Tech: Molding In Fenders On Your Custom

This project is part of my ongoing 1947 Ford coupe custom project. After seeing many examples of molded in fenders with cracking bondo seams, I came up with this plan to make the fenders on my car very solid. This is not a 100% metal finished job by any means, and does require some filler to get you 100%, but with the "valley" or "fillet" all made of metal, its a solid foundation that wont allow for any flexing of the sheet metal.

First step is to weld the fender onto the body. I didn't properly clean the metal before welding (it was media blasted and rust free, but had epoxy sealer remnants deep in the seam), so this weld bead looks kind of sloppy. I did media blast the final weld before taking any further steps, and the blasted weld is what's pictured. Make sure to apply weld through primer in the fender seam, and I also filled the seam with seam sealer once the whole process (all welding!) was done. Next apply a coat of weld through primer to the outer weld bead.

 

I skipped a few picture taking opportunities here, but this parts easy. Cut some metal strips (I used 19 gauge mild steel). The amount of "valley" you want will decide how wide to make the strips. I made mine 1.25" wide. Next find a piece of steel pipe 9I used the handle from a small floor jack) that has the contour of the valley you want. Clamp the metal strips edge against the pipe in a vide, and using a body hammer, slowly form the metal strip around the metal pipe. When done, you will have pieces shaped like this. They don't have to be perfect, they will receive further shaping on the shrinker/stretcher and when tacked onto the body of the car.

 

On longer straighter sections of the body, your filler pieces will often fit with no shrinking or stretching. The light stretching from the process of rounding the filler strips will stretch and curve them a bit anyway. Be sure to coat the back of these strips with weld through primer before proceeding. Place the strip on the fender, so that it sits fairly well, and tack it in the center of the strip, at the top and bottom.

Now using a blunt shaped object, hold the out edge of the strip tight against the body, and tack it there as well, top and bottom, on both sides. Now, using a ball pein hammer (the larger the better) work the edges of the strip tight against the body and fender. Working close to a tack weld, tacking it, and then repeating works best. I used a "dead blow" style ball pein hammer here, which worked really well. Go lightly, you don't want to damage the body or fender panels.

 

Now in a tighter curve, your going to need to shrink and/or stretch the filler pieces to fit the contours of the fender. When you shrink on one side of the strip to help it hug the fender, the opposite side of the strip might require stretching to keep the strip from deforming. Weld these into place in the same manner as the straight runs. Dont forget the weld through primer on the back.

 

About now you will have everything tacked in, with your tack welds about 1 inch apart. Now weld it solid, being very careful to avoid too much heat buildup. I made good use of the trigger on my MIG to do about an inch at a time (zap zap zap from tack weld to tack weld, not one continuous bead), and did 3 or 4 of them around the whole fender, allowing things to cool before proceeding to another 3 or 4).

 

Now its time to grind the weld bead. If you were careful, the bead shouldn't be too high, and the penetration should be good, there wont be too much grind. I used two 3" cut off wheels on a pneumatic cut off tool, as well as a 4.5" stone on an electric grinder to do most of the grinding. This part takes a long time. You only want to grind the weld, NOT the body panels! I finished it off with a 40 grit flap wheel on the electric angle grinder. At this point, once the welds are all ground, the job will start to take shape, and look like something.

 

The body work part is next. I used Duraglass for the majority of the work. This stuff isn't the easiest to work, but its much stronger than any of the bondo type fillers. It also doesn't cure as brittle. I cut a plastic spreader to the shape of the fillet, and used that to spread the filler on, and it got me the basic shape pretty close. I used an air file and D/A to rough it out, and finished the duraglass with 40 grit on a round and teardrop Durablock. I then skimmed the whole fender and quarter in Rage Gold, and blocked in 40, then 80, and then primed with Slick-N-Sand. The bodywork part alone could be a whole tech, and to get it perfect is very time consuming.

 

its nice to see some one take the time and use weld thru primer.

nice job

 

Metabo grinder? Aint they the catsass? I love mine. Its outlasted 4 Dewalts.

By the way... NICE JOB!

 

And finally after many hours block sanding the reworked area, some U-tech Black Epoxy Sealer (the latest formula dries to almost gloss, great for checking panel straightness) gives a better idea of how the area will look with some shiny paint (although the car will be painted gloss deep maroon)

 

Thanks. Yes, a Metabo 4.5 quickchange. The list of reasons why you should buy this grinder is very long. Let see. Quick change, rocks! The guard doesnt need a wrench or screwdriver to relocate, it has several detents to set it too, I use the hell out of that. Its so balanced, no vibration or "gyroscope" effect, and fits your hands well. Has a clutch, it engages of a cut off whell gets stuck. And my dealer told me that if you drop it, the power switch pops out of the "on" position, but I havnt tested that feater yet (dont plan to either).

Yea, they rock, and for $20 more than a Milwaukee, or upper end Dewalt, its a no brainer.

 

Great write-up. It looks fantastic.

 

Nice tech. Thanks for that. I've got the same job ahead of me. Man, that fender ain't never coming off!!!

 

Great job! Car's looking good....going to bring it out to Gettysburg next year? Finished?

 

beautiful work. the large radius you built in with the filler panel looks great.
my metabo grinder is the most used tool I own bar none. i actually have two..one with a 1 mm cutoff and one with an 80grit flap. one doesnt usually stop spinning before i pick up the other! saves precious seconds when your creativity is flowing well.

 

Wow, that looks excellent.


Metabo huh, I'll have to check that out.

 

beautiful job,thanks for posting

 

My thoughts exactly. Looks very good.

 

That looks great! I really dig the size of the radius you made. It's big enough to make it all flow, but small enough that it keeps good character to the line. Sometimes you see fades on these Fords with almost no definition left between the fenders and body.

 

The mold job looks great Chad!

Metabo!......never heard of it. Where can I get one?

 

Thanks!

Metabo's slogan on some of their advertising is "You wont find this puppy at Home Depot". Kinda funny.

A local industrial supply should carry them. Both of the large nut and bolt firms in Baltimore sell them, so I'd try to find a big fastener dealer in your area (I dont know if Fastenall sells them, but they arnt what I'd call a large fastener company, their local inventory is very small, and way overpriced). I got mine from Leonard Jed In Baltimore.

Also ww.thetoolwarehouse.net sells them as well, and I'm sure many other online stores, but I've had great success with tool warehouse.

 

Thanks for the info, Frank

 

Nice thread. I'm filling the seams on my Hudson this winter...I won't have to add the filler pieces as the seam is on a nearly flat surface, i.e. no valley.

 

Hey ChadS, thats going to make a nice 47, they look so good with molded fenders. I did a pair of 50 Stude truck rear fenders the same way you did one time. Its a lot of work!

 

Yeah - wow man - that looks killer. I always wondered how that was done. My dumb ass would have tried to smooth the weld right at the fender and body. Nice job.

 

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" width="100%" UNSELECTABLE="on"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">Looks awesome nice job. Rags
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Nice work, Great article

 

Looks good.

 

I would like to. Finished may be kind of tough. I'll be working on it this winter but I dont have heat in the garage, so I guess a torpedo kerosene heater is my only economical choice. So I cant shoot any primer with that, so while I can knock out metal work, I wont be able to do bodywork all winter. We'll have to see how it goes, I dont plan on rushing anything on this car.

 

Car is looking awesome Chad.