoat when its really bad and then re-gelcoat the entire car. Miles Wilkins says never do this. He says re-tissue the entire area as if it were a large stress crack and then use spray filler, followed by primer, etc. His reason is that gelcoat is only used in the mold process and is not to be done for repairs.

I'm on a budget and I'm prepping everything myself starting with the hardtop and fiberglass bumpers. Any expert opinions/help is a appreciated. So far with the hardtop I've used a razor blade to remove the top layer of paint (worked very well), and I'm now dry sanding down to the original paint and exposing some old repairs. Still have a couple more hours of sanding and then can take pictures if anyone is interested and can offer expert advise.

That book is apiece of crap. Thirty years old and full of "don't" and "better not." Times, tech, materials have changed for the better since it was written. So has the LOTUS for that matter . . .

ALWAYS grind a stress fracture (it's a fracture after all, not just a little crack in the surface) right down to the sub-strata and build up from there. Never spray filler onto anything, and hand-lay all of your repairs. Unless you're planning on maintaining the gel-coat color, forget about resurfacing with it it's brittle and subject to fading and cracking all over again. Use a suitable (flexible) paint and primer meant to be sprayed over aged fiberglass surfaces. Remember that the strength is in the cloth and resin, not just the resin. Filling a crack with resin alone might seem easy, but will just lead to more cracks. You HAVE to chop the cloth/mat and do it right, NOT do it easy.

Fiberglass repair is simple and successful if you do it right. It's much easier than most will let on and can be very effective, pretty much invisible/perfect. Looks around on the internet, check the videos on YouTube. Don't listen to anything handed out by and old timer. Dismiss anything from an experienced body man unless their under thirty five as they'll just be repeating outdated crap and procedures approved by an insurance carrier and leading to a speedy, cheap repair.

Be careful of what you read, and throw that book away.

In reply to TeamEvil:

I think you didn't read my post or I didn't explain it right. The piece of crap book tells you to do it exactly as you described. It's the other so called experts who say differently. Anyway the book stays, because after posting on several forums, including corvette forums I was told to do as you say, and that's the exact procedure in the book I have.

I'll do my best to be clearer next time, and I'm sure my work will turn just fine.

I was a bit lost in your first post but having done quite a bit of fiberglass work I have been doing it the way Mr Evil says and it seems to be the best way to go.

Sorry, misunderstood. By all means, follow the book's directions if they line up even somewhat with what I described.

I was confused and misread your post, at least you had it together enough to understand mine.

Didn't mean to be mean, but there is just SO much stupid info on a simple procedure and if it's done wrong, you end up with disappointment and wasted time/money. When done correctly, it can be SUCH fun and so satisfying.

Luck !

TC

Fiberglass cars are a bit rare, but fiberglass boats are not. There's a lot of good fiberglass repair information to be had from boat repair books, boat forums, and even boating stores.

Along the same line, the fiberglass repair kits sold in auto stores tend to be...bad. To put it mildly. Go to a boating store, and you find much more and of higher quality.

This thread interests me.

Even if I am an "old timer".

I've owned multiple fibreglass cars (TVR, Jensen CV-8 Jamaican MG). Your best bet is to go to your local Corvette body shop and ask them what sort of repairs you should be doing - telling them you want them to prep and paint it will no doubt get you some free advice.

From experience here, I would recommend googling West System products and go from there. I've been using their stuff for repairs, mold making, etc, and have been very pleased. It's epoxy based and not polyester based, so it is more expensive resin/hardener. Having said that it does an excellent job of keying into old/unknown polyesters.

As far as cracks go, what I would do is grind out the crack completely. At the ends of the crack, drill out the endpoints. Once complete, mix up a batch of West System Epoxy and add in one of their fillers (they have many and the website says what to use, where) and lay this slurry into the crack. Sand/smooth to just below the surface around the crack. Next, lay in a layer or two of chopped mat/epoxy on top of that, a layer of tissue/epoxy next, top with epoxy mixed with a fairing material (typically glass spheres), sand/smooth and done! You'll have a top notch crack repair that will blend in nicely with the surrounding area and will not re-crack. I've used this method for repairing cracks, filling in holes left behind from rear view mirrors on doors, adding on flares, etc.

Nice thing about the West System stuff is you dispense with metered pumps -- no guesstimating on the hardener and having it kick too early or not at all.

YMMV, not a paid spokesperson, just a happy customer, etc.........

90 percent of my fiberglassing experience is on Kayaks, but I agree with Orphan above. Spring for good quality epoxy like West Systems. Theirs also has a good viscosity. I used to use MAS and it was too runny for my taste. You can always thicken, but thinning usually sacrifices strength.

Also, Poyester Resins are Really bad for your body. A good epoxy not nearly as bad. Use excellent ventilation and charcoal mask filters anyway, but I shudder to think of that Polyester crap. If you use Cab-o-sil for filler, a similar caution applies. That ground up glass-fiber dust likes to stay in your lungs.

I've never used mattes. I always build up layers of fiberglass cloth with the biggest piece on the bottom and feather back. More time consuming but stronger, and usually lighter.

Good luck!

+1 on previous 2 posts. I teach fiberglass repair at a local jr college, and work in aerospace composites, and while west system is pricy, they have such great outlines and tutorials online that it is well worth it. Gel coats can be used on repairs, but you will need to ask your resin supplier for an additive called surfacing agent to get it to cure completely. Plus the old gel coat will have aged (color faded), so the flex paint is good advice. Safety first, beware the catalysts, and no hand washing with acetone. Ventilation always. Thin layering, build to proud, then sand back to contour/texture. Have fun, we all only got good by diving in and making mistakes.

Thanks all for the West System lead. I look forward to tackling the hardtop this Winter, and the rest of the body in a year or 2. The hardtop is no brainer, but I have 3 choices on the body. One is a 26R flared body (love the look), two is a replacing my ugly flares with stock fender flares but bringing them out slightly to fit Panasports and 185/60-13 tires, and three is to go 100% stock which means I can only run stock steel wheels with 145/80-13tires. A tuff decision because it will ultimately be more valuable in the end stock. Right now I plan grafting on the stock fender flares, but massaging them enough to run the Panasports and 185/60-13 tires. It's all a slippery slope however as the slightly flared fenders mean more mods including a custom roll bar, fine tuning the suspension, a 140-150 HP reliable twin cam (125 HP now), and finding a set of elusive close ratio gears for the trans. Current trans is a wide ratio (not original) but I do have semi-close gears I can install, but really want the close ratios. Updates in a few months.