When working with fiberglass its quite easy to repair a crack or something by just adding some more fiberglass and resin and sanding it down.

Now if a polyurethane bumper gets a crack or something what options do you have to repair those? or are there any? can you throw some fiberglass on the back or some bondo up front?

 

Either might work as long as the repair area is small. The big problem is the bumper and repair will expand and contract at different rates, so it may not last. Plus, as soon as you bump something you'll find that neither repair material is as flexible as poly.

In case you don't get enough answers here, you might want to try posting or searching on http://www.autopia.org/

 

Go to any auto body shop supply store. They have many different types of poly glues, filler, etc.

When I cracked my poly bodykit, I reinforced it from behind by adding a thinsheet of ABS plastic and gluing it in place from behind the damage, usig a black poly glue/filler. Then on the front I actually roughen up the crack by using a dremel with a cutting wheel. I make it like a little Grand Canyon so that the poly filler has enough area to grab. I use the same poly glue for filler. I also take saran wrap and place it over the top to make the filler lie smooth and hold it's shape. It fills and sands a little like bondo but it won't crack when flexed from heat expansion.


Good Luck !

 

For instance if someone backed into my L-Sportline rear bumper & knocked it in some, how do you get it to look get it to pop out & looking uniform once again?? Do I heat it up & put a straight edge on it to straighten it out again so there no more contours, waves??

 

Most of the time , poly material will pop back almost to the original shape. Depending on the type of impact, I suppose it could get streched or deformed. That level of damage is a lot tougher to repair. You should do just as you would with standard bodywork. Straighten as much as possible and then fill in the low spots with polyurethane filler.

 

3M, SEM, and Fusor make adhesives you can use to repair polyurethane.

 

You can weld it. They make plastic welders that you can use with poyurethane. A really good welder will be about $300. It's like a concentrated heat gun where you feed in the rod, like tigging. Then you can sand it down and paint.

 

Thanks for the helpful info and please tell me if this sounds rediculous.

I think thinking about cutting a bumper length wide ( the long way) extending it about a couple inches and reconnecting the the two peices with some aluminum sheets in the back and use a rivet gun to hold it in place. Then use a filler of some kind to fill in the gap.

I know this sounds rediculous but its just for fun to see if I could do it. Its not going to be on my bumper but a spare. Just want to mess around and see if its possible.

Also if I want to make some cut outs and start shaping different inlets and such should I form it in the aluminum sheets then cover it with fiberglass weaves or just put the polyurethane on it?

This is just basically one of those experiements that come about when you have too much time.

 

How about just make your own fiberglass bumper. Cover the bumper in baby powder and lay resin-soaked mat all over it. After it hardens remove the old bumper and now you have a mold. Cover the inside of the mold with the powder and lay the mat on the inside and now when it dries, and you remove this, you will have a fiberglass replica of your bumper. You could cut this and refiberglass it and it will be just a strong.

 

you know I was thinking of exactly the same thing but either way I am going to have to do all the custom work first in order to get the mold I figure may as well use the original and keep the flexibility of polyurethane.