ATV Axles 101: Reasons They Fail and How to Choose Replacements

With ATVs and UTVs getting bigger and more powerful engines, all that new power affects already stressed components, including those directly involved in power transfer. Axles, drive belts and clutches are seeing more frequent failures, largely due to subpar materials and designs. This is one cost-cutting measure big quad brands use to keep end prices down. The practice though means you’ll be paying more in the long run.

What Axles Do 

To get power from the engine and transmission down to the wheels, you’ll need ATV axles in top condition. The parts also support the weight of the quad and rider and face increased impact from spraying rocks and obstacles when taking your quad for a spin. While your factory axles are decently built, the high engine loads, increased friction, searing temperatures and metal fatigue all lead to premature axle failure. 
Bent, fractured and snapped axles are a too often occurrence that can leave riders in the middle of nowhere. Moreover, the parts affect the steering and gear changes, so basic maneuvers like turns or changing gear are out of the question. To avoid the hassle, a good idea is to have a working spare. 

Why They Fail 

Apart from regular service items like brake pads, spark plugs and oil changes, ATV axles and drive belts are some of the more frequent replacements on any quad. Factory units don’t do the engines and chassis any favors, and show signs of wear when you’re harder on the throttle. Stock axles can last anywhere between 5 and 5000 miles in leisurely rides. But, if you’re like most ATV owners who like to have a bit of fun, or use a UTV for work, chances are you’ll be looking for replacements sooner than later. 
Part of the reason quad bike axles throw in the towel are the high engine loads and torque from high-powered engines. Many performance quads now put out over 100 horsepower.  Delivered at high RPMs, this causes gradual metal fatigue and prolonged bouts at full speed can lead to bent or snapped axle shafts. Moreover, ruptured CV boots and leaking lubricant increase friction and heat, causing wear in the joints and bearings. You might miss the usual warning signs that something is wrong, until the whole assembly seizes and the quad rendered useless. 

Signs of Bad Axles 

The good news is that axle failure shows up through changes to power output and handling and something that you can spot earlier if you know your quad. These usually build up gradually before units fail completely. Things to look for are: 

• Clicking, popping and grinding sounds during turns – damaged and neglected ATV and UTV axles can be identified by loud popping and clicking sounds when turning. This is often down to ruptured CV boots and leaked grease. While the factory thermoplastic boots are relatively strong, it takes just a few hits from sharp rocks or stumps to cause punctures. The increased friction of metal parts wears down the CV joint splines, and eats away at the bearings. And riding on will cause the axles to bind and bend, with grinding noises and vibrations felt through the steering wheel or handlebars.  
• Clunking noises when braking – if you’re hear clunks when applying the brakes, be sure this is the excess play in axle shafts and joints. Shifting weight during deceleration means misaligned shafts, joint splines, hardened rubber bushings and other components are worn to the point that shafts can snap right off.  
• Humming sounds when on the throttle – jolting while accelerating can mean clutch and pulley problems, loose or worn drive belts, and damage axles that struggle to get power down. The noise can heard when negotiating technical terrain with the quad in low gearing, and during gear changes. Some quads can also be harder to get into reverse. 
• Power loss – this can happen gradually with slower than usual acceleration, or hesitance on inclines, but axles beyond repair will stop getting power to the wheels. Advanced wear and tear, increased friction and metal fatigue all team up to kill axles, often before you reach home. 

What to Look for in Replacements

As with all ATV parts, choosing the right ATV axle depends of several factors. You’ll want something that’s better built, lasts longer than what came with the quad, suits your riding style, fits the bike without modifications, and is covered by warranties. Assess you riding habits in terms of where and how you ride, how axles determine things like performance or agility, and most importantly whether axles get the best out of your quad. 
Buyers get to choose between original equipment (OE) or aftermarket options. Go the OE route if you’re satisfied with what you have and the factory axles have run up a couple of thousand miles with no issues. Just be ready to pay more. Most quad owners though are better off with the dozens of aftermarket axles. These are most often cheaper, use better materials and production processes, are rated for high-powered and heavy machines, and guaranteed to last longer. 
Manufacturers offer heavy-duty and extreme duty axles meant for different machines and different uses. Heavy-duty variants trump OE parts in that the shafts are made of thicker and high-grade carbon steel for superior tensile strength, higher heat resistance and extreme torque loading in serious off-roading and work tasks. This means they’ll endure faster speeds and high engine loadings without complaining or showing signs of wear. 
Power transfer is made easy with machined CV joints, industrial bearings and thick rubber boots to prevent punctures. Pre-assembled units boost performance and durability in mid-spec machines with power averages of 50hp. A decent option for mudding, light technical trials, high-speed runs, or hauling gear at the worksite. 
Bigger-engined ATVS and side-by-sides need to support more weight, put out substantially more power and torque and endure more abuse. If you’re considering new axles for 750cc machines and above, better look to extreme-duty aftermarket units. Here shaft diameters grow bigger and are made of stronger 4340 Chromoly steel to deal with higher revs and longer power spikes. 
These are paired with precision joints with CNC-machined surfaces offering improved wheel articulation and more ground clearance, induction heat-treated ball bearings to reduce friction and improve stability in the joints, and heavy-gauge and puncture-resistant neoprene boots packed with high-pressure moly grease. Pre-assembled units deliver more with the throttle full out, in rock-crawling, racing and when towing hundreds of pounds of building materials and equipment. 
Look for parts with clearly stated warranties. And to ensure you’re getting a quality product that also fits, look for relevant ISO certifications. Shop for aftermarket ATV and UTV axles at well-stocked quad bike specialists, or contact dealers for original equipment replacements.