Best adhesive for this plastic repair?

[Oro_O]

Doing some maintenance and this uber-fragile mounting clip finally broke. I'll buy another one soon, they aren't terribly expensive, but in the mean time I'd like to stick it back on so the part is in place.

I am thinking possibly rubber cement so the acetone melts each surface a little and makes a strong welded bond. I think super glue would be too brittle. Gorilla Glue? I haven't used that much and don't know all it's properties. Others?

 

[92saturnsl2]

I would use a 2-part epoxy. There's some varieties that are made for plastic, but any quick setting epoxy will do.

If there's a lot of force on those tabs, I don't think any kind of adhesive will work long term.

 

[JimPghPA]

Very likely the only way to fix that would be to get the plastic to weld. There is a liquid that causes plastic to weld to plastic, it is called THF. Unfortunately it is hard to keep in stock because it evaporates very easy. The glue for putting PVC pipe fittings together has THF in it, and may work, but you would have a better chance with pure THF. Companies that mold plastic sometimes stock THF. Some of them buy it by the 55 gallon drum.

 

[AutoMechanic]

I’d use Epoxy that has always worked for me on plastic or JB Weld

 

[spasm3]

I would use a small amount of JB weld and get it together. When it sets, wind a lot of rounds of unwaxed dental floss around it, past the crack. Then put JB weld all around that.

 

[Imp4]

I'd try the JB Weld that is specific for plastic.

JB Weld PlasticWeld

 

[ctechbob]

Very likely the only way to fix that would be to get the plastic to weld. There is a liquid that causes plastic to weld to plastic, it is called THF. Unfortunately it is hard to keep in stock because it evaporates very easy. The glue for putting PVC pipe fittings together has THF in it, and may work, but you would have a better chance with pure THF. Companies that mold plastic sometimes stock THF. Some of them buy it by the 55 gallon drum.

I think this is going to be the only thing that has a chance of working. Clean it with the cleaner and then use a pipe cement that's rated for multiple plastics. Nothing else is going to melt any of the plastic and is going to rely on just sticking to the outside.

 

[JHZR2]

Do we know the type of plastic? It’s sometimes marked. Some plastics with low surface energy need additional treatments and special epoxies. I have a thread about that on here someplace.

 

[Driz]

Glue won’t work long if at all. Me I’d leave the good tab and make a new one from a similar piece of steel. something thin like flashing or a dog food can cut out. Make it the same size as the original ( both ears together). Bend to shape then glue and screw to attach to the good ear. I’d either drill or melt a pilot hole in everything ( both ears) Then carefully put one small pan head screw in each ears middle. I’d epoxy sandwitch the tin to those ears if bulb access is via the lens but not if it (tin) needs removal to change a bulb.
It took longer to describe this than it will to make it. Guaranteed it will outlast the car. Maybe someday someone will explain how they can make a plastic so tough those tiny Stainless steel slide rails won’t break off a pistol with a plastic frame yet snap when it’s a clip on a pannel. They do it with such amazing regularity too. Junk by any other name is junk..

 

[RooflessVW]

Looks like a job for Double Bubble

 

[wdn]

The best adhesive for plastics that I have used is Quick Grip by Beacon. I don’t thing there is a good solution for the repair you are attempting though.

 

[PimTac]

“I'll buy another one soon, they aren't terribly expensive”


This right here. How much will the adhesives and other items needed to repair this cost? Chances are you will spend time trying to fix it and have it break again.

Buy a couple.

 

[Silver]

I'd try to make a reinforcement out of alum flashing or similar like mentioned above and epoxy it after scuffing it up. Nothing is gonna hold that short of a very tedious and very lucky weld. There are some hobby grade glues that come to mind but goodness, they'd cost as much as the light.

Heck just silicone the backing onto the car. Or tape over it with packing tape.

 

[mk378]

If you just want to get it back attached to the car until you get a new one(*), forget the clips. Do what @Silver suggested, put a little adhesive between the flat part of the back of the light and the car body. Foam double-stick tape would likely work and be removable.

* a new light, or a new car.

 

[wrcsixeight]

My plastic fixing process revolved around superglue, and fiberglass, sometimes carbon fiber, both I have plenty of on hand from my other interests.

I use superglue to glue the two halves together and let it cure and treat it as ultra fragile

I can go as far as digging grooves with a dremel and cut off wheel/saw, and even farther drilling tinny holes at opposing angles within that groove.

Cut fiberglass to fit inside the groove, fill the groove with superglue, tweezers to lay the fiberglass into the superglue, then the nose of the superglue bottle to fully saturate the fiberglass. It does not go fully clear but it is obvious when it is fully saturated.
I don't stress the break for many hours, preferably overnight, and if it is still stinky the next day I let it go longer.

This process can yield repairs far stronger than the broken piece ever was

Issues can be the fiberglass sticking to the tweezers. This process does not work well with superglue gel. and some superglue brands are more prone to glass sticking to tweezers than others.

All surfaces get wiped with isopropyl alcohol first, knowing it might make black plastic white.
Black sharpie can do wonders for cosmetics.

On repairs which need to remain highly flexible I attempt to saturate fiberglass with Shoe goo/amazing goop.

On the broken part in the OP, I'd use two dabs of rtv and masking tape or double sided tape while awaiting delivery of new part and save my superglue for something else. If the part was unavailable new, Id probably use more masking tape and clear rtv rather than fixing that small tab, is its likely the other side will just break too.

 

[willbur]

Doing some maintenance and this uber-fragile mounting clip finally broke. I'll buy another one soon, they aren't terribly expensive, but in the mean time I'd like to stick it back on so the part is in place.

I am thinking possibly rubber cement so the acetone melts each surface a little and makes a strong welded bond. I think super glue would be too brittle. Gorilla Glue? I haven't used that much and don't know all it's properties. Others?

View attachment 30068

Devcon Plastic Welder- claimed 3600 psi strength.

 

[otis24]

Super glue mixed with baking soda

 

[Touring5]

JB "Plastic Bonder" would be my first choice. Second would be to "weld" it with a soldering iron. I've seen people make some amazing repairs on HDPE with that technique and using milk jug pieces as the "solder".

 

[MasterSolenoid]

So anything you do will be temporary / until you get a replacement.

What about slipping a piece (or two) of Shrink Tubing over both pieces and heating it up.
That would at least hold the broken piece on.

 

[atikovi]

Try this and you will never buy anything else. I use it on bumpers, grilles, dash parts, anything plastic. It's what Ford and GM uses on the production line.