VRaptor SpeedWorks, LLC
04-24-2020, 02:40 PM
I'm posting this because this is probably the 5th GTM we've had in here like this. This is a car that we're working on for a customer. The customer purchased this kit 2nd hand, so I have no idea who the original owner was that did this work. With everyone stuck at home, I figured there might be some inclined to start in on projects like this....so I'm just putting this out there....hopefully it will help someone.
These photos represent how NOT to bond stuff to your car. The roof scoop on this car was bonded in exactly the same way.....and we removed it in exactly the same way. The parts came off pretty much completely intact. No damage to the part and no damage to the body. That should not be possible. If the part is properly bonded to the car, it is now all one piece that can not be separated without destroying both the part and the part it's bonded to. If you look at the photos, yes, that is bare, shiny gel coat that was underneath the bonded part. And the part was bonded to bare, shiny gel-coat. You can not simply set the part on top of the body, slather some fb mat and resin over the edges and deem it "bonded" to the car. It doesn't work. Out of all of the cars we've had thru here with parts bonded like this, many of those parts I "un-bonded" with a simple few taps with a dead blow hammer to break the parts loose from the body.....no damage to the part or body. The bottom side of the fb parts are not prepped and the surface of the body is not prepped and even if they were, you still can't simply bond the parts together by spanning a couple layers to fg mat over the edges and onto the body.
If you want to do this properly, first, you don't need a 5" wide flange all the way around the part. On these fender louvers, we'll trim the perimeter of the part down to probably about 1/4 of what it currently is when we prep it to bond back on. The bottom side of the part and the top side of the body MUST be properly prepped for a good bond....and that means getting rid of 100% of anything shiny. Use 36-40 grit on the body and the part in the area where the 2 pieces are going to be bonded. Once both parts are thoroughly roughed up and we have a good fit between the part and the body, we generally drill 1/8" holes thru the part and body every 3-5 inches (depending on the size of the part) to securely hold the part to the body. Then remove the part, clean the part and the body with alcohol or degreaser/wax remover, apply a generous bead of 3m 8115 so that it squishes out and leaves no air voids and cleco the part to the body, scrape down the excess 8115 and/or use the excess epoxy to blend the part to the body (like we did with the roof scoop in the photo) and let it set overnight. The next day, we remove the clecos (yes, they will be "stuck" in there a bit and will require some twisting to loosen them up and remove them) and then rough up all of the epoxy (no shiny parts left) and apply bodyfiller over the edge to blend the part into the body. You can not apply body filler over glossy gelcoat. It has to be sanded/roughed up for the bodyfiller to stick. You can see in the photos that these fender vents were fiberglassed right over shiny gelcoat and then bodyfiller was applied over the shiny cured resin and shiny gelcoat. That won't last. It will loosen and flake off over time. Everything must first be prepped and roughed up. Yes, the 8115 is expensive...but this is not the time to skimp and use as little as possible. You want it to all squish out from beneath the part when you cleco the part down and then paddle out or scrape off the excess.
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These photos represent how NOT to bond stuff to your car. The roof scoop on this car was bonded in exactly the same way.....and we removed it in exactly the same way. The parts came off pretty much completely intact. No damage to the part and no damage to the body. That should not be possible. If the part is properly bonded to the car, it is now all one piece that can not be separated without destroying both the part and the part it's bonded to. If you look at the photos, yes, that is bare, shiny gel coat that was underneath the bonded part. And the part was bonded to bare, shiny gel-coat. You can not simply set the part on top of the body, slather some fb mat and resin over the edges and deem it "bonded" to the car. It doesn't work. Out of all of the cars we've had thru here with parts bonded like this, many of those parts I "un-bonded" with a simple few taps with a dead blow hammer to break the parts loose from the body.....no damage to the part or body. The bottom side of the fb parts are not prepped and the surface of the body is not prepped and even if they were, you still can't simply bond the parts together by spanning a couple layers to fg mat over the edges and onto the body.
If you want to do this properly, first, you don't need a 5" wide flange all the way around the part. On these fender louvers, we'll trim the perimeter of the part down to probably about 1/4 of what it currently is when we prep it to bond back on. The bottom side of the part and the top side of the body MUST be properly prepped for a good bond....and that means getting rid of 100% of anything shiny. Use 36-40 grit on the body and the part in the area where the 2 pieces are going to be bonded. Once both parts are thoroughly roughed up and we have a good fit between the part and the body, we generally drill 1/8" holes thru the part and body every 3-5 inches (depending on the size of the part) to securely hold the part to the body. Then remove the part, clean the part and the body with alcohol or degreaser/wax remover, apply a generous bead of 3m 8115 so that it squishes out and leaves no air voids and cleco the part to the body, scrape down the excess 8115 and/or use the excess epoxy to blend the part to the body (like we did with the roof scoop in the photo) and let it set overnight. The next day, we remove the clecos (yes, they will be "stuck" in there a bit and will require some twisting to loosen them up and remove them) and then rough up all of the epoxy (no shiny parts left) and apply bodyfiller over the edge to blend the part into the body. You can not apply body filler over glossy gelcoat. It has to be sanded/roughed up for the bodyfiller to stick. You can see in the photos that these fender vents were fiberglassed right over shiny gelcoat and then bodyfiller was applied over the shiny cured resin and shiny gelcoat. That won't last. It will loosen and flake off over time. Everything must first be prepped and roughed up. Yes, the 8115 is expensive...but this is not the time to skimp and use as little as possible. You want it to all squish out from beneath the part when you cleco the part down and then paddle out or scrape off the excess.
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