GL1800 Mud Flap

Revised: 02/07/2003


I noticed that after every ride the back-end of the GL1800 gets very dusty and with water on the road it gets worst. I realize that motorcycles attract road dirt, but I wanted to cut down on it as much as possible. Fellow wingers suggested that a mud flap would help reduce the amount of road dust to the rear-end of the GL1800, so that is what I did.  I searched the Internet for a suitable mud flap. I found that there was little selection and was surprised of the cost. Some of the mud flaps had fancy names like Debris Modulators; I guess to justify the cost. The mud flaps looked nice, but my wallet is small so I decided to make one my self.


Pep Boys Auto Parts Mud Flap for RVs/ large trucks $9.99
Pep Boys Auto Parts Reflectors $4.69
Home Depot Aluminum 1/8” x 3/4” x 36” $2.79
Home Depot Machine Screws/with nuts #10-24 x ¾” .89
Home Depot Cap Screws ¼” x 1-1/2” stainless 4.24


The Mud Flap:

I bought a set of large mud flaps the are designed for RV/large trucks. I looked for a mud flap that was not too heavy.  I trimmed the mud flap to be about 10” wide and 11” long.

The mud flaps come in pairs; I only used one mud flap, so I have a spare and in the future I might add some chrome and LEDs to the spare mud flap, you know, make it look like a Debris Modulator.

The Reflectors:

At first I wanted a plan mud flap with no lights or reflectors. I wanted to keep it simple, and then I saw some high reflective material that is almost paper-thin and weights almost nothing. I decided to give the reflectors a try and see how well they hold up.

The Bracket:

Home Depot has a selection of steel and aluminum plates in all different sizes. I bought two pieces of 1/8”x3/4”x36” aluminum.  I decided to go with aluminum, for the following reasons:

  1. To keep the weight down.
  2. It is easier to cut and drill.
  3. If something were to get caught, in the mud flap, aluminum will give (more forgiving) more than steel.

I used 5 pieces of aluminum to make the mud flap bracket.

  • For the horizontal braces I used 2 pieces, one shorter that the other.
  • For the vertical braces the two the same size.
  • For the center support, one small piece




The Screws:

I used 1/4”x 3/4” stainless steel cap screws and c-clip nuts to secure the mud flap horizontally. Machine screws/with nuts (#10-24 x ¾”) were used to screw the mud flap to the braces.


  1. I removed the rear tire/fender. It has 5 screws, 2 on the top, 2 at the bottom, and 1 behind the license plate.
  2. I removed the c-clip nuts at the bottom of the bike. I could not fine stainless steel 6mm x 25mm cap screws, so I used ¼” c-clip nuts and screws.
  3. If I had to do it again I would only drill the holes indicated in the above illustration last. It makes aligning the vertical support easier.
  4. I cut the mud flap to size and screwed on the two horizontal aluminum piece.
  5. I put the c-clip nuts on the ends of the longer piece and installed it on the bike without the fender.
  6. At the cross member bard above the mud flap I screwed on a vertical brace on both sides.
  7. At this point I used a large Crescent wrench and angle the brace so it would align.
  8. Once the vertical braces are aligned drill the holes where you need them. (I did not do that so the braces look an off alignment. I does not really matter because they an not be seen.)
  9. I removed the bottom 2 crews and the mud flap stayed in place. I installed the fender and all the screw and I was done.


I hope you get the idea. Times like these I wish I had a digital camera.