I have a brand new front end but was trying to salvage the lower front bumper spoiler. I have a rip on the left side. Is there anyway to fix that or should I just go with a new piece???

 

You can get a plastic welder and melt the rip together. More from the back side.
Then do it a little in the front. Make a low spot on the front when you melt it together.
Then your going to want to use fiberglass to fix the front. then just sand flat, primer and paint.

Bondo tends to crack, so you need a filler thats flexiable.

 

You can also use plastic epoxy. I haven't done this yet. But it seems to have worked well for quite a few others.

 

Yeah, a two part epoxy will work. I like the consistency of the loctight brand epoxy putty. It's sandable and fairly flexible.

Of course the best way to fix it is to plastic weld it, but this is extremely difficult if you don't have someone who has done it to show you how. It's very difficult. I've got 4 welding certs in stick, mig, and tig. 2 of them are in stainless and aluminum. But I've never been able to quite get the knack of plastic welding. Could just be cheap equipment, I only tried the harbor freight unit.

I also learned a trick on fiberglassforum.com that might work. Get yourself a spare piece of the same plastic that the piece is made out of... shred it into fine pieces with a cheese grater and stick it in a metal container. Pour in some thinner, not a lot, and mix it up. If you continue to add thinner in small quantities and get the timing right, you will eventually get a paste-like texture to it. you can spread this around your rip and when it hardens it will bond with the surrounding material. I'll try to find the link for this process.

EDIT: Here it is: http://www.fiberglassforums.com/showthread.php?t=194

Mathius

 

anyone ever done this? got pics?

i tried it on a little piece of plastic and it seamed like it kinda melted the plastic around it which bonded it together? but i did it like 3 hours ago and it is still not dry, and it was only a little piece? would that mean i used too much acetone?

 

Sounds like you're close. You can go to the source site for more info if you want.

Found these for you:
http://www.mp3car.com/vbulletin/fabr...s-plastic.html
http://www.mp3car.com/vbulletin/fabr...bs-sludge.html

You'll have to do a search for more.

Mathius

 

so sounds like I would be better off buying a nice used one. I can do all the prep work as long as it doesnt have holes and rips in it. I found one on ebay for under $100 that will need to be stripped and primered so I think I might just do that. Lol, I found a brand new one for over $300, what a rip off!!!

 

wait, so is my bumper and gfx made out of abs?

i made a mix with abs should i of done that with a piece of the gfx? would it work the same if it is not abs, but the mix is made out of what ever ur fixing?


i hope i did not just tear up my gfx for no reason

 

Your gfx are not made of ABS and I doubt urethane will melt in acetone, so this would most likely not work. If you need something repaired, I got time for a project like that.

 

I never told you it was ABS. I said it might work, provided you with the directions and the links to research it yourself. If you didn't look into it more and just started tearing up your gfx, whose fault is that?

Mathius

 

hey dude, i did not blame anyone,

i just thought it was and decided to go for it,
i really had no choice, i have to repair this piece one way or another, so it really did not affect it!

but it did work for a 4th gen center console i had, so thanks for the info!

 

Alright, we're cool. I didn't realize the stock GFX weren't ABS or that it had to be ABS for that trick to work. Like I said, I read about it but never tried it.

One of the major struggles I had with plastic welding is not knowing how to identify what the base plastic is. The welder I used came with different colored plastic rods, each color signifying something else, but since I had no clue how to identify them, I just went by feel.

Seriously, the epoxy solution is not the best one, but it will work and it is by far the easiest. Like I said, I prefer the epoxy putty, and the texture of the Loctite stuff is pretty good.

I would also look into talking with the poster above who said he had time to help you with it. From the context of his message it sounds like he has experience with this, and unless he's going to charge you an arm and a leg, it would be worth it. Even better, if he'd be willing to take the time to show YOU how to do it, and then you have another skill you've learned, that is probably a bit more rare than what most people can do.

Stay away from fiberglass for this type of repair unless you plan on wrapping the whole part in fiberglass. Fiberglass doesn't flex well and it won't repair the rip properly, plus the fiberglass resin alone is not strong enough to bond to the plastic.

Mathius

 

If you need help identifying plastics (and the different color rod that welds them) or other types of repairs for different types of plastics http://www.urethanesupply.com has a lot of good info in their how to section.

And yes, Popballs and I are going to tackle a few projects on his car. I have the "free" time and he has a short list of things I can help him with.

You can't teach an old dog new tricks, but maybe this old dog can pass a few tricks on to someone that can use them.

 

i fixed my original peice two times and it failed both times from scraping from being so low....and i work at a body shop and have the tools to melt and what not and the finish materials, i eventually went with a new one, from gm there is no aftermarket available...if you can scrapes are any point on the front gfx, get a new one, you can fix the old one all you want, if you hit, it will break and crack again....

but if you do have to fix yours and no way around it, make a plate from sheetmetal and glue it in and screw it in from the front makin sure to sink in the heads of the screws, do the body work and prime and paint, thats the strongest way to do it

 

The best way to fix a plastic bumper cover I've found is like this (I am a bodyman BTW). It does require some flexible/sandable plastic repair adhesive and matching adhesion promoter liquid, which can be hard to find if you aren't in the autobody business though. You also need some fibreglass tape (not cloth or mat, fibreglass tape is different)

First - clean your bumper. You want to get as much of the possible contaminants off as you can. Use wax and grease remover, then soap and water wash (carwash soap is good, as long as its the non-wax stuff), then wax and grease remover again.

*once you cut into the plastic, do NOT clean it with anything but blowing off with compressed air - no cleaners!!*

Now you want to grind down the bumper, with a bevelled edge leading into the crack. You want to do this on both sides of the plastic. Your bevelled back area should extend out from the crack for about 2" or so on either side of the crack, and both sides of the plastic, though a bit more isn't a bad thing. (see pic below)

Now, you want to open up the crack somewhat. You'll want a gap between the two sides around the thickness of a penny or two (2-3mm). Now the grinding is done. Blow off anything left behind from grinding. Apply your adhesion promoter to all the exposed plastic, and let it dry as-per directions on can.

Now, get some fibreglass tape and cut a peice that will extend almost to the end of your ground off plastic. Don't put it on yet, just hold onto it for a minute.

Take a piece of aluminum tape, and apply it over the crack on the outside of the bumper to seal it off from the back. Get out your plastic repair adhesive and a clean putty knife. Mix up a fairly large batch, or use the mixing gun if you have one. Spread a thin layer on the ground off plastic on the inside of the bumper (opposite the side you put the aluminum tape on, the side you don't see), and apply your strip of fibreglass tape. Push it into the adhesive. Now, spread more adhesive overtop of the fibreglass tape with the putty knife and cover ALL the plastic you ground away and put adhesion promoter on. The entire strip should be covered and buried under the adhesive. Its like frosting a cake. Push down on the knife a bit while spreading to force some to squeeze through the crack. Let it cure. The aluminum tape is stiff enough that it should hold the crack together in the right position if the bumper isn't sitting funny.

Now that the backside is cured and done, flip it over and pull the aluminum tape of slowly. If any adhesive squeezed through - good. Scuff the adhesive that squeezed through with some 40 or 80 grit sandpaper untill there are no shiny spots left on it. This will give something to bite into for the adhesive going on this side.

Blow off anything on the bare plastic or glue, and apply adhesion promoter to all exposed plastic and cured adhesive. Do not touch with bare hands or use any chemical cleaners here.

Now, mix up more adhesive and spread it out over the crack and ground off plastic, just as you did with the backside, but WITHOUT using a fibreglass tape strip. Apply the adhesive thick, so the surface level is a bit above the surface of the bumper itself after its filled in the ground away area. Use the putty knife again to spread it out and cover all exposed plastic and adhesion promoter. Let it cure.

Now that its cured on both sides, you can sand down the adhesive on the visible side of the bumper (the part you did in the last step). Use a sanding block or DA sander, NOT YOUR BARE HAND! Start with 80 grit to get it fairly close, then 180 grit to finish sanding it down to the bumper surface and match the bumper contours. The 180 grit will also remove the deep scratches left behind by the 80 grit paper.

If you took your time sanding, the adhesive will be just like applying body filler to metal, and will be invisible once its primed. This is why they make sandable plastic adhesives.

The pic I made may help make sense of some of it...

 

We use a 3m product.It is a patch that is glued to the back of the repair.The front of the repair is dug out and a bondo like material is layed over the area.Then it gets blocked, primed,sanded and painted.It works really well and I have been happy with the results.

 

Thats pretty similar to what I described above, only mine you actually make your own patch, instead of taking one out of a package. Same idea though.

 

got an idea

what if you epoxyed a piece of urethane on the back of the repair