C3 front end fiberglass assembly

[Steven C.]

I know that the front ends were assembled from 4 pieces: hood surround, 2 fenders, lower front valance. I know bonding strips and bonding adhesive were used to hold the insides of these panels together.

Here are my questions:

Where were front ends assembled...St Louis?
How were they joined on the outside?

I've seen suggestions for grinding a trough, and using fiberglass mat on the outside, but this doesn't sound "factory" to me.

Thanks in advance for the help.

[Harmon C.]

Re: C3 front end fiberglass assembly

Steve

On the outside the bonding material was finished to make a smooth finish about 1/2" wide of the material. Over the years it will dry and shrink making cracks on original cars. Most people don't want cracks in their new paint jobs so the area is ground out and filled. I have seen resorations that try to make a flat spot the way the seam looked to them but I don't know if the seam was flat as delivered or aged that way. Lyle

[John H.]

Re: C3 front end fiberglass assembly

The front and rear clips were subassembled off-line at St. Louis from all the individual parts and bonding strips in large vertical bonding fixtures that held each part in position with vacuum cups on the outside contours, then the bonding strips were "buttered", placed in position, and held in place by swing-in clamps until the bond "went off". The outside surface areas of the fixture where the bond seams were located were contour-machined from Teflon so the bond that squeezed through the gaps between the panels didn't stick to the fixture.

[Steven C.]

Thank you John & Lyle *NM*

[Terry F.]

Re: C3 front end fiberglass assembly

I found the edges of the panels beveled approx 45 degrees where they are butted together. The actual panels never seem to touch and the gap can vary a bit but is mostly uniform along the bonding seam. It seems that the bonding adhesive was used to smooth the v-grove that forms between the panel edges. So the edge of the panel was sort of locked in place with there beveled edges. Hope that make sence.

I believe that many original panels if not all the one's in those years were lightly sand blasted over the areas that would get adhesive applied to it. The process is sort of neat in that it blows away the resin and leaves the fiberglass stand exposed. Makes for a great bond but is only slight stronger than simply grinding it with 60. Use vinyl gloves and rub the adhesive into the glass in a thin layer if using original formula. Try not to form air pockets under the seam or panels.

When the front end was attached to the car, the height of the seam was adjusted with little blocks/pieces of fiberglass that were glued in place in bonding areas. I assume they would be stacked in there and ground down untill the surface of one panel met the surface of the next panel (like the edge of the door panel and how it meets the fender edge). I have found this when carefully cutting panels apart on cars 68/69 mostly. I have used the technique and found it to greatly improve the assembly of panels. It is incredible how deep I have found adhesive in some areas and it is not consistant. Each car was different. Right side of car is different than the left side but I would try to make them the same as much as possible.

More info than you probably wanted.

Later, TErry

[Terry F.]

Re: C3 front end fiberglass assembly

One more thing.

If you are building a front end for your car and the front end is off the car I would suggest this. Very carefully align the rear edge of both doors to the rear quarter panels. Take your time and do a nice job. Make sure your door hinges are good and tight. If you need suggestions, let me know. It is a golden opportunity to improve things and make decisions. Measure the front top corner of the doors in relationship to the stainless trim, etc. Put two shims under each hinge and try to call it good. But make that rear door edge nice as can be. Look at the whole situation. You may want to trim the leading edge of the quarter panel if it is built out too far, etc. But that would only be done after really looking at the situation. When you fit the front end, you want the door to be as close to the final position as possible.

Enough, too much said. Terry