Fixing Cracked/Cracking Plastics

[cfaas416]

I'm performing a mini overhaul on my 2007 ATV and there are several areas where the plasics are cracked or starting to crack. Over the years I have tried most of the "exopy" solutions I could find and nothing seems to hold and be flexible to take the abuse I put it though. Anyone have any suggestions/techniques they recommend for this type of situation?



Thanks in Advance

 

[rkevins]

I hope someone has some good advise here, I would like to do the same to a 1990 model honda too, and have been thinking of asking the same thing

 

[cfaas416]

We've even tried on some "samples," to melt the two back together but no go, very brittle and not easy.

 

[e-tek]

First off is to find out what tpe of plastic you have: ABS or PVC. To do this you take a sliver and burn it genlty with a lighter. Generally, Whitish smoke is a PVC and black is an ABS. This is the key to the type of adhesives you'll use.

Of course - like anything - there's much more to it. Here's a great info source:

http://www.boedeker.com/burntest.htm

Oh ya - most automotive parts are ABS and an acrylic solvent type of glue is best. These types of glues generally "melt" the plastic together rather than sit on top....I've done a lot of old interior repairs and learned this the long slow hard way!!

 

[kbs2244]

This is a good time and excuse to learn how to weld plastic.
Most body shops will have a guy that does it.
You might want to make friends with that guy and pump his brain.

If you have HF near you can get their higher level kit for less than $200.00

Or:

http://www.hejet.com/

www.plasticweldingtools.com

Just like “real” welding, there are some basic things to know, material matching being the most important, then it is just a mater of practicing your technique.

I have not tried it myself (I have a neighbor who works at a body shop) but it is something on my list.

 

[shoot summ]

I used to "weld" the plastic on our 250r's by taking pieces of scrap fenders from the same model and color. I made a spoon type tip for my soldering iron, I would use a heat gun to get the plastic pretty warm, then use the soldering iron to melt over the crack laying some of the scrap plastic in at the same time. I would do the front and back. In some cases I would use safety wire to stitch the crack together until I got the "weld" started. I would dress the weld on the front side, smooth it out a bit, never could get the shine of the original plastic, but they always held.

 

[Bobhdus]

I use a Hot Air Plastic Welder made by Seelye. It is fairly easy. As said before, match up the material. There are plenty of videos on how to make repairs using this process. This type of repair is far superior than glues.

 

[Ric in Richmond]

If I am not going for a "like new" appearance just function I drill a 1/4 hole at the end of the crack and then a pair of small holes every inch or so along the crack. Then I grab my safety wire pliers and stitch the crack closed with individual "stitches" of safety wire. Keep the twist on the unfinished side and makes sure you put a pig tail on the end so you don't cut your self.

 

[dogmir]

There is another way to do this also. I use both methods in repairing scooter plastics which are generally ABS. You can make liquid ABS with abs shavings and MEK. Or you can use a plastic epoxy by permatex. I get this at Farm and Fleet which is a chain in the midwest but I am sure you can find it just about anywhere.

It works great with ABS. It has methylacrylic acid in it so it will bond chemically and physically. I just take a dremel and carve out the crack to make a valley out of it. This gives the epoxy more surface area to work with. I then fill the crack. Wait about an hour flip it over and do the same thing to the other side of the crack then sand it down. Sometimes you need to apply more then once to fill any tiny voids etc. I have even filled in big gaps with this method by using masking tape on the back of the hole and just flooding the area with this epoxy. If you take your time and sand it right following all of the angles and lines once painted you will never know it was cracked.

Permatex Plastic Weld

 

[cbacres]

Great info. My son is working a several ATV projects that this will help on.
What about painting? We never had painted any of the plastics due to the paint not flexing with the plastic. Anyone know of a pait that will flex, or do you think the weled plastic can be buffed to match surounding plastic?

If anyone has ideas, I have some extra plastic to try on.

 

[Bobhdus]

Check out Seelye videos at link below. I have used Hot air welding on numerous occasions for repairing of PVC piping where I work. There are times when hot air welding is preferred over tearing out a whole section and buying new fittings and re gluing. I have yet to have a repair fail (probably made at least 50 repairs with hot air welder). We use a Seelye brand welder but HF has some cheaper as do other Automotive repair suppliers. I bought a nice Seelye Welder for home use on Ebay last week for $100 that has a burned out heating element ($55 part), Seelye is made in the USA and is designed for Industrial applications therefore you can repair them (unlike the import brand Welders).

http://www.seelyeinc-orl.com/videos-and-tutorials.html

 

[zuk123]

I've been looking into it to fix some trim on my new project car.

I found this to be really helpful:

http://www.urethanesupply.com/identify.php

That will help identify it, then look thru their products, guides, and how to's. It doesn't look difficult, and the stuff doesn't look too expensive.

zuk

 

[zuk123]

As far as flex paint, someone who does it for a living will have a better answer, but I found the products from SEM paint and Colorbond when I was looking.

zuk

 

[mdbeck1]

As far as flex paint, someone who does it for a living will have a better answer, but I found the products from SEM paint and Colorbond when I was looking.

zuk

Check with a body shop. The 70's era of cars had a hard metal bumper with a piece of flexible plastic between it and the grill. There were special additives for it. I'll bet there is something similar for today's front bumpers. It seems like the stuff we used was a Dupont product.

 

[DHS]

When I was a kid dad stitched up the cracks on the Honda with a bunch of zip ties. It looked cool, kinda like Frankenstein.

 

[Gus_Mahn]

I believe most ATV fenders are polypropylene which can be plastic welded. There are tons of youtube videos on the plastic welding subject. After welding melt some stainless mesh into the rear side of the plastic for reinforcement.

 

[cbacres]

Thanks for the imput.

 

[Bobhdus]

I've posted a few replies here but for some reason a moderator must approve them. If your interested in some specific details with welding Plastics, send me a "pm".

 

[Gus_Mahn]

I've posted a few replies here but for some reason a moderator must approve them. If your interested in some specific details with welding Plastics, send me a "pm".

I'm always interested in finding better ways to do things. If you have suggestion, please post them up.

 

[Bobhdus]

I'm always interested in finding better ways to do things. If you have suggestion, please post them up.

I've been trying to post stuff, (links etc...) but I think the "anti-spam" settings for this site is deleting my posts. Anyways, if you do a search for Seelye Inc, Plastic welders and go to their main site, look under their FAQ tab and you can go to their videos. That page will show 4 of them. The one on the bottom left is the best one and can take you to their Youtube page. They really get in depth on the how-to's. There are more vid's there as well. There is so much out there on this topic, and a lot has already been covered now on this thread.

The main thing is to match the plastic and pay attention to the heat/ air psi settings. You don't want to discolor the plastic. My profile has 3 pics of some 8" CPVC pipe that I welded (with multiple passes). I will take some more photos and post this next week. I'm no expert but I do a lot of this Hot air Welding and stand by it as opposed to glues and epoxies. Thanks!

 

[cfaas416]

Great stuff thanks for the suggestions. I think im goin to start with the "welding" idea and see how that works. Thanks again!

 

[03protege]

Great stuff thanks for the suggestions. I think im goin to start with the "welding" idea and see how that works. Thanks again!

If you are finding it hard to justify the price of buying a kit I have seen several youtube videos of guys using various types of soldering equipment and steel mesh and successfully welding plastic together. It appears much slower than a plastic welding system, but much much cheaper.