Figuring out aero is always the hardest part of building a car for me. Having an S13 makes it even harder because every possible combination of aero has been done by somebody at some point. It’s really hard to do something that stands out.

Instead of trying to figure out some new mix of aero parts, I’ve been trying to figure out ways to take things I already have and customize them in a way that makes them unique. My first shot at executing this idea was taking the factory hood and modifying it to look like a Koguchi Power/Wonder vented hood. If you go back and read that post you’ll see it turned out decent. So, I figured I’d give custom front fenders a try.

I’ve had a pair of used Origin Type 3 fenders laying around for a while now. I got them years ago from UpGarage for about $40 and they were actually in really good shape. The biggest issue was the fact that they Origin fenders so, of course, they fit like absolute shit. Also, the previous owner had “plastic dipped” them, which was actually a pain in the ass to get off.

My biggest gripe with Origin fenders, besides sub-Duraflex quality, is the split vents. I’ve never really liked the look. In contrast, I love the big flare of the Type 3 arches. My first idea was to turn the split vents into a single vent like you see on Vertex fenders. So, I cut out the middle section that split the vents and filled in the hole. They definitely looked better, but I wasn’t satisfied.

I then started thinking how good the fender would look if they didn’t have a vent at all. It was going to be a lot more work, but I what’s the worse that could happen? I ruin $40 fenders?

I used a cut-off disc on a dremel and carefully cut it out. the entire vent areas of the fenders. I made sure to leave a good amount of material along the arch so the overall shape didn’t change.

If you’ve done fiberglass work you know how great aluminum tape is. If you haven’t and you plan on trying your hand at repairing cracked aero or a larger modification like this, you need aluminum tape. Get a roll. Tape the front side of the piece and fiberglass the back. When the glass cures, peel off the tape and voila, you have a solid structure to lay bondo or more fiberglass on. I had to span a big area so I had to overlap strips.

I forgot to take more pictures of this process, but once I flipped the fender over all I had to do was lay fiberglass cloth over the area and brush in resin. Because the cut out area was so large I wanted to give it plenty of strength, so I went with 3 or 4 layers of glass.

This is what the front looked like after the backing fiberglass had cured and I peeled the aluminum tape off. I know had a sold structure to build upon. Notice how much height I need to fill between the topside of the fender and the backing glass…

It can’t be filled with bondo. Over time it would crack for sure. Instead, I needed to lay a base of fiberglass first. For this I used “kitty hair”, which is basically resin jelly with fiberglass strands mixed into it. In the picture above you can see I’ve laid a bunch of it on there. The idea was to have enough built up, so I could sand it back and blend it all seamlessly into the existing fender surface.

After a ton of sanding I had a basic blend done, but the section where the vent had been cut out still dipped in a bit. So, another layer of kitty hair went on and I did more sanding. Then I did more sanding, and then I did more sanding. After that I did more sanding. Soon after, you guessed it, I did more sanding…

Eventually I had everything blended pretty well. The hardest part was the transition from the flat area into the fender arch. Most of my time was spent getting that just right. You can’t eye-ball these blends either. You have to “look” with your hands. I kept running my hands up and along the arch until it felt perfect. Your way make look good, but if it doesn’t “feel” good it’s going to look like shit when you get to paint.

You can see in the picture above how I managed to get the blend up into the arch pretty damn spot-on. You might also notice wonky edge on the lip of the arch. I actually fixed that later.

Once I was done with the basic blend I moved onto the bondo layer. The idea here was to fill in any pits or holes left by the glass layer, and create a nice smooth surface ready to be primed. I probably ended up knocking back three layers of bondo before I had everything filled and the surface nice and smooth.

My next step was to spray some primer as a guide coat, which helped me identify high and low spots as I sanded. Primer isn’t a require for this. I could have just used spray paint. It all gets sanded off as you go. You don’t have to spray a solid coat like I did either. I just do that so I can get an idea of what the area I modified will look like once it goes to paint.

After a quick test fit I was happy with the result. However, the actual fitment of the fender wasn’t great. If the gap along the hood was good, then the gap between the fender and door was bad and vice versa. Typical Origin quality…

To get the fitment right I actually ended up chopping the bottom section of the fender off. Then I made a bracket to bolt it down to, which allowed me to get the hood and door gaps right. With the side skirt on, both the bracket and bolts holding the fender down are completely hidden.

The final step was to extend the body line of the door into the fender. I didn’t take any pictures of this process, but you can see in the picture above the black line I drew in the fender right before I got started. To make the actual line I used a cutting disc on a Milwaukee grinder and slowly cut along that black line. Then I just folded a piece of sand paper in half and ran it up and down the line I grinded into the fender to bevel it out to match the door.

And with that I called the fenders done and I was happy with the result. It was a ton of work, and by work I mean sanding. Once they’re painted you’ll never be able to tell they came with a massive vent. I’m also excited to see how they’ll look with the massive rear fenders I’m working on now, but that’s for a later post.