What Plastic Types Are in ATV Fenders and Other Parts?

ATVs use plastic materials in just about every component that isn’t metal or rubber. Any time you need to repair cracked or damaged plastics, such as fenders or body panels, you must know what type of plastic the part is made of for a durable result.

ATV fenders and body panels are typically made of thermoplastics such as polyethylene (PE), polypropylene (PP), or thermoplastic olefins (TPO). Components such as footwells, fender flares, inner fender panels, and other black plastic trim are often made of ABS (Acrylonitrile Butadiene Styrene).

To determine what type of plastic a specific part of your ATV is made of, you need to do some investigation. This post covers several methods that hopefully will lead you to a definite answer.

Why Does the Type of Plastic Matter?

Most people don’t give a second thought to what type of plastic is used in their ATV before facing a damaged plastic component that needs to be repaired. 

Cracks and holes in the plastic parts of your ATV, like the fenders, are common, especially if you often ride off-road. In fact, damaged plastics, such as cracks, are the most frequent type of damage seen in ATVs.

Buying a new part is the easiest way to repair damaged plastics. But if your budget doesn’t allow it, and function matters more to you than aesthetics, you may want to repair the damage at home or a body shop.

Any time you want to repair damaged plastic, you need to know what type of plastic the components are made from to ensure a sturdy and durable result. 

Plastic Welding

If you are considering welding the crack, you must ensure you get welding rods of the same plastic-type as the component you are repairing. 

When welding plastics on an ATV, heat and a new plastic strip are used to melt and fuse the cracked areas. If you use welding materials other than the original plastic type, the weld becomes brittle and is more likely to break again.

Gluing Plastics

If you’re looking to use glue to repair the crack, you must choose the right type of glue and apply the correct procedure.

ATV plastics are chemically resistant, meaning they are unaffected by most chemicals. That is why you need glue designed to bond to your specific type of plastic. Generic adhesives or glue intended for a different kind of plastic may not adhere correctly. 

Also, some plastics, such as PE, cannot glue without preparations such as flame treatment before gluing. 

Why Do They Use More Than One Type of Plastic?

ATV manufacturers and their engineers choose plastic types depending on various factors:

Cost: Some plastics are cheaper to buy and manufacture while offering the required quality and properties. Some manufacturers cut costs more than others that focus more on quality. 

Material properties: Some plastic parts, such as those more exposed to impacts and flying debris, need to be of a more rugged and impact-resistant type of plastic. Less exposed parts that are more visible still need to be tough while also being flexible and offering prettier visuals. 

Raw material availability: Markets go up and down, and manufacturers may choose a plastic-type depending on what is available. 

Manufacturing equipment: Some manufacturers may choose plastic-type depending on their existing equipment. Buying a new production line of machinery to use a different type of plastic may not be profitable. 

The Different Plastic Types Used in ATVs

Here’s the revised table with the types of plastics commonly used in different parts of an ATV, without the properties column:

Understanding plastics involves more complexity than it appears at first. In fact, the science behind plastics is so intricate that fully grasping this subject typically requires education in material technology.

Back when I got my degree in engineering, there was a class called “material theory.” While I’m no expert in plastics, I decided to look at some fundamental properties that make thermoplastics ideal for ATVs and the practical differences between the most common types.

Most ATV Plastics are Thermoplastics

With a few exceptions, most plastics used in ATVs are a form of thermoplastic.

A thermoplastic is a general term that covers any plastic polymer that becomes pliable or moldable when heat is applied and solidifies when it cools back down. 

Thermoplastics are an excellent material for making ATV components because they can be molded into almost any shape and form using various methods, including:

• Injection molding – A technique where plastic pellets are heated until they melt and then injected into a metal mold.
• Compression molding – A method where preheated plastic is compressed between two metal mold parts.

Thermoplastics are versatile materials that are relatively easy to fabricate. They are recyclable, some easier than others.

ATV plastics are exposed to regular gasoline or oil spills and must withstand these chemicals. That is why plastics such as polyurethane (PU) that break down or get soft from gasoline exposure are uncommon in ATVs.

Polyethylene (PE), or specifically High-Density Polyethylene HDPE

Polyethylene is the most widely produced plastic in the world. You’ll find it in everything from plastic shopping bags and bottles to ATV fenders. 

The term “polyethylene” is an umbrella term that includes several sub-categories of PE plastics that all use polyethylene as a base. 

The type of polyethylene used in ATV fenders is high-density polyethylene (HDPE). As the name implies, it’s a more dense type compared to other available grades of PE.

When someone says their ATV fenders are PE, they probably mean HDPE, as no other type of PE is suitable as fender material.

Why HDPE is an excellent choice for ATV fenders and body panels:

• Chemically Resistant – Will likely not get damaged from chemicals it may become exposed to on an ATV:
  • Excellent resistance to most solvents, even acetone.
  • Very good resistance to alcohols, dilute acids like battery acid, and alkalis.
  • Moderate resistance to gasoline, oils, and grease.
  • Resistant to brake fluid, but brake fluid will damage any paint. 
• High tensile strength – does not tear easily. 
• Moisture resistant – is not affected by water.
• Hard but semi-flexible – Remain stiff but flexible in temperatures ranging from -50°C to +60°C (-58 °F to 140 °F).
• High impact strength – can withstand hard hits from things like flying rocks. It tends to stretch rather than shatter.
• Low friction – Mud and dirt do not stick easily to the wax-like surface.
• Inexpensive – but typically more expensive than polypropylene (PP).
• Can be welded – Various welding techniques exist, but a particular type of heat gun and PE-welding rods is most suitable for DIY applications. 

Disadvantages of HDPE:

• Low melting point compared to other thermoplastics. HDPE melts at 120 to 130 °C (248 to 266 °F).
• It is not possible to glue without pretreatment. The chemically resistant properties prevent most glues from bonding unless you pretreat the surface. One way of pretreatment is by flame treatment.
• PE can become brittle from UV radiation in sun rays. Carbon black is commonly used as a UV stabilizer to make the plastic more UV-resistant. 
• Paint and decals don’t stick well to the wax-like surface.

Typical uses of PE or, more specifically, HDPE in ATVs:

• Front and rear fenders.
• Body panels, such as side panels.
• Gas tank and brake fluid container.
• Skid plate

Polypropylene (PP)

Polypropylene is also a thermoplastic and is the second most widely produced plastic worldwide. 

Polypropylene (PP) has many similar properties to pole ethylene (PE) but is slightly different in some aspects.

PP vs. PE plastics in ATVs:

• PP is more heat resistant with a higher melting point than PE.
• PP is mechanically rugged with good fatigue resistance but less impact-resistant than PE.
• PP is stiffer than PE but is still flexible. It becomes brittle below 0 ºC. 
• Mixing PP with ethylene (copolymerizing) improves mechanical strength and low-temperature properties to a level that competes with ABS.
• PP has high chemical resistance similar to but not as good as PE.
• PP is vulnerable to degradation from UV radiation in sunlight and is susceptible to oxidation.
• PP is not as resistant to moisture (more permeable), but the difference is negligible regarding its use in ATV fenders. 
• PP is slightly lighter than PE.
• PP is less expensive than PE.
• PP is more straightforward to repair than PE as it can be glued using hot melt glue made of polypropylene. It can also be welded, and holes can be filled the same way as PE but using a PP-welding rod. 
• PP is recyclable but not as easy to recycle as ABS and PE.

Typical uses of PP in ATVs:

• Front and rear fenders.
• Body panels, such as side panels.

Thermo Plastic Olefin (TPO)

Thermo Plastic Olefin (TPO) is a generic name for more complex thermoplastic forms that are becoming increasingly popular in exposed plastics such as ATV fenders and automobile bumpers. 

TPO plastics are blends of several components added to improve material properties further over conventional thermoplastics. TPOs typically contain fractions of three primary components:

• A thermoplastic base, most commonly PE or PP.
• Elastomer or synthetic rubber for increased elasticity.
• Fillers such as fiberglass, carbon fiber, and others improve rigidity and tensile strength.

TPO also goes by Thermo elastic olefin (TEO), where olefin is just a term that refers to polymer plastics such as PP, PE, and others. 

Please note that TPO and TEO are only generic names, so you cannot be sure what the properties and the various components are just by knowing it’s a TPO.

Other benefits of TPOs:

• TPO is UV-stabilized and does not degrade from sun rays. 
• TPO is paintable.
• TPO is easy to mold into various shapes. 
• More durable than PE and PP.

Typical uses of TPO or TEO in ATVs:

• Front and rear fenders.
• Body panels, such as side panels.

Acrylonitrile Butadiene Styrene (ABS)

ABS is a thermoplastic made of different base materials than the other plastic types in this post. 

Acrylonitrile and styrene offer strength and rigidity, while polybutadiene rubber adds toughness and flexibility. Additives such as fiberglass are used to improve toughness further.

Benefits of ABS plastics in ATVs:

• Stiff and sturdy: ABS is tough; there’s no doubt about it. LEGO bricks are made of ABS plastic, which should speak for itself. 
• Excellent impact resistance: ABS is known for its ability to withstand impacts better than other polymer plastics. This makes ABS plastics an excellent choice for the more exposed areas of an ATV.
• Easy to repair: A mangled component from ABS can be reheated to its melting point and reshaped. This property applies to all thermoplastics but is more critical in parts that are more likely to take a hit. ABS plastic is relatively easy to weld.
• It has good chemical resistance but is not resistant to solvents. Acetone and alcohol will dissolve ABS.
• Shiny and impervious surface: Makes cleaning easier. 
• Remain impact resistant at lower temperatures: ABS can be used between −20 and 80 °C (−4 and 176 °F).
• ABS is lightweight.

Disadvantages of ABS plastic:

• Low melting point. It’s not ideal for high heat exposure, like near an ATV exhaust pipe.
• Degrades from UV exposure: ABS also gets damaged from sun rays, but additives are used to improve UV resistance. 

Typical uses of ABS plastics in ATVs:

• Airbox and air intake hoses
• Footwells and floorboards
• Fender flares, mudguards.
• Inner fender panels and covers.
• Other trim components.
• Cargo boxes.
• Your painted fenders may be ABS.

Acrylic Plastics

Polyacrylic Acids (PAA) and Poly Methyl Methacrylate PMMA are acrylic plastics often used in ATV headlights and rear lights.

Acrylic plastics offer a sturdy, lightweight, and impact-resistant substitute for glass. It is much harder than the other plastic types. 

Thermoplastic Elastomers (TPE)

TPE, sometimes called thermoplastic rubbers, is a mix of plastic and rubber commonly used in the tracks on ATV belt kits.

Identifying the Type of Plastic in Your ATV

Now that you know the most common plastic types in ATVs, how do you know what plastics your ATV is made of?

Check for Imprints Markings

Plastic parts may or may not have imprints or markings that indicate the plastic type for recycling purposes.

The symbol design varies based on when and where the part was made. The most common markings to look for are the recycling symbols created by the Plastics Industry Association. 

The symbol consists of a triangle formed by three circling arrows with a number inside the triangle that indicates the plastic type. Underneath the triangle is an abbreviation for the plastic type (HDPE, PP, etc.)

On older ATVs or some Chinese models, you may find markings that only contain abbreviations, like the fenders on this youth ATV.

The markings are usually placed somewhere out of sight inside the wheel wells, inside the airbox lid, or behind body panels. 

You might have to remove the part to find the symbol, but you must remove it anyway if you plan to repair it.

Check the User Manual or Service Manual

Usually, you will find information about body panels and fender plastics in the manuals. However, the data is generally not easy to find and may require too much searching for some people’s liking.

Do a Flame Test

If you can cut off a piece of plastic, you can perform what is known as a flame test. Make sure you do this outdoors somewhere fireproof. 

Cut off a small plastic sample and light it on fire. Do NOT breathe in the smoke, as it can be highly toxic.

Observe the color of the flame, the scent, and how the plastic burns.

• Polyethylene (PE) – Drips, smells like candlewax
• Polypropylene (PP) – Drips, smells mostly of dirty engine oil and undertones of candle wax
• Acrylonitrile butadiene styrene (ABS) – Not transparent, sooty flame, smells of marigolds
• Polyurethane foam (PU) – Yellow flame, acrid smell, plastic crumbles

Do a Solvent Test

Cut off a piece of the plastic and place it in a solvent like acetone. If it dissolves or goes softer over a few hours, you know it is ABS plastic.

If All Else Fails – Ask Your ATV Dealer

They may or may not know the answer, but they should be able to send a request to the manufacturer directly.