New Product - Ball Joint Rebuild Kit
06-30-2005, 01:27 PM
#16
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Brendan if everyone had the same sense of NEED that you do there would be no 928s driving around on the streets at all ! 
The loads on the upper ball joints are far, far less than those on the lower ball joints which actually support the weight of the car since the spring and shock attach to the lower A-arm. The uppers basically keep the wheel from falling over. Yes they do get bad just not nearly as often as the lower ball joints.
The loads on the upper ball joints are far, far less than those on the lower ball joints which actually support the weight of the car since the spring and shock attach to the lower A-arm. The uppers basically keep the wheel from falling over. Yes they do get bad just not nearly as often as the lower ball joints.
07-01-2005, 11:11 AM
#18
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The question I was asked in a private email was - "what can make an upper ball joint go bad?"
Usually it is rust, from a bad boot allowing water in, and then dirt. Jim Bailey points out that the weight is on the lower ball joint and that is why they wear out faster - and of course that is right.
There is one other thing that will destroy an upper balljoint - a good pothole/bad snubber combo. The shock snubber is that little 3" molded foam squishee that rides on the shock piston. Often left out of spring and shock replacements as unneccesary.
They actually have a significant engineering background, they are a spring supplement that engages just before the spring becomes totally stacked and, like a progressive spring, they resist compression exponentially as they are compressed.
They perform two functions:
Safety: if you were doing some evasive maneuver with your 928 (the cow that just wandered onto the highway (I'm in WI after all, we think about stuff like this)) and your spring loads up as you yank that steering wheel hardover like the helmsan at the Titanic, should the spring be allowed to stack - you spring rate would very suddenly go from something to infinity. When the spring stacks, you go from HAVING a spring rate to NOT - in effect to a solid suspension, in a second. Tons of oversteer get thrown in, the car spins, the driver fights to recover, etc etc. Bad cow.
Impact Control with the soft or worn shock/bad or missing snubber/pothole combo, the sudden impact upward drives the weight of the car UP into the upper ball joint like a hammer. A shattered ball joint bushing is a possible result of this pothole event. See picture.
Usually it is rust, from a bad boot allowing water in, and then dirt. Jim Bailey points out that the weight is on the lower ball joint and that is why they wear out faster - and of course that is right.
There is one other thing that will destroy an upper balljoint - a good pothole/bad snubber combo. The shock snubber is that little 3" molded foam squishee that rides on the shock piston. Often left out of spring and shock replacements as unneccesary.
They actually have a significant engineering background, they are a spring supplement that engages just before the spring becomes totally stacked and, like a progressive spring, they resist compression exponentially as they are compressed.
They perform two functions:
Safety: if you were doing some evasive maneuver with your 928 (the cow that just wandered onto the highway (I'm in WI after all, we think about stuff like this)) and your spring loads up as you yank that steering wheel hardover like the helmsan at the Titanic, should the spring be allowed to stack - you spring rate would very suddenly go from something to infinity. When the spring stacks, you go from HAVING a spring rate to NOT - in effect to a solid suspension, in a second. Tons of oversteer get thrown in, the car spins, the driver fights to recover, etc etc. Bad cow.
Impact Control with the soft or worn shock/bad or missing snubber/pothole combo, the sudden impact upward drives the weight of the car UP into the upper ball joint like a hammer. A shattered ball joint bushing is a possible result of this pothole event. See picture.
07-01-2005, 01:00 PM
#19
When I went to college in Green Bay Carl, the cows weren't on the road as much as drunk college students and deer. Both didn't react very quickly and could provide the hazard you speak of.
