Fixing various plastic cracks and missing pieces
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Advanced
Joined: Aug 2020
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Fixing various plastic cracks and missing pieces
I’ve been using a conservative amount of super glue to help repair some of the cracks on various trim pieces. However, many pieces have broken off and the pieces lost. Do you guys have any recommendations for long term crack repair or sculpting new pieces?
I’ve considered fiberglass but I’m not sure how well it adheres to plastic and it’s very messy to work with. The car has plenty of spots where the screws have broken the plastic around the areas they’re meant to hold down.
I’ve considered fiberglass but I’m not sure how well it adheres to plastic and it’s very messy to work with. The car has plenty of spots where the screws have broken the plastic around the areas they’re meant to hold down.
Instructor
Joined: Feb 2021
Posts: 183
Likes: 41
From: N.E. Ohio
If my car I would attempt plastic welding . But be prepared for a lot of filing and sanding . Plastic welding is a skill however and if I failed to achieve what I considered a good repair I would then buy new reproduction pieces as I'm very particular about appearance and function .
Melting Slicks
Joined: Feb 2015
Posts: 2,069
Likes: 262
From: Park Ridge New Jersey
check out this seller on ebay, he seems to make a number of plastic pieces
https://www.ebay.com/itm/15277826404...53.m1438.l2649
https://www.ebay.com/itm/15277826404...53.m1438.l2649
Drifting
Joined: Feb 2017
Posts: 1,274
Likes: 399
From: Tacoma WA
2024 C4 of the Year Finalist - Unmodified
There is a product called Plastex that I have used to rebuild broken ears on trim parts. It works very well forming a plastic that becomes a part of the original piece to then be shaped and finished. You can find it at Plastex.net and I am not sure if it is sold anywhere else other than at their website.
Intermediate
Joined: Aug 2021
Posts: 33
Likes: 2
Permatex Plastic Welder
Permatex makes a two part epoxy called Plastic Welder. It can be purchased at local auto stores. I used it on the passenger side lower kick panel. The three plastic tabs that go under the passenger vent all crumbled into pieces when I loosened the bolts. I put them back together like a puzzle using the plastic welder epoxy. Once cured, I was shocked how strong they were. I tried to break the tabs again because I was skeptical and thought it was a waste of my time, to my disbelief they didn't break with moderate force applied. So I left them alone and reinstalled the panel without an issue.
The reaction from the two parts creates heat and I think it helps adhere to the plastic. I got some on my finger and it burnt me.
The reaction from the two parts creates heat and I think it helps adhere to the plastic. I got some on my finger and it burnt me.
Racer
Joined: Aug 2021
Posts: 321
Likes: 44
I was going to remove some of the parts that are cracked, and glue them from the back side. I used a hot glue gun to reinforce glued areas with some extra material when I had room. You will have better luck if you use a glue made specific for the type of plastic. I used to have a plastic factory near me and I’d stop and ask an engineer what he recommended. Some of the methods already mentioned are worth a try. Plastic welding from the back side with a soldering gun, melting the crack back together, then reinforce when there is room. Take care tightening the stuff back down.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Permatex makes a two part epoxy called Plastic Welder. It can be purchased at local auto stores. I used it on the passenger side lower kick panel. The three plastic tabs that go under the passenger vent all crumbled into pieces when I loosened the bolts. I put them back together like a puzzle using the plastic welder epoxy. Once cured, I was shocked how strong they were. I tried to break the tabs again because I was skeptical and thought it was a waste of my time, to my disbelief they didn't break with moderate force applied. So I left them alone and reinstalled the panel without an issue.
The reaction from the two parts creates heat and I think it helps adhere to the plastic. I got some on my finger and it burnt me.
The reaction from the two parts creates heat and I think it helps adhere to the plastic. I got some on my finger and it burnt me.
FWIW, a YouTuber "SweetProjectCars" has a great vid on plastic parts repair.
EDIT: Oh yeah...on my riding lawn mower hood, I used screen (mesh) MELTED into the backside of plastic to reinforce a repair. For that, I used a Harbor Freight heat gun to melt the screen into the backside. FWIW...that can get plastic so hot it warps. Depending on the part, that might be OK...if you can redo (straighten) the visible surface using Bondo Glass.
PLUS: Link to aforementioned YouTube vids.... YouTube Repair Vids list
Last edited by GREGGPENN; Oct 2, 2021 at 04:44 PM.
