Okay so I have a 5 speed manual 2006 S40 2.4i. I recently did the struts, sway bar end links, inner and outer tie rods + boots and control arms for both sides on the car. The reason I did all this work is my clutch went out so I had to take out most of this stuff to replace to drop the tranny and I figured if I was in there might as well change it. I didn't change the CV Axle on either side but I did remove them to drop the tranny of course. So got everything back together and it well all working fine. My check engine light came on but that was due to me not securing the boot going to the throttle body right. While I was fixing that I noticed a little fluid on the floor of my garage. Well did a diagnosis and it's the tranny fluid I filled. Not coming from the drain or fill plug and all bolts are as tight as I could without a torque wrench. Looked above drain plug and noticed an 1/4 inch gap between CV Axle and tranny and noticed it looked a little like fluid had been coming from there. Well after messing with everything for a while noticed the retaining clip is in bad shape. So I had the idea to see if it'd go back in all the way with out the clip, removed the clip and put a little gear oil onto the spline of the male end going into tranny on CV Axle. CV Axle still did not fully go in, went in a little farther but still a gap. After trying to force it for a good while no luck. I plan on getting a new clip, but any idea why it won't go in . Just an fyi I looked in there and the splines don't seem to be damaged but who knows.

 

The C-clips can easily get munged, but should be on the axle. I've always just used some brute force to get CV axles in (on any car I've owned). Often, I'll do that by using the knuckle like a big ol' hammer, but inserting the axle in the knuckle (before reconnecting the knuckle to the control arm/ball joint) and pulling the knuckle out away from the car, and swinging it in forcefully, using the weight and momentum to drive the axle home.

If it really won't go in, even without the C-clip, I have to wonder if there is something fouling the path, like a chunk of seal or a piece of the C-clip (was it complete when you removed it?). You might have to take a look inside the hole the axle shaft lives in with a borescope (you can get a smartphone version for chump change online in a day or two).

 

Was messing around with it some more, took a pick and lightly felt around inside the axle housing felt no loose pieces of metal and seen nothing moving around. Put on latex and felt nothing, looked at the top of the CV Axle end going into the tranny and noticed not all of them are in line with the rest of the splines after where the c clip sits. Ordering a new CV Axle will let you guys know what happens.

 

Not quite sure what you're saying, but I think you're saying that the splines got munged somehow. Yeah, that'll do it. ;-)

FWIW, I tried some el cheapo (Chinese) axles on my V50 and they were a total washout. Ended up going with Cardone remanufactured (not new, which I believe are not designed to the same spec as an OEM axle).