Lower Control Arms Replaced...Still Popping?
1999montana
07-08-2007, 12:15 PM
Hello Folks,
Completed the Re and Re on the lower control arms on Friday. Much to my disappointment, the popping sound was still there on either side.:banghead:
Here is what the old control arm looked like:
http://i183.photobucket.com/albums/x149/1999montana/LowerControlArms001.jpg
Here is the product that replaced both at $266/pair (an offshore replacement complete with ball joints). PartSource allowed me to return the old ball joints as they were defective the day I installed them. They leaked grease through the bottom of the joint under pressure. As a matter of fact, two more sets tried at the store did the same thing on the counter!
http://i183.photobucket.com/albums/x149/1999montana/LowerControlArms003.jpg
http://i183.photobucket.com/albums/x149/1999montana/LowerControlArms002.jpg
A brief chronology of this problem leading up to the 'popping' sound follows.
About two years ago, I replaced the front shocks and shock mounts. Because of the 'over tightening' warning that came with the shocks, I approached the shock mount tightening with caution. It required a max 44ft/lb torque on machined threads that could easily suspend a sherman tank! Go figure!
Ended up removing the shocks and re-tightening them with brute force after the vehicle settled on its wheels and a gap appeared between the top plate and the rubber mount. Not tight enough!
Shortly after, the popping sound became noticeable.
To view the shock mounts in motion would require a level of trust in the driver, while the observer watched for movement coming down our driveway onto the apron. Haven't done this yet, but think I will.
Last year I replaced the lower ball joints because there was an 1/8" of up and down play in the left one. Since these are not serviceable, I concluded that lack of grease had worn the joint out. The ball joints cost $158/pair and were a real challenge to remove.
Recently, I discovered that the leading bushing in each control arm (a stupid hockey puck design that does not match the geometry of the control arm or its movement nearly as well as the rear bushing does).
This leading bushing was beginning to separate, so I assumed that any movement in the control arm might cause the popping sound as the control arm shifted and found its natural operating position.
Observations:
There was no play in the steering, or abnormal tire wear to suggest an alignment problem. The vehicle did not wander, and the steering linkage from the rack and pinion was solid right to the outer tie rods.
After shock replacement, there was a noticeable toe-out and a negative camber angle. The toe-in was adjusted and eliminated this condition, but the camber angle remained.
Again, after the ball joints were replaced, there was a small toe-in adjustment made, but the replacement of the ball joints did not affect camber angle.
Once the control arms were replaced, the camber angle went positive and a small toe-in adjustment was made to compensate for the re-positioning of the center-line of the knuckle over the ball joint. The vehicle steers straight as an arrow with zero wander or pull.
Possibilities / Eliminations:
1) The rack and pinion (or an inner tie rod?)
2) The mounting point of the shocks in the shock mount
3) Possibility that the nut on the end of the shock piston is still not tight enough to prevent the shock from moving the upper and lower mounting plates (up and down) instead of the plates being firmly sandwiched in the rubber part of the mount.
Any thoughts or suggestions on next steps?
Completed the Re and Re on the lower control arms on Friday. Much to my disappointment, the popping sound was still there on either side.:banghead:
Here is what the old control arm looked like:
http://i183.photobucket.com/albums/x149/1999montana/LowerControlArms001.jpg
Here is the product that replaced both at $266/pair (an offshore replacement complete with ball joints). PartSource allowed me to return the old ball joints as they were defective the day I installed them. They leaked grease through the bottom of the joint under pressure. As a matter of fact, two more sets tried at the store did the same thing on the counter!
http://i183.photobucket.com/albums/x149/1999montana/LowerControlArms003.jpg
http://i183.photobucket.com/albums/x149/1999montana/LowerControlArms002.jpg
A brief chronology of this problem leading up to the 'popping' sound follows.
About two years ago, I replaced the front shocks and shock mounts. Because of the 'over tightening' warning that came with the shocks, I approached the shock mount tightening with caution. It required a max 44ft/lb torque on machined threads that could easily suspend a sherman tank! Go figure!
Ended up removing the shocks and re-tightening them with brute force after the vehicle settled on its wheels and a gap appeared between the top plate and the rubber mount. Not tight enough!
Shortly after, the popping sound became noticeable.
To view the shock mounts in motion would require a level of trust in the driver, while the observer watched for movement coming down our driveway onto the apron. Haven't done this yet, but think I will.
Last year I replaced the lower ball joints because there was an 1/8" of up and down play in the left one. Since these are not serviceable, I concluded that lack of grease had worn the joint out. The ball joints cost $158/pair and were a real challenge to remove.
Recently, I discovered that the leading bushing in each control arm (a stupid hockey puck design that does not match the geometry of the control arm or its movement nearly as well as the rear bushing does).
This leading bushing was beginning to separate, so I assumed that any movement in the control arm might cause the popping sound as the control arm shifted and found its natural operating position.
Observations:
There was no play in the steering, or abnormal tire wear to suggest an alignment problem. The vehicle did not wander, and the steering linkage from the rack and pinion was solid right to the outer tie rods.
After shock replacement, there was a noticeable toe-out and a negative camber angle. The toe-in was adjusted and eliminated this condition, but the camber angle remained.
Again, after the ball joints were replaced, there was a small toe-in adjustment made, but the replacement of the ball joints did not affect camber angle.
Once the control arms were replaced, the camber angle went positive and a small toe-in adjustment was made to compensate for the re-positioning of the center-line of the knuckle over the ball joint. The vehicle steers straight as an arrow with zero wander or pull.
Possibilities / Eliminations:
1) The rack and pinion (or an inner tie rod?)
2) The mounting point of the shocks in the shock mount
3) Possibility that the nut on the end of the shock piston is still not tight enough to prevent the shock from moving the upper and lower mounting plates (up and down) instead of the plates being firmly sandwiched in the rubber part of the mount.
Any thoughts or suggestions on next steps?
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