This axle is not from my Cobra, but it's pretty typical of all modern IRS axles. The stock Ford parts are a little different. But most heavy duty aftermarket parts look like this. I'm pretty sure, anyway.
After 8 seasons of racing this car, I noticed that the left CV joint was rattling a little bit. Not much, just a little. I took it apart to see what was going on.
Assembled, the joint looks like this.
Disassembled, it looks like this.
When I opened mine up, it looked like this. Even though this is sealed, and had no leaks, it was all dried out.
After taking it all apart and cleaning everything, I find a lot of wear in there. Look at the top center, where the ball bearings impact the gear.
I greased it up, and put it all back together. I flipped the bearing cage over, so the thrust surface is now on the other side, where there is minimal wear.
I'm contacting The Driveshaft Shop to see if I can get some new ones. Might as well replace them both at the same time.
So, what's the point? The point is, I should have been taking the axles apart for cleaning/lubing on a regular basis. If you have this type of CV joint, you should too.