Fiberglass repair???

Figured you Lotus guys might have some insight into redoing old fiberglass car body's.
I'm working on 2 hardtops and a Berkeley if I can get to it this winter.
In my youth I made fiberglass motorcycle tanks and seats to fit flat track frames made by a friend of mine so I have some experience with new glass but not old. Wondering if there is any info or experienced folks on this forum that can give me info on old glass. The info on the internet that I have found covers boats mainly.
Specifically wondering if all cracks and crazes in the gel coat need to be v'ed out and filled. Boat info mkes it sound like they do and if so I have a big job ahead of me.

Kurt.

There are many ways of doing this. I would first have the hardtops plastic media blasted. This wil;l show every defect. If you are going to dig out the cracks, then you will need to cut small pieces of Fibreglass matt out to fill the hole. I use 1.5 matt along with tooling resin. You may also sand down the whole surface down to the matt and re-apply resin/gel coat. You will need a special gun for this operation. Be sure to seal the new finish with a quality primer...nothing that contains MEK, etc in its make-up.
Hope this gives you a starting point.

Thanks much D.
I sold my pressure pot gel coat gun many years ago but may just sand away the worst of the crazing. I can get some 1.5 matt but gel coat and tooling resin are probably going to be a problem. Around here there are virtually no small fiberglass manufacturers left and the last time I tried to get something from a big company they would'nt even let me in the gate!
Your suggestions made me realize that I really need some tooling resin at the least and I will contact some supppliers to see if they can give me the name of a company that may be cooperative. I will probably be brushing on several coats and be skinning the whole piece with filler.
Thanks again,
Kurt.

Not a problem. If you have any problems sorting out your needed supplies, drop me a note and I will help you from this end. Sounds like you know what is required to make this job happen! Be careful of using body filler, as it tends to shrink over time and the imperfections will soon be seen.

Thanks again. I'll keep your offer in mind but wish you were a little closer. I imagine shipping a gallon of resin would be a little expensive if you have it!

Kurt.

I am in California at the monent. The resin is in the circa $40.00 per gallon range. Could probably place it in one of those flat rate boxes?

I have always had good results with products from Tap Plastics, they have an online catalogue and ship promptly. Home Depot boat resin is cheaper, but I have learned that the Tap stuff works better.

IMHO, the only way to get out gel cracks and keep them out, is to grind and fill. You could try a two part poly paint with a whole bunch of flex agent, paint over the cracks and hope for the best, if you are feeling lucky. If you do, let me know how it works out, the body shell of my eleven replica is spiderwebbed with cracks and I am looking for an easier way too........

Whoops---Sorry, I have'nt been back here for a while. Grantura I'll pm you if your still available.
Westfield, I plan on making up a little tool that will scrape out a v by pulling it along the crack. Thinking a heavy wire (#9) sharpened to a v and maybe case hardened. Maybe a little heavier if necessary.
Plan on using that on the long stray cracks and grinding away the spots where it looks like someone dropped something heavy on it.

Kurt.

If it's an impact spawl, you will need to go at least an inch beyond the visible cracks. The 'spider-webbing' or craze cracking will be less problematic, usually just surface issues.

Hello,

I haven't heard anyone mention an alternate method to grinding out the cracks, specifically the use of 'tissue' fiberglass cloth. Ray at RDent.com sells this very thin matte which seems to work quite well for the normal stress crack issue. I've done a few spots some time ago, which haven't resurfaced any cracks and it doesn't print through the paint like courser matte will. IIRC you sand down to the matte, then build up using this thin cloth. Sand flush and primer/paint. It has a stronger surface strength to prevent cracking like the gel coat will. I'm no expert, but it sounds great for areas where there is alot of crazing like around the hood/trunk/door corners and door handles.

Also, I assume when you refer to older fiberglass, its polyester resin, not epoxy resin we are talking about?

Jerry Rude
73 Europa

I assume that Lotus used the very cheapest resins in their bodies, I know Westfield do. Remember that when Chunky was saving pounds on his cars, it was pounds sterling that he was concerned about, not pounds avoirdupois!!!

Jerry, I'm assuming you are talking a very fine light weave cloth not mat. If you are, it sounds like the chips!!
Ideal would be super fine cloth layer after bad gel is ground away.
Kurt.


Kurt, you are exactly right, and sorry for using 'matte' and not 'cloth', as it is not a woven pattern material. And you do just grind the gel away, down to the existing matte or cloth and build up with the thin cloth to the surrounding surface level. It gives a surface that has some strength compared to pure resin on the surface like with gel coat. Only works on repairs I expect though? Anyways, it works great and if you don't want the crazing to return, this gives better assurance than just restoring the gel.

Jerry

Jerry can't find RDent and am going ahead with just a coat of resin over ground down crazing and opened cracks. No patience!

Kurt.

I knew a fellow who bought an old Corvette, 1954 and the body was so severely spider webbed that it was almost impossible to repair it where the spider webbing didn't come back. He was fortunate enough to find a supplier that made replica bodies out of modern fiberglass. That was the only way he solved the problem.
I would say that a good source for information on fiberglass techniques and suppliers is a boat manufacture. As you know, almost all boats today are fiberglass. JMHO. PJ

Roger said:

R.D.Enterprises

Click to expand...

Thanks much Roger. Helps to know your way around!! I might give them a try.

Kurt.

I have an old boat as well as a fiberglass bodied car and can tell you that in my case the gel coat issues are very different between the two. The boat, a 1983 Campbell , has gel coat cracks and crazing only due to impact damage. The fiberglass structure is so thick and stable that the gel coat never flexes under any condition and keeps the gel from cracking. The car body is more like the sort of fiberglass used on racing motorcycle fairings. It is very thin and has no bracing or structure, much like an eggshell. It is very light and rigid when it is attached to the car, but when it is open it is extremely flexible. This means that it develops stress cracks in the areas where it typically flexes as well as cracking at the edges where it contacts the chassis structure. On the boat the fiberglass is a minimum of 1/4" in the thinnest location while the car body is no thicker than 3/16" anywhere, plus the boat has plywood and solid spruce gussets, stringers and bulkheads. Of course, the boat has 550hp and struggles to top 70 and the car easily reaches 100 on 97hp. Horses for courses.....