JE928Sx4.

I havn't done a writeup yet, but these are the pictures. Fairly easy to do as far as 928 repair jobs go. You don't even need to take the brakes off.

Here are the pics starting with failure to replacement and the final picture of a failed AL ball joint and a good one.

http://members.rennlist.com/jeifert/ALBJ01.JPG
http://members.rennlist.com/jeifert/ALBJ02.JPG
http://members.rennlist.com/jeifert/ALBJ03.JPG
http://members.rennlist.com/jeifert/ALBJ04.JPG
http://members.rennlist.com/jeifert/ALBJ05.JPG
http://members.rennlist.com/jeifert/ALBJ06.JPG
http://members.rennlist.com/jeifert/ALBJ07.JPG
http://members.rennlist.com/jeifert/ALBJ08.JPG
http://members.rennlist.com/jeifert/ALBJ09.JPG
http://members.rennlist.com/jeifert/ALBJ10.JPG
http://members.rennlist.com/jeifert/ALBJ11.JPG
http://members.rennlist.com/jeifert/ALBJ12.JPG
http://members.rennlist.com/jeifert/ALBJ13.JPG
http://members.rennlist.com/jeifert/ALBJ14.JPG
http://members.rennlist.com/jeifert/ALBJ15.JPG
http://members.rennlist.com/jeifert/ALBJ16.JPG
http://members.rennlist.com/jeifert/ALBJ17.JPG
http://members.rennlist.com/jeifert/ALBJ18.JPG
http://members.rennlist.com/jeifert/ALBJ19.JPG
http://members.rennlist.com/jeifert/ALBJ20.JPG

Garth S

JE, a most thorough job! Now that it's over, what is your view as to why the joint failed?
My assumptions may be wrong, but ruptured boots, loss of grease, and the worst - addition of an abrasive (sand & grit) allow the ball to 'eat' it's way out of the socket, proceeded by a lengthy period of 'play' in the b.joint - and, yes, a steel carrier is superior to Aluminum in keeping a failing joint together. However,normally there's lots of time to detect this movement prior to catestrophic failure!
Why my interest? I still have the oem Aluminium carrier ball joints in the '80. They are routinely checked for play (not foreplay), and are absolutely tight - with intact grease boots [any dissassembly has been done via the 'hammer' method - no 'pickle fork'].
So, as long as they're free of play/tight, I've continued to motor on: Anything I've read about the various failures of these Al ball joints would suggest that there must have been detectable suspension 'slop' /movement for some considerable time prior to failure (ie., they don't degrade from 'tight' to 'failed' within hours, days, or even weeks of agressive road driving).
If there's good evidence to the contrary, be glad to hear it, will have considered myself fortunate to date, and...will add ball joint replacement to the growing winter list!

Dennis Wilson

Garth,

From what I have heard, the aluminum doesn't wear out. It fatigues and breaks. It would be interesting to see what type of inner wear JE had on his when the crown broke off. BTW I think I'll check mine for the third time to make sure the are steel (figure 8 shaped).

Dennis

Garth S

Dennis,
The longest 'ear' of the steel BJ is 12mm thick vs. ~18 mm for the Al.
The cadmium yellow ones that grab your shop magnet are a dead give away - man, that's six ball joints!
Your comment is to the point: it's the failure mode/mechanism that's of interest. metallurgical failure due to fatigue (cycling)/cold working is a very different issue than abrasion/erosion type of failure. The former leads to unpredicted and sudden failure - the latter is (most) often progressive and predictable. If fatigue is the issue, then replacing the BJ's yesterday wouldn't be soon enough.

John Struthers

JE,
Thanks for the flicks.
Dennis, others, and myself would probably agree that the end result is a fracture.
Such is the nature of aluminum wether cast, rolled, extruded, or, forged. But I think in the end because of maintenance issues like torn/failed grease boots/seals the addition of abrasives, pressure point wear, suspension impacts, and loading all will be contributory.
Then there is the issue of location. Salt natural or road clearing, some cities have incredably bad surface streets and I haven't forgotten those ski-jumps that the Oklahoma Highway Department installed on the Interstate for my driving pleasure heading up to the Sharks in the Ozarks Gathering.
Of course all of this is compounded by the way the sHARKs seem to migrate upon sale to new owners. It would be easy to point out one cause then not take itnto account that 'X' number of early model 928's in Texas had low speed ball joint failure only to find there were enormous differences in mileage, origin of purchase. What if there was 50,000 miles cross-range, half the cars came from 15 bad years in Jersey and a third of those had salvage titles. An 1/8th came from Boston, Detroit, or Minn., another 1/8th had been parked for two years with a flat front tire on the downhill slope of a hillside in Pennsylvania before sale. Of course the remaining sHARKs would have been delivered and run only in Texas , and were meticulously maintained by born again Porsche Mechanic wannabe's for their entire life.
A lot of our sHARKs have been back and forth across the USA, thru a variety of owners and environments, babied and beaten.
Garth,
In a way I agree... in a way I don't!
Aluminum can and does fail regularly, sometimes catastrophically. Remember those "instant convertible airliners?
Sometimes people let a small shimmy/wobble develope into something big... this can happen by degrees... barely perceptable to someone who hasn't hit the twisties in awhile. And for someone who only puts 4-10,000 miles on a car in a year probably doesn't notice because their slightly, intermittenly wobbling, 928 still handles better than whatever else they've been using as a daily driver.
In a way, because I use ramps most of the time for maintenance, I could be a candidate for bearing failure.
I do, however, check for radial and axial play by doing the tire jerk at the 12/6 o'clock , and the 9/3 o'clock, weekly. And check all tires for pressure, cuts/nails and odd wear daliy.

Marc Schwager

So Garth, are you feeling lucky? :-)

JE928Sx4.

There was still grease on the ball and in the cup. I couldn't tell if the cover was cracked before the failure. The cover on the other side was fine. The ball at this point will not drop back into the cup unless I decided to force it in with a machine press. I think my brother was having too much fun and was hitting road bumps (or something) too hard. On the same ride he managed to knock off the remaining piece of the front spoiler that was still attached to the fender (a casualty of a parking space concrete stop a year earlier). The car had been off the road for a year due to some electrical problems that required me to pull the rear cover and replace the taillights (not a pressing issue for me as I had other cars :-). He managed to do this within three hours of the car passing inspection.

My personal opinion Garth, you're gambling on the AL ball joints.

WallyP

Worn lower ball joints do NOT normally give any symptoms. The only way to tell is to specifically check them - and that requires that you know how to do it. It isn't obvious, and it isn't especially easy to do.

Very risky for the average owner...

Garth S

Thanks JE/everyone for the input: Like many owners of pre-'83 cars, perhaps I've been lucky ( for the past 18 yrs); however, as Marc( or Clint would have) said, "are you feeling lucky?" - not at all, just trying to sort fact from fiction.
I was, and would have continued on in blissful ignorance of such issues as Al Ball joints: however, fired up a home PC only several months ago, and in fumbling around ,found this Gold Mine - the Rennlist/links/tips/etc.
Yes, it is a pain to look for( vertical) movement in the ball joints - to ease my conscience, had a 'consult' done by the front end specialist of the local Ex-Porsche dealership: he concluded that these were 'as new', furthermore, they had never seen signifigant BJ wear nor failure!
So, am I feeling lucky?; well, you feel luckier when there's a 'plan B' as backup: I've got eccentrics & brackets for the steel BJ's glass beaded and ready to go - "for a few dollars more", will add the steel carrier units!
Is it a necessary move? - I'm not convinced: Will I do it, and is it cheap insurance? Yes, I'm convinced!
Thanks again for the dialogue.

hupp

Is it necessary to replace the upper ball joints?

WallyP

The lower joints are MUCH more heavily loaded, and react almost all of the bracking and cornering loads. However, the design means that looseness due to wear has virtually no effect on the operation of the lower joints, but a major effect on the operation of the upper joints.

To put it another way, wear causes no problems with the lower joints until they fail (at which point it is a BIG problem), but any wear in the upper joint lets the upright wobble around and is noticeable pretty quickly.

Since the upper joints are lightly loaded, there isn't any real problem with wear - as long as the boots are perfect and the joints are clean and well greased.

This is a good thing, because you can't replace the upper ball joints - you have to replace the entire upper arm, and that isn't cheap.

Since we (and the other vendors) sell replacement boots, and replacement is not too difficult for the average DIY owner, the suggestion seems obvious - check the boots on the ball joints, especially the upper ones! (The boots are more expensive than they should be, but we don't have any choice about that.) Call Jeannie at (828) 766-9280 if you need the boots - or ANY other part available from Porsche for your 928.

Toejam

About what was the total parts cost for the project? I need to do this ASAP.

JE928Sx4.

It my brothers bill but I recall it was about $340.00 with delivery. We only replaced the ball joints, 4 eccentrics and new upper boots. Everything else was reusable.