From the photo, looks like the ball shell split apart. Not a ball stud or fastener failure. The other half of the ball joint isn't in the photo to tell if the the boot split, possibly letting water/dirt/salt into the joint and the grinding the ball socket until the shell got too thin to withstand the force. Or if the shell crimp was faulty/weak. Certainly something to have inspected regularly, starting at 60k miles or so, I'd think.
I agree, it would be nice to see the rest of the ball joint to get a better idea. And your comment about 60k miles warranting an inspection is a good one. In fact, maybe a bit sooner.
About 6 weeks ago at 60,190 miles I had a local mechanic install new Mazda OEM front lower control arms and quality Japanese aftermarket outer tie rod ends (Mazda had the tie rod ends on national back order). I supplied the parts (purchased online) and his shop is a 5 minute walk from home. Reasons being that months back I had to seal ALL of the cracked and split boots on both of these components and regreased them with a grease needle through the boot (there was no play in the joints and it steered nice and easy as if the original grease was dry or something- so the joints were still good yet). Also discovered that the big bushings on the rear of the LCA's were torn in few spots and had been for a while apparently. So I decided to burn some money and start with fresh components with new boots and the possibility of never having to mess with them again. Kind of like a "mid-life refresh". Moral of the story: inspect these things regularly.
Not particularly relevant to this thread but in keeping the "mid-life refresh" spirit , a couple weeks ago I replaced rear pads and rotors. Two days ago that same mechanic replaced the stabilizer bar bushings with some OEM bushings I supplied. And even though the original bushings looked good, not wallowed out (real good in fact -good enough to question even changing them --I did this on a hunch) they made a nice difference in firmness and tightened up the front end even more. Comparing the I.D. measurements of a fully closed (by hand)bushing there was about a 2 mm difference between new and old ( new~ 17.75 , old~ 19.50-19.75 mm) so some compression did occur over time. Oh, and I replaced the stabilizer bar end links about 6 months ago. The only front suspension parts not changed are struts which are not due yet. And inspecting the front brakes which were done 2 years ago, rotors and pads are fine, just regreased slider pins. And around this time, the front and rear suspension components got a thin application of a rust inhibitor.
Doing ALL of this may seem unnecessary to some folks, but some things were necessary and some done to avoid doing it later since there were 9 years and approx 60 K miles on these parts already. Except for normal maintenance (filters, oil changes, wipers etc), I'm only looking at changing the coolant and tranny fluid around 75-80k and otherwise good out to 95-100k which is 5 years away at my current mileage of 7K/year.
And finally, I've mentioned in the past about the DIY enjoyment factor that can diminish with advancing age. Lack of good facilities (lift ,air tools) makes it more of a struggle sometimes also.
These factors played a big role in my decisions to get this stuff done. Down the road "I just don't wanna mess with it".
Well there I've gone and bared my soul in this long winded post but maybe there's a few older folks that can identify with what I've said.
And, OH YEA, I'm getting a new set of Pirelli's installed next week (different thread). Happy Boy!!!
Jmaz over and out.
