How to Install or Replace the Trailer Fender?

The main purpose of the mudguard is to protect the trailer on the road from dirt, rocks, water, and other hazards. Mudguards are an important safety accessory that can help prevent wheels from lifting up debris, which may fly into other trailers on the road and cause unsafe conditions.

Installing or replacing a trailer fender can easily be accomplished by yourself with just a few basic tools. The following will go over the steps needed to install a new or replace an old fender.

If you have a trailer without an old fender attached you can skip this step. If you do have an old fender on your trailer, it is most likely secured in 1 of 3 ways. The most common ways would be bolted on, bolted to mounting brackets, or welded on. Each method of mounting provides its own set of challenges you may face, and will each be covered individually.

The simple bolt-on method can be both the easiest and hardest method to remove depending on the condition of the hardware used to attach the fender. If you are lucky enough to have good serviceable screws you can just remove them and save them for the replacement fender. Chances are, however, that if you are replacing the fender, the bolts/screws are rusted, stripped, or in some way degraded.

Use a dissolving agent of some kind (WD-40, lemon juice, or regular cola will all work fine). Get some of the agents around the end of the bolt or screw and then tap the head with a hammer, which causes the screw to vibrate and seeps some of the dissolvers into the threads of the screw, as well as loosens up any corrosion that has bonded between the trailer and fender. Allow it to sit for a few minutes then try removing the screw.

If all else fails, you can use a screw extractor to drill into the top of the screw and create a deeper, sturdier screw head that can typically then be forced out with some muscle or power drill in reverse.

Removing a welded-on fender can be a bit tricky. If it was attached correctly and welded well, it will be fixed quite snugly to the trailer body. Without the proper tools, this becomes a very labor-intensive chore. If you have a weld remover that would be your first go-to option. Just run the chisel along the current weld to break it up. You will need to run from end to end on both the top and bottom of the fender to get all the welds apart so that you can then remove the fender.

If you do not have access to this tool, you can either take it to a welding shop to have it removed (typically not too expensive). Or if you want to take care of it yourself, using a small chisel (or flat head screwdriver you don’t want any more if you don’t have a chisel) and a small hammer, use the point of the chisel and hammer it lightly into the welds at the seams of the fender.

This method is a last resort and should only be attempted if you are confident in the steadiness of your hand, and don't have other options. If you can remove the bulk of the welding bead you should be able to then pop or pry your fender off. You should not have to apply a lot of force here, which could bend your fender.

If you have a brand new trailer, with no existing mounting holes or brackets this step will be pretty quick and easy. Either way, place a wheel stop of some kind on your wheels (a wheel chock or simple 2x4 would work) to keep the trailer stable while working.

If you plan on mounting your trailer with mounting holes, you will want to hold the fender up to the trailer body and use your clamp/friend to hold the fender in place just above where you want your fender to sit. Allow for the mounting lip (typically 1” long) so staging the fender 2” above the wheel well works great.

While it is held in place measure the distance from either end of the fender to the wheel well, and center the fender so that both ends are an equal distance from the well. Then use your marker and mark a few spots to place your mounting holes on the trailer body (one at either end, one to three along each arch depending on length, and one or two near the center). 

Mark a spot vertically center on the fender itself right above the dot on the trailer body. Doing this right at the base of the mounting lip as it is staged, will cause the fender to mount just a ½” above your wheel well if you center your screws on the fender when mounting.

When mounting your fender using a bracket attached to the trailer body, you will want to hold the fender up to the trailer body and use your clamp/friend to hold the fender in place right where you want your fender to sit. If you have existing brackets your fender should sit centered and in line with both brackets ready to be fixed on. If you are fixing new brackets to your trailer, hold the fender in place, and using your marker, draw a small straight line either vertically or horizontally, depending on how your brackets attach to the trailer body for mounting.

Go ahead and remove the clamps, and using your drill, make the holes in the trailer body and fender body right on those dots you just placed. Then it is as simple as lining up the holes on the trailer and fender and screwing them together (once it is lined up or to help line up the holes, using the clamps again might help to hold it in place so you can get those screws in. You will want to get all the screws in, then go back and make sure they are all tightened down once all are fixed in place.

Hold the fender up between your lines and double-check before bolting on the brackets that your fender fits between those lines, centered over the wheel well. You can remove the fender, and will want to line up the mounting face of your bracket right on the line you just marked. Secure the bracket to the trailer body on both ends of the wheel well along your marked line, and then bolt the fender to the bracket.

Use your brackets to hold the fender in a place where you need it mounted, and run a light weld along the base of the mounting plate to help hold it in place (the E6013 is a perfect electrode for this job), and then repeat along the top of the mounting lip with a heavier bead. Let your welds solidify, then run through and check for missing spots or thin beads, and repair where required.

HAWAY provides a variety of high-quality single-axle trailer fenders, tandem trailer fenders, and three-axle trailer fenders, which are durable and have thoughtful after-sales service. If you want to know more about trailer fender solutions after reading the above, please feel free to contact us.

As a professional manufacturer of trailer parts, we always insist on providing customers with high-quality and safe products. We have an experienced manufacturing team and strict quality management system, which can carry out all-round quality control of our products. At the same time, we can also provide thoughtful one-stop service according to the diverse needs of customers. If you want to buy our trailer axle, please contact us immediately!