Obligatory not a gator, but I thought you all would enjoy.
The ball joints on the Yamaha rhino's are not serviceable, and must be changed on a regular basis. Failure to do so will result in catastrophic failure and maybe death. This is not a hard thing to do if you have the right tools and can turn a wrench.
here is a diagram of the suspension system;
The parts we are changing are number 2 on the diagram.
The first thing you need to do is gather up your tools. You will need a good impact gun, a screwdriver, and a socket set with some extensions. you will need a 12mm, 3/4",11/16", 7/8" and a 10mm socket. If you have an MY 2005 or above, you will need a 32mm socket, as well. For MY 2004, you need a 27mm. The 32 and 27mm sockets are for the hub nuts. You will also need a vice and a ball joint press. I use the evertough #67045 press from o'reilly.
Step 1 is to jack it up and support with stands;
Next, use an 11/16" socket and impact gun to remove the wheel.
Now, we need to take off the brake caliper. Use a socket wrench/breaker bar with a 12mm socket and 3" extension. You can see the caliper in the above pic on the right side of the hub. The 2 bolts are directly behind the hub.
There is a bolt on top of the steering knuckle that holds on the brake line. Remove with a 10mm socket. (pic is of the bolt removed) Now, take the caliper and set it on top of the A-arm so that its not just hanging.
Now for the fun part- the hub nut! The hub nut is staked to the axle so that it can't back off. Pry the indented part out of the cutout in the end of the axle with a screwdriver. You may have to carefully cut the staked part of the nut off with a small cutoff wheel.
You can see the punched in part in the above picture.
Now that it's unstaked, take a strong impact gun and either a 27mm or 32mm socket (whichever fits) and buzz the nut off.
With the nut removed, slide the hub and brake rotor assembly off the axle stub shaft;
Now, remove the cotter pins (#14 on the diagram) and then use a 3/4" socket to remove the castle nuts (#13). There are 3 of them- one on each ball joint and 1 on the steering joint. Once they are off, take a big chisel and place the end on top of the steering knuckle, and then give it a good smack with a sledge hammer. The top joint should separate from the knuckle. Now, take a jack and place it under the end of the stud on the bottom joint. There is a nice little pocket in the end of the A-arm. Place the end of the chisel in it and hammer it again. The knuckle should be free from the suspension.
Go ahead and slide it off the end of the axle. If its stuck, DON'T YANK ON IT! you can accidentally pull the axle out of the differential. Instead, tap it off with a hammer.
Now its time to press out the upper ball joint. Take off the snap ring (#3) and then set up the press.
Use the 7/8" socket and impact gun to turn the press. make sure that the pres is installed straight on to the joint, and that its not pressing crooked.
Now, use a file and remove any crud from the inside of the hole, and then take some grease and lube up the hole for the new joint (see pic). take the new joint and start it straight in the hole, and then set up the press;
again, use the impact gun to turn the press, taking care to make sure the new joint is going in straight. Failure to make sure its going straight can result in damage to the snap ring grove in the new joint.
now for the bottom joint. Remove the snap ring and then use a vise to press the joint flush with the knuckle (sorry, no pic). The bets way I have found to get these out is to take a cutoff wheel and cut off the stud. Then use the receiving tube from the press kit and set it up so that the joint can come out into it, and place the stud behind the joint so that the vise has something to press on.
Please not that it shouldn't be to hard to turn the vise- if it is, the receiving tube is not in the right spot and the joint is catching it. Adjust the setup and keep going.
Once its out, use the file and clean up the hole, and then grease it up and start the joint.
I made a custom pressing tool for these joints out of some 11/4" (I think) angle iron. I made a couple of square tubes, and this makes it super easy to press the joint in.
Notice the pressing tube on the front, and the receiving tube on the back.
Now that the joint is in, reinstall the snap ring and then assemble everything in reverse order that you took it apart. The 3/4" nuts on the joints require a torquing of 22 lb-ft. You may need a crowsfoot wrench for the top joint. Don't forget the install the cotter pins!
A note on the hub nuts- 2004 model year has a different nut than MY 2005 and up. Make sure to order the correct ones for your machine! I like to replace them because once you put them back on and re-stake them, they can come off easier than originally possible. For 5 bucks, its cheap insurance.