What is nut size for ball joint on 2001 Xterra

it depends on if they have been changed before. normal size is 18mm changed is 19mm on tie rods. also check the condition of the anti-roll bar rubbers as they can cause this problem to. also check the traling arm on the steering this can do this to.

Instructions

1. Remove the Upper Control Arm
   • 1Disconnect the ground battery cable using a wrench.
     
   • Loosen the front wheel lugs located on the same side of the upper ball joint you need to replace. Use a lug wrench.
     
   • Raise that same front wheel off the ground using a floor jack and support the vehicle on a jack stand.
   • Finish removing the tire.
     
   • Take the cotter pin off the upper ball joint stud holding the steering knuckle arm. Use a pair of nose pliers.
     
   • Remove the castle nut from the upper ball joint stud using a wrench or ratchet, ratchet extension and deep socket.
     
   • Loosen the two bolts securing the back of the upper control arm to the mounting bracket. Use a wrench to hold the bolt head as you loosen the retaining nut with a ratchet and socket.
     
   • Pull the control-arm ball joint off the steering knuckle arm. You may need to use a Pitman arm puller to free the ball joint.
     
   • Finish removing the two bolts from the back of the upper control arm and lift the upper control arm off the vehicle.
     
   Install the New Upper Control Arm
   • Set the new upper control arm in place and install the two bolts and retaining nuts to secure the back of the upper control arm to the mounting bracket. Remember the bolt heads should point inward toward the shock absorber with the retaining nuts on the outside of the mounting bracket. Do not tighten the bolts yet.
     
   • 11Insert the control-arm ball joint on the steering knuckle arm and start the castle nut with your hand over the ball joint stud. Do not tighten the nut yet.
     
   • Tighten the two bolts on the mounting bracket to 67-foot lbs. (91 Nm) using a torque wrench. Hold the bolts with a backup wrench as you tighten the retaining nuts with the torque wrench.
     
   • Tighten the ball-joint castle nut to 45-foot lbs. (61 Nm) using the torque wrench, ratchet extension and deep socket.
     
   • Install a new cotter pin through the joint-ball stud hole using the nose pliers. If necessary, tighten the castle nut just a few degrees to clear the stud hole through one of the castle nut slots.
     
   • Mount the tire on the wheel assembly and install the wheel lugs using the lug wrench.
     
   • Lower the vehicle and finish tightening the wheel lugs.
     

http://groups.yahoo.com/group/villagerquest/ Ball Joint Removal

1. Remove the wheel and tire assembly. For additional information, refer to Section 204-04 .

1. Remove the suspension lower arm ball joint cotter pin.

1. Remove the suspension lower arm ball joint nut and separate it from the wheel knuckle.

May have to leave nut partially on and hit the nut hard with a hammer to knock the tapered stud down and out. May have to hit side of knuckle to help get it to drop. or rent a pickle fork to drive between the bal joint and knuckle.

1. Remove the suspension lower arm ball joint to suspension lower arm nuts and remove the ball joint.

Removing the Ball Joint Step 1 Loosen the lug nuts on the front wheel assembly with the ball joint you need to replace. Do not remove the lug nuts.
Step 2 Set the transmission in neutral (manual) or park (automatic) and raise the wheel off the ground using a floor jack. Then support the car on a jack stand.
Step 3 Chock the rear wheels and apply the parking brake.
Step 4 Remove the wheel lugs and the wheel assembly.
Step 5 Remove the mounting nut and dished washer that secure the stabilizer bar to the control arm. Use a wrench or ratchet and socket.
Step 6 Unscrew and remove the mounting bolt and nut holding the inner side of the control arm to the car's body. This will relieve the tension on the stabilizer bar. Use a wrench to hold the mounting bolt as you unscrew the nut with a wrench or ratchet and socket.
Step 7 Unscrew the bolt on the steering knuckle that holds the control-arm ball joint to the knuckle. Use a wrench or ratchet and socket.
Step 8 Spread the steering knuckle joint that holds the control-arm ball joint to the knuckle. Use a large screwdriver or pry bar. Then separate the ball joint from the steering knuckle.
Step 9 Pull the control arm from the stabilizer bar.
Step 10 Remove the stabilizer bar spacer from the control arm and keep it in a secure place. You will need to use it on the new control-arm ball joint assembly.
Installing the Ball Joint Step 1 Insert the new control-arm ball joint stud into the steering knuckle joint. As you look through the mounting bolt hole on the steering knuckle, align the notch on the ball joint stud with the hole. Insert a new ball joint mounting bolt and start a new nut on the bolt. Tighten the nut.
Step 2 Mount the stabilizer bar spacer in the control arm, then insert the stud bolt at the end of the stabilizer bar into the control arm mounting hole and spacer.
Step 3 Set the other end of the control arm in its mounting position and insert the mounting bolt. Then start the mounting nut on the bolt by hand.
Step 4 Hold the head of the mounting bolt that secures the control arm to the car's body using a wrench, then tighten the nut.
Step 5 Secure the stabilizer bar to the control arm with the dished washer and mounting nut. Tighten the nut.
Step 6 Install the wheel assembly and lugs. Tighten the lugs with the lug wrench just enough to hold the wheel assembly firmly in place.
Step 7 Lower the vehicle and finish tightening the wheel lugs.
Step 8
Remove the chocks from the rear wheels.

It depends on exactly which ball joint of the 3 per side your changing, but here are the details.

COMPRESSION LOWER ARM & LATERAL LOWER ARM ASSEMBLIES
Removal
1. Loosen compression lower arm ball joint nut. Using steering linkage puller, separate ball joint and
knuckle. Remove nut, bolts and compression lower arm assembly. Remove dust cover.
2. Remove stay. Remove shock absorber lower mounting bolt. Loosen lateral lower arm ball
joint and knuckle nut. Using steering linkage puller, separate ball joint and knuckle. Remove nut, bolt and
lateral lower arm assembly. Remove dust cover.
Inspection
Using preload socket, ensure breakaway torque for compression lower arm ball joint is 4-22 INCH lbs. (0.5-2.5
N.m) for 2000 models. On 2001 models, breakaway torque is 22-54 INCH lbs. (2.5-6.1 N.m). Ensure
breakaway torque for compression lateral lower arm ball joint is 13 INCH lbs. (1.5 N.m). Check compression
lower arm, lateral lower arm, dust covers, and bushings for damage and wear.
Installation
To install, reverse removal procedure. Use NEW ball joint nuts. Lubricate lip and inside of dust cover with
multipurpose lubricant. Using installer, install dust cover. Check front wheel alignment.
UPPER ARM ASSEMBLY
Removal
Using steering linkage puller, loosen upper arm ball joint and knuckle nut. Remove self-locking nut. Remove upper arm and upper arm shaft assembly. Remove dust cover.
Inspection
Using preload socket, ensure breakaway torque for upper arm ball joint is 3-13 INCH lbs. (0.3-1.5 N.m).
Replace upper arm assembly when measured value exceeds specification. Check upper arm, dust cover, and
bushings for damage and wear.
Installation
1. To install, reverse removal procedure. Use NEW self-locking nuts. Lubricate lip and inside of dust cover
with multipurpose lubricant. Using Ball Joint Installer (MB990800), install dust cover.
2. Ensure upper arm shaft assembly is installed at indicated angle. Verify upper arm shaft
assembly installation. Check front wheel alignment.

Once you have the correct arm off and a replacement joint (if available, some are not serviceable and require the arm to be replaced) then you will need a press or a ball joint press to change the joint. Such as
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=38335

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46389

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=66958

or http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46967

u need 35mm nut socket to remove wheel nut then remove brake caliber and rotor then you to with a gear puller pull the wheel axle from cv shaft ,then remove upper and lower ball joint nut with ball joint fork start banging with hammer or airtools

support vehicle under A frame remove wheel. loosen nut on top of ball joint.seperate spindle assembly from ball joint w/ball joint seperating tool AKA pickle fork.remove nut.ball joint is riveted to lower A frame-chisel off or drill out rivets.install new ball joint w/nuts &bolts supplied with it

Jack up the car remove wheel remove brake caliper and remove rotor rent a ball joint press remover and installer tool (at schucks you get money back when you bring it back) if it's 4 wheel drive you will have to remove the axle shaft next pull the snap ring off on the top side and put tool on the lower tie rod end and press out, next do the top press out top joint next sand ball joint sockets so it is clean lube with WD-40 next press in top ball joint and then lower ball joint. In this order otherwise you will have to un install the top ball joint by removing the pin then nut.

depends on what you mean by "hard" if your mechanically inclined no, if you aren't, yes. You will need to remove the tire, the brake assembly and then get a large (32 or 34mm probably) socket to take off the spindle nut, I think on the dakota you have to remove the ball joint with a ball joint separator, remove the bearing assembly from the half shaft. (standard procedure on most vehicles) Hope this helps!

1.did you install the right ball joints? double check that.depends on gvw
2.worn out tapers in knuckles
3. did the new ball joints come with washers to put under the nuts to get the castle nuts in the right spot and did you use them?
4.is it the joint that is moving or the stud? Was it a cheap ball joint? and did you have the correct tool to install the joints ie a press and sometime a funny socket for the uppers if they are threded in?