Paint/Body Corvette Materials, Techniques, and How To

C3 header bar bonding

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Old 12-01-2017, 10:06 PM
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Ksp3cialK
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Default C3 header bar bonding

So I have been reading a lot about this, I have an 81 so fortunately no rivets, unfortunately the bar just fell away from the fiberglass.
I have read many other post about adhesives, but they are all old, it's 2017 now and I'm sure technology for this stuff is better.
What is the best for the most affordable price? I'm considering west systems 610 at $24 for 190ml. Does anyone have experience with this? Also JB weld Plastic weld seems to bond metal to fiberglass with a 3500 psi rating? I'm not willing to spend almost 40 for a small tube of sem that I know I'll need a few for the job.

Any advice would be wonderful, thanks in advance!
Old 12-02-2017, 05:25 PM
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For what this is worth:

I would advise those who read this that a person should not look at it on how much it costs. If less than $40 a tube (X2) is going to break the bank...oh well. The last one I had to do I got by with one tube....and I used every drop.

SEM is what I use. If you have questions about this product...call them directly so I do not have to type it out. There are other adhesives form other companies that can bond steel to SMC... if you choose to use them that is entirely up to you. LORD FUSOR is one of them.

http://www.semproducts.com/product/d...roduct-details

http://www.ashland.com/industries/tr...ural-adhesives

www.lord.com/products-and-solutions/adhesives

I do not know if you are just looking to pump some stuff between the beam and the body to get it to bond again...or if you are going to do it correctly by taking it apart and the beam out.

Best of luck if you plan on pumping adhesive in where it has separated and not completely remove it. because if it is not prepped correctly or applied correctly...it just may not work..and then having to do it again with that adhesive in there making it much harder.

And just also be aware that not all of these adhesives are exactly the same. Some may require an epoxy primer to be applied to the prepped bare steel in order for it to adhere due to its chemistry....while others being epoxy based can go directly on clean rough bare steel as long as you coat the bare exposed areas of steel entirely.

DUB
Old 12-02-2017, 05:57 PM
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The beam is already out and fairly rusty so I will be purchasing a new one, I plan to somehow get the old adhesive off and do whatever prep is needed for the materials to bond properly. It's just the exact adhesive to use is where I'm lost. I don't want to be too cheap but also would like to save where I can to put into other parts of the car and eventually new paint. This car will just be a driver and maybe the occasional casual show.
Old 12-02-2017, 07:10 PM
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To aid you in removing the adhesive that is still stuck to the body...you can use a heat gun and heat it up and it will soften and your can scrape it off.

DUB
Old 12-03-2017, 07:49 PM
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I'll have to give that a shot, upon more research, I found some data for the west systems six 10. Seems very strong when cured and that it can bond metal and fiberglass. I would use the PLIOGRIP stuff but the special gun required cost a lot.
Physical properties of cured epoxy
Specific gravity ........................................ ........................................ .......................1.18
Hardness (Shore D) ASTM D-2240.................................... ...................................80.6
Compression yield ASTM D-695..................................... ...............................9,690 psi
Tensile strength ASTM D638 ........................................ .................................6,440 psi
Tensile elongation ASTM D-638 ........................................ ..................................7.9%
Tensile modulus ASTM D-638 ........................................ .......................3.71E+05 psi
Flexural strength ASTM D-790 ........................................ ........................... 11,300 psi
Flexural modulus ASTM D-790..................................... ...............................3.51E+05
Heat deflection temperature ASTM D-648..................................... .....................127°F
Onset of Tg by DSC..................................... ........................................ ................127°F
Ultimate Tg ........................................ ........................................ ..........................133°F
Old 12-04-2017, 05:32 PM
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If you go with the SEM stuff.....I am quite sure that in your area...you contact SEM and get the name of the area rep or a place that sells it...and they will loan you the applicator gun for a one-time use kinda thing.

If you go with the WEST SYSTEMS stuff...make sure you follow whatever they say about how you have to prep the metal/SMC to the letter.

DUB
Old 12-12-2017, 11:20 AM
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I called West systems up and they recommended me thir G/flex 655 saying its the best they have.
https://www.westsystem.com/specialty...poxy-adhesive/

He also mentioned the metal needed to be freshly sanded to adhere the best. He seemed very confidant that the product would have no problem holding the bar in Tennessee heat with the weight of the headlights.
Old 12-12-2017, 05:29 PM
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Not that this matters...but the SEM 39747...it only took one cartridge to install it. So that will at least let you know that about 7 fluid ounces can do the job. The G-flex 655 looks like a good product. And at 9 fluid pounces...you are good to go. And if you use it ...I am sure it will do everything that West Systems says it will do.

These products are made so that the sun will never get the panel so hot that it actually falls apart. The odds that someone is going to be out in Death Valley...is not likely.

You are aware that the support beam you are bonding in is also held up at each end by the bolt-on gussets that bolt to it and the front face of the inner skirts.....and also the center support rod aids further support so the adhesive is to bond the beam to the body.....so the strength of the adhesive is not the only thing being used to help keep the beam from pulling away from it due to the headlgiths assemblies being so heavy. GM did take the weight into consideration of the headlight assemblies. For what they may be worth to those who read this.

DUB
Old 12-12-2017, 06:30 PM
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Interesting, I was actually going to ask about this, this car was a bubba car and did not have this center rod I don't believe, I'll have to look into that more. Also the gussets you were talking about, when I test fit the bar with a headlight in using a C-clamp, I got the one all lined up and looking good, I noticed the gussets are not touching the bar. There is about a half inch gap, maybe less as I did not measure. Is it normal for there to be a spacer in place? I have an 81 and I did not get the bonding strip because the original did not have one.
Old 12-12-2017, 06:57 PM
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The gussets that are bolted to your inner skirts have some movement to them due to the hoes in the fiberglass are larger than the actual bolt diameter.

As for if shims are needed between the gusset plate and the support beam..do what you need to do to get all parts fitted and installed.

DUB

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