View Full Version : Plastic Repair ?

December 1st, 2004, 10:06 AM
Upper on my zx11 is stress cracking around mounting screws to lower. I'm looking for suggestions (specific products/methods) on the best way to repair (or at least stop further damage from occurring) without having to repaint. Cracks are small and spider web like now and only 2 inchs long max. Thanks.

December 1st, 2004, 11:02 AM
You can always try the "Donnelly" method of copious amounts of JB Weld!
Seriously though, he has had good results with that. You can apply it to the back (inside) of the plastic, and maybe it will hold.
Do a search of our BBS archives, I know it is detailed in here somewhere.

December 1st, 2004, 11:11 AM
One thing about JB weld. Once dried, it is very brittle. I tried to fixt mounting tabs on the fender, and couldn't get it to stay fixed - they kept on braking off.

Jim P.
December 1st, 2004, 12:02 PM
Use some strips of glass cloth and use the slow cure JB Weld.. work it thru the cloth really good.. not so brittle and holds well... try it..

December 1st, 2004, 01:07 PM
2 part epoxy over fiberglass tape on the back. Make sure you clean the hell out of the back, then sand it with 100 grit, then clean it again before applying the tape and epoxy.

Check out http://www.urethanesupply.com/ for more info. I have the book How To Repair Plastic Bodywork (http://www.urethanesupply.com/book.html) if you would like to borrow it.

The Big Spank Daddy
December 1st, 2004, 08:52 PM
The GPZ is still going strong with no signs of the JB-Weld failing. The upper fairing was broken completely in two, with misc other bits broken off including the tabs for the right lower fairing.

Cracking, spider webbing? Sounds more like a bad paint job. Are you sure it's the plastic and not just the paint?

The true fix will have to start with the "cause" of the craking and spider webbing. Any repair will on be temporary until that the source of the problem is found and corrected.

As for JB-Weld being "brittle", can be, but you can adjust the "mix" and cure time (via temp) to keep it from being brittle.

December 5th, 2004, 12:36 AM
I have used the fiberglass/epoxy method in the past and have had fairly good success. However, traditional 2-part epoxy (or JB weld) is brittle as previously stated and will eventually crack or flake off due to stress.

I have more recently used the same method with fiberglass, but instead of standard epoxy I used Plastic Weld (found at most Auto Parts stores) as well as Marine Epoxy (found this at Walmart). Both are "flexible" after curing so they work better in the long run.

You probably want to do this on the underside of the fairing. For prep, you need to rough up the surface with some coarse sandpaper first, extend this about an inch or two past the length of the crack. Clean the surface with rubbing alcohol, cut fiberglass to cover the same area sanded and apply it, then apply the epoxy. Make sure the fiberglass is fully saturated and stuck well, but scrape off all of the excess epoxy. You shouldn't have a thick layer of epoxy left on top of the fiberglass, if so it causes the fiberglass to lose its strength and flexibility.

Hope this helps--


The Big Spank Daddy
December 5th, 2004, 12:45 PM
Good point about starting with the back side. That is what I did with the GPZ fairing and I also used some fiberglass screen material for support. Also, I used less hardner making it a bit more flexible.

Ed Seaver
December 5th, 2004, 12:53 PM
Plastic Weld works great.
I'm more adventurous( read experi mental ) and like to use MEK (found at any hardware store)and mix it up with bits and pieces of old fairings. Makes one hell of a glue made of plastic. Also I notch the corners of the crack(where the two pieces join) for more surface to adhere to.

December 5th, 2004, 09:30 PM
OK, to beat this dead horse, another trick is to get the platic placed how you want it (assuming there is a crack all the way through) then while it is in place put aluminum tape on the front. Then get a dremmel and v-groove the the crack on the back. Sand with 100 grit, clean the area extensively and then use the epoxy/fiberglass tape method above.

Of course, if the crack is all the way through you are not going to be able to ignore the front side. So once the back sets, sand and apply a layer of epoxy and then prep for painting as normal when it sets (sand, clean, primer, etc.)