Switch to SMC

keywestjack

keywestjack

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Joined
Apr 24, 2008
Messages
258
When did GM go to SMC body pannels. I was watching a video from Ecklers and it suggests 1980. I have been told it was earlier.
 
When I went to Carlisle I ask the same question to the GM group. To my surprise they didn’t know but, said ask a retire guy named John at the GM tent who was a retired engineer at GM. Here is what he said." In the early 70's they started using SMC (not the kind that is used today) on flat panels at first." "So, the early cars contained both pressed fiberglass and SMC because the tooling was very expense to make." "As the years went on so did new tooling which replaced the old tooling until the whole car was SMC." He even told me how the process in making SMC was done but, that would take a good 1/2 day to explain so I won't go into it.

Danny.
 
The stuff in C4 vettes is different, it's a lot more resin and a lot less ibers, that's what Ecklers refers to as SMC and that stuff started in 82. The 82 hood and doors are made of that stuff.
 
Then what kind of bonding adhesive and resin should I use on my 77, polyester (for non SMC) or epoxy for SMC? The video said do not use polyester for SMC.
 
Evercoat SMC adhesive can be used as filler and it's compatible with fiberglass and SMC. It also comes in a 1 qt can so you don't need the expensive mixing cartridge gun :thumbs:
 
Come on guys, what's SMC?
Thanks

Although I don't know what SMC is, if I buy a repro panel for my 1970 as I'm planning, is it going to be "SMC" or is it going to be ????
 
It is a different process for making fiberglass panels. The problem is that repairs to either are different in the kind of resin used. It is my understanding that if you use polyester resin on SMC the repair will fail. Other than that I defer to one of the other guys for more explanation. Jack
 
SMC is a sheet that's molded in a hot press, for this process the sheet contains releasing agents so it doesn't stick to the mold. These release agents are what give problems with bonding regular polyester resins to it.
 
68/70Vette said:
Although I don't know what SMC is, if I buy a repro panel for my 1970 as I'm planning, is it going to be "SMC" or is it going to be ????
Click to expand...

Most repro panels are hand laid fiberglass, dunno if SMC panels are available from aftermarket suppliers or only GM "licensed" ...

You can tell by the price, if it's reasonably priced it's fiberglass :D
 
MYBAD79 said:
68/70Vette said:
Although I don't know what SMC is, if I buy a repro panel for my 1970 as I'm planning, is it going to be "SMC" or is it going to be ????
Click to expand...

Most repro panels are hand laid fiberglass, dunno if SMC panels are available from aftermarket suppliers or only GM "licensed" ...

You can tell by the price, if it's reasonably priced it's fiberglass :D
Click to expand...

:thumbs: The tooling cost too much for the amount they would sell I would think so by doing it by hand laying is the cheapest way. There is nothing wrong with it just use the compatible materials when working with it.

Danny
 
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The old GM guy was correct. SMC panels were introduced in 1971, the rear quarters were first. Over the next few years they switched more panels over to SMC.

THE C3 SMC IS NOT THE SAME AS C4 AND LATER SMC! You CAN use polyester resin on a C3. I should know, I have about a gallon of it on my 71 and it stuck just fine.
 
zwede said:
THE C3 SMC IS NOT THE SAME AS C4 AND LATER SMC! You CAN use polyester resin on a C3. I should know, I have about a gallon of it on my 71 and it stuck just fine.
Click to expand...

But if you are in doubt as to which to use, (I am learning here so let me know if I am wrong) use the epoxy resin as it is compatable for both.
 
No reason to doubt. The Dynatron polyester resin which is what we used on my '71 specifically states "for fiberglass and SMC" on the can.
 
Call these guys:

http://uscomposites.com/index.html

I've ordered from them before, they sell high quality products and they not overpriced. They have several epoxy and polyester resins, see which one they recommend for SMC

I am repairing my pace car style front spoiler and bought a QT Bondo resin from the local store. That stuff is junk compared with the resin from UScomposite, it's way too thick and does not "wet" the mat as good as it should. If you don't force it into the fabric or mat some of it will stay 'dry'
 
MYBAD79 said:
Call these guys:

http://uscomposites.com/index.html

I've ordered from them before, they sell high quality products and they not overpriced. They have several epoxy and polyester resins, see which one they recommend for SMC

I am repairing my pace car style front spoiler and bought a QT Bondo resin from the local store. That stuff is junk compared with the resin from UScomposite, it's way too thick and does not "wet" the mat as good as it should. If you don't force it into the fabric or mat some of it will stay 'dry'
Click to expand...

This is the epoxy from them. You use it for everything.
You can get either 5:1, 3:1 or 1:1 depending on your desired work time and strength, but all has at least 10x the adhesion of polyester or vinyl ester resins or any of the other bs stuff. Buy the pumps that screw into the bottles, only a couple bucks apiece and makes your mix very accurate.

DSC07019.jpg


This stuff comes in very handy as a filler or an adhesive.

DSC07018.jpg


They are off of Griffen Rd if you get up this way.
 
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