Best Adhesive for Exterior Applications?

[Joe_Cool]

Hey Everyone,

I'm reaching out to see if anyone can provide some insight on what all-weather adhesive would be best to secure a carbon fiber gurney flap to my S650 PP spoiler. I'm looking for an adhesive that is more permanent than 3M strips but not strong enough that it will damage the clearcoat/paint if taken off. I've had the NYTOP CF gurney flap installed on my S650 for the last 2 years, the gurney flap is still in great condition after daily driving my car in Michigan, however the 3M strips that hold the gurney flap to the spoiler are starting to deteriorate, and because of this the gurney flap is currently mounted on the car pretty loosely, enough to where it will definitely come off if I take the car on the highway. Since the Woodward Cruise is coming up, the last thing i want is for the gurney flap to fly off on the way there, so I am reaching out to better understand what type of adhesive would be best to secure the gurney flap that will withstand Michigan's temperature fluctuations, weather variables, and also strong enough that the gurney flap will be secure but not permanent enough that the adhesive will damage the paint if i decide to remove it. After a little research it seems like Permatex 81158 (general purpose silicone adhesive) would be my best bet for an adhesive, however i am no expert in adhesives and would rather seek insight on different adhesives and applications before applying the Permatex 81158 and potentially ruining the spoiler. Thanks in advance for your input!

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[Starship Enterprise]

3M adhesive tape and 3M adhesion prep. The Permatex silicone IMO is only good for creating a moisture barrier to keep water from degrading the tape. Put a bead of Permatex around the 3M tape without touching it.

I had nothing but 3M tape hold on a hood scoop and rear louvers for 18 years on my 06 Mustang.

Did you use 3M adhesion prep on the flap the first time? It’s a pretty important step.

 

[86pagt]

3M adhesive tape and 3M adhesion prep. The Permatex silicone IMO is only good for creating a moisture barrier to keep water from degrading the tape. Put a bead of Permatex around the 3M tape without touching it.

I had nothing but 3M tape hold on a hood scoop and rear louvers for 18 years on my 06 Mustang.

Did you use 3M adhesion prep on the flap the first time? It’s a pretty important step.

Totally agree with this …and make sure you use legit 3m tape l. I’m not sure if NYtop uses 3m or some off brand.

 

[Joe_Cool]

3M adhesive tape and 3M adhesion prep. The Permatex silicone IMO is only good for creating a moisture barrier to keep water from degrading the tape. Put a bead of Permatex around the 3M tape without touching it.

I had nothing but 3M tape hold on a hood scoop and rear louvers for 18 years on my 06 Mustang.

Did you use 3M adhesion prep on the flap the first time? It’s a pretty important step.

Totally agree with this …and make sure you use legit 3m tape l. I’m not sure if NYtop uses 3m or some off brand.

I would not have guessed any adhesive strip could hold on for 18 years, that's impressive! When installing i did prep the surface with both diluted isopropyl and the adhesion prep. The issue with the gurney flap's design and their use of adhesive strips was over time grime would get in between that flanged part of the flap that meets the spoiler, and the thickness of the adhesive strips left enough room for dirt and moisture to get into the flanged part, so over time the strips lost their stick since they were exposed to the elements. Suggesting to apply a bead of Permatex around the perimeter as a weather barrier is a great idea but since i am by no means an expert i was worried about how good the bead would look with my skill set. So I went ahead and removed the 3M strips completely, applied a bead of Permatex across the entire inside of the gurney flap, and not only is the gurney flap rock solid but it now fits near-flush onto the spoiler where there is a much smaller chance of grime to get in between there over time. Yes, there is still a chance of grime getting in there since i did not apply an external bead but the gap in between the flap and spoiler is near minimal now. I did not think the Permatex would bond as well as it did, but it's ideal for the fact that I know the gurney flap won't come off while driving, but at the same time if i ever choose to sell my car the next owner better like the gurney flap because it doesn't seem to want to come off anytime soon. Time will tell on its adhesive capabilities but for now I'm actually quite satisfied with how the Permatex turned out. I wish i had a before photo showing the gap but the photo attached shows how it now fits when using a bead of Permatex on the inside only.

 

[Starship Enterprise]

86pagt. Oh yes! I wouldn’t trust anything but 3M brand. I got some rear quarter window louvers that came with some cheap chinese brand tape and clone brand adhesion promoter. The louvers are super nice, but every review said not to trust the tape. I heeded their advice…lol.

Joe Cool: Glad it worked out for you! Based on the Ford parts I applied, the permatex is an additional adhesive, but I was pretty sure it’s true intent was to provide a barrier for water and dirt so the 3M tape is protected. But it sounds like you went with only Permatex for the bond, which should be just fine.I think it should hold well since you used the good stuff, and grime shouldn’t affect the silicone like it would the 3M tap.e

Also your flap takes some high pressure so solid adhesion is important. The only area on my 06 GT where the 3M tape struggeled was with my aggressive front splitter. The front bumper only allowed for a very thing strip of tape, and the downforce pulled down hard on the splitter. It never fully released, but did slide down a little, so I had to put a few tiny screws through the top lip of the splitter to lock it in place.

Speaking of adhesion, when I removed my stock rear spoiler I pulled up too hard and broke the 3M tape bond that holds the lip of the rear trunk module flush with the trunk. Always bugged me that the lip stuck up a little. Today I had the idea of drizzling thin Cyanacrylate (Crazy Glue) down into the trunk seam, and held it down while my wife sprayed kicker down into it. It worked! The trunk seam now sits flush.

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