When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I used 3M fiberglass resin on my 80 to mold the bumper in. I didn't realize that there were 2 different kinds of resin. I have been using 3M fiberglass resin on my 73,77 and 80 for the last 25 years. I never had any problems. My 77 had the front bumper molded in with that for 8 years and it never cracked or had a problem. I put a 3/4 nose on the 73 and never had any problems either. Well the nose on the 80 is all painted so I am not going to change it until something if anything happens.
Can't find any info on if 20124 works on SMC. The 3M 692 resin is OK on SMC, hopefully 3M puts the SMC additive in the 20124 as well. Maybe give 3M a call and check?
If it doesn't have the SMC additive it won't stick. If your repairs are sticking you're good.
They are sticking fine. I also ground down the nose with 40 grit .There dosen't seem to be any problems. If it happens I will fix it over the winter. But like I said I used it on a 77 and didn't have any problems for the 8 years I had the car.