OK, fiberglass guys. I'm willing to take on almost anything mechanical or electrical, but my skill and knowledge on fiberglass paint and bodywork is zero. The battery box in my '74 was rotted out when I got the car (Bubba had jammed a 2 x 6 in the bottom of the box to hold the battery in ). I went down to a local salvage yard and cut a box out of a '71 last fall. Having scanned through some stuff on here, it appears that the early C3s have a different fiberglass composition than the later C3s. After laying underneath my '74 this afternoon and comparing the two boxes, it appears that the construction of the two parts are also different, in that the earlier box is a molded one piece unit, but my later one is comprised of several sheets joined together at the corners. It's along some of these joints that the box has split apart when Bubba jammed his 2 x 6 in.

The questions are: can I join these two different year boxes together? and if so, how the hell do I go about it and make it look reasonably professional? I'n not even sure what material I need to purchase to make this work. Sure do wish I knew someone in the immediate area who knew their fiberglass really well......

Any detailed help or instructions would be extremely appreciated.

Steve

 

Steve,
If I can do this job you sure can. I had to splice a bottom in my 69 about6 years ago. I called Gary Gruhala got a box cut out of a junker and cut the side walls on my 69 and the junker box so they were in alignment. I made up strap to bolt them together then ground a big "V" in both sides. I started glassing from the inside using mat not cloth. prime it with resin,lay in mat, roll it to remove air, build up several layers as you work you way out of the "V". When that is hard you can finish grind it. Then go to the outside and grind the "V" into the joint and into the new hard mat from the inside. Don't grind through the mat,just into it to get a good bond and start the same process on the out side. I had the suspension out to rebuild it so I had room to work.

 

Gary,

Thanks for the response. It sounds like you had a similiar situation to mine. The battery box is a lousy place to begin my fiberglass repair education; it's not the most accessible location. Like you, all of the rear suspension is out of the car, as is the drivers side interior, so it's as good as I can get it.

Regarding materials, I've located this stuff at Ecklers for the resin:



and this for the adhesive (I've got split seams in the box corners all the way to the door level):



These are both specified for 1973 and up cars with sheet molded fiberglass. Apparently, sheet molded fiberglass has a mold release agent in it that the early years didn't have, which means the materials to repair it have to be different. The only fiberglass mat that Ecklers lists specifies for 1972 and earlier cars. The box that I cut out is definitely from an earlier year, as the remains of the car were for a chrome bumper unit. I'm not sure whether the above items will glue the differing types of fiberglass together properly or not. Guess I need to call Ecklers tomorrow.

I think that I understand strapping the two parts together and grinding them down into a wide "V" and layering the fiberglass mat and resin to form the bond. It just seems like a bit of an "artistic" thing, and I'm more used to the definites of the mechanical side..... Oh well, I can only screw it up so bad. Thanks again Gary.

Steve

 

I thought the SMF came out later then '73? I'm not sure but I thought it was more like '80? I used a resin kit that NAPA sells for $12. If you go to a local body supply shop they have the mat and resin too. I used the heavier matting the 2nd time and like it better. For a roller they probably have one too but I got mine from McMaster-Carr. Be sure to clean it good right away.

Good luck

 

Everything that I have been able to read indicates that SMF began in 1973. The best method for indentifying SMF is that a panel is smooth on both sides from the molds used. On my '74 every panel is smooth on both sides. In addition, all of the 'Vette part suppliers out there list differing materials for the '73 and up cars. So I'm pretty certain I've got SMF.

I'll give your NAPA option a shot and see what they carry. My only concern is to do it right, given the necessary strength required for this area. The last thing I want to see happen is to hit a bump and have the battery drop out onto the road!

Steve

 

Steve,
My '74 had a fair bit of the bottom of the battery box eaten away by battery acid, by the look of it, but most of the sides were still OK. My repair looks "Bubba", but as I'll never drive it to Bloomington etc. I don't care.

All I did was to use duct tape from one side, across bottom, to the other side, on the outside of the box, completely covering the hole, then taped some stiff cardboard to the "flexible" tape (again, underneath) to give it stiffness. Then I placed several layers of mat and resin on the inside and up the inner walls to replace what had been eaten away.

When it had hardened, I pulled all of the tape and cardboard away from underneath and it doesn't look too bad. Again, no-one will ever see it and if they did, so what? Few people out here would know what they're looking at anyway. And it's as solid as when new.

Hope this helps. and

Regards from Down Under

aussiejohn

 

I never worked with the SMF, but if it works similar to the older resin, plastic sheet does not stick to it. This makes it perfect for laying fiberglass. The plastic always faces the working surface and acts as a release barrier. Build your luan/cardboard form behind it and start laying your mat on the inside. You could use a sheet of fiberglass cloth to span the gap in both directions, like an X, but do the curves and finish surface in mat. The cloth will provide some additional strength. After one layer sets up, you can remove the form and check your contour and adjust before going to the next layer. Grind and fill as you go and it will be perfect. As I said, I never worked with SMF, but if it works similarly to the older resin, you won't have any problem.

When laying fiberglass mat on the outside, you can lay it up on the plastic sheet while on a bench, pick the whole sheet up with the layers of mat soaked in resin and place it against your working surface. Roll it down over the plastic to remove bubbles, Did I say use clear plastic so you can see where the bubbles are? After the resin sets up, you pull the plastic off. This sure makes the job less messy! If you are laying up several layers of glass at one time, I like to mark the perimeters with a sharpie, so I can see how my layers are overlapping. Use heavy, quality plastic sheet, not the light dry cleaner material. It will tear when you attempt to remove it and just makes life more difficult. Let us know how the job went.

 

Aussiejohn,

It sounds like my '74 is very similiar to yours. And I probably shouldn't be so concerned about the appearance. The procedure sounds simple enough. As I noted earlier, my biggest concern is around the strength of the repair. Thanks for the help with the techniques.

Red 69,

I think that working with SMF is pretty much the same as the older stuff; it just requires different materials. Your techniques are also helpful. I guess I'll be making a trip to the local stores to locate the necessary materials and see what happens. I'll post some pictures once the repair is done. Thanks everyone!

Steve