Author Topic: Fan shroud plastic identification ???  (Read 1453 times)

DAVEN1256

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Fan shroud plastic identification ???
« on: May 17, 2020, 07:13:50 PM »
Can anyone identify the type of plastic an original '68 small block fan shroud (GM part number 3893812) is made from?

I want to attempt to repair some cracks in my original shroud. There are a lot of plastic repair products out there but they're all specific as to what types of plastic they will repair.

So before I can choose a product, I need to know what type of plastic I am dealing with.

Thanks.....Dave

169INDY

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Re: Fan shroud plastic identification ???
« Reply #1 on: May 17, 2020, 09:04:21 PM »
Yes, it can be a bear determining the base material then matching the appropriate repair method and medium.
I always hear guys talking about the 'burn' test.

http://engineeredplasticsblog.info/how-to-get-a-rough-idea-of-a-plastic-material-type-when-you-dont-know/

& then you see the Plastic Welding kits, Weller, eastwood etc,,,,,,,
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS
68 Z28 M21 LOS

rare396bronze

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Re: Fan shroud plastic identification ???
« Reply #2 on: May 18, 2020, 12:06:39 AM »
That shroud is still available from gm! I checked on one for a customer about 2 weeks ago it is the only still available.

169INDY

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Re: Fan shroud plastic identification ???
« Reply #3 on: May 18, 2020, 03:20:57 AM »
Avail interesting, I wonder how it measures up to the vintage NOS and originals.?
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS
68 Z28 M21 LOS

rare396bronze

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Re: Fan shroud plastic identification ???
« Reply #4 on: May 18, 2020, 03:34:16 AM »
Ordered one a year ago from gm  for a customer doing 68z28. Here was very happy with it.

169INDY

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Re: Fan shroud plastic identification ???
« Reply #5 on: May 18, 2020, 03:55:15 AM »
Does it have the curved arch in the top?
Photo please?

opps I know this is not what the op was looking for but It may be relevant?

Jim
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS
68 Z28 M21 LOS

KevinW

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Re: Fan shroud plastic identification ???
« Reply #6 on: May 18, 2020, 12:39:17 PM »
ABS repair rods worked well for me on kick panels, RS shields, etc.  Pretty sure the shroud is of ABS mix (stiff but flexible=ABS :)

DAVEN1256

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Re: Fan shroud plastic identification ???
« Reply #7 on: May 21, 2020, 12:28:48 AM »
Thanks for the replies.
 
I tried a burn test with a few slivers I cut from a hidden area. That really told me nothing. What I saw could fit several types of plastic. I'm not going to cut anymore off.

I've used a product called "Plastex" by G.T. Motorsports on other plastic items and it has worked great. It says it works on ABS but it will not bond to my shroud. It does say it will not bond to polypropylene and polyethylene.

I did see that this part is still available from GM. My past experience buying old parts that GM still makes new is that they will fit and will work but are not necessarily carbon copies of what was made 50 plus years ago. Can anyone comment on how close these new shrouds look to an original shroud?

Thank....Dave

KurtS

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Re: Fan shroud plastic identification ???
« Reply #8 on: May 21, 2020, 04:06:42 AM »
Pretty close....
Kurt S
CRG

z28z11

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Re: Fan shroud plastic identification ???
« Reply #9 on: May 21, 2020, 10:26:23 PM »
I have a recent NOS shroud from GM, plus a used OE shroud I can compare it to - which details do you want to compare ?

The NOS shroud is really close - not much difference in any details -

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06  1949 3100 5wd 235/6

169INDY

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Re: Fan shroud plastic identification ???
« Reply #10 on: May 21, 2020, 11:28:43 PM »
Does it have the curved arch in the top? or comparison of both; top view side by side pics or two pics so we can look down on both
Jim
68 SS/RS L35 Th-400 LOS
69 Pace Car L48 Th-350 LOS
68 Z28 M21 LOS

z28z11

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Re: Fan shroud plastic identification ???
« Reply #11 on: May 22, 2020, 01:57:34 AM »
Kurt is right (as usual) - pretty darn close. The OE is on the left, NOS on the right. Details right down to the "staple" marks are exactly the same in my view. Looking at the part numbers, you can tell they were made by the same suppier, if not the exact same mold. I may have labeled the part number pics wrong - the one listed as OE is probably the NOS - I think that's a '95 date stamping you can see below the part number.

Same weights, same materials. They are both heavy ABS, or whatever combination of plastic. The only thing I can't guarantee is if they made any vendor changes in the last year or two -

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06  1949 3100 5wd 235/6

HOGDADDY

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Re: Fan shroud plastic identification ???
« Reply #12 on: May 22, 2020, 02:23:48 AM »
Here is one I purchased around 1990 IIRC. Hope to use it one day.
I also bought the other for a/c too at the same time just in case.

It has 2 dates '93 & '94.

DAVEN1256

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Re: Fan shroud plastic identification ???
« Reply #13 on: May 23, 2020, 05:00:38 PM »
Thanks for the replies and info so far.

The pictures posted by z28z11 and Hogdaddy have raised new questions for me about my shroud.

Look at the areas circled in red in the first three pictures. The first picture is z28z11's OE and NOS shrouds side by side, the second picture is my shroud, and the third is Hogdaddy's NOS shroud from the 90's Where my shroud and Hogdaddy's shroud are cut out behind the upper mounting bracket bolt hole, both of z28z11's shrouds appear to have some material there with a hole in it. I don't know if my eyes are fooling me and seeing something that's not there. On mine that cutout needs to be there for the shroud to sit on the upper mounting bracket. The fourth, fifth, and sixth pictures are also of my shroud.

I also have no part number or date code on my shroud like all the others. Between the lack or a part number and the differences in that cutout area, I'm wondering if my shroud is original and correct. My shroud has been with the car since at least 1978.

Thanks.....Dave















HOGDADDY

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Re: Fan shroud plastic identification ???
« Reply #14 on: May 23, 2020, 05:31:54 PM »
Your eyes are fooling you that is the bottom of the shroud. The difference I see compared to original is in the rear of the circular part of the shroud.

Looks like you've done a good job repairing yours I wouldn't buy another.
« Last Edit: May 23, 2020, 07:31:54 PM by HOGDADDY »

 

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