{Chrysler 300} upper ball joints / heads up

[John Grady <jkg@xxxxxxxxxxxxxxxxx>]

Recently there was an exchange with James about upper control arm bushings etc . 
related to that was a recent failure here that really could have taken me out  .
The upper joints were checked many times , over 15-20 years as recently as six months ago . What i describe is forensic on my part and I am extremely grateful to a sharp person at a state inspection station that fortuitously found what we had missed .
I will describe what seems to have happened ( see pic) 
After many thousands of miles where the upper ball joint motion is apparently dealing with an up and down action / wear primarily , as opposed to rotary ( steering ) motion , the sides of the hemispherical part of the inner ball joint wear  a spade shaped pattern into the round outer housing at right angles  to the car long axis . Soon it apparently could not turn due to that wearing in one place so the steering ( rotary ) motion we think was allowed by the center mount bolt turning within the hemisphere ; this  is a press fit I think when new as in a brand new joint the hemisphere turns with steering , and angled grease lines point to that as to how it steers and moves up and down too . 
However once the hemisphere is frozen to rotation due to matching wear pockets it is still capable of moving in the spade shaped recesses for suspension travel . 
So what really happens is it gets tight as anything to any reasonable side force at a ball joint check , even with load off wheel ( lifted by lower control arm ) it is apparently ( to you ) zero play . 
Because the clamp bolts in the A frame bushing had been stripped (!) the rubber bushings were not acting in torsion to hold the A arm somewhat , the A  arm moved easily up and down on the bolts  with the  ball joint housing  , (turning freely on the control arm bolts ) This is wrong !!! 
They had deep grooves from this . See pix . If you think about it , pushing up to check a ball joint side to side play or wear depends on the A arm not going up freely too (!) . 
It is critical those A arm frame adjuster bolts are torqued enough to clamp the control arm inner sleeve really tight and so prevent rotary motion — by bending the “ ears “ inward .

 Now it appears to me that wrong nuts may have been placed on the bolts long ago ( are they tall nuts ? they should be !) On attempted reassembly they were stripped  junk .—  to solve this we had acorn nuts on hand with a lot of internal thread without bottoming , they achieved the required torque . Which is very close to max for this size bolt — and the bolt is missing some thread area due to the flat on it , so from an engineering perspective says it needs a tall grade 8 nut . Watch out !

  Flat on bolt side is not an issue as tge design depends on tension induced friction to lock  all together like a rod bolt once aligned . It is going nowhere . 

Back to ball joint , the tech was very  thorough , maybe pushed down on upper arm or just saw something funky , ( stud out of ball joint “more than normal” ? ) but ball joint went completely loose as beyond worn  out when spindle was pushed into upper arm ( which looseness would have happened, ? a noise , while   driving — if bushings were tight ) 

Failed inspection . 

So when we first went to disassemble and pushed bolt up , the remains of hemisphere fell out in 4 pieces cracked along the grease lines , ball joint housing still solidly in control arm . Out came the center stud free in the breeze . You get this , right ? You meet a guard rail, —- after a big pot hole bumps spindle up wards . 
The hemisphere in this joint was made of powdered metal technology , any engineer doing a press fit into that material should be fired . I had a chinese oil pump in my slant six , powder metal drive gear was press fit cracked at bottom of the tooth profile = zero oil pressure . Steel will stretch to yield on a press never fail like this . Junk way to do things .  Powder metal in tension is just stupid . 
Once cracked like this ,  inner bolt was free to turn for steering so you seem happy … note rotary wear pattern around that bolt ( shiny place ) 


A Big heads up here , (!!!! ) — press down on control arm , try to push bolt up in to really check it .

More reading led to Missouri State Police inspection document —- car by car instructions . 
Someone there knows about this . 


As all our cars are quite old and the torsion bar setup primarily  loads the lower joint not upper , and so replaced more often , upper may be ignored too long ..  
I did a search on Ball Joint life ,75 to 150 k is norm . 
This email is already also too long , but check this danger out . 
Also got into the “thread in ball joint“  problems , but that is another long one .. 
 Think about this , old cars have it   
John G 

Sent from my iPhone

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