My DIY Fender/Mudguard Fillers

After losing a bolt holding the ECU in place and needing better access on the driver’s side to try to get as close as possible to the engine compartment so I could try and find the darned bolt, I decided to remove the left front mudguard/fender. As long as it was off, I also decided to try fabbing some simple fender fillers from 1/8” ABS sheet, so I bought a sheet of 24” x24” x 1/8” thick Black ABS sheet, smooth on one side and textured on the other for under $30 on Ebay. 3/16” or ¼” Black textured ABS sheet should also work nicely and provide a little better fit for the fillers. I then ordered a bag of 100 #8 x ¾” Black Oxide Truss Head via Amazon screws to secure the fender fillers for a total investment of around $35. I originally wanted to buy #10 size, but chose the #8s since they were available for Next Day delivery. I also think ½” length screws should be sufficient and believe the #10 screws would not require as many for a secure fit.

I made a template and transferred the template to 3 PDF files which can be printed and assembled into a full-size template. Trim the 1^st and 3^rd sheets on the Cut Line and carefully align the 3 sheets and then tape them together using masking tape, in case anything need to be re-positioned. Once all 3 sheets are properly aligned, the Alignment lines should each measure 2” long. If they do, then the template should be full-size and ready to use for marking/cutting. If doing it over again, I’d cut the ABS slightly larger than the lines would indicate and then carefully trim things down for a better fit. It would also have helped had I been able to cut things a little straighter, etc.

I didn’t cut the ABS sheet on an exact diagonal across the sheet, so I ended up cutting vertical drops at the top and bottom edges of the fillers. I later redrew the extended lines of the template if anyone doesn’t like the vertical cuts I used.

I also probably used way too many holes for securing the fillers. I pre-drilled 20 screw holes (11/64"? for the #5 screws). The ones I felt were the most necessary are indicated using Black dots with Blue circles around them. The green dots are ones I had pre-drilled and then placed screws in becasue the holes were there, but probably didn’t need to have drilled the holes at all. Feel free to use different size fasteners and holes and try to not drill unneeded holes that then must be filled.

Here's some pictures with (hopefully) helpful info -

Note - I haven't gotten around to installing a floor vent on the passenger side.

I guess my Slingshot is due for a decent cleaning.

If anyone has any questions, just let me know.

(I still haven’t found the bolt!)

Afterthought - I forgot to mention that I drilled only the Filler strips and then let the truss head screws drill their way into the supporting body panel. If I ever decide to re-install the fenders/mudguards, the holes I made will be covered. I also removed the clip-nuts and saved them along with the original fender 6mm screws.

Quote from FunCycle

You did not need all of those screws, just use the ones that are already there. If in doubt you could use double side tape also. The end piece where there are no screws I just used the tape with no problems

I agree. I was originally going to use the clip-nuts with 6mm screws, but I was too lazy to measure exactly where I needed to drill the fillers for the screws and when I decided to use smaller screws I went overkill. At the time I was making it, it seemed OK, and I wanted to cut and drill both pieces as mirror images since it was easier to do them together as a single piece. I was also concerned that leaving an edge w/o a securing screw was an invitation to a wind-induced vibration, so more fasteners was natural train of thought. I also hate using double-stick tape on pieces I may want to remove in the future. Unfortunately, I have a tendency to overthink/overdo things and I just didn't think about it.