In order to get good welds, you'll need to clean the paint off in the immediate area. I would use MIG and weld the entire length of the crack using weld dots. I'm afraid you're going to lose some paint. If you just put a tack at each end, it won't stop the crack. Here's a couple of photos of the repair I did on one of my fenders that had similar but worse damage.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Thanks for those. So I guess I should just try and expose as little bare metal as I can to weld to then maybe see about a little color match or something?
You might try welding from the back. Try a few spot welds to see how it does. If seems OK, do a fillet weld made of spots. Don't need to grind the weld. If it fills in nice, bondo the front side to smooth out the radius. As Kevin says it must be cleaned down to bare with a wire wheel NOT a grinding disc. I assume you know the routine about warping.
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Thanks, I was thinking I might get away from removing too much paint if I go from the back. Heat will burn it off the front anyway. I'll likely attempt it this way first and see.
You really need to drill a hole at the end of the crack to stop the split prior to welding.
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Thanks Tuts, I had heard of doing that before. Was waiting to see if it got suggested. Does it matter what size hole? I'm assuming you weld it up after?
If your weld dot at the end of the crack is full penetration, you really don't need to drill the ends. But it's a good idea. 1/16 inch should be adequate. The bigger the hole, the more weld metal (shrinkage), and harder to fill.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
If you have access to a TIG you can use heat dam or heat block putty to prevent warp and cut way down on paint damage.. A good TIG weld will require very little if any grinding.
If you're going to stop drill the crack make sure you're at the end of the crack. It's very common for folks to miss the end of the crack. If that happens the crack will continue to propagate. The most reliable method of finding the crack ends is to use liquid penetrant or magnetic particle testing. Welding the crack should remove the need to stop drill IF you weld the whole crack. Start the weld beyond where you think the crack terminates and end it past the visible other end as well.
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Looks good. I had to replace some of those weld-in nuts on the right side inner fender as well.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I have not done it but if you do some research you can find some guidance on duplicating and color matching your new paint to simulate the old patina. You could practice on some scrap until you figure out the best procedure/combination of paints. Fortunately it is a small area and if you take your time it might not even be noticeable to anyone that you had to touch up the patina.
Thanks Dave, the artistic paint stuff isn't really my thing, but I'm willing to try it. From what I've found, the paint code 830 is 'Commercial Blue'. Wondering where I can get modern codes for it.
I got a PPG code for Mariner Blue, which might be the American equivalent of Commercial Blue. Will see if I can get a small batch whipped up and do a comparison.
So, I'd like to start cleaning up inside the fenders, but I'm hesitant to remove them as I've read alignment afterwards is difficult. If I leave the inner fenders attached to the grill/rad bits, does this make it easier to reattach the outer fenders later?
On your pics 3 posts ago, those show the mounting flange where the fender proper is lapped over it and spot welded together. Welding those corner cracks isn't an issue as long as you get good penetration. If your welds are hollow, you need to turn up the wire feed a touch. The ones that stand tall, especially if there's a sharp definition to the base metal means that you need more heat. It's a balancing act. If you're concerned about burn thru, you could use a backer made of copper (a piece of old copper pipe flattened and shaped to match the fender works well.) If you use a backer, you need to turn the heat a bit higher, as the backer will soak up some of the heat.
Last edited by klhansen; 10/15/20216:33 PM. Reason: post inserted in between
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I think those cracks were just from the nature of the fender construction and the years of rattling down the road. One of mine had almost identical cracking. The fender to body mounting and the flexing of that assembly would definitely do it. If you stiffen up that point, then it'll just rattle and crack somewhere nearby.
A heavy application of undercoating would probably help dampen vibrations.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Wire-wheeling and rust converter continues, will have some pics to upload soon. I was thinking about painting the underside of the fenders with POR and then topcoating with bedliner. I did this with the belly of an old Terr-Jet and it seems to hold up pretty well. Unless there are better suggestions?
I think that apron was designed to rust out. Looks like you're getting it dealt with.
Mine was full of gravel, like the truck had been submerged in a stream.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Suggest you start a build thread. This one is getting a little far afield from "cracking fenders".
But it's looking good.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
