Cracked Bondo

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dkamp

dkamp

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Terre Haute, IN.
On the roof area I noticed a hairline crack about 12-15 inch long on the Paint (Chrysler Code 5025).
It occurred after it sat in the Hot sun all day at a car show. Its normally kept in a garage.
I can see that it is from the Bondo cracking. Since it is in a difficult portion to view, is there an easy way to fix it?
What are my options?
David
 
dkamp said:
On the roof area I noticed a hairline crack about 12-15 inch long on the Paint (Chrysler Code 5025).
It occurred after it sat in the Hot sun all day at a car show. Its normally kept in a garage.
I can see that it is from the Bondo cracking. Since it is in a difficult portion to view, is there an easy way to fix it?
What are my options?
David
Click to expand...

Only way to fix it is to take it to bare metal.

You could fill the crack, but the bondo has already separated. Unless you seal the crack perfectly, and I mean 100% perfectly, you'll still get moisture into that void and it will rust and continue to lift the bondo.

And the bondo cracked because it was improperly applied or the metal was improperly prepped. So it's gonna keep happening regardless of what you do to fix it, unless you remove it all and start over.
 
Short answer...no, there is no easy way to fix a crack in bodyfiller. Looks like @72bluNblu beat me to it :)
Ill add that the metal was probably improperly repaired so the bodyfiller was applied too thick, too many hacks just slap a big wad of filler over dents without a proper repair. That would be my guess without seeing it.
 
Thank you for your answers, this is on my 46 Dodge Truck where my dad Extended the cab 36". I don't think the Bondo is very thick since that area is the rounded portion that stayed unmodified (not the flat extended potion added or the seam).
Can a plastic or epoxy be forced into the crack? or is this simply a waste of time waiting for more separation under the crack?
 
dkamp said:
Thank you for your answers, this is on my 46 Dodge Truck where my dad Extended the cab 36". I don't think the Bondo is very thick since that area is the rounded portion that stayed unmodified (not the flat extended potion added or the seam).
Can a plastic or epoxy be forced into the crack? or is this simply a waste of time waiting for more separation under the crack?
Click to expand...

Anything you do will only be delaying the inevitable. If it cracked once, it will continue to crack as long as it's there.
 
Anything you do other than repairing it RIGHT is going to make it look like infected dog butt in short order. The reason it's cracking is because moisture got under the filler and caused it to lift. The only way to repair it correctly is to go back to bare metal, work as much of the metal perfectly straight as you can to reduce the filler even further and refinish it.
 
I'm defiantly not a body guy, so it hope of minimizing the body guys time fixing it, should I grind the crack and widen it as I see the metal showing discolor of rust appearance?
If that portion is correct, do I then spry a Primer, then use filler, then primer on top of that?
Sorry to be a resource hog....
 
you might find something under there that was inappropriate filled or just covered up. There might be a better base fix than just covering it with bondo once you see what lies underneath. That's a nice-looking ride! Take it all the way down where there is no longer any bondo.
 
There's filler in a wide area around the crack. It's all gotta come out. All of it.
 
Cracked Bondo can come from several different causes, some of which have already been mentioned, but unfortunately once it's cracked it's a problem that requires getting down to the bare metal again. Here are the issues that can be the root cause as I see it in most problems.

1. Poor adhesion (not creating enough tooth for the filler to adhere to)

2. Low quality filler

3. Improperly mixed filler

4. Filler applied to thick

5. I suppose flexing is always a possibility, but I doubt this is the issue here.

You're just not going to know what you will have to deal with until you get it ground down.

Tom
 
I doubt the heat caused it. Issues arise like said above ^^. On the roof, if seldom driven, maybe there was some vibration of the sheetmetal there? Anyway, it needs fixed like said. A body filler with fiberglass (not talking about Kittyhair) is stronger, waterproof, and yes hard as heck to sand!
 
PROSTOCKTOM said:
Cracked Bondo can come from several different causes, some of which have already been mentioned, but unfortunately once it's cracked it's a problem that requires getting down to the bare metal again. Here are the issues that can be the root cause as I see it in most problems.

1. Poor adhesion (not creating enough tooth for the filler to adhere to)

2. Low quality filler

3. Improperly mixed filler

4. Filler applied to thick

5. I suppose flexing is always a possibility, but I doubt this is the issue here.

You're just not going to know what you will have to deal with until you get it ground down.

Tom
Click to expand...
Agree!!! Most likely the filler work was poorly done. By poorly done, I mean it was probably applied on a poorly prepared surface or it was applied in a deep dent. Either one could cause the filler to crack. @RustyRatRod is right when he says that all of the filler needs to come out. You may very well wind up stripping down the entire roof. Do it once, do it right.
 
Have to remove the filler to see what has failed underneath it. Could be many things such as moisture/corrosion, incomplete welding/pin holes, or excessive thickness. I like applying filler over an epoxy primer (chemical adhesion rather than mechanical) followed up by an epoxy primer over the repair. That way the filler is between two waterproof layers.
 
Not to make this a which camshaft should I use in my engine post. I will say using Evercoat Rage Gold filler is all I use.

I learned very quickly that you get what you pay for in fillers.

Recently I watched some guys doing a $50,000 black paint job on a 59 El Camino. They skimmed the entire car with Rage Gold.

Tom
 
PROSTOCKTOM said:
Recently I watched some guys doing a $50,000 black paint job on a 59 El Camino. They skimmed the entire car with Rage Gold.

Tom
Click to expand...
We used to just put a coat or two of spray filler over the entire car/bike rather than skim the complete vehicle with spreadable mud, then block that down, thats after the major body work was done of course
 
440 Mike said:
Have to remove the filler to see what has failed underneath it. Could be many things such as moisture/corrosion, incomplete welding/pin holes, or excessive thickness. I like applying filler over an epoxy primer (chemical adhesion rather than mechanical) followed up by an epoxy primer over the repair. That way the filler is between two waterproof layers.
Click to expand...
I liked the thinking with that idea too, after a few years I got a crack in the bondo:BangHead:
 
If the seam where the top was welded together to make it an extended cab was spot welded at intervals instead of a solid welded seam, it will flex. That can cause cracks in filler. If the filler was applied to bare metal, especially during cooler/cold weather, it will cause condensation between the filler and bare metal, and it will form rust, which could eventually cause a crack. It is best to apply filler over good epoxy primer. By good, I mean SPI epoxy primer or PPG DP90LF. I agree with @PROSTOCKTOM that Rage Gold is the best filler to use! That is a very nice truck, so I hope you can get it fixed properly so it lives on for many more decades.

:thumbsup:
 
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