Roma

Hello Together,

instead of doing some TLC this Winter I have to do a bit difficult repair on the rear body.

First it looks not too bad



but after removing the bumper








Last picture shows red the crack from inside, yellow I marked some kind of patch wich I think is original as you can find them in all areas where panels come together


I would appreciate to get a lot of info how to start best

Thanks a lot in advance

Frank

DUB

I will get back with you later today due to I am not on a computer that works that well.

Seeing how you are in Germany...talking on the phone to speed this up adn cover a lot more information faster is up to you if you want to call me or not.

The repairs can be done by either using polyester resin or an epoxy resin and fiberglass mat.

I do not know what types of body filler or adhesive you have access to also. I would recommend using Vette Panel Adhesive from EVERCOAT but I do not know if you can get EVERCOAT products there and if that specific product is being shipped in to your local paint and body supply stores.

I see you have cracks but I can not tell by the photos if you have actually panel separation at these cracks where the bonding strip. that you circled in yellow has broken free.

DUB

Ron Eagan

Not to bad to repair, first you will need to use epoxy resin. West Systems or 3M work well. Clean up the inside really good, use 40 grit paper to cut into the SMC. Cut mat glass to cover the internal cracks. Brush the epoxy on the effected areas and place the mat over them, then brush again with the resin soaking the mat. On the outside grind all the cracks into a "V", fill the areas with epoxy resin and glass as needed. To finish sand the effected area, you can use a Dyna Glass, or Tiger hair to help finish. A coat of polyester filler mat be needed in the end to fill imperfections. Pretty easy fix, hope this helps.

Ron

DUB

Could not get on the computer last night when I got home.

This car is not an SMC body car...just so we are all clear on this .This is s press molded polyester fiberglass body from the factory. Clearly ....this is a 1969.

DUB

Easy Mike

20mercury

Here you go, great How To CD's. A bit pricey but well worth the cost, I bought both for the C3's

https://www.corvettecentral.com/c3-6...r%26count%3d18

https://www.corvettecentral.com/c3-6...r%26count%3d18

(Hoping one day DUB will do a "how to" soon to!)

Ron Eagan

Epoxy resin work with SMC, regular fiber glass resin will not. I use the west systems often. You can but it at West Marine, here in Florida ACE hardware carries it. I restore C3's and use it all the time. Any questions please feel free to ask.

Roma

Thanks all for your replies.

I am already equipped with the following

Hope to be ready to start on Friday

I keep you updated

Thanks
Frank

Roma

Started to grind

Roma

Now the crack is good visible


Im a bit afraid now to mill it V-shaped. Should I realy do it and how wide ?

Thanks

Frank

zwede

Yes, it needs to be wide. About 4 cm I'd say. Try not to grind through, although it's not the end of the world if you do. Then 2 layers of tape along the edges and resin and mat. Tape is so you know when to stop grinding. Use an angle grinder with a 40 grit flap wheel.

This is a front edge of a door, but you get the idea.

jim2527

Have fun:

https://www.corvetteforum.com/forums...-drag-car.html

DUB

Frank,

That crack is in the bonding adhesive in the bonding seam. For it to do that I am a bit more concerned IF the boding strip on the backside of this area is actually still bonded to the quarter panel and taillight panel.

DUB

Roma

Hi Dub,

I carefully looked and test if its loosen, I think its still bonded and not chracked. When I grind more I assume getting to the bonding and see whats the condition

I try toget the VPA you refer to, but looks like its not available in Europe. Would you think I can use regular Epoxy mixed with cotton flakes ?

Thanks

Frank

DUB

I would only be able to comment by saying to TEST out your idea when adding any material to the epoxy resin so you can see for yourself if it is going to work or not.

I do know you can add thickening products to the resin to give it more body and structural strength.

I understand that the Vette Panel Adhesive is not often times able to be obtained in Europe and Australia. So finding a product you can get your hands on and test it may be your only alternative. I am still amazed that the countries that can get in EVERCOAT products...cannot seem to be able to ship a gallon or even a case of the Vette Panel Adhesive for those who need it.

DUB

Roma

Hi Dub,

I found some in the UK , but takes 2 weeks for delivery.

Meanwhile I grinded more. Would you think I have to do more ? Looks like Im nearly through

zwede

If I understand your plan correctly, you will use resin, right? AFAIK resin will not bond to seam filler so since this repair is in the seam you need to grind wide enough so you are in fiberglass on both sides of the repair. So yes, you need to go much wider. Also your angle is too steep. You want plenty of surface area for the resin to bond to.

Should look something like this. Note that this was the first round of 'glass. The panels were held together with screws. The 'glass was ground down, screws removed and then the seam was ground a bit wider and glassed again.



After grinding it almost looks like a single piece.

DUB

When I have to do a repair on a seam much like what you have. I will grind out the factory adhesive. IF I still see a crack and I literally get down to the bonding strip and the crack is NOW under the panel it is bonded to. I HAVE TO MAKE SURE that THIS CRACK cannot be opened up.

NOW...sometimes this can be tricky due to due to the strength in the panel and bonding strip it often times will not allow me to slide the tip of a small flat blade screwdriver INTO this crack and allow me to see if it open up due to their is very little to NO flex in this area due to the strength I just mentioned in the panels.

I may in many cases get to the backside of the panel an see IF I can slide my tool between the bonding strip and the quarter panel an see if I can get it to open up to the point to where I can see the crack on the outside open up. If I can ...there are many different way to repair this.

One of them is to heat up the bonding strip and get it to release partially. Cut it off. Prep it and bond it back on. And I do not worry about where I cut the bonding strip due to it will not effect how it works,

Another way is to prep the area and laminate it up on the backside. But leaving the bonding strip there with the crack still there may or may not come back and haunt you due to what I previously mentioned on how much strength is in this area.

I myself would use the VPA and fill in the seam and not laminate it up on the outside. Simply because I can use the method of using fiberglass mat and the VPA like is shown in the thread that you have seen.

But do as you wish due to there is generally always more than one way to repair something.

And when you get the VPA.....you will see that this is some seriously stout repair adhesive/filler. IF you have problems in using the VPA...let me know. I will be glad to give you tips on using it. JUST MAKE SURE that the date code on it is WITHIN the date for it being a good product and STIR it up very well which can take some time.

DUB

zwede

Yep, many ways to do this and keep in mind I've done exactly one car and DUB has done thousands. So use a similar ratio considering the advice (in other words, trust DUB about 1000x more than me).

Roma

Thanks to you both,

so next thing,

- will try to move a screwdriver under the bonding

- then grind the crack from outside till its no more visible or Im through.

I give you an update when I did it

Thanks

Frank