How to Install Dump Truck Mud Flaps

Installing dump truck mud flaps isn't very difficult when you have the right tools. Follow these steps and you'll never have to pay someone else to do it for you again!

Difficulty: Moderate

Instructions

Things You'll Need:

• dump truck
• 2 mud flaps
• drill
• 2 - 1" metal strips (same length as the top of the mudflap) or fender washers
• 8 bolts with washers and nuts (lock nuts preferred; bolts should be 5/16" or 3/8")
• 2 wrenches (should fit bolts)

1. Locate the rear-most body support or rib on the undercarriage of the truck. It should be behind the rear tires; this is spot where you mount the mud flaps. Many trucks will have pre-drilled holes. If not, you’ll learn how to drill them in step four.

2. Examine the mud flap. Most arrive with notches that you just need to punch through for installation. If the mud flap does not have holes, notches, or marks indicating bolt placement, use the drill to put four holes across the top. Holes should be evenly spaced across the top of the flap and sit between one-half and one inch from the edge. However, if the mounting bracket has holes in it and the mud flaps do not, mark the mud flaps to match the brackets and drill the holes there.

3. 
   Pointing to I-beam mounting bracket where flap are typically installed (photo is of custom installation)

   Next, examine the mounting bracket. If it’s a C-channel piece, you’ll mount the mud flap directly to the flat surface of the metal. If it has the I-beam shape, fill the space on one side with a strip of wood so that the surface is flush with the edges of the metal. This provides a solid, flat mounting surface. You’ll bolt the wooden strip in during installation so for now all you need to do is fit and position it.

4. If the bracket does not already have holes in it, it’s easy to find the correct position to place them. Hold the mud flap, with the holes already drilled through it, up against the mounting bracket. When properly positioned, the mud flap should cover the width of the tread from both tires. Mark the metal bracket through the holes in the mud flap, then remove the mud flap and drill the holes.

5. 
   Proper use of a metal strip

   Next, thread the bolts through the metal strip or fender washers. Without the extra support the heavy rubber mud flaps will quickly tear loose, so don’t skip this step! If you use metal strips made from plate steel, you’ll first need to mark them through the holes in the mud flap and drill holes in each strip.

6. Push the bolts through the metal, then the flap, and then into the mounting bracket. The flap should be sandwiched between the two pieces of metal for durability and backed with a washer and a lock nut for stability. Tighten the nuts and bolts with a wrench.

7. 
   The ideal flap length for a working dump truck

   Before you call it a day, check the length of the mounted mud flaps. They should not hang more than about halfway down the tire. Any longer, and they’ll be caught on curbs, in dirt piles, and pinned beneath the tires in some situations – any one of which may require a new installation!