Dealing with a clicking or vibrating 2005 yamaha grizzly 660 rear axle is a bit of a rite of passage for anyone who actually rides their quad in the woods or through the mud. If you've been hearing that rhythmic popping sound every time you make a sharp turn or under heavy load, you already know something is up. The Grizzly 660 is a legend for its power and reliability, but even the toughest machines have parts that wear out, and the rear axles are often the first things to go when you're pushing the bike to its limits.
It's easy to get frustrated when a ride is cut short by a mechanical failure, but honestly, the rear axle on these older Yamahas is pretty straightforward to deal with. Whether you're a seasoned mechanic or someone who just picked up a wrench for the first time last weekend, understanding what's going on back there can save you a lot of money and a massive headache.
Why the Rear Axle Fails in the First place
The most common reason for a 2005 yamaha grizzly 660 rear axle to give up the ghost isn't usually a failure of the metal itself, but a failure of the rubber boot protecting the CV joint. Those rubber boots are constantly under fire from sticks, rocks, and thick mud. Once a boot gets a tiny tear, the specialized grease inside leaks out, and more importantly, water and grit get in.
Once sand and water start mixing with the remaining grease inside the CV joint, it basically becomes a grinding paste. It doesn't take long for the bearings inside that joint to start wearing down. That's where that "click-click-click" sound comes from. If you catch a torn boot early, you might be able to just replace the boot and grease, but if you've been riding on it for a while, the damage is likely done, and you're looking at a full axle replacement.
Another factor is simply the age of the machine. We're talking about a quad that's nearly two decades old. Rubber gets brittle over time, and even if you haven't hit a sharp branch, the boots can crack just from dry rot. If you're buying a used Grizzly, the axles are one of the first things you should check.
Diagnosing the Problem
Before you go out and spend your hard-earned cash on new parts, you want to make sure the axle is actually the culprit. Sometimes a bad wheel bearing or even a loose lug nut can mimic the sounds of a failing CV joint.
The easiest way to check is to get the rear end of the Grizzly off the ground. Use a sturdy jack and some jack stands—never trust just a floor jack when you're tugging on a heavy machine. Once the wheels are up, grab the tire at the top and bottom and give it a good shake. If it wobbles, you're looking at a wheel bearing.
Next, grab the axle bar itself and try to move it back and forth. There should be a tiny bit of play (the axle needs to move as the suspension travels), but it shouldn't feel "sloppy." Finally, rotate the wheel slowly by hand while looking at the rubber boots. If you see any grease sprayed around the inside of the wheel or on the frame, or if you see a visible rip, that axle's days are numbered. If you hear that clicking sound while spinning the wheel by hand, it's definitely time for a swap.
OEM vs. Aftermarket Axles
When it comes to buying a replacement 2005 yamaha grizzly 660 rear axle, you've got two main paths: sticking with original Yamaha (OEM) parts or going with an aftermarket brand. This is where people usually get stuck.
OEM parts are great because you know they'll fit perfectly and the quality is consistent. However, they are incredibly expensive. For a machine that's been around since 2005, spending several hundred dollars on a single factory axle can be a tough pill to swallow.
Aftermarket axles have come a long way. You can find "budget" axles online for a fraction of the cost of OEM. While some of the super cheap ones can be hit-or-miss, brands like Rhino, Tusk, or East Lake Axle have built a solid reputation among the ATV community. Many of these aftermarket options are actually "heavy-duty," meaning they have a thicker shaft or larger CV joints than the original stock parts. If you're running oversized tires or a lift kit, going with a heavy-duty aftermarket axle is usually a much better move than staying with stock.
Tips for a Smooth Installation
Swapping out the rear axle on a Grizzly 660 isn't a job that requires a degree in engineering, but it is a bit messy. You're going to need a few basic tools: a large socket for the hub nut (usually a 30mm or 32mm depending on the axle), some snap ring pliers, and a good bit of patience.
One of the biggest hurdles is often getting the old axle out of the differential. They are held in by a small circlip on the end of the splines. Sometimes they pop right out with a firm tug, but more often than not, they require a bit of "persuasion." A pry bar can help, but you have to be extremely careful not to damage the differential housing.
Pro tip: If the axle is stuck, try pushing it into the differential first and then giving it a sharp, quick jerk outward. The sudden momentum is usually what seats the circlip and lets it slide out. Also, make sure you clean the area around the differential seal before pulling the axle. You don't want dirt falling into your clean diff oil.
While you have everything apart, it's a great time to inspect your rear brake pads and the differential seals. If the seal looks like it's weeping oil, replace it now. It's a five-dollar part and a two-minute job when the axle is already out, but a massive pain if you have to do it all over again next month.
Keeping Your New Axle Alive
Once you've got the new 2005 yamaha grizzly 660 rear axle installed and everything bolted back together, you probably don't want to do it again anytime soon. Maintenance is key here.
After every ride, especially if you've been in the mud or water, give the underside of the quad a good wash. Mud that dries on the rubber boots can become abrasive and eventually wear through the material. While you're cleaning, do a quick visual check. If you spot a small tear early enough, you can sometimes fix it with a "boot kit" before the CV joint gets ruined.
Also, be mindful of your riding style. Full-throttle starts with the wheels turned all the way to one side puts an incredible amount of stress on the CV joints. If you can avoid "pinning it" while the suspension is at its maximum angle, your axles will thank you.
Wrapping Things Up
The 2005 Yamaha Grizzly 660 is an absolute beast of a machine. It's one of those quads that just refuses to quit, even after years of abuse on the trail. But like any mechanical tool, it needs a little love to keep performing at its best. Replacing a worn-out rear axle is just part of the game.
It might feel like a big job when you're looking at a pile of tools and a greasy garage floor, but once you get that new axle in and hear how quiet the machine is on your next ride, you'll know it was worth the effort. There's a certain peace of mind that comes from knowing your driveline is solid when you're miles away from the truck in the middle of nowhere. So, grab some shop towels, maybe a cold drink, and get that Grizzly back in tip-top shape. The trails are waiting.