Front fender cracking out

[langus480]

Hello all,


What is the best method/ procedure to stiffen up the front fenders to keep them from cracking out?


Is there some type of modification or doubler's to help stiffen the fenders?

[Oldbluoval]

What you are talking of doing is what’s been done for 90 years and basically is just bad wrong. The fenders crack because they are in stress. Do not know if you are referring to front or rear…..more often fronts.
If you want to cobble them up go ahead , weld rebar, pieces of angle iron , whah ever is on the garage floor…..it will look like that.
Find the stress, fix it and repair the fenders properly.

[Dean Lemoine]

I put a layer of fiberglass under mine, then a thin layer of undercoating. Is it the correct thing to do? Probably not, but that’s what I did.

[kenparker0703]

Blue oval is right.

[langus480]

I purchased a set yesterday from Sam at Arizona Model A's, and his comment was that the front fenders are prone to cracking due to the design of the fender.


I posted this question since I was curious about a hidden patch that would strengthen the area?

[Bob Bidonde]

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Test fit the fenders with their support brackets. Cracks can only occur in the metal where there is a tension stress / strain. The tension typically occurs where the fenders / support brackets are bent into position by force. Bending is a no no. Do the metal work to fit the fenders so they fit with a very small amount of bending.

[langus480]

All,


After posting the question and searching for an entirely different subject (searched for date stamp production day) I stumbled across this information regarding patching and strengthening the fenders.


http://modelahouse.com/tech/fender/index.html


Seems like a chronic problem

[BRENT in 10-uh-C]

Originally Posted by langus480

All,

After posting the question and searching for an entirely different subject (searched for date stamp production day) I stumbled across this information regarding patching and strengthening the fenders.

http://modelahouse.com/tech/fender/index.html


Seems like a chronic problem

Well I guess since you posted those links, I will also tell you that what Bill said above about the fender being in tension is correct. Correct that problem first.

FWIW, the key 'takeaway' to making this repair last is that you must have the reinforcing wire be welded in a different location than where the repair panel is joined to the fender metal. Otherwise the stress riser will cause it to crack where it was fused together.


On a side note, I wish I could remember when that tutorial was first written but I feel certain I originally posted this here at least 15 years ago, ...and maybe as long as 20 years ago. As I recall, these tutorials and those by a few others was the catalyst that caused us to have the Fordbarn Workshops. I can't remember if we had the first one of those in 2006 or '07. Bob definitely had the proper forethought to post it on his website for it to be preserved.

[rotorwrench]

All metals fatigue over time and use. Their are ways to relieve stresses tuch as normalization or shot peeing after weld repairs but sheet metal takes more care to do that and especially if it is thin. It can be done though.

Another important part or relieving stress is to maintain the suspension in top condition. Worn or broken components don't help at all.

[Rob Doe]

Thank you, langus for that post. My Model A experience matches Rotorwrench's post #9. I have a cracked fender that I have waited too long to address. It is in the outside corner of the front fender where it meets the running board. It was originally done poorly and does not have a proper fit to the running board.

When we first got the car, the tires were old, the front end was loosey goosey and going down the road the lights and front fenders were shake rattle an roll for sure. Things are different after 3 years of learning and amateur repairs. A few thousand dollars and sweat equity.

I have seen Brent's tutorials before. I will tig the cracks and weld in a small patch and grind. If I get any sort of reasonable result I will attempt to split the rear flange from the fender and mate it to the running board then patch the gap.

[Oldbluoval]

“I purchased a set yesterday from Sam at Arizona Model A's, and his comment was that the front fenders are prone to cracking due to the design of the fender.”

There’s a lot of credibility in that statement.. Look around and all external fenders were prone to splitting. However, if fender stress is relieved between the frame, running boards, fender braces and light bar, they should remain split-free longer than any readers currently on this board!
Imho

[Rob Doe]

A question I have, I have a small rose bud that I could use to heat the fender to normalize it? Can someone describe this procedure?

Do the directions of the cracks, there are two, which emanate from a small triangular hole, indicate a directional stress or strain???

[BRENT in 10-uh-C]

Originally Posted by Rob Doe

A question I have, I have a small rose bud that I could use to heat the fender to normalize it? Can someone describe this procedure?

Do the directions of the cracks, there are two, which emanate from a small triangular hole, indicate a directional stress or strain???

We do use that process with chromoly tubing when we are building a race car frame however it really does not work the same way with sheetmetal. In sheetmetal, we typically just planish the weld while it is still hot which relieves stress induced by the heat of the welding process and the drawing from the cooling process.

[Oldbluoval]

It’s likely not as much the fender as the braces and light bar.
But twisting the fender as needed could be in order.
I’m not sure you could identify any small area of the fender enough. And too much heat (red) will cause warpage and “tin canning” of sheet metal

[rotorwrench]

Rosebuds put out way too much heat for thin sheet metal. I use really small tips just to weld thin sheet metal. To normalize, it takes a knowledge of exactly what specific amount of heat it takes within a very short range of temperature and then how large an area to heat. It's complicated. I would recommend reading any material about the process before ever even applying any heat at all. When I weld with a torch, I generally relieve stresses by careful metal work. I don't like to use the term Hammer when working metal because it's more like slapping the metal rather than any dead blows unless it needs to the stretched a bit due to shrinkage that happens while fusing the two edges together. Folks used to call it hammer welding but I try not to use much filler in the process so that I keep hammering to a minimum. I don't have to file it as much that way which makes the metal even thinner than it already was.

[langus480]

Originally Posted by BRENT in 10-uh-C

Well I guess since you posted those links, I will also tell you that what Bill said above about the fender being in tension is correct. Correct that problem first.

FWIW, the key 'takeaway' to making this repair last is that you must have the reinforcing wire be welded in a different location than where the repair panel is joined to the fender metal. Otherwise the stress riser will cause it to crack where it was fused together.


On a side note, I wish I could remember when that tutorial was first written but I feel certain I originally posted this here at least 15 years ago, ...and maybe as long as 20 years ago. As I recall, these tutorials and those by a few others was the catalyst that caused us to have the Fordbarn Workshops. I can't remember if we had the first one of those in 2006 or '07. Bob definitely had the proper forethought to post it on his website for it to be preserved.

Dang, its hard to believe that the Old Ford Barn has a long track record. I wonder if there is a way to be able to search for prior posts like the one you mentioned regarding the repair of the fenders...be great to know.

[langus480]

Originally Posted by rotorwrench

All metals fatigue over time and use. Their are ways to relieve stresses tuch as normalization or shot peeing after weld repairs but sheet metal takes more care to do that and especially if it is thin. It can be done though.

Another important part or relieving stress is to maintain the suspension in top condition. Worn or broken components don't help at all.

Coming from the Helicopter world, I recognize that cracks are a cause of something, and if the stresses can be mitigated then the focus of the crack no longer is necessary as they will not develop further.



However, being able to repair existing cracks is a whole matter entirely and that's the reason for the question.



obviously the fenders are prone to crack out, even by design of only a small support at the front, and no structure at the crown, I'm thinking that even a person sitting on the front of the fender or leaning on the front would induce enough stress to bend the metal crown warranting the structure to crack out somewhere.


My thoughts/ questions are, is there a way to strengthen the thin metal to prevent further cracking and strengthening the fenders at the same time?

[langus480]

Originally Posted by Oldbluoval

“I purchased a set yesterday from Sam at Arizona Model A's, and his comment was that the front fenders are prone to cracking due to the design of the fender.”

There’s a lot of credibility in that statement.. Look around and all external fenders were prone to splitting. However, if fender stress is relieved between the frame, running boards, fender braces and light bar, they should remain split-free longer than any readers currently on this board!
Imho

Bluoval, when you say that "fender stress is relieved between the frame, running boards, fender braces" ect, what would be an effective material to use to aid in preventing the stresses?


What are people using?


I am curious, as others likely are, regarding the remedy and where to find such materials for the remedy.

[Oldbluoval]

You get the fender back in proper shape off the car. This might include removing previous welds, patches, bends, bad body work,’damage of most any kind. This usually requires body work skills acquired by experience. Once the fender looks visually correct, loose fit it
To the car. It should mate to holes in the frame. See how it mounts to the RB. RB brackets can be deceivingly bent also. Then see how the fender bracket mates to the fender.
If front fender, both fenders with both brackets and the light bar should be tightened to see that stress isn’t caused by the full assembly.
Basically, your asking for a brief explanation of years of body work experience
There is no Cliff’s Notes version of such.
Go to YouTube and do some searching. There’s a wealth of
Info there

[rotorwrench]

I learned a lot from David Gardner's tutorial DVD (Classic Metal Shaping) but I've noticed that he no longer produces it. He uses oxy-acetylene like I do. I already had the welding down but his metal forming techniques were the old way of coachwork from the early years of automotive and aviation metal work. He still has some good video links on his web-site.