Insert Cracks

[VX MileHigh]

I have searched and have not found any information about what is actually causing the cracks in the hood insert. I used to do fiberglass repair and I was wondering which way to tackle the cracks. I have thought of two approaches to fix the problem. One approach would be to grind out a "V" groove in the cracks from the top and then refill that groove with resin and chopped up fiberglass. The other approach would be to take resin and glass fiber to reinforce the bottom of the insert and then fill the crack with glazing putty. Has anyone done either of these fixes and did they last?

[rowhard]

One approach would be to grind out a "V" groove in the cracks from the top and then refill that groove with resin and chopped up fiberglass.

Either way would work, but in my humble opinion, the first would be the best but the most work. You would then need to do the bodywork with primer and fillers to get it smooth enough for paint. Of course if your going to cover it in lineX or something, then maybe not.

Think I might go as far as molding in a back-up thin strip of aluminum along the seam on the underside for some strength.

[tom4bren]

I was going to also recommend a combination of both approaches. My cracked insert will need to have some surface work done (raised crack edges) & refilled. But that's not going to add strength to keep it from cracking again. Glassing from the back will be required for that (as long as you don't make it too thick to seat properly on the hood).

Since I'm a total goober when it comes to bodywork, I'll get it LineX'd after.

[VX MileHigh]

Either way would work, but in my humble opinion, the first would be the best but the most work. You would then need to do the bodywork with primer and fillers to get it smooth enough for paint. Of course if your going to cover it in lineX or something, then maybe not.

Think I might go as far as molding in a back-up thin strip of aluminum along the seam on the underside for some strength.

Do you think it is the flexing of the insert that is causing the cracks? Or is there too much pressure on that curve in the insert? Either of those causes is going mean that your idea of an aluminum strip embedded in fiberglass on the bottom of the insert would help to prevent the cracks from returning. The expanding of the crack and refilling it with resin and glass fibers would also help to hold everything together. As far as LineX on the insert, I have not decided whether I want to that or not.

[tom4bren]

There are pix of my LineX'd hood insert in my gallery if you want to see how it looks. My only complaint is that VA clay tends to penetrate the texture & is a PITA to get out.

The crack is caused by a mold seam on the back side of the hood insert (they all crack at the same place). Filling in that mold seam would help since you're gonna be all covered in resin anyway

FWIW, I was told that the hood insert is made of a special material that fiberglass doesn't stick to very well. I've no idea if it's true or not. If so, prep will be of extreme importance to ensure that the resin has something to stick to.

[VX MileHigh]

When I looked at the back of my insert, it sure looked like blown fiberglass. If I rough that up, I would think that it would stick fairly well. Does anyone have any additional information about the materials in the hood insert? The upper surface may be a different story but since I will be taking that seam down an 1/8 of an inch or so, I hope that it will stick. I have seen pictures of several inserts that have been LineX'ed, I am just not sure that is the look that I want. My body work takes forever to get it the way that I want it. So far, I have redone the insert three times because it just isn't right. This time I am hope that I can get it done right. Now, painting is where my skills are lacking.

[tom4bren]

The last post in this thread is where I mentioned the material:

http://www.vehicross.info/forums/showthread.php?t=16054

I never bothered to check into it further (& never fixed my old insert either). I procrastinate real bad.

[VX MileHigh]

Your reply caused me to do some additional research. If SMF is what the hood insert is made of then fiberglass resin should work. Researching SMF I found that it is Syntethetic Mineral Fibers, i.e. fiberglass, rockwool and other materials. I tried to find if there was a special resin but I can't seem to find any. I worked with different types of fiberglass in the past and used the same resins. There are some resins that are for harder final products, whitewater resin comes to mind. I am not sure what the jet ski person was talking about. There is a different method that Chevy uses on Corvette bodies but they can still be repaired with regular fiberglass resin and any number of SMF materials. I am still wondering it there is something that is done differently for the top surface. I don't see any reason that an epoxy of any type could be used to fix the crack from the top and a normal resin could be used to strengthen the back. The only thing is that both resin and "epoxy" are both two part epoxies. I am not trying to argue and I would really like to know if I am not taking something into account.

[tom4bren]

I'm guessing that the jetski guy just didn't want to work on it.

Like I said, I'm willing to assume that with adequate prep, glassing it will work out fine.