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Hardtopper
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Discussion Starter · #1 ·
I have the full bomex kit, in red... has 2 small cracks in front from the usual hitting the parkstop... Hasn't been on my car because its not painted black yet but.. would any of you guys know any websites or be able to give me any tips into how i can patch up cracks on fiberglass? I would like to get the body kit prepped up to get painted again, but I do not know a whole lot about fiberglass. Any tips? Thanks
 

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You could read some write-ups on building fiberglass speaker boxes......all the same steps apply to fixing a glass bumper. Just be sure to sand/scratch the shit out of the cracked regions so that the new glass work will have something to bite to. Use 40-80 grit paper.
Other than that, check some boat shops for good fiberglass kits.....or just use what the hardware stores have. Then follow the instructions. The rest is quickly learned by actually doing/trying it all out (maybe on some practice parts first).
Be sure to mix the hardener correctly. If you dont mix enough, then it'll will never get totally hard....but dont use too much either. Get some latex gloves <----- this will pay off ;) (even if they do tear a little bit).

But really, you'll pick it up quick by just mixing a few batches. Once you've done that, you'll be ready for the bumper. But then you have to know how to block the glass down as if it was bondo.
 

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Some other points:

There's some stuff available called Kitty Hair that you can get from automotive shops....this is just like bondo only it has plenty strands of hair mixed in it. It sands like bondo and there's no glass to get in your skin. I'm not sure if this is any stronger or weaker than traditional foberglass kits though.

If you use fiberglass, then what you will be looking to do is make 90% of the repairs on the back-side of the bumper and then just do some minor finish work on the exterior side. On the backside, you could also incorporate the use of mat weave (There's more than one type/style). This can be applied within the first application (or two) of fiberglass for added rigidity.
 

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Hardtopper
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Discussion Starter · #4 ·
Thanks for your help, I searched online right after I posted this to see if I could find anything and I came up with one good website who basically said some of the things you did, but yours was a little bit more clear. Thanks :)
 

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Just to add a few pointers to what blkturbo wrote: out of good measure I'd also stop drill the very ends of the crack to prevent migration. Cracks can migrate underneath a repair and if it's hit again that'll be the area most suseptable to crack again.
Also, chances are the bumper was fabricated with polyester resin so your best bet is to use polyester resin for your repair. Polyester isn't good at bonding with epoxy (and itself to some degree) and if you use fiberglass mat, the binders used to hold the strands together aren't compatible with epoxy either.
Good Luck.
 
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get a DA sander, get 320grit, sand it down, then hit em with 600grit, get some bondo, mix it with hardener, apply one coat and wait to dry, apply another coat and wait to dry, do this 9 times, then sand it down with 600grit, then hit it with 1000 grit. and there you go, just add your primer and then its ready to paint :D
 

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j2supraman said:
get a DA sander, get 320grit, sand it down, then hit em with 600grit, get some bondo, mix it with hardener, apply one coat and wait to dry, apply another coat and wait to dry, do this 9 times, then sand it down with 600grit, then hit it with 1000 grit. and there you go, just add your primer and then its ready to paint :D

320 ---> 600 ----> 9 coats of bondo with no sanding in between ----> sand the bondo with 600 ----> then sand with 1000 ----> then prime ??
(320 ---> 600 is a huge jump in grit and way to smooth to pile on 9 coats of unsanded bondo layers to)
(sanding bondo with 600 would take forever)
(1000 is way too smooth for primer to adhere on optimal levels)

First, it's best to do what ATLSUPDAWG#2 said to make sure there is a good bond to the glass. The grits above are way to smooth for this much/type of repairs, and bondo isn't the best product to fix fractures in glass with.
 

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I would never use bondo on an application like that, Bondo is not durable enough for to be on a front bumper, it would crack very soon.
I would use Tiger-Hair. I have never had to drill to stop a crack. If you drill a hole you are giving it somewhere else to possible go and take a chunk out of the bumper. Just apply the tigerhair that you can get at an auto restoration/paint store. Mix it all up. apply thin at first. Over-cover the area by 1"-2" more if you feel the need. Make sure to cover the back side of the crack as well.
Tiger hair is strong so I would sand it with...80 grit. Any lower and its just going to take it all off. But apply a good amount of it over it. smooth it out with a squeegie. the thin coat is just to get what you can into the crack. Next time apply generously. Use some clamps if you need to. then sand again 80, then 100, wet sand with 120, and climb the scale upto 400-600.
I would strongly recommend against bondo. Bondo was made for metal surfaces. not plastic or fiberglass or polyurethane.'
jeff
 

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the_desi_supra_raja said:
do they have gauges like kirkMKIV's icon? where can i get them


Who's "they" ?? :D
 

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spoolin_conquest said:
I would never use bondo on an application like that, Bondo is not durable enough for to be on a front bumper, it would crack very soon.
I would use Tiger-Hair. I have never had to drill to stop a crack. If you drill a hole you are giving it somewhere else to possible go and take a chunk out of the bumper. Just apply the tigerhair that you can get at an auto restoration/paint store. Mix it all up. apply thin at first. Over-cover the area by 1"-2" more if you feel the need. Make sure to cover the back side of the crack as well.
Tiger hair is strong so I would sand it with...80 grit. Any lower and its just going to take it all off. But apply a good amount of it over it. smooth it out with a squeegie. the thin coat is just to get what you can into the crack. Next time apply generously. Use some clamps if you need to. then sand again 80, then 100, wet sand with 120, and climb the scale upto 400-600.
I would strongly recommend against bondo. Bondo was made for metal surfaces. not plastic or fiberglass or polyurethane.'
jeff
What you are recommending is a superficial repair. If it's a crack in the surface then this kind of repair is warranted. However if its a crack that has gone all the way through and a repair is done as you stated above it will undoubtedly crack again in the same spot if it is hit or bumped. To avoid this the only way to achieve a superior repair in an area of the bumper that is subject to being knocked around a little is to use cloth and resin. Body filler should only be used to produce a final smooth surface for painting.
Just FYI, bondo and many 2 part fillers are plastic based (polyurethane) and provide just as much, if not better adhesion to plastics and FRP's.
 

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ELITECUSTOMBODY
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I'm with ATLSUPDAWG#2,
spoolin_conquest, did you know that there are dozens of products that are designed for finishing fiberglass repairs? Evercoat,USC,Bondo,3M and many more companies produce materials to repair fiberglass,
I recommend using short strand fiberglass filler from Evercoat,it's called Everglass,use a heavy grit grinder disc to V out the edges of the crack from both sides ,mix the filler accordingly ,apply it to the damaged area from both sides , you can sand it with 40 grit,then 80,when you're done smoothing it out, apply a thin coat of body filler,sand it with 80 grit to 120 to 180 then shoot few coats of a quality 2K or a two part primer ,and when the primer is cured,blocksand and prep it for paint
I strongly suggest NOT TO wetsand your bodywork,that is if you don't want to create problems after the part gets painted,cause some of the moisture may be trapped between the bodywork and topcoat and that tends to bubble up, crack and do all kinds of weird shit,believe me,I've repaired my share of ghetto rigged cars from shops that have no idea of what they're doing.
 

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well im not sure about the whole not wet sanding idea. What I was saying is that bondo should not be used to be the primary crack repair substance. I have used Tiger-hair all the time and it works awesome. I have used bondo as a finishing, but I have also used......Blah cant think of the name. Its in a tube. real thin applications...its usually blue...ahhhhhhhh blonde moment. I'll post again when I remember the name of it.
Why not wet sand? moisture would have no effect on it if it has cured enough time. Wet sanding smoothens the surface.
I know there are numerous products. I use tiger-hair because of it has always worked very good for me.
why experiment when I know something works very well?
And if you have experienced "bubbling" from wet sanding on body work it was obviously not done right. Wet sanding is normal practice in body work. Bondo is adhesive to plastics yes, Not saying its not used. Im saying its a finishing product, not a repair product, bondo is not strong. unless its half inch thick hahaha
jeff
 

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ELITECUSTOMBODY
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Icing,Half-Time,Blue Ice,that is a few names of the thin glazing catalized putty ,I never experienced "bubbling "from wetsanding,i've seen someone do it and i ended up repairing the cracks and bubbles.
Think for a moment.How can you prevent rust that started to form under body filler that was applied to bare metal before "Wet sanding smoothens the surface"?you're scerwed and cant do shit about it without grinding the rust & filler off and redoing everything dry sand.
Oh.. and I'm with you that any dumbass should know that bondo is not made to repair fiberglass,fiberglass should be repaired with fiberglass
Stefan
 

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blkturbo! said:
You could read some write-ups on building fiberglass speaker boxes......all the same steps apply to fixing a glass bumper. Just be sure to sand/scratch the shit out of the cracked regions so that the new glass work will have something to bite to. Use 40-80 grit paper.
Other than that, check some boat shops for good fiberglass kits.....or just use what the hardware stores have. Then follow the instructions. The rest is quickly learned by actually doing/trying it all out (maybe on some practice parts first).
Be sure to mix the hardener correctly. If you dont mix enough, then it'll will never get totally hard....but dont use too much either. Get some latex gloves <----- this will pay off ;) (even if they do tear a little bit).

But really, you'll pick it up quick by just mixing a few batches. Once you've done that, you'll be ready for the bumper. But then you have to know how to block the glass down as if it was bondo.
Fiberglass will stick to just about anything, no matter what the surface is like (rough or smooth), it doesnt really matter. As for fixing a bumper, kirk you know I have fixed countless numbers like I told you including my own, just lay the clothe over the back, apply some resin, and then fill the front.
 

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yea Icing. And if someone has rust behind previous body filler, they can grind and all, thats just someone who did not know what they were doing when that repair was made.
jeff
 

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ELITECUSTOMBODY
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spoolin ,you misunderstood,say you repaired a panel and it has a bare metal area that is covered by body filler and you start doing you favorite wetsanding and that filler,which will get saturated by water,remember that bodyfiller is not waterproof,so that means the moisture will come in contact with bare metal ,which will start forming rust under the filler.that is why it'snot recomended to wetsand bodywork before priming it first with good epoxy or 2k primer.
 

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Hardtopper
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Discussion Starter · #18 ·
How would you guys go about removing the paint safely from the fiberglass? I need to get it prepped up to get painted.. after paint is off I will be able to fix the cracks alot easier. I appreciate all the help.
 
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