Vovchandr Posted May 24, 2020 Share Posted May 24, 2020 As some of you know, my glued on fenders (Sikaflex) have failed on last NJMP 7's event. Even though they drove down to NJ just fine for hours from NY, I suspect the increased temperature of hot days and track have put the glue to the limit and failed. Ironically I was prepared and I brought my bolted on spares as well. Swapped after the fail and then the bolt inserts failed next... Either way I had to wait until temperature was warm enough to reapply the adhesive. Maybe this thread will help somebody in the future as this is a pretty common subject within the 7s community. Sikaflex is generally accepted as the top go-to adhesive but it comes in many varieties as well as different ways of application. I don't glue the fenders directly on as I like the ability to take them off for service issues and other parts swapping. So I ordered the big head fasteners. I originally used Sikaflex 292i (white). One side held just fine, the other fender 3 out of the 4 have failed to adhere to the stainless Bigheads. https://www.amazon.com/gp/product/B008F8VYMM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 This time around not only am I switching to Sikaflex 221 (black) I'm also using the Sika recommended primer on the one side. (Sika primer 207, pretty expensive for such a little bottle!) https://www.amazon.com/gp/product/B00NW5LWHA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 https://www.amazon.com/CRL-Black-Primer-207-Polyurethane-Adhesives/dp/B0737DN7CY The primer should help adhesion to the Bighead fasteners. Being a believer of don't fix it if it aint broken, I did not redo the side that hasn't failed but I laid a generous amount of new Sikaflex over the top for good measure. Link to comment Share on other sites More sharing options...
Vovchandr Posted May 24, 2020 Author Share Posted May 24, 2020 Pictures of the failed bond after scraping remnants off fender Sent from my Pixel 3a XL using Tapatalk Link to comment Share on other sites More sharing options...
Vovchandr Posted May 24, 2020 Author Share Posted May 24, 2020 Doubling down on ones that haven't failed Sent from my Pixel 3a XL using Tapatalk Link to comment Share on other sites More sharing options...
Vovchandr Posted May 25, 2020 Author Share Posted May 25, 2020 Failed side with primer Waiting 7 days for full cure now Sent from my Pixel 3a XL using Tapatalk Link to comment Share on other sites More sharing options...
Austin David Posted March 19, 2022 Share Posted March 19, 2022 What's the prevailing wisdom here? I've seen a few concerns about sika pulling off on racetracks and I've heard an anecdote about road use in Utah, possibly caused by HUGE temperature swings. 2015 book seems to want them screwed to the wingstays, Ikea 2.0 clearly says to use the powerglue / Sika stuff. I'm a 5200 fan myself. How aggressively should I attempt to fix these things, for road use? Link to comment Share on other sites More sharing options...
KnifeySpoony Posted March 19, 2022 Share Posted March 19, 2022 I used sikaflex 221 (there are many formulations, but I arrived on this one for reasoning that I cannot recall). I have had no issues up to 120mph on bumpy track surface. My technique was the one advised in the new build guide - ie the entire wingstay is enclosed in glue. Link to comment Share on other sites More sharing options...
Austin David Posted March 19, 2022 Share Posted March 19, 2022 Thanks (again) -- so that's gonna be something like (p136-141 in the 2.1 Ikea book): - prep the stay w/ 100# sandpaper + acetone - layer of adhesive on top of the stays - tape the wing down, wait 24h - remove the wheel, add MORE adhesive at the sides of the stay, full length under the wing - let it cure more Link to comment Share on other sites More sharing options...
Vovchandr Posted March 19, 2022 Author Share Posted March 19, 2022 My quick advice is buy the expensive sika primer if you use sika Link to comment Share on other sites More sharing options...
KnifeySpoony Posted March 19, 2022 Share Posted March 19, 2022 Some people do this: But I did this (not my photo, my glue is black) Link to comment Share on other sites More sharing options...
Austin David Posted March 19, 2022 Share Posted March 19, 2022 I have the fibreglass / painted wings, a LOT of texture on the bottom. I'm actually spending more time lining the wires to pass through the stay. Looks like I'll be able to start glueing this evening. Link to comment Share on other sites More sharing options...
Vovchandr Posted March 19, 2022 Author Share Posted March 19, 2022 Big difference is also if you want them removable and you use big heads or if you want them permanently attached. permanently is obviously easier and has more material to bond with Link to comment Share on other sites More sharing options...
Pokey Posted March 19, 2022 Share Posted March 19, 2022 1 hour ago, Vovchandr said: Big difference is also if you want them removable and you use big heads or if you want them permanently attached. permanently is obviously easier and has more material to bond with I used an epoxy. While the bond is definitely permanent, when the time comes to replace the wing I'm planning on trying to saw through the adhesive with a thin wire, and if that doesn't work cut the wing off and then use a wire wheel to grind the residual from the wing stays. I'd consider just replacing the wing stays but suspect that would be more work than either of the aforementioned. Link to comment Share on other sites More sharing options...
Vovchandr Posted March 19, 2022 Author Share Posted March 19, 2022 1 hour ago, Pokey said: I used an epoxy. While the bond is definitely permanent, when the time comes to replace the wing I'm planning on trying to saw through the adhesive with a thin wire, and if that doesn't work cut the wing off and then use a wire wheel to grind the residual from the wing stays. I'd consider just replacing the wing stays but suspect that would be more work than either of the aforementioned. As somebody who's had to remount his fenders a number of times I'm very happy with big heads. I've had to redo the silicone when it failed and it's a PITA to be scraping it off, reprepping the surface and re aligning the fenders. I much rather just cut a few zip ties and remount. Replacing the stays can be annoying as well as an option. So far zip ties is the easiest method by far. Link to comment Share on other sites More sharing options...
Austin David Posted March 19, 2022 Share Posted March 19, 2022 How do you wire the indicator lights? The book has them grounded to the wingstay, and the hot/signal wire snaked through and tied across the wishbone. Did you splice in a disconnect? Or are you not using it at all, because racecar? Link to comment Share on other sites More sharing options...
KnifeySpoony Posted March 19, 2022 Share Posted March 19, 2022 I didn't install my repeaters, because racecar. Link to comment Share on other sites More sharing options...
Vovchandr Posted March 19, 2022 Author Share Posted March 19, 2022 No wires here. Because racecar. Link to comment Share on other sites More sharing options...
Pokey Posted March 19, 2022 Share Posted March 19, 2022 Yes, grounded to the stay. Below are pictures of the entire run from indicator to harness. Link to comment Share on other sites More sharing options...
Vovchandr Posted March 19, 2022 Author Share Posted March 19, 2022 Are we talking headlight blinkers or fender blinkers? Link to comment Share on other sites More sharing options...
Pokey Posted March 20, 2022 Share Posted March 20, 2022 I showed both, but believe the question was the indicator on the wing given that is the one that grounds to the stay. Link to comment Share on other sites More sharing options...
Austin David Posted March 20, 2022 Share Posted March 20, 2022 Fender blinkers, ya. I'm splicing the ground through, and the first time I have to remove it, I'm gonna splice the signal wire too. Sleeved all the way and the terminals tuck into the stay just fine. Esp if it's not molested with a ground screw. Link to comment Share on other sites More sharing options...
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