CVs - quality control issues?
 

Last summer I replaced the two inner CVs on my SC, hoping the whine would go away. It didn't (because it was a failing pinion gear). But the CVs didn't quite seem right. The cages would not hold the balls. The outer ball races had a striated look to them. And what I suppose was the heat treatment left a funny color pattern. Perhaps this was noticable only because the outers were not the sort of gray/black color I recall they used to be when new.


http://forums.pelicanparts.com/uploa...1170318003.jpg

When removing them while trying to locate the source of a banging noise I found one of this pair (the one shown) not to show any significant wear (as should be the case given its relative youth), but it was very tight at mid-travel - when trying to push the center section axially from side to side. The grooves in the picture are very clean because I tried to enlarge them a bit with a sanding roll just to see if that would do anything - which it didn't.

I find also that the splines on the inners are looser. These new ones had about 0.012" of circumferential movement (I haven't done the math to turn that into an angle), which was quite noticeable. The used (but OK) CVs I stuck back in have almost no movement on the splines, so I don't think it is the axle splines that have worn (though, since they were made in 1976, they could be excused if they did).

A while back CVs came in blue and orange Loebro boxes (with GKN Automotive also on them). Now the boxes are silver and GKN is the headliner, though they have a small Loebro logo and "Glaenzer spicer" as well.

Are these no longer the reliably precise part they used to be? Everyone used to harp on tossing old ones if the balls fell out of the cages, and these were that way from the get go. But it was the tightness in the motion that worries me more, as that contributed, I believe, to an in and out motion of the axle that led to the banging.

Walt Fricke

Walt,

I don't not know the answer to your question, but I'm going to be re-building my four in the next month and you've given me a few other things to pay attention to.

Thank you,
Matt

1. Did you buy from Porsche (dealer) or in the aftermarket?

2. Are there any telltale small marks, letters, codes etc. anywhere on them that might be a giveaway?

Just did one axle on my SC last week as the boots were ripping. Same CV description and box design as yours....also had the heat treating marks on one side only. Mine was very tight from new and moved according to design.

The boot was another story, as the flange on the EMPI boot was drilled improperly and all six bolts would not go through the CV and into the tranny flange. Had to return and send out for a replacement after refitting the entire thing.

Maybe yours was just a "bad apple".

I've been buying CVs from Zims for many years. I'm waiting to see if anyone who actually knows says what I think: there is only one supplier of these items.

Here's what is marked on the side of the CV itself: GKN61 C153120199006 031027 1[with a partly stamped C or a symbol like a tau with no top] Next line: 03 10 14 1C [the 10 might be 1symbol, but it looks more like a misstamped 0]

And it may be that this one was just a bad apple, though both had the loose cage issue. I think I thought the extra tightness in the one would go away with a little use.

Walt