How to fix crack in plastic fender

[slowrev]

It is good to know that plastic fenders and such can be repaired.
How do you determine the type of plastic and what are the methods used ? Any good web sites on this ?
Ben

 

[Cactus]

I have cracked the fenders on my JD 4400 as well as the hood. Try this stuff and then a little sandpaper and some JD green touch up paint . I have had goold results....this stuff is really strong and works great...

JB Weld

 

[slowrev]

Cactus,
JB Weld is great stuff I glued the front aux hydraulic pump back on my tractor with it, after a relative broke the mounting flange off of it. However it is rigid when dry and I am not sure about the long term effects of gluing flexible plastic with it. Might be good as long as it does not flex any more where you used it. Another possible "fix" could be to use fiberglass on the backside of the plastic and fill the crack with resin, sand and paint.
Ben

 

[Cactus]

Slow rev,
I think the plastic around it would break before the JB Weld would....That is my opinion and it has worked for my application.Thats just my opinion from what I have seen and experienced on my application.I always make sure I have some at hand.

 

[slowrev]

Cactus, My experience has been that the JB weld would pull loose from one side or the other of the repair. But then I have not used it on flexible plastic tractor fenders either. Of course you can re apply if this happens.

JB Weld is great stuff, I also try to keep some on hand. Do you like the quick or slow set type better ?

Ben

 

[Cactus]

I normally stock the slow setting type....I have some plastic around the lights on our Land Rover Discovery that I cracked while off roading I am going to attempt to repair before going the dealer route.

 

[slowrev]

Cactus,
I prefer the slow setting type as well, seems to cure out a bit stronger.
I repaired the cast pot metal headlight housing on my old IH with it and it worked fine. I did find that it does not adhere too well on the hard plastic door trim parts in the wifes lincoln though. Got some regular epoxy and that worked better.
Ben

 

[jinman]

</font><font color="blue" class="small">( I had a big crack in mine after winding up a chain harrow around the rear wheel (ouch!). Tried fixing it... held together about a day with cycloarcanate (super glue)... a week or so with JBWeld, a couple of weeks with duct tape... and the fender was looking worse and worse on my nice new tractor.

Finally gave in and spend the $800 to replace it with a new one. MUCH happier now, not looking at the ugly cracked fender and reminding myself of my past error every time I get in the thing.

)</font>

John, my fenders and hood on my TC45 are fiberglas. I suspect yours are too. I think yours could have been repaired with normal fiberglas repair methods, unless it was just too far gone. Many tractors are using ABS or something similar that has no fiber substrate.

I am thrilled personally with the material in my fenders. They can be scratched, scraped, or chipped and they will never rust. I have a half-dollar sized chip out of one of my rear fenders where a limb got caught between the wheel and tire. Had that been metal, I'd have a dent and probably a bent fender. With the fiberglas, I just have a chip missing that makes it look a little "snaggle-toothed." /forums/images/graemlins/smile.gif

 

[Boomerang1]

SMC is usually gray, shiny, stiff and has small fiberglass strands. fiberglass will not stick to this and will peel off. ABS is greasy and slippery. polypropylene is sometimes yellow with tiny sparkley specs. Years ago we used to burn a small piece and compare the smoke to a chart we had. The smoke was very toxic so that practice was stopped. We used to weld plastic with a tool that looked like a soldering iron and used plastic welding rods. Now you can buy repair material in a double tube that mixes the material in a dwell tube which spirals the mixture up the discharge nozzle mixing part A and part B in equl amounts. It has been a number of years since I have messed with any of this stuff but the people at the supply shop should be able to tell what you have. I think if you try to use JB Weld, the repair will not hold.

 

[RedHawkRidge]

Would be helpful to clarify that references to "fiberglass" when discussing plastics are misapplied. Fiberglass is the reinforcement, not the plastic. It is applied to the part, then coated or impregnated with a plastic, usually in the form of resin. The resin is a "thermoset" plastic, that is, it cures and sets to a permanent state. Epoxies, melamines, polyesters, plenolics are examples of thermoset plastics.
When plastic structures are referred to as fiberglass, I think they are mostly polyester resin with glass embedded.
CB-Weld is just 2-part epoxy, with either fast or slow cure curing agents.
The most effective repair system is 2-part slow cure epoxy resin that is coated to the cracked part, then woven fiberglass cloth is laid down into the resin, with additional resin added over the surface -- more plies of glass cloth the stronger the patch.
jim