Is the new axle OEM or aftermarket?

While the two (old and new) are out, put them side by side on some newspaper
on the floor and look *carefully* at each section to ensure they are the
same length and have the same features. The inner CV joint should telescope
in and out - it is possible to pop it apart so the joint won't telescope. If
that happens, you have to finagle with it - like setting a broken arm but
without the hollering - until it slides back together.

If they are the same, be sure the inner end actually snaps into place. If it
pulls out with little effort (don't pull by the main part of the shaft
unless you want to go back to the previous paragraph) it didn't snap. The
outer part, where the splines fit into the hub, will undoubtedly have a lot
of friction. Lightly grease the splines before fitting them together and be
prepared to push a lot.

Now I will stir up a controversy. Some manly people tell me they get the
splines together enough to get the nut started by muscle power. Rocking side
to side helps. More power to them; that is ideal. I usaully end up banging
on the hub with the butt end of about 2 feet of 2x4, thus abusing the wheel
bearings. Bang on one side and then the other, just hard enough to make
progress. I don't have a real mallet with enough mass to do the job without
really whaling on the hub, so I use the 2x4. I haven't had to replace any
bearings yet, which is my standard of "good enough." BTW - I have sometimes
had to use the same 2x4 to snap the inner splines in place (previous
paragraph). Run the nut on flush with the end to protect the threads first.

Once the nut has a couple threads to grab, use the nut with a socket and
gentle torque to draw the splines together. Put the washer under the nut
when you can. Be sure to torque the nut to spec before dogging the washer,
though, or the slack will let the splines erode and really mess things up.

(It really helps to have a friend hold things straight if you have to wield
the 2x4.)

Mike

There are two possibilities I can think of.

1) Splines are the wrong size.  (This can happen with cheap
remanufactured units.)
Go beat the auto parts store manager over the head with the thing.
Consider Raxles.com, or new / remanufactured axles from the local Honda
stealership.  AFAIK, Honda rebuilds them right, and refurbs will work
nearly as well as new.

2) C clip out of spec.
Does it start to go in, then stop?  The retaining clip diameter may be
too large.  Remove the clip, and squeeze it slightly, tightening the
curve a little.  Try again.  If this works, be sure to give the axle a
tug after it is seated, to make sure the clip isn't too small now.  If
the axle pulls out with ease, widen the clip slightly.