CV joint evaluation?

[Mike Kunz]

Hi,

Just disassembled both CV joints on the pass. side axle...what a mess!

What is the criteria for evaluating wear on a CV joint and at what point should they be replaced?

Thanks!

Mike

[Will98D]

These joints are called cross-groove joints due to the angle of the grooves. There should be no rotational lash in the joint, which would be checked with the joint assembled. I hope you marked the inner and outer races and cage before disassembly as they should go back together in the same positions; you can get away with the balls not going in the same spots as the tend to be so uniform. Inspect the inner and outer race grooves for signs of Brinnelling (pockets) or spalling/pitting. Spalling is where you have a piece that's actually broken ("flaked") away from the surface. If you have pockets you can feel or any spalling or pits I would replace the joint. Also look at the cage windows for the same things. You can probably live with some SMALL pockets on the lands of the windows if you accept that they may 'click' once in a while at high angles, but no spalling/pitting is allowed. The spalling is due to subsurface cracks from stress, and usually the material from the surface down to the depth of the heat treatment pops off the top. Also look at the splines of both the axle bar and the inner race. They should be clean and free from polished spots (indicating movement relative to one another), as I believe there is an interference fit of this joint to the bar. Lastly, during reassembly make sure you get the groove of the inner and outer races oriented properly one-to-another. With the joint at a full-out position during assembly, the balls on the inner race/cage will be alternatively close together and farther apart, and the outer race needs to mate up the same. You can force it together the wrong way and then the joint will be locked in the middle, not a good thing. Use the proper amount of grease (maybe someone knows how many grams, I don't) as too little wears out the joint and too much puts added stress on the boot. If this one also has gaskets between the joint and flanges be sure to remember them. Good luck.

[karlp]

Can Bus or type 1 joints be used?

[Mike Kunz]

Thanks for the amazing detail, Will!

In the case of my CV's, the only noticeable wear can be seen on the ball (groove) surfaces of the outer race, i.e. polish marks as you noted.

How critical is this type of wear and does it warrant replacement?

Also...regarding assembly....I did not mark the assembly beforehand unfortunately. However, am I correct in stating that there are only two possibilities for assembling the inner race/cage to the outer race, that is,,, a wrong way and a right way? As far I can tell, the position of the cage itself is irrelevant as it is symmetrical. I can tell which way the inner cage was installed because the axle spring washer left a circular mark on the race.

So, am I correct in saying that there is only one way to assemble the joint if I use this orientation (circular mark) as a reference? In other words, if I assemble the inner race/cage into the outer race, is there more than one way to do that, or do I have it covered?

If I'm totally wrong...how do I reassemble?

Thanks!

Mike

[Dave at Pelican Parts]

karlp, do not use Bug or Bus CVs. One or both fit, and will work. For a while. I've seen more of those fail than I really care to think of... Every time I see a dead CV joint with no roll pins, it turns out to be "from some VW". Use the right parts, unless you want to be stranded somewhere.

Or worse, have the half-shaft come loose and flail around breaking things.

Mike, I think the photo in Haynes of a mostly-assembled joint shows you the correct orientation. From what I have read (haven't done the job myself) the important bit is the position of the inner race with respect to the position of the outer race. I don't think the snap-ring position has anything to do with that...

--DD

[Will98D]

Mike, hope the info helps... I spent the past three years as a halfshaft engineer so some of this must have rubbed off. If you have polished spots on the outer race ball grooves but no indentations then you are probably OK with continuing to use the parts. The normal failure mode for one of these joints would be a broken cage at high angle, and then things get rather crunchy and bad sounding, so you'll know you're sunk. There are two ways to assemble it, true, and only one is correct. Look at the grooves and hold the inner and outer races close together as if the inner just pulled out of the outer. You will see that the two ball grooves that are close together must mate with two ball grooves that are close together on the other race or it won't assemble. People get into trouble when they let the balls be at mid-stroke or farther back and them force them a bit, because then the grooves are 60 degrees out of phase (1/6). If you look at the grooves as I mentioned and think about how the balls would have to roll along them then you should get it right. The cage is symmetrical, but for future reference it is preferred that the races and cage retain their original positions.

I have no idea on Bus or T-1 joints... probably the answer is no.

[Mike Kunz]

Thanks everyone, that should help for sure.

Dave - the mark I wrote of wasn't from the snap ring at the outer end, but from the sheet metal spring washer on the inside axle end (which prevents the inner race from wandering further in on the axle than it is supposed to).

So, is this a relevant indicator of the past assembly?

Thanks!

Mike