Author Topic: Blazer top - what material?  (Read 2539 times)

Offline haroldwca

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Blazer top - what material?
« on: May 02, 2022, 10:16:47 PM »
I was under the impression that Blazer tops were fiberglass, but was recently challenged on that point.  The contention is that they might be SMC (sheet molding compound).  All that I know about SMC is what it stands for.  What's the right answer ?  I picked up a 1975 full top at the local pick and pull, and I hope to put a truck under it someday.  The top needs work, and I thought I'd bring it back to life while I look for the right vehicle.  Thanks to any who respond.

Offline ehjorten

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Re: Blazer top - what material?
« Reply #1 on: May 03, 2022, 09:12:30 AM »
SMC is fiberglass. It is just a method of producing fiberglass parts where there is a matched mold that is closed on sheets of fiberglass and resin that then flows under pressure. It is a sheet material that is made by chopping glass fibers onto a sheet of plastic film on which resin, initiator, and usually a filler mixture has been applied. Another film also having the resin mixture on it is placed on top creating a sandwich and then it is passed between rollers to compact it.
SMC matched die molding has the advantage that both the interior and exterior surfaces are finished. Complex shapes such as ribs and thin details can be molded. Higher production rates are possible. Labor costs are lower than open mold. Minimum trimming of parts is needed. Closer part tolerances are possible.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
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1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline VileZambonie

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Re: Blazer top - what material?
« Reply #2 on: May 03, 2022, 06:47:10 PM »
Once you start sanding, you'll see  ;D Prepare to itch
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline JohnnyPopper

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Re: Blazer top - what material?
« Reply #3 on: May 03, 2022, 06:49:25 PM »
Have a pair of panty hose standing by... ;)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline fitz

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Re: Blazer top - what material?
« Reply #4 on: May 04, 2022, 09:35:06 AM »
Can't help with any advice, but that's a rare top that you found.
Nice job.

Offline haroldwca

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Re: Blazer top - what material?
« Reply #5 on: May 06, 2022, 07:47:08 PM »
SMC is fiberglass. It is just a method of producing fiberglass parts where there is a matched mold that is closed on sheets of fiberglass and resin that then flows under pressure . . .

Interesting, and thank you for the immense amount of information.  The reason for the question is that the other source of information seemed to indicate that the resins were incompatible.  But since were are talking about the same material, I can proceed without concern for any incompatibilities.  I have worked fiberglass before, but nothing on the scale of that which I will be undertaking.  No matter - I am unintimidated by the scale of this project.

Can't help with any advice, but that's a rare top that you found.
Nice job.

Thank you.  I spotted it on a truck that was literally rusted up to the door handles.  The only thing left on the truck worth having was the top and a few bits of Blazer only trim, which I scavenged also.  Honestly, a lot of people would have probably walked away from the top, but recognizing that this is a three-year-only top, I have rolled the dice that I can fix it.  In my 25 years of junkyarding, I have only seen two full-convertible K5 tops in the boneyard.  Logisitcs didn't allow me to score the first one I saw about 15 years ago.  I wasn't about to let the second one go by.  It WILL be used eventually. 

Vile, I know what you mean about the itching.  Johnny, I'll have to plead ignorance on what you have in mind for the hose.  Can you elaborate?

Thanks to all.

Offline JohnnyPopper

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Re: Blazer top - what material?
« Reply #6 on: May 06, 2022, 08:44:27 PM »
The weave on pantyhose is so fine that it will pull the fiberglass shards out of your skin.

I used to keep a pair that had runs under the seat of my truck for when I had to go into attics.

Made sure my wife knew that she gave them to me... ::)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline VileZambonie

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Re: Blazer top - what material?
« Reply #7 on: May 07, 2022, 06:10:35 AM »
How bad is the top? Do you have pics? Mine came out really nice and looks great now.
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline fitz

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Re: Blazer top - what material?
« Reply #8 on: May 11, 2022, 06:33:13 AM »
If you don't own a 73-75 k5 you might want to go back to the truck and cut off the windshield frame.
This may come in handy it you decide to retrofit your top onto a 76-91 truck.

Offline haroldwca

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Re: Blazer top - what material?
« Reply #9 on: May 11, 2022, 05:25:41 PM »
I would have if it hadn't been as rusty as the rest of the truck.  There was really not much structural integrity left across the windshield header.  The bed floor was the best part of the truck, if that tells you anything. 

Vile, I tried to upload pics last night, but it didn't work out.  I'll give it another try.

Offline VileZambonie

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Re: Blazer top - what material?
« Reply #10 on: May 12, 2022, 07:18:45 PM »
If you or anyone else for that matter comes across a 73-75 set of sill plates, I'm in the market! If you are having a hard time posting pix, they are probably too big and need to be resized.
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline haroldwca

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Re: Blazer top - what material?
« Reply #11 on: May 12, 2022, 08:49:02 PM »
I'll keep you in mind.  The sill plates on this particular truck were long gone.  There was no sheet metal left for them to be attached.  I'm curious that you specify '73-'75 sill plates.  How are they different from post-'76 models?  I've seen catalog listings for '73 - '77 Blazer sill plates, but I know that catalogs sometimes sell items as "fits" rather than "exact replacement".

I'll try to re-size the previously mentioned photos in a later post.

Offline VileZambonie

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Re: Blazer top - what material?
« Reply #12 on: May 13, 2022, 02:40:23 PM »
They sell a generic fit but not these pieces
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              ⌠ŻŻŻŻŻ'   [☼===☼]
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline blazer74

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Blazer top - what material?
« Reply #13 on: May 13, 2022, 10:18:15 PM »
73-77   Blazer for the sill plates.
« Last Edit: May 13, 2022, 10:20:21 PM by blazer74 »

Offline VileZambonie

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Re: Blazer top - what material?
« Reply #14 on: May 14, 2022, 08:51:03 AM »
Yes 73-77 are the same design
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                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10