whitestreak3

Hello,
I'm nearly ready for paint on my 81, but before I get to that I need to get a stress crack taken care of. It was showing through the paint when I bought the car, and I want to make sure that the same thing doesn't happen after I've put a new paint job on. After doing a bit of research, I went and picked up some Evercoat SMC resin, as well as some fiberglass mat. From my understanding, now I will grind out a trench, starting at about a half inch from each side of the crack, with the crack at the center. The crack goes through through to the underside of the panel. So I need to grind all the way down to the fiberglass matting on the underside of the panel, correct? It looks like someone tried to repair this. They put a support on the underside of the panel, but it doesn't look like there is any matting is up top. Should I just leave their repair job on the underside, which is very attached to the panel, alone and just use fiberglass mat and resin up top? Also, how long do I have to wait before applying another layer of mat and resin on top of another piece? Any tips/warnings would be appreciated! Thanks

DUB

DO NOT USE THAT RESIN. I have tried using this stuff for years and even when I talked with Evercoats Tech Dept...when I use it..I can pop it off when cured. Seems to not link up and adhere. BUT use it if you feel it is the best for you....but you have been warned.

ANY other advice REQUIRES you posting a photo. NOT all stress cracks get repaired the same. AND NOT KNOWING where the stress crack is...like I wrote..I can not comment further.\

DUB

whitestreak3

Sorry DUB, it is on the front of the drivers side fender, perpendicular to the hood. Here's some pics

DUB

Thanks for the photos.

NEXT STEP: You need to clean off the underside VERY WELL so we can see what is going on there.

This is IMPORTANT and will allow me to better direct you in a repair that I would do if it were in my shop.

I AM CURIOUS....you might want to go look on the other side and see if it cut and repaired the same way.

DUB

whitestreak3

Already checked, the other side doesn't have it. I have tried with 60 grit to clear that thing off, but it is a very long, slow process. For now I can let you know that it seems like a plate or sheet of some sort, very well attached to the back side with some sort of resin and mechanical attachments (I think that's what all the holes up top are from. I'm thinking that even though the previous people did a repair on the bottom, they didn't use any fiberglass matting up top....maybe that's the reason the crack showed back up? Let me know what you think!

DUB

A lot of it is going to deal with how well this patch is ACTUALLY stuck to the underside.

If it stuck well...and you are sure of it...then it will require doing some grinding on the top surface and see what is going on in this crack that you have...and then it will need to be laminated and ALL of those filled in holes will need to be addressed.

How wide is the panel that is under the repair???

DUB

whitestreak3

Thanks DUB, the panel is about 5 inches wide. That piece is really stuck to the underside, so you're saying I can just leave that alone and use resin/matting on the topside? Also, is there a curing time between applying layers of matting on top of each other? Can I just apply a saturated mat, get all the bubbles out, and apply another resin saturated mat right after?

DUB

If it is stuck...GREAT.

Then it will be up to you to PROPERLY PREP this area so you can easily laminate the seam in and also the holes. You will ( or should) spend more time in getting the surface prepped correctly that it may take to actually laminate it. It has so much to do with properly tapering out the area and NOT having any steps in your prep where air or excessive resin can collect. And keep in mind...it would be in your best interests that when you are done laminating..you grind this lamination down a little and cover it with some Vette Panel Adhesive.

AS for the amount of fiberglass mat you apply. I would apply NO MORE than three layers at one time. Maybe stop at two...but I have many tricks in how I prep the fiberglass mat and how I tear it and how wide I need it to be and so on. And that is if you are using ounce and a half fiberglass mat. AND...I hope you are NOT planning on using that SMC resin form Evercoat. I would NEVER use it UNLESS I am making a complete part. But for laminating...I have been SEVERELY BURNED by it and had to go back in and do jobs ALL OVER again. The choice is yours.

The end of the seam where it meets up with the hood gap...this is going to be touchy and may require you separating the fiberglass so it is half as thick so you can control it and make that sharp 90 degree bend. So..obviously...you can apply more layers there due to the fiberglass mat is not as thick.

WEST SYSTEMS epoxy resin....and if you get it and use it...make sure it is warmed up to at least room temps (70-85F). BECAUSE if you try to use it when it is cold...it gets thick..and then you trying to get your ratio of resin to mat correct...is much harder to accomplish .

DUB

whitestreak3

Thanks DUB for the recommendations....when you say "laminating," you are just talking about the resin/glass mat, correct? Do I just fill in those holes with some body filler? After I grind out the "v" trench and sand with 80 grit, what is the best way to prep/clean? Will acetone and some heat (to get out moisture) do the trick? Thanks again for all the help

DUB

YES

I carefully grind out a dish for each hole. I make sure it goes down deep...thus the 'dish' will get larger due to the depth you grind out. So each of these holes may have a dish ground out the size of a quarter Which is one reason I HATE IT when people drill into panels to hold them together. IF a person drills into a panel to secure it. COMMON SENSE would often dictate that these holes can be very, very close to the actual seam...IF NOT actually in the width of the seam itself...so these holes can be repaired at the same time of the seam itself....and not so much HAVING to be dealt with individually. I then carefully laminate then in and when cured I grind them down and apply VETTE PANEL ADHESIVE....and NOTHING BUT Vette Panel Adhesive.

IF you are finding that dishing out these holes and tapering the seam with a very gradual 'V' notch....they may touch with each other. KEEP IN MIND that if they do...it is much easier to grind them in a manner that allows the fiberglass to lay down flatter and not have a bunch of ripples to go over.

If you choose to not laminate these holes and dish them out and JUST fill them...that is up to you and if you choose to do just that...Use the Vette Panel Adhesive.

You can use a 24 or 36 grit 3M Rol-loc disc. 80 will work but I would prep it with the 23 or 36 grit discs myself. And your tool does not have to be at MAX throttle when grinding.

I seriously hope that you do not have moisture when you grind this out.
I will 'blow-wipe' it off and if I can get it the way I want it..I will then carefully wipe it with acetone and blow it off again. Keep in mind i have dry air so if your compressor is blowing out moisture when you blow it off...You might need to reduce the amount of air flow. And to check and see if you are blowing moisture...blow the air stream onto a mirror. If it fogs up...you have moisture....which...depending on how much moisture your compressor is spitting out...can be dried with a heat gun....but that alone does not do anything about any compressor oils that are being spit into your panel.


If you laminate and do all was has been suggested. Just remember to cover your lamination with Vette Panel Adhesive...because as good as you might think you got all the air out of your lamination...IF left sanded and NOT covered...when you go to prime....there is a very HIGH probability that you will see open air pockets that you exposed by sanding the lamination. Because you are not planning on vacuum bagging the lamination. Just 'saying'.

And obviously it is your car and you can do it the way you feel. So the choice of resin and body filler is up to you.

DUB

whitestreak3

Thanks DUB for all the time you've given me, I definitely feel more prepared for the job!