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Username Post: Under-dash A/C plastic cracked - Glue or ??        (Topic#364013)
BigDogSS 
"12th Year" Silver Supporting Member
Posts: 4904
BigDogSS
Loc: SoCal
Reg: 12-21-01
01-17-21 06:22 PM - Post#2812285    

Hi All,
One of the plastic pieces for the under-dash HVAC system is cracked. What glue or silicone or RTV or ???? can I use that will withstand both A/C and heater?
Any suggestions or help would be appreciated. Thanks!

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



Edited by BigDogSS on 01-17-21 07:04 PM. Reason for edit: No reason given.

 


tooomuch7 
Frequent Contributor
Posts: 1331

Loc: Hartford Ohio
Reg: 03-18-02
01-17-21 06:43 PM - Post#2812287    
    In response to BigDogSS

I have some plastic pieces to glue also,I’m going to try Gorilla glue for plastic.

http://www.picturetrail.com/gallery/view?p=999&gid=5387542&uid=2695815&members=1


 
BigDogSS 
"12th Year" Silver Supporting Member
Posts: 4904
BigDogSS
Loc: SoCal
Reg: 12-21-01
01-18-21 10:36 AM - Post#2812327    
    In response to tooomuch7

Here are a couple of pictures.

Attachment: 2021-01-18_10.26.39.jpg (2.28 MB) 3 View(s)




Attachment: 2021-01-18_10.26.47.jpg (3.01 MB) 4 View(s)




    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



 
tooomuch7 
Frequent Contributor
Posts: 1331

Loc: Hartford Ohio
Reg: 03-18-02
01-20-21 02:53 AM - Post#2812454    
    In response to BigDogSS

Wow,that’s pretty bad.

http://www.picturetrail.com/gallery/view?p=999&gid=5387542&uid=2695815&members=1


 
59fins 
Member #212 "20th Year" Gold Supporting Member
Posts: 2438
59fins
Age: 60
Loc: Surprise Az USA
Reg: 04-07-00
01-22-21 09:58 PM - Post#2812681    
    In response to BigDogSS

How thick is that plastic?
Is it visible?
Can you get to the back side?
Almost looks like the plastic thickness of the defroster piece?
There are shops , body shops that do plastic welding, locating one may be the problem? Watch several demonstrations through the years, does not look hard to do, but it can also be hard not being able to get to the back side.
If it is thicker like the material on foot defuser at floor where heat comes out, or on regular a/c car that tube above defuser where a/c vent tubes are attached.
There are different types of plastic repair materials used to repair plastic bumper covers on newer cars, they are like regular 2 part epoxy, JB weld makes some for small jobs, and comes in different colors, I’ve used their black on cluster housings and a/c vents, on hard plastic tubes, in short, to use any product because you haven’t got a replacement, practice a bit on a different piece. Everything has to be clean, preferably both sides, first application is to hold it together, then work it with thin applications if possible.
The pieces in the pics, at least one of them appears like a repair may have attempted to be repaired before?
Hard to tell what the part is close up, red overspray suggests it’s not in a place that is seen, so your looking for function more than appearance?


Bill H.
67 SS




 
BigDogSS 
"12th Year" Silver Supporting Member
Posts: 4904
BigDogSS
Loc: SoCal
Reg: 12-21-01
01-25-21 04:34 PM - Post#2812919    
    In response to 59fins

Thanks Too and Bill.
Actually, this is from a 1976 T/A I'm helping to restore. The red overspray is actually the reflection from my red toolbox. I cannot get to it from the backside as it is in the middle of the duct. It has not been fixed before. I'd like to at least fix long crack first and see that comes out before tackle that larger chunk that missing. That part in under the center of the dash, at the bottom. The pictures are showing the bottom of the piece and I'm pretty sure it will not be seen.
Harbor Freight sells plastic welder that I'm think about trying.

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



Edited by BigDogSS on 01-25-21 04:39 PM. Reason for edit: No reason given.

 
59fins 
Member #212 "20th Year" Gold Supporting Member
Posts: 2438
59fins
Age: 60
Loc: Surprise Az USA
Reg: 04-07-00
01-26-21 09:37 AM - Post#2812981    
    In response to BigDogSS

Denis,
Just thinking out loud, the 2 yellow arrows does not need to be fixed? cause it appears maybe some seam sealer was used there at one time?

And the red arrows are the main deal, the big arrow a screw probably goes through? As why is broke in the first place? Guessing..

And if it is where a screw goes through, is it from the top of pic going down? Cause if it is, how long of a screw is it?
The reason I say that, it may be that the screw may draw that together when installed (fingers crossed), put a small washer that would fit the big arrow area? before tightening it up, use do dum dum (3m strip calk sealer) stick it in the crack before you tighten it up, no hard to tell if that is a screw area, and if it is, is there enough to grab it? Once the crack is pulled together the dum dum will cleanup pretty easy. The Yellow arrow areas, not sure if they are supposed to be that way or not ?

When plastic welding, you need to know what kind of plastic it is, and I think the only place you would benefit is the area of the big red arrow, being a novice plastic welder that is if you try that way, practice on something first.... cause it could look worse than the crack ...

Not sure there is a perfect answer here, but if it not seen, I would keep it as simple as possible, once the screw is in place, dum dum could cover the area of the screw as well.

my 2 cents anyways





Attachment: med_1610994987-2021-01-18_10.26.47.jpg (233.33 KB) 3 View(s)




Bill H.
67 SS




 
BigDogSS 
"12th Year" Silver Supporting Member
Posts: 4904
BigDogSS
Loc: SoCal
Reg: 12-21-01
01-26-21 03:32 PM - Post#2813008    
    In response to 59fins

Hi Bill,
Correct, The yellow arrows are just seams, no crack there. I attach another picture from the internet. So it looks like the crack on the piece is facing the interior, which is probably why it is broke. That area (big RED arrow) is a half-circle (mount) that bolts to a bracket. See GREEN Arrow. I want to focus on the crack first (small red arrows), then try to repair the broken mount area (big red arrow).
Is the 3M stuff black? Others have suggested JBWeld. I might be able to clamp it while it dries.

Attachment: TA_duct.jpg (41.96 KB) 3 View(s)




    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



Edited by BigDogSS on 01-26-21 03:58 PM. Reason for edit: No reason given.

 
59fins 
Member #212 "20th Year" Gold Supporting Member
Posts: 2438
59fins
Age: 60
Loc: Surprise Az USA
Reg: 04-07-00
01-26-21 06:57 PM - Post#2813044    
    In response to BigDogSS

Agree, I'd go with the 2 part JB weld black plastic repair, the 3M stuff does not harden, it is a sealer.



Bill H.
67 SS




 
gcrkfrd 
"3rd Year" Silver Supporting Member
Posts: 241
gcrkfrd
Age: 74
Loc: Neosho, MO.
Reg: 04-01-18
01-28-21 05:47 PM - Post#2813165    
    In response to 59fins

I bought the plastic welding, hot air blower at HF, to play with. Fixed ac duct on Br--co, and bumper, on Lin--ln, used the small tip like a soldering iron, cut filler rods out of scrap duct, and bumper.

They asked me, why a Four door, and a Six, and I told them, JUST BECAUSE.


 
59fins 
Member #212 "20th Year" Gold Supporting Member
Posts: 2438
59fins
Age: 60
Loc: Surprise Az USA
Reg: 04-07-00
01-28-21 09:08 PM - Post#2813175    
    In response to gcrkfrd

That sounds like a great way to go, and using like material is even a better thought. I have looked at them, but their selection of rods were sketchy, but if you have like material it makes common sense!

Bill H.
67 SS




 
56sedandelivery 
Gold Supporting Member
Posts: 5909
56sedandelivery
Age: 69
Loc: Everett, Wa.
Reg: 02-26-08
02-02-21 07:14 PM - Post#2813510    
    In response to 59fins

It would seem those pieces would be reproduced by one of the Camaro/Firebird, aftermarket parts suppliers. If it's so brittle it's breaking up the way it is, it'll just continue; glue it there, it breaks here, etc. I am Butch/56sedandelivery.




 
BigDogSS 
"12th Year" Silver Supporting Member
Posts: 4904
BigDogSS
Loc: SoCal
Reg: 12-21-01
02-03-21 02:36 PM - Post#2813557    
    In response to 56sedandelivery

Good point, Butch. Yes, they do make a reproduction. But believe or not, the piece really is not that brittle. I've "man-handled" with scrubbing and cleaning with no additional issues. I even sanded and painted the molded in metal air deflectors.
With all of that said, if we encounter any additional problems, I will push the issue to buy a new one.

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



 


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