Roger L

Hi Guys, need some advice on best way to tackle this minor body repair on my '66, what materials to use and best way to repair without making it into a bigger project then necessary. I removed the 2 original rear bumpers and planned to replace with 2 OEM bumpers that were re-chromed already in hand. After removing mufflers and lower valance and unbolting bumpers I noticed the holes in side of body have been enlarged/ broken out, the fiberglass in this area is very thin.. I would like to repair these holes in a manner that will not effect the paint on the outer body, what filler to be used could be touched up on outside as I would have to get down under bumper to see it. Any repair to mounting hole would not be visible when new bumper is installed if the repair is limited to inside of body, so no plans to be sanding on outside in this area. As I don't want to have to paint outside which will just lead to other cosmetic issues, just touch up brush.
What filler material should I use that will also add strength to this area and should I reinforce this body area on inside with fiberglass mating and resin as this part of body looks extremely thin and delicate.
What are suggestions in replacing these side bolts, should they have a rubber bushing and washer on bolt or just make bolts hand tight as I see no value in tightening them up against bumper and stress body again.
Need advice to properly install the new bumpers without stressing the body skin as I am certain they will not exactly be the same as ones removed, any tips will be helpful as this is a first for me. Thanks for reading the post.
Roger

KC66

You could try tapping it up good from the outside and glassing some fiberglass matt from the inside. Then re drill holes.

KC

DansYellow66

Without damaging any visible paint this is probably the best approach. Sand the area around the hole underneath with some 80 grit paper, tape the outside of the hole off and then lay 3 or 4 layers of mat and resin on the underside - compacting it with the brush. Then redrill the hole. This way, if someday you decide to repaint the car you will have the underside done and just need to re-glass the outside.

Roger L

Thanks guys for input that sounds like the plan, 3 or 4 layers of mat

DansYellow66

As an after-thought you might want to make that about 5 layers. That has always been a stressed area. No use being skimpy.

mudbone64

Have you done any research as to how you should apply the layers of fiberglass mat? Believe me when I say I'm no pro. In fact I'm not even sure I'm a novice. However, if you haven't already you might want to study up a little on the procedure before you begin applying mat and resin. It's my experience that a successful repair job heavily begins in the preperation. Sand the damaged area back, mask the area off, create a backing, pre-cut your mat and stagger the sizes etc. It's not that hard but it is a controlled mess.

Mike Geary

Having done a number of these, I suggest that you shred up some mat and use pieces with long fibers to make this type of repair, rather than trying to cut precise pieces and fit them in.

These thinner shredded pieces will lay in much better to the irregular, concave surfaces and not want to pop back up as much. Don't go crazy with the resin.

Often, I will just do a couple of these thin layers to make sure it's taking the shape I want and let that set up before going on to the remaining layers.

CADILLACRAZY

You can buy body filler with glass fibres in it that is specifically for bridging larger holes, I have used it and it works well and is a hell of a lot easier to use than glass resin that will run everywhere.
After the first layer you can sandwich/ laminate in a piece of aluminium sheeting bent to shape if you want between it and a second layer.
And as mentioned apply from inside and first stick some wide packaging/cellotape to the outside surface to stop it coming through and will give you a nice smooth outer surface when removed......beautiful.................

Roger L

Thanks guys for all the suggestions mudbone64 you are right as it is a controlled mess. I didn't want the resin to spread out past the finished body and needed a rigid surface to push resin against as plain tape over hole would not have worked; so I fabricated a small aluminum cover out of thin material, bent it to match the shape of bumper attachment area on body. I lined the inside of aluminum cover with a thin film of poly-ethylene plastic so resin wouldn't adhere to aluminum cover. I taped it tight to outside of body. Then applied resin to back side, added mat. I repeated this until I applied 4 layers of mat and extended the mat several inches past the damaged area on inside, filling in the area solid where bolt goes thru and extending fiberglass mat past the repair so entire area is reinforced.
The results although may not be perfect were better then expected as outside of body was untouched, hole filled, and area reinforced, this repair will all be concealed behind the bumper mount never to be seen again. I will need to drill or dremel a new 1/2" bolt hole and start reassembly
I think the real fun begins now getting the bumpers lined up and re-installed in a location as they should have been. Thinking about removing all existing bolts and shims and starting from "scratch"
Thanks for input it all helped, Roger

KC66

Great job Roger, looks like you got it. I used to do a lot of fiberglass boat work. The tape probably would have worked ok. But no harm in the way you did it. I know I was a bit brief in my first post. One way to apply with out making too big of a mess would be to wet out your fiberglass matt on a piece of cardboard or something and pick it up and place it on the spot you want then you could brush it a little to flatten out with a brush. Add next layers the same way. The correct way is to use the roller with grooves to get out all air bubbles and excess resin out by rollering the matt. As far as starting with a large piece and laying smaller pieces on top that is correct if you are going to feather it out. But on the backside its not needed. The best way I found is like the other person stated is to just tear the matt with long fibers sticking out and blend it that way instead of cutting straight edges.

KC

DansYellow66

Looks great. You could probably lightly sand the surface and dust a couple light coats of the closest silver touch up paint you can find over it. But, I doubt once the bumper is on that anyone snooping down around the underside will be able to see anything. You may want to invest in a set of those rubber cushions sold for mounting between the body the the bumper. The idea being that the light bolt tensioning goes into compressing the rubber instead of the bumper directly to the fiberglass. You can even make your own out of some black rubber material like an old inner tube or a make-your-own gasket sheet stock. No need to tighten the bolts past snug-tight.

Westlotorn

Is there any concern about blending the backside so it has an original appearance?
I do not know if it could be done. I ask because mine has so many cracks I want to fix/repair and I think they would be stronger if I reinforce the back of the body in those places before painting the car.

DansYellow66

My 2 cents are that if the repair is in a place that is visible from underneath, yes - you will probably want to work at blending the backside area into an original appearance by sanding flat. There are resin tints that can be used to match existing fibergalass colors. But in this area where the bumper bolt is - it's not really visible because of the rear pan and bumper braces. Scuffing up the backside surfaces for good adherence and using the approach of pulling a piece of woven matt from the sheet instead of cutting it a piece with sissors helps the repair blend in quite a bit. Sanding to level the patch and then brushing a very light coat of resin over the area makes for a pretty decent appearance.

Roger L

Re-Chromed bumpers on, body repair is not visible and structurally very solid, thanks for support

DansYellow66

Beautiful

Westlotorn

Very Nice