Hey guys, my daughter and I are almost at the point where we're ready to re-install the decklid on her Fiero. One of the problems is that it appears as though the frame of the decklid broke on the underside. It doesn't appear as though it ever managed to damage the top of the decklid, but the frame structure is cracked (no idea how that happened, I bought it like that).
There are metal plates that have been screwed on to the fiberglass frame to shore it up, and it looks like maybe they used some JB weld in a couple of places.
I'd like to completely remove these weird brackets and properly fix the fiberglass structure underneath. I helped my uncle restore his 69 Corvette back in... I dunno... 1998 / 1999... I kind of remember how to do it, but nothing I can't figure out by looking at YouTube videos. I seem to recall that I'm supposed to drill out cracks, sand everything down to bare fiberglass, lay resin and the hardener, sand, and use filler.
What I wanted to know is... is there anything that I'm supposed to do differently with our Fiero? Is the decklid made of straight fiberglass, or is it SMC / Sheet Molded Compound? And... with that being the case, does it mean that I need to do anything differently?
Hi Todd . the Fiero panels are not fiberglass. they are made with ABS plastic and require their own special repair techniques. I would talk to a certified GM bodyshop. My 88 Corvette was made of the same material. sleek
Hi Todd . the Fiero panels are not fiberglass. they are made with ABS plastic and require their own special repair techniques. I would talk to a certified GM bodyshop. My 88 Corvette was made of the same material. sleek
Hi Sleek, from what I can tell though, not all the panels are the same. My 84 Corvette, which is also a C4 like yours... some of the panels are definitely fiberglass, while others are SMC. The hood, decklid, and quarter panel are made from a different material than the fenders, doors, and bumpers. Are you saying that they're all made of the same thing?
Looks like it's SMC... and not exactly fiberglass (but pretty close).
I found this in another thread too:
"You need to use SMC filler/bonding agent ("Vette Panel Adhesive") on all the SMC panels. Mix some fiberglass mat chopped with scissors on anything structional (filling holes, backing up cracks, etc.). On the other panels, I think the SEM product I mentioned in another of your threads will work on all of them. Check the label/instructions. As for prep, PPG epoxy primer will work better than anything for adhesion on all of the panels, with the *possible* exception of the TPO; on any hard plastics (such as the interior plastic) you should use a plastic primer - I'll get you a part number for that when I get time. ~ Paul"
I guess what I'll do is try to sand it down by hand first, and then drill some holes where the cracks are. I may even try to cut a hole so I can stuff fiberglass cloth inside there and inject the mold in it, and then try to repair it... I'll have to see how bad the damage is when I take those metal plates off...
But I THINK I'll have everything I need.... ultimately I'll just need to remove some material and replace with the SMC filler and chopped up fiberglass mat, and then sand smooth, and then paint.
The hood, roof, decklid, and rear panel are made of SMC - Sheet Molded Compound, similar to fiberglass, but not fiberglass. You need to use a specific resin that is compatible with SMC.
I learned something new today. I knew it wasn't fiberglass as such. on my corvette I had a panel off of it and it had the part number and ABS imprinted on it. It looked like the same gray glossy material of the fiero hood and deck lid but I certainly was wrong. LOL sleek
I learned something new today. I knew it wasn't fiberglass as such. on my corvette I had a panel off of it and it had the part number and ABS imprinted on it. It looked like the same gray glossy material of the fiero hood and deck lid but I certainly was wrong. LOL sleek
I'm going to have to learn this too. I picked up a C4 Vette a couple of weeks ago. The previous owner pulled the battery out by bending backwards the little fender panel that's in front of the door. Snapped it right across the body-line. Completely ridiculous.
Figured I'd post a couple of pictures... my daughter did about 2/3rds of this, and I just went over it to make sure coverage was good.
She used a sander to sand down the paint, expose the "glass" and drilled holes along the cracks. We then used the two-part SMC "Epoxy" stuff that was mentioned in that other post (which I quoted above), and built up a base of it (filling the holes and cracks) with a little bit of chopped glass mixed in.
She then laid multiple strips of cut fiberglass "chopped glass" sheet pieces on the frame piece. She then went back over it again with a scraper, applied more sheets, more resin, and then more sheets. It's a little messy looking, but we'll sand all of that down later. I also ordered some plastic body filler (not "bondo"), which we'll smooth over after we've sanded it down so it looks totally smooth... and then we'll paint it with the stuff mentioned in this thread: https://www.fiero.nl/forum/Forum2/HTML/148146.html
Let me know what you guys think... I find it weird because I was expecting it to be just like fiberglass and using that resin stuff that you brush on with a paint brush, but this stuff was more like epoxy. It's taking forever to dry, but it says it takes 3 hours to set.
I thought one would drill holes at the ends of the crack, not along the crack.
I instructed her to do both. The end of the crack I think will help stop further cracking, but my thought is that along the crack (a few here and there) would provide a greater place for it to bite into the material. I'm going to go out and check to see how it dried... 13 hours later...
The stuff is very flexible. I ordered exactly what was mentioned in the other thread, specifically for SMC... and it's more like hard rubber. The stuff just peels off. This is what I used: https://www.3m.com/3M/en_US/p/d/b40071610/
What the hell do I need to order to fix this, this stuff clearly wasn't the right stuff, even though it says it was for SMC?
[This message has been edited by 82-T/A [At Work] (edited 11-12-2024).]
It's far more like the fiberglass resin that I remember using with my uncle when he restored his Corvette... and it dries as hard as a rock, which it is supposed to. I'm really frustrated I wasted my time and money... on the other 3M crap. That's not for SMC... even though it says it is. That's for like bumpers and flexible crap. I am so pissed. I mean, not like raging pissed... but would like to hear from others who have used that stuff. Maybe I did something wrong?
The first stuff you used works well on flexible SMC panels. The flexibility stops it from cracking. However, it's not the right stuff for structural repairs. The second stuff you bought is the correct stuff. Don't be afraid to grind down deep into the area to remove all old repaired/ damaged material. Feather well into the good material, then build up with layers of mat fiberglass and the SMC resin.
The first stuff you used works well on flexible SMC panels. The flexibility stops it from cracking. However, it's not the right stuff for structural repairs. The second stuff you bought is the correct stuff. Don't be afraid to grind down deep into the area to remove all old repaired/ damaged material. Feather well into the good material, then build up with layers of mat fiberglass and the SMC resin.
Thanks Neil... that makes sense then. Ugh... ok, well, that was a practice run. Haha...
It's far more like the fiberglass resin that I remember using with my uncle when he restored his Corvette... and it dries as hard as a rock, which it is supposed to. I'm really frustrated I wasted my time and money... on the other 3M crap. That's not for SMC... even though it says it is. That's for like bumpers and flexible crap. I am so pissed. I mean, not like raging pissed... but would like to hear from others who have used that stuff. Maybe I did something wrong?
Sorry to look in so late. I've always used the EverCote when bonding to the SMC panels. I'm still concerned on the structural strength of EverCote and glass matt and having it bond to that crack. It looks like the break is in a high stress area where the hinge mounts. Are you using a wing on the back? That will increase the stress on that area. If you get rid of the springs and go with struts, you might have a better chance on not recracking the repair.
Originally posted by RCR: Sorry to look in so late. I've always used the EverCote when bonding to the SMC panels. I'm still concerned on the structural strength of EverCote and glass matt and having it bond to that crack. It looks like the break is in a high stress area where the hinge mounts. Are you using a wing on the back? That will increase the stress on that area. If you get rid of the springs and go with struts, you might have a better chance on not recracking the repair.
Bob
Never too late, thank you for the advice. I was able to strip off all the old green stuff that we'd put on the other day. For the most part, it peeled off. I was able to get a hold of an area where I maybe hadn't removed the gelcoat, and then used some pliers to carefully peel it off. It tore up some of the fiberglass / SMC that was underneath, which I think is actually a good thing, because it exposed more material that the new stuff can bond to rather than a perfectly smooth surface. For the rest of it, I had to use a box cutter, and / or a sanding disk.
I ended up mixing the fiberglass / SMC resin with the hardner, and applied multiple layers of pieces of chop mat over the areas that I had dug out. I then layered a couple of larger pieces over what I had repaired. I checked it last night (after it had been drying for a couple of hours), and it was really warm, but rock-solid.
I'm going to look at it again. I figured what I'll do is sand it down just a little bit, and then use plastic filler to fill in the holes, and then prime and paint the entire back.
As for the break... it's weird. It was broken before I got it, but I THINK what happened is that someone was towing the car backwards, and the trunk flipped up and backwards, causing it to break backwards. Really weird. The top panel has zero damage at all, but it looks like they re-bonded it to the decklid, and they had installed two metal brackets (which I removed). They hadn't done ANY fiberglass repair at all... not even glue... just attached two metal brackets over it. It has a luggage rack, no spoiler.
I think it should be ok. I'm going to check it out tonight after work.
