I'd feel better if you had a mechanic look at the parts. There very well could be something wrong there, but until I see it myself, I'm betting you just have a bad seal. If you reach inside the differential to that splined gear, that will move around. There's just the teeth of two mating gears holding it in place while the half shaft is out. You'll see two machined and polished surfaces on the inner cv joint next to its splines. The smaller diameter one rides on a bushing and there will still be some play there between the cv joint and that bushing. The larger diameter surface is where the lip seal rides. That seal is flexible enough to move around and follow the cv joint as it wobbles. If there's leakage there, there's one of two causes. The seal has become dry-rotted and / or hardened from age and heat, and it has cracked, or that bushing has been chewed up. I've never actually run into a chewed-up bushing. There would likely be no damage to the cv joint because that surface is hardened, but the bushing is made of very soft metal and you would feel the roughness, and you'd find a pile of gold metal flakes when you wipe your finger inside. Many bushings have oiling grooves in them. Don't let those fool you into thinking that's damage or wear.
With excessive wobble from a worn bushing, the cv joint can move far enough away from the lip seal to allow it to leak, but you would most likely also feel a vibration at certain speeds. Rotating parts that wobble have a "resonant frequency" they like to vibrate at, just like the pendulum on a grandfather's clock. At anything other than that rotational speed the shaft or joint is less likely to vibrate. Hit that magic speed though and you'll feel it. That much wobble would cause quite a bit of fluid leakage while you were driving, and usually less leakage standing still.
If you can see into the center of the seal. Try to see if here's any cracks in the rubber. If you see any, the rubber is hardened and brittle. Pop a new one in and the leak should stop.
Tuesday, October 8th, 2013 AT 10:32 PM