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  #1  
Old 01-28-2019, 08:29 PM
berntd berntd is offline
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Default Remove a large dent from a fender: How?

I have a big shallow dent in my project car's rear fender.

The dented in / pushed in are is ~20" / 500mm wide and it is in about 1/2" at the deepest point.

I can push from behind with my porto power and when I push in the correct place, I can get the whole panel to mostly be corrected.

But it will not stay like this and revert back to being dented as before.

If I over-push it in that spot, I end up with a smaller dent outward inside the big where I pushed from behind but the whole big dent just reverts.

I cannot easily see what / where the dent is locked into the metal so I have no idea how to go about it.

So how does one actually remove such a big dent?


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Bernt
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  #2  
Old 01-28-2019, 08:39 PM
eaglefordracer eaglefordracer is offline
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Default You've got an oil can..

The metal is stretched into the dent. You need to do some shrinking to get the metal to come back to original. I like to use hot shrinking, heating small areas, not red hot, just until metal doesn't rise to anymore, then hammer back into itself. You will have to be patient and let metal cool after each shrink.
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  #3  
Old 01-28-2019, 09:20 PM
Mr fixit Mr fixit is offline
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Hi Burnt,

In Frank Sargents book The key to metal Bumping he talks about this method and the fact that you never should heat a spot larger than the face of your hammer and only when it's necessary. The size usually should be 3/8" or smaller in the place where you determine the impact started.
Heat it to a dull cherry red and then hit it with a dinning hammer, then use a dolly to back this up and hammer off dolly to get the metal to flatten out, then quench with water. You can air cool but the water allows you to start over quickly for the next spot. You can over do it, so go slow and check it after each time you shrink.

I'm just a beginner here, but I have done this with good success and it works real well. You just need to read how the damage got there and reverse the process with shrinking and hammering off dolly.

I highly recommend this book if you can find it.

TX
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  #4  
Old 01-28-2019, 09:41 PM
BTromblay BTromblay is offline
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Quote:
Originally Posted by berntd View Post
I have a big shallow dent in my project car's rear fender.

The dented in / pushed in are is ~20" / 500mm wide and it is in about 1/2" at the deepest point.

I can push from behind with my porto power and when I push in the correct place, I can get the whole panel to mostly be corrected.

But it will not stay like this and revert back to being dented as before.

If I over-push it in that spot, I end up with a smaller dent outward inside the big where I pushed from behind but the whole big dent just reverts.

I cannot easily see what / where the dent is locked into the metal so I have no idea how to go about it.

So how does one actually remove such a big dent?


Regards
Bernt
Hi,

You need to use your porta-power to push the dent back to the correct place, and unlock the panel. To unlock it, use a slapper (or hammer if that is all you have) and dolly on the lock area only. The lock is holding the dent in, you need to unlock the dent to get it out. Once unlocked, you may need to shrink, as needed.

B
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  #5  
Old 01-29-2019, 04:10 AM
berntd berntd is offline
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Default

20190129_200535.jpg

20190129_200554.jpg

20190129_200626.jpg

20190129_200638.jpg

20190129_200357.jpg

20190129_200415.jpg

20190129_200427.jpg

20190129_200434.jpgOk.
Thanks for the great replies.

I do have this book but in these cases it is zero help as there are no kinks or traces on how the imoact happened. It is a shortcoming in the book and others I have.

I do not think this is an oil can as I was taught that those pop in or out and are bi-stable.

I think BTromblay has the correct approach but I am not able to determine what or where this dent is locked in and where to slap/hit.

In this case, this was already "repaired" and there is zero hope telling what/how/where.

I have encountered various somilar dents in doors which I also have yet to manage.
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Last edited by route56wingnut; 01-29-2019 at 09:09 AM.
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  #6  
Old 01-29-2019, 11:20 PM
fciron fciron is offline
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Looks to me like the damage is at the body line. Try jacking it out to the correct profile and working the "valley" with a caulking tool.
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  #7  
Old 01-29-2019, 11:37 PM
ozcad ozcad is offline
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I agree with fciron. Further, where you have drawn a circle above the line between 6 and 7, I would tend to that damage first. it appears that above that circle and to the left, there is a potential high (difficult to see in photo) that may be pulling tension on the panel below. It appears to correspond with your profile gauge lifting off the panel in the last photo.
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  #8  
Old 01-29-2019, 11:55 PM
ozcad ozcad is offline
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Adding to my previous post, I would address all the smaller and more obvious highs and lows surrounding your problem area first. Then you might find that the big dent is no longer a big dent without even touching it. This will also give you a better idea of where the tension in the panel is as you move in towards the problem area. The damage at rear of the wheel arch that heads up to between 4 and 5 marking would be as good a place as any to start. Final comment from my old boss from 35 years ago, " if you try to fix this with 10 hard hits, you'll have to add 1000's more hits to undo what you just did. Take your time and hit it gently a few hundred times, and you'll get it done fast".
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  #9  
Old 01-30-2019, 01:32 AM
berntd berntd is offline
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Thanks for the great advise.

I forgot that I have pictures with gloss and a video.
This problem has been stopping my progress for a while.
Here are those pictures.

20181229_104823.jpg

20181229_104930.jpg

20181229_104852.jpg

20181229_104936.jpg

20181229_104951.jpg

And video clip:
https://youtu.be/3iwDPSphPsg

Regards
Bernt
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Last edited by galooph; 01-30-2019 at 09:04 AM.
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  #10  
Old 01-30-2019, 09:37 AM
David Ward David Ward is offline
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I would agree with ozcad, working on the little areas first can pay dividends in getting the entire panel back to shape. Reworking an old repair is frustrating, and I’m facing the same thing on my car. Take it slow and plan your shrinks if you need them. You don’t want to chase your tail on a large panel.
Dave
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