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HECK YES....you follow instruction VERY WELL!!!!!!!!!!!!!!
My only question/concern is that in this photo. I can see that you did grind down the resin and mat. But I can also see that deep in the low areas they have not yet been sanded or ground on. Hopefully you did make sure that these dark low areas were ground on so the VPA would stick.
DUB
Yes I went back and hit those areas as well before the VPA was applied. My rule of thumb was basically sand everything with 60 grit regardless of material before applying something on top of it.
Yes I went back and hit those areas as well before the VPA was applied. My rule of thumb was basically sand everything with 60 grit regardless of material before applying something on top of it.
Thanks DUB. So on to the next repair. This is located on the drivers side rear fender. Before stripping the paint, I was able to see a small crack in this area but the pictures below show what was underneath. The previous owner told me that he had shaved the lip on the top of the wheel arches to fit a larger tire.
From exterior before removing old repair
Backside of panel showing globs of resin used for repair.
After removing the old patch and cleaning it up a bit
Back side after removing old patch
Different angle
What is the recommended approach on this one? I would think I could approach this by first making a back support that I could use to temporarily support one layer of mat, then laminate it, and finish it up with VPA to create the final shape of the wheel arch?
Your thoughts are correct...but this is going to be quite different in HOW you laminate it...and IF the resin you have will stick. And this is due to different materiels GM used...which do require different types of resins.
I can not tell from your photo IF the panel looks the same as the top hood surround.
Is all the primer off of it??? Because you can have what would be basically called SMC..and the resin you have may not stick.
DUB the rear quarters are different from the hood surround. The hood surround is darker grey and you can see the fibers in the glass. The rear quarters are light grey and more of a solid color. I tried to capture the contrast between the front quarters and the rear quarter in the picture below.
I'm told that '71 is the first year GM started using SMC panels and they used them for rear quarters only. So if that's correct it is likely those quarters are an early version of SMC. Your resin would then have to be SMC compatible in order to stick.
Alright finally got all of the materials I needed and made the repair. This one was definitely more challenging than the nose mostly because of the awkward location but below are some pictures. Trimmed up the edges Created my new vertical backboard with tape I used thin pieces of support metal I was able bend to the shape of the wheel arch to act as my backboard for the fiberglass. A previous owner had trimmed the lip all the way around the wheel arch so I prepped the whole arch with my metal supports to extend the lip.
When I layed the fiberglass, I split the 1.5 oz mat into two thin layers. I layed down three of these thin mat layers and then one layer of full 1.5 oz mat. After letting everything dry for 3 days I removed my metal backing and trimmed the lip to size. I then sanded the new fiberglass and hit it with VPA. I shaped the VPA to my liking and then put one last thin coat VPA and feathered everything in. The only thing I might do further is add about a 1/16" back to the lip on a spot I sanded down too far where the lip width is a little smaller than the rest. Other than that, I'm satisfied with how it came out. Sorry for the blurry photo Sorry for the blurry photo Primary areas of repair
The wheel arch was the last of what I consider the major repairs. So now it's down to small cracks. Below some of the first. I appreciate any input on how to approach these. I plan to grind these down and fill with VPA but my main question is how far to grind? The cracks are hairline cracks that are rather difficult to see. In the pictures below I have put tape at the start and stop of the cracks located on the top of the ridge.
AS ODD as it may sound. VPA can be used as a filler on SMC panel. BUT it can not be used to repair actual cracks in SMC.
NOW...due to the strength in this area...because you know it is strong due to the shape of the panel creating a 'V'....so to speak...which give is a lot of strength.
So the 'odds' that the crack would come back is questionable because I wonder how it got cracked there in the first place.
You could use VPA. I would make sure I grind enough on the outside panel to make sure I get to the bottom of the crack. If you do not find the end of the crack and get it prepped....what you do could be useless. SMC type panels do not crack like the earlier polyester panels. When they crack ( if it is actually a crack and not a blemish in the panel) The cracks like to shear laterally. SO when you grind o nit...do not be surprised that it travels further outward than what you might think. I have prepped cracks that go out as far a 1-1/2" from the actual visual crack I can see on the exterior panel. THEN...I would go inside the car and get up in where you can sand and prep the inside of the panel where you just ground it so an adhesive can be applied on the underside and give it even more strength.
EVERCOAT 994 ( SMC Panel Adhesive) is actually what I would use....and that is because I keep it in stock for repairs just like this. Keep in mind that the 994 is an ADHESIVE and not a body filler. Even though I use it in bonding on panels ( hence----adhesive) I can not use it to bodyfill work. That is when I use the VPA.
You can also use WEST SYSTEMS epoxy resin #105 and the #206 hardener if you choose to do that. I have that on hand also...so it would be a toss up on which I would use....the 994 or WEST SYSTEMS epoxy resin. A lot of it would depend on how much I had to grind away and so on.
THEN ...when all major repairs were made. I would finish the exterior in the VPA
DUB seeing as I already have the west systems epoxy resin on hand, that is what I will use. So are you recommending that I use the epoxy resin without any mat at all?
DUB seeing as I already have the west systems epoxy resin on hand, that is what I will use. So are you recommending that I use the epoxy resin without any mat at all?
NO...Use some mat..and from the crack I can see in your photo.
With it being right on the top of the peak of the panel. Using strands and individually laying them may work. And...if you do grind through ...I would apply some of the mat and resin on the inside also if you feel it will strengthen this area.
Hard for me to 'say' with complete assurance to you without seeing what you have going on until after it is ground on.
NO...Use some mat..and from the crack I can see in your photo.
With it being right on the top of the peak of the panel. Using strands and individually laying them may work. And...if you do grind through ...I would apply some of the mat and resin on the inside also if you feel it will strengthen this area.
Hard for me to 'say' with complete assurance to you without seeing what you have going on until after it is ground on.
DUB
Alright here are the areas of the cracks after I ground them out. I did not have to go all the way through to get rid of the crack but you can see from the picture that the texture of the panel is starting to change to show more fiber strands as I went deeper. From the tip of the peak I probably ground down about 3/16" worth of material. Thoughts?
Alright here are the areas of the cracks after I ground them out. I did not have to go all the way through to get rid of the crack but you can see from the picture that the texture of the panel is starting to change to show more fiber strands as I went deeper. From the tip of the peak I probably ground down about 3/16" worth of material. Thoughts?
I would fill it with VPA and NOT think twice about it.
The previous owner of the car used it for auto cross racing so that may have contributed to the cracks. Because I ground away some parent SMC material to remove the cracks I figured I would apply the west system and matt to restore any strength I compromised. So I applied two layers of matt and let it cure for two days.
I then trimmed up the fiberglass and then sanded it down.
I put a skim coat of VPA over the repair and feathered it all in.
The next repair is located at the drivers side rear bumper corner. I have not verified with a flash light yet (I will after work today) but I'm assuming this crack goes all the way through the panel. I apologize, I have not thoroughly cleaned this area very well yet. The car was never hit and looking at the back side of the panel I see no further evidence of propogating cracks. I'm assuming this crack formed from misalignment of the bumper/frame brackets? Anyway, would you recommend cloth on the back side of the repair? Should I just "v cut" the crack or cut away more?
I would start prepping the crack from the outside...and that is ONLY because you wrote you cannot see any cracks on the inside. SO...these cracks may be all within the area where the bonding strip is...and you can 'V' it out and repair it from that.
And not knowing if VPA by itself would do or not because I have not seen it fully prepped. So giving an exact answer is hard to do until i see it prepped.
I do know that I am really careful if I begin to apply any mat and resin on the backside of this area ( or an area like this) and that is due to I want ANY metal bumper supports to fit nice and flush against the body and not have a laminated area laid up at an incorrect angle or humps in the lamination and thus puts strain on the fiberglass and possibly crack it when bolts are tightened.
I would start prepping the crack from the outside...and that is ONLY because you wrote you cannot see any cracks on the inside. SO...these cracks may be all within the area where the bonding strip is...and you can 'V' it out and repair it from that.
And not knowing if VPA by itself would do or not because I have not seen it fully prepped. So giving an exact answer is hard to do until i see it prepped.
I do know that I am really careful if I begin to apply any mat and resin on the backside of this area ( or an area like this) and that is due to I want ANY metal bumper supports to fit nice and flush against the body and not have a laminated area laid up at an incorrect angle or humps in the lamination and thus puts strain on the fiberglass and possibly crack it when bolts are tightened.
DUB
Sorry for the long break, it's been pretty hectic over the holidays. I have cleaned up the area now so you can better see the crack and I also took pictures of the backside of the panel. DUB you mentioned that you would only put Matt and resin on the exterior of the panel if there were no cracks on the interior of the panel, after carefully checking, there are no further cracks in the interior of the panel however the one primary crack does go all the way through the panel. Knowing this for sure now would you still recommend only applying Matt and resin to the exterior panel with a V notch?
YES...I would make sure I 'V'd' it out rather well so I know I can laminate in some matt and taper the 'V' out well enough so the matt will be able to follow that surface without wanting to lift up. You might find that your use strands of your matt applied individually instead of a piece of mat so you can get the bottom of the 'V' to fill in well.
Your inside photo is GREAT. I would apply masking tape on the inside to keep all of the resin from dripping on the inside. BUT ( contradiction is coming)...I 'might' apply a layer of matt on the inside....BUT...that is AFTER I took the bumper brace and test fitted it and LOOKED to see how close the bracket is coming to the opening that you 'could' just apply tape over. Hopefully that made sense.
I generally do not like to apply matt and resin on the inside of these area where the factory has the mounting surface of the bumper brackets so nice and flat. IF I do...then I also make sure the surface is flat by using a trick with the VPA.
