May 10, 2016, 02:15 PM
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Bubbling Sail Panel Issue for Dummies
Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
OK, been driving myself crazy reading about this - just received my C/F sail panel and need to know exactly which epoxy primer and glue to buy. And the epoxy primer goes over the entire underneath of the panel, but the urethane only goes in a strip around the outside of the bare steel?
TECH Regular
Joined: Jun 2019
Posts: 494
Likes: 42
From: Hatboro, PA 19040
From what I read and see on you tube, ANY decent epoxy primer will do, but you can find GM's recommended primers on their TSB (service bulletin) you can find on links on the main page for this section.
You should stick (no pun intended) to one of the two urethane glues named in the GM TSB.
See the you tube video from TWA Motorsports (10 minutes), time index 5:49, He talks about cleaning the roof metal up and priming it with a special primer, it does NOT have to be bare metal, nor should it be.
Some also epoxy prime the top of the new sail panel also, for some reason.
Where did you get your replacement panel from?
From the TSB:
The following urethanes are available from outside auto parts suppliers:
U400 HV Essex (Dow)
3M® Urethane 08690
Also: "V cut the urethane tube and apply a 19 mm (3/4 in) high bead around the perimeter of the roof and the three dots across the back."
Also:
Products used and links Urethane https://goo.gl/mkQL9B Primer https://goo.gl/ZthkFj Adhesion promoter https://goo.gl/1oJrB9 Corner Trim https://goo.gl/sF7bBk 2 Sided tape https://goo.gl/5hsKHU
Also:
I believe this is different than the epoxy primer for the underside of the panel -- this primer gets brushed on to what's left of the original glue bead on the metal roof. See the video about 5:49 in to it.
3M Single Step Primer, 08682- Designed specifically to promote urethane adhesion
You should stick (no pun intended) to one of the two urethane glues named in the GM TSB.
See the you tube video from TWA Motorsports (10 minutes), time index 5:49, He talks about cleaning the roof metal up and priming it with a special primer, it does NOT have to be bare metal, nor should it be.
Some also epoxy prime the top of the new sail panel also, for some reason.
Where did you get your replacement panel from?
From the TSB:
The following urethanes are available from outside auto parts suppliers:
U400 HV Essex (Dow)
3M® Urethane 08690
Also: "V cut the urethane tube and apply a 19 mm (3/4 in) high bead around the perimeter of the roof and the three dots across the back."
Also:
Products used and links Urethane https://goo.gl/mkQL9B Primer https://goo.gl/ZthkFj Adhesion promoter https://goo.gl/1oJrB9 Corner Trim https://goo.gl/sF7bBk 2 Sided tape https://goo.gl/5hsKHU
Also:
I believe this is different than the epoxy primer for the underside of the panel -- this primer gets brushed on to what's left of the original glue bead on the metal roof. See the video about 5:49 in to it.
3M Single Step Primer, 08682- Designed specifically to promote urethane adhesion
Last edited by k3000; Oct 8, 2020 at 01:02 AM.
TECH Regular
Joined: Jun 2019
Posts: 494
Likes: 42
From: Hatboro, PA 19040
If someone here knows, I would love to know chemically speaking if the sail panel issues are any different when replacing with a carbon fiber panel instead of a fiberglass / FRP one? Specifically does carbon fiber suffer from the same bleed through if not properly primed and using the GM recommended urethanes?
I assume you won't be painting the panel? I'm thinking you want the carbon fiber look?
I assume you won't be painting the panel? I'm thinking you want the carbon fiber look?
Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
If someone here knows, I would love to know chemically speaking if the sail panel issues are any different when replacing with a carbon fiber panel instead of a fiberglass / FRP one? Specifically does carbon fiber suffer from the same bleed through if not properly primed and using the GM recommended urethanes?
I assume you won't be painting the panel? I'm thinking you want the carbon fiber look?
I assume you won't be painting the panel? I'm thinking you want the carbon fiber look?
From my research, it still needs the epoxy primer, which kind of makes sense that the issue is the glue not having a barrier. Now, it looks like $1000 plus shipping is what it takes. Glad I jumped on it when I did. Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
Also:
I believe this is different than the epoxy primer for the underside of the panel -- this primer gets brushed on to what's left of the original glue bead on the metal roof. See the video about 5:49 in to it.
3M Single Step Primer, 08682- Designed specifically to promote urethane adhesion
I believe this is different than the epoxy primer for the underside of the panel -- this primer gets brushed on to what's left of the original glue bead on the metal roof. See the video about 5:49 in to it.
3M Single Step Primer, 08682- Designed specifically to promote urethane adhesion
Should I use something like this for the underside of the panel?
https://www.walmart.com/ip/RUST-OLEU...dSellerId=1194
TECH Regular
Joined: Jun 2019
Posts: 494
Likes: 42
From: Hatboro, PA 19040
Hopefully someone who understands this better will chime in!
Yes, the 3M Single Step Primer, 08682 seems to only be for priming the urethane on the metal side.
And apparently you don't have to get every last bit of the old urethane off, bu that's still making me nervous leaving any of it on there!
Wow, that epoxy primer is expensive! I wonder if it's any good? Only 1 person rated it on Amazon so far, and the rating was 3 out of 5 stars.
Yes, the 3M Single Step Primer, 08682 seems to only be for priming the urethane on the metal side.
And apparently you don't have to get every last bit of the old urethane off, bu that's still making me nervous leaving any of it on there!
Wow, that epoxy primer is expensive! I wonder if it's any good? Only 1 person rated it on Amazon so far, and the rating was 3 out of 5 stars.
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I used some sort of spray on epoxy when I replaced my sail panel but don't remember the brand. I do know it was expensive. I cleaned off all the old urethane so I didn't have to worry about the old stuff causing any future problems. Most came off with a putty knife and then some sanding to ensure everything was clean.
Joined: Nov 2001
Posts: 34,631
Likes: 2,553
From: Schiller Park, ILL Member: #317
FWIW, there is no solid evidence that GM ever changed the urethane (adhesive/glue) on the latter 4th gens leading to this issue. Omission of the underside primer seems to be the primary or sole cause, therefore any minor residue of old glue on the metal structure likely wouldn't cause any future issues as long as the underside of the new panel is prepped properly. But, of course, it's best form to strip it clean of old adhesive during prep.
Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
Thank you all for the help. I guess I'll get the spray epoxy primer for the underside of the panel, I have the 3m primer on the way, but I was a bit concerned because it is only a 30ml bottle and I was thinking that isn't even close to enough to cover the entire sail panel. I'll keep you all posted as I have a black T/A and I'm going with carbon fiber sail panel and hood
TECH Regular
Joined: Jun 2019
Posts: 494
Likes: 42
From: Hatboro, PA 19040
I've only read the GM service bulletin about 15 times, my reading comprehension does not appear to be what it used to be, LOL! I can finally tell you with certainty that you need to hit the underside of the panel with 2 to 3 coats of a 2K epoxy primer for one thing, and you should also leave some urethane on the metal roof that was there to begin with. And you're supposed to use that 3M product on the original urethane on the roof and to prime the 2K epoxy primed panel. Basically, the 3M product is an adhesion promoter for the urethane bead. It says right in the service bulletin not to remove all the original urethane from the metal roof, and also says that in the TWA Motorsports You Tube video. You only use the 3M primer where the urethane bead will be, on BOTH the metal roof and also the new panel. But also 2K epoxy the entire bottom of the new panel, with several coats.
Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
I've only read the GM service bulletin about 15 times, my reading comprehension does not appear to be what it used to be, LOL! I can finally tell you with certainty that you need to hit the underside of the panel with 2 to 3 coats of a 2K epoxy primer for one thing, and you should also leave some urethane on the metal roof that was there to begin with. And you're supposed to use that 3M product on the original urethane on the roof and to prime the 2K epoxy primed panel. Basically, the 3M product is an adhesion promoter for the urethane bead. It says right in the service bulletin not to remove all the original urethane from the metal roof, and also says that in the TWA Motorsports You Tube video. You only use the 3M primer where the urethane bead will be, on BOTH the metal roof and also the new panel. But also 2K epoxy the entire bottom of the new panel, with several coats.
What color is yours?
TECH Regular
Joined: Jun 2019
Posts: 494
Likes: 42
From: Hatboro, PA 19040
Black as well! Is there any other color? !!! LOL
I got a good deal on this car too, and it basically had everything I wanted on it except maybe a WS6 hood.
I'm not sure, but I think i'm over it not being a real WS6 car! I don't see myself reselling it any time soon!
I got a good deal on this car too, and it basically had everything I wanted on it except maybe a WS6 hood.
I'm not sure, but I think i'm over it not being a real WS6 car! I don't see myself reselling it any time soon!
Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
As far as I'm concerned there is no other color on an LS1 trans am! And yes, My thought on a WS6 is that if you're going to keep it stock, then by all means go for it, but if you're going to change the hood, suspension, and exhaust, then why pay the premium for a WS6?
Staging Lane
Joined: Apr 2020
Posts: 51
Likes: 15
Oh, and I went ahead and ordered the rustoleum 2K epoxy primer: https://www.walmart.com/ip/RUST-OLEU...2-Oz/109998602
TECH Regular
Joined: Jun 2019
Posts: 494
Likes: 42
From: Hatboro, PA 19040
Your thinking on the stock WS6 makes sense to me.
I REALLY like that hood, just be careful with it, no gas struts!
That primer seems like a good choice for doing it yourself. Would love to hear from some of the other folks here about it!
I REALLY like that hood, just be careful with it, no gas struts!
That primer seems like a good choice for doing it yourself. Would love to hear from some of the other folks here about it!
Well damn it's now my turn to fix the sail panel, only took 19 years for it to start. I noticed a little bit a waviness before I parked it for the winter, now I've noticed a few tiny bubbles. So I guess I'm on the hunt for a 93-97(early98) panel or trying an aftermarket. I'll probably go with a used panel as aftermarket fiberglass parts make nervous in regards to fitment.