how do I know if ball joints are failing?

okay, so I just read 4 pages of posts about ball joints and how to put new ones on. What I couldn't really find was how to check if they're bad or not.

Do I just jack up the truck and wiggle the wheel at the 12oclock and 6oclock position?

Do I need to jack up the control arm as well?

crowbar between tire and ground?

I've got a 97 Jimmy 4WD.

Yeah pretty much what you said. Jack the front up, make sure its secure, hands at 12 and 6 and push and pull, if there is movement, get a crowbar underneath the tire pry up, again if you notice movement, its usually the ball joints.

To check for idler arm,pitman arm,tie rods, while the truck is up, hands at 9 and 3 and push and pull. If you see movement at any of these points, you have a worn joint.

Its easier to have someone do the push and pulling while you are looking at the joints, its easier to see what is bad. An experienced tech can do this on their own very quickly. Either way, just make sure your truck is secure on jackstands, and not just on a jack while your pulling and pushing on the truck.

Ball Joint Inspection - '97 Blazer 4x4
(See Figures 13, 14 and 15)

Before performing this inspection, make sure that the wheel bearings are adjusted correctly and that the control arm bushings are in good condition.

1. Make sure the vehicle is parked on a level surface.
2. Raise and support the front of the vehicle safely by placing jack stands under each lower control arm as close as possible to each lower ball joint (as far outboard as possible). Make sure that the vehicle is stable and the control arm bumpers are not contacting the frame.
3. Wipe the ball joints clean and check the seals for cuts or tears. If a seal is cut or torn, then the ball joint must be replaced.
4. If necessary on 2WD vehicles, adjust the wheel bearings before proceeding.

http://img.villagephotos.com/p/2006-5/1178639/BallJointCheck01.jpg
(Fig. 13) - Check total ball joint horizontal deflection by rocking the wheel (a dial indicator is used to measure play)

5. Check the ball joints for horizontal deflection (looseness):
a. Position a dial indicator against the lowest outboard point on the rim.
b. Grasp the tire (top and bottom), then pull outward on the top and push inward on the bottom; record the reading on the dial indicator.
c. Grasp the tire (top and bottom), then pull outward on the bottom and push inward on the top; record the reading on the dial indicator.
d. The difference in the dial indicator reading is the horizontal deflection of both joints. If the reading exceeds 0.125 in. (3.2mm), the lower ball joint should be checked for wear in order to determine what component(s) must be replaced.

(Note: The lower ball joints used on 2WD vehicles use wear indicators to determine wear)
.

http://img.villagephotos.com/p/2006-5/1178639/BallJointCheck02.jpg
(Fig. 14) - A dial indicator may also be used to check lower joint vertical deflection
.

.

http://img.villagephotos.com/p/2006-5/1178639/BallJointCheck03.jpg
(Fig. 15) - Use a prybar to carefully pry between the lower control arm and outer race (NOT on the drive axle joint/seal)

6. On 4WD vehicles (no wear indicators), check the lower ball joint for wear:
a. With the vehicle still supported by jackstands, place a dial indicator against the spindle in order to measure vertical movement.

DO NOT pry between the lower control arm and the drive axle seal or damage to the seal will result.

b. Pry between the lower control arm and the outer bearing race while reading the dial indicator. This reading will show vertical deflection (looseness).
c. The lower ball joint is not a pre-loaded joint and may show some looseness, but it should be replaced if movement exceeds 0.125 in. (3.2mm).

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Proper procedure for checking Tie-Rod end, Center Links and Idler Arm for looseness or wear.

The suspension should be normally loaded on the ground or on an alignment rack. When raised by a frame contact hoist, the vehicle's steering linkage is allowed to hang, and proper testing cannot be done.
Jerking the front wheel and tire assembly back and forth (causing an up- and down-movement in the idler arm) is not an acceptable method of checking, as there is no control on the amount of force being applied.
Check the idler arm ends for worn sockets or deteriorated bushings.
Grasp the center link firmly with your hand at the idler arm end.
Push up with approximately a 25-pound (110 N) load.
Pull down with the same load.
http://img.villagephotos.com/p/2006-5/1178639/IdlerArmCheck.jpg
The allowable movement of the idler arm and support assembly in one direction is 1/8 inch (3 mm), for a total acceptable movement of 1/4 inch (6 mm).
The load can be accurately measured by using a dial indicator or pull spring scale located as near the center link end of the idler arm as possible.
Keep in mind that the test forces should not exceed 25 pounds (110 N), as even a new idler arm might be forced to show movement due to steel flexing when excessive pressure is applied.
It is also necessary that a scale or ruler be rested against the frame and used to determine the amount of movement.
Observers tend to overestimate the actual movement when a scale is not used.
The idler arm should always be replaced if it fails this test.


Center Links - may also be called a Drag Link, Connecting Arm or Steering Arm Rod.

• When inspecting the center link, look closely to insure it has not been bent or damaged.
• Grasp the center link firmly and try moving it in all directions.
• Any movement, or sign of damage, is reason for replacement.
• Tapered openings seldom wear but should be checked for enlargement caused by a loose connection. If necessary, replace the center link.

Tie-rod end

• Tie-rod end and center link inspections are similar.
• Grasp the tie-rod end firmly.
• Push vertically with the stud, and inspect for movement at the joint with the steering knuckle.

Any movement over 1/8 inch (3 mm) or observation of damaged or missing parts, such as seals, is sufficient evidence that replacement is necessary.
An additional check of the tie-rods can be made by rotating each tie-rod end to feel for roughness or binding, which could indicate that the socket has probably rusted internally. A special puller is often required to separate a tie-rod end from the steering knuckle.

Great inspection diagram

okay, so I just read 4 pages of posts about ball joints and how to put new ones on. What I couldn't really find was how to check if they're bad or not.

Do I just jack up the truck and wiggle the wheel at the 12oclock and 6oclock position?

Do I need to jack up the control arm as well?

crowbar between tire and ground?

I've got a 97 Jimmy 4WD.

The lower ball joints are the load carrying joints. Lifting the vehicle MUST be done as close to the ball joint as possible to remove the load from the joint.

The lower ball joints are the load carrying joints. Lifting the vehicle MUST be done as close to the ball joint as possible to remove the load from the joint.

What happened to your pictures???!!!!

The previous posts are correct but I want to add a test. Grab the tie rod ends and make sure they rotate slightly. A siezed tie rod will not show wear but will break suddenly. If you can not rotate it slightly then replace it.