Article: How to diagnose suspension problems An article written by Jerry Hastings for www.Helium.com
Continued from previous blog...
While large differences in an A-frame or straight front axle and a strut type front suspension exists, many of these suggestions will also apply to strut types. The front spring and strut are an assembly and therefore must be diagnosed as such. Check for abnormal slack in much the same way as used on ball joints.
Straight front axles with kingpins must be checked in two directions for slack. Jack the vehicle up securely (normally a large vehicle weighing many times as much as a small car-jack stands are recommended), then push hard sideways on the top of each tire while observing for any abnormal movement in the kingpin area. Next place a long prybar under the tire and pry upward while observing for any abnormal movement between the axle eye and the spindle.
Excessive slack observed while pushing on the top of the tire is a result of kingpin and bushing wear. Excessive slack while prying up on the tire is a result of bearing or shim wear (bearing between the axle and spindle on the bottom side of the axle and shims between the axle and spindle on the upper side of the axle-the kingpin is through both).
If the vehicle sets lower than it used to or leans to one side, spring fatigue may well be the problem. However, care should be exercised to eliminate frame damage (many cars and light trucks have unibodies-not frames per se). Did some sort of trauma happen to the vehicle or is there door and/or window sealing problems? This could also signal frame or unibody damage.
Unusual tire wear, especially on the front, may be a sign of suspension problems but cannot be depended on exclusively. For instance, wear on the inside of the tires is a sign of excessive ball joint or kingpin wear and resulting slack BUT may be from several other wheel alignment problems instead.
Tire dipping can be a contributing factor of shock problems BUT may also be tire and wheel imbalance or out of roundness. Shimmy in the front is usually from a bent wheel, out of round tire (dipping as a result), extreme tire/wheel imbalance or other out of round causing problems.
Although shocks are lumped into the suspension category, they really are not part of a suspension. They are just another link from the body or frame to the axle or suspension and who's function is to control bounce and/or sway. Problems with shocks are usually self evident. Excessive leaning during turns, excessive vehicle bouncing, clunking noises and more are signals that the shocks need replaced.
Perhaps one of the most ignored areas of a vehicle's suspension is the rear spring eye bushing and pin or the pin hole in the spring hanger as well as loose hanger to frame bolts. Wear and slack in one or more of those areas can cause a myriad of handling or wheel alignment issues. Normally any slack will be back and forth movement at the tire. Check for these problems by chocking the front tires securely, then unlock the brakes and put the transmission in neutral. Next pry forward and rearward at the tire with a pry bar or something, and observe for any movement in these areas. Continued........,
