Good morning everyone,

A question for the group. I'm doing a frame-off on an '80. Considering the age of the car, should the body panels be separated at the bonding strips and re-attached with new adhesive?

I have two small areas to repair on the left side - both are over the bonding strips. I inspected the areas underneath the car and found that about 3" of adhesive and broken loose at these spots causing the damage to the exterior side.

I'd really hate to repair these two dings, drop the body and paint the car, only to have other sections of the joints separate later on. What's your experiences here?

 

Generally, those that tackle the joints,will grind them down in a "V" and then place resin and mat, in your case epoxy resin. I would not break off the panels and re-glue them since you have to have them jigged up. Good luck on your project.

 

X2 for a grind back and application of epoxy and mat. 3 layers of 1.5 ounce mat seems the "standard" lamination for a seamless and permanent fix for factory bond lines. I did it to mine more than a year ago, it's still in primer in an open carport in coastal GA where the temps have exceeded 90 degrees for 50 days straight now(!!!)... I think the technique works.

 

Yes, grinding back and fiberglassing is a permanent fix. You need to grind down to the bonding strip, don't leave any seam filler. It took way more than 3 layers to fill it up, though. Think we were up to 5 or 6 layers. It's a lot of work, but the seams will never show.

Here's what it looks like fiberglassed and rough sanded with 36 and then 80 grit.

 

Would be a bit easier to glass seams than to dis-bond panel and re-bond at least to me anyway, not sure why a jig would be necessary though to re-bond. I do agree with Zwede more like 5 or 6 layers, better to have to sand off a bit more than to have to add after initial glass lay up. I noticed the bonding adhesive on my front clip was very brittle and had cracked when bonding it back on to the firewall, and was one of the major reasons for glassing in the seams on it. It's not going to crack or show through now .

A couple of links to pictures of when I glassed in mine and there are more in my profile:

http://forums.corvetteforum.com/albu...ictureid=70938

http://forums.corvetteforum.com/albu...ictureid=70939

http://forums.corvetteforum.com/albu...ictureid=70935

http://forums.corvetteforum.com/albu...ictureid=70936

ikwhite

 

I have a couple of questions if you don't mind.

- What did you use to grind out the old bonding adhesive?
- How did you keep the area you ground out so symmetrical?
- How far did you go above/below the seam?
- What did you use to tint the resin to match the fiberglass on the car?
- any other suggestions/gotchas that ya'll came across that you think might be helpful for others about to do this?
- How much resin & glass did this take? more than a gallon?

Thanks
KO

 

- What did you use to grind out the old bonding adhesive?

I use a die grinder with a 3" mandrel and 36 or 40 grit sanding disc.

- How did you keep the area you ground out so symmetrical?
- How far did you go above/below the seam?


You can run a tape line above and below about 1" to 1.5" of each side of the bond seam as a rough guide. It's not that critical to be symmetrical more important that you have a good tapered V shape to your grind, and not a sharp edge. Most times I just freehand it. Take it down to the bonding strip in the center to remove bonding adhesive in the area you are going to glass.

- What did you use to tint the resin to match the fiberglass on the car?

I mix a black and white epoxy tint in with West Systems 105 epoxy and 206 slow hardener.

- How much resin & glass did this take? more than a gallon?

I mix about a cup full of resin at a time, then when throughly mixed using a tongue depressor, I pour into the bottom of a plastic two liter coke bottle that I have previously cut off. I buy one ounce chopped strand mat buy the yard, and to do a seam I would probably buy two or three yards, just make sure to have more than enough. I pull and tear apart enough hand sized easy to manage pieces from my chopped strand mat to fill the seam ahead of time. You want to have enough glass to layup about 5 or six times the full length you have to fill. A gallon should be plenty more than enough to do all the seams and then some.


- any other suggestions/gotchas that ya'll came across that you think might be helpful for others about to do this?

You can use 1.5 ounce mat, but I like to use 1 once with epoxy, thats my preference.Try to get a mat that is loosely bound and not tightly stitched with a binder that needs MEKP to dissolve as epoxy resin has none, regular polyester resin does.

I layout and have ready my mat and any tools( roller, brush, acetone and container to clean and keep roller,paint brush in between mixes),then mix my resin, brush on some resin into the whole seam then start to layup my glass with a 2" to 3" paint brush. Once I run out of resin I give a quick roll with my steel ribbed roller to remove some of the air that gets trapped and compress the glass, then I mix another batch and start where I left off, layup glass with brush and resin and roll, I do this until I feel that I have enough coverage that I will not need to add any more glass. After I have enough coverage I roll out the whole seam hard as rock to compress and remove any air.
Once it has cured you do not really want to have to add more glass as you will loose the chemical bond advantage.

After curing I use a DA with 36 grit to quickly bring my seam down to the dual tape line and paper that I had previously laid down before glassing, then switch to 80 grit block, then skim coat with rage gold, sand and epoxy prime etc...

I have uploaded a few pictures for any that are interested just look in Albums, Show All Albums then in the Seam Bonding Album of my Forum Profile.

or just go here.

http://forums.corvetteforum.com/album.php?albumid=15353



There are several good threads, books, DVDs on glassing already and I advise anyone wanting to do glass work that research is key and that the above are just some of the technique that I use and have found to give me good quality results.I am not a professional.


Hope this help KO as I have been to your project thread more than once for info and enjoy it.


ikwhite

 

Thank you very much for the detailed information.
It is very useful. I started this last week before I went on vacation.

I had a few days by myself so I used the glass that I had on hand. I did the two rear quarters first. I used 8 layers because I always seem to have low spots anytime I have done this. I did run into a problem. I used the same hardener that I always have, but it was a new container. This time, it was still wet 24 hours later. Not sure if it was a bad batch or just because I had that many layers. I'll see when I get home tomorrow if it set up or not.

Thanks again.

KO