Getting stuck deep in a mud hole is usually a badge of honor, but hearing that nasty "pop" followed by a rhythmic clicking means you're likely staring down a Polaris Sportsman 570 rear axle replacement sooner than you planned. It's one of those repairs that sounds intimidating if you've never done it, but honestly, once you get the hang of how these CV axles are seated, it's a job you can knock out in your driveway with a basic set of tools and a bit of patience.
The Sportsman 570 is a workhorse, but like any ATV, those rear axles take a beating. Whether you're running oversized tires, a lift kit, or you just spend way too much time in the thick stuff, those CV joints are the weak link in the chain. If you've noticed a torn boot leaking grease or a vibration that feels like your rear end is about to fall off, it's time to stop riding and start wrenching before you end up stranded miles from the trailhead.
Signs You Actually Need a New Axle
Before you go out and drop money on parts, you want to be sure it's the axle and not just a loose wheel bearing or a busted bush. Usually, the first sign of trouble is a clicking sound that gets louder when you're turning or when the suspension is compressed. If you look under the machine and see grease sprayed all over your A-arms, that's a dead giveaway. Once that rubber boot tears, dirt and water get into the bearings, and it's game over for that joint.
Sometimes the axle doesn't snap; it just gets "slop" in it. If you can grab the axle bar and wiggle it back and forth significantly at the joints, the internal race is worn out. If it's already snapped clean through, well, you probably already know because you've lost drive to that wheel and things are sounding pretty crunchy back there.
Gathering Your Tools
You don't need a professional shop to pull off a Polaris Sportsman 570 rear axle replacement, but having the right sockets makes life a lot easier. You'll want a good floor jack and some jack stands—never work on an ATV supported only by a jack. For the actual hardware, you're looking at a 27mm socket (or a 1-1/16 if you're in a pinch) for the hub nut, and usually a 15mm for the A-arm bolts.
Don't forget a pair of needle-nose pliers for the cotter pin and a big pry bar. The pry bar is going to be your best friend when it comes time to pop the axle out of the transmission. Also, grab some rag and some grease. It's a messy job, and you'll want to clean the area around the transmission seal before you put the new axle in so you don't shove trail grit into your gears.
Getting the Old Axle Out
First things first, loosen the hub nut while the tire is still on the ground. That nut is torqued down pretty tight, and trying to break it loose while the bike is on a jack just leads to the whole machine wobbling around. Once that's loose, jack up the rear, take the wheel off, and pull the cotter pin out of the castle nut.
Now, you've got to get the hub out of the way. You don't necessarily have to take the whole rear suspension apart. Usually, if you unbolt the upper A-arm from the bearing carrier, you can tilt the whole assembly down far enough to slide the axle stub out of the hub. Just be careful not to put too much tension on your brake lines. I usually use a bungee cord to hang the hub assembly out of the way so it's not dangling by the hose.
The trickiest part of the Polaris Sportsman 570 rear axle replacement is getting the inner CV joint out of the transmission. There's a little "C-clip" on the end of the splines holding it in place. You want to give the axle a good, sharp jerk straight outward. If it's being stubborn—and they usually are if they've been in there a while—take your pry bar and gently wedge it between the inner CV housing and the transmission case. Give it a quick pop, and it should slide right out. Just don't go crazy with the pry bar; you don't want to crack the aluminum casing.
Prepping and Installing the New Unit
Before you shove the new axle in, take a second to look at the seal on the transmission. If it looks chewed up or it's been leaking, now is the time to replace it. It's a five-dollar part that will save you a massive headache later. If the seal looks good, wipe out any old dirt and put a light coat of grease on the splines of your new axle. This helps it slide in easier and prevents it from rusting into place for the next time you have to do this.
Aligning the splines can be a little fiddly. You'll feel it start to catch, and then you need to give it a solid push to get that C-clip to seat. You'll know it's in when you hear or feel a "click" and you can't pull the axle out by hand. If it feels like it's hitting a wall, don't force it with a hammer. Pull it back out, rotate it a tiny bit, and try again.
Putting It All Back Together
Once the inner side is seated, it's just a matter of reversing what you did. Slide the outer end back into the hub, bolt your A-arm back up, and get that hub nut back on. Don't forget the cotter pin. It's a tiny piece of metal, but it's the only thing keeping that castle nut from vibrating off while you're pinning it down a forest road.
When you're tightening everything down, make sure you're hitting the right torque specs. For the Sportsman 570, that hub nut usually wants about 80 ft-lbs, but check your specific year's manual to be safe. Under-tightening can lead to premature bearing failure, and over-tightening can strip those soft threads.
OEM vs. Aftermarket Axles
When shopping for your Polaris Sportsman 570 rear axle replacement, you're going to see a massive range in prices. You can find "budget" axles online for sixty bucks, or you can go with high-end heavy-duty brands that cost three times that.
If you're just a casual trail rider with stock tires, the mid-range aftermarket axles are usually plenty fine. However, if you've got a 2-inch lift and 28-inch mud tires, those cheap axles are going to snap like toothpicks. In that case, investing in something like a Rhino or a Demon axle—which are designed to handle more extreme angles—is definitely worth the extra cash. It's better to pay a bit more now than to be doing this same job again in three weeks.
Final Maintenance Tips
To keep from having to do another Polaris Sportsman 570 rear axle replacement too soon, make a habit of checking your CV boots after every ride. If you catch a small tear early, you can sometimes just replace the boot and the grease rather than the whole axle. Also, try to avoid "full throttle, full lock" situations. When your wheels are turned all the way to one side and you're buried in the mud, that's when the CV joints are at their most vulnerable.
Anyway, it's a straightforward job once you get past the fear of that C-clip. Take your time, keep things clean, and you'll be back out on the trails before the weekend is over. There's a certain satisfaction in fixing your own rig, and plus, you'll save a fortune on shop labor rates. Happy riding!