re-splining axle shafts

[tr8todd]

I'm in the process of narrowing one side of an Explorer 8.8 rear end.  Called Mitchell driveline about having the longer axle shortened and resplined to match the shorter.  I was told that in order to do this, you had to remove at least 4 inches of shaft.  Guy on the phone didn't seem very knowledgeable.  He put me on hold a couple of times to go ask someone else what I thought were fairly easy questions.  Can't understand why you would need to remove so much.  Anybody have any ideas or can dispute this claim.  I ended up just ordering 2 new axles.  Since they were uprated direct replacements, they were cheap enough.  $225 delivered for the pair sure beats going to the junk yard and removing two and then haggling over the price.  Ever since the Jeep guys started installing these Explorer axles, you'd think they were made of gold.  Use to be I just had to get them before the Mustang guys found them.  They were anywhere from $75 to $150 for a complete disc brake limited slip unit with a piece of driveshaft.  Now they want $400 for the complete units.  I'd buy them 2 at a time to get both short axles.  Now I'm left with a stash of long axles, housings, rusty brakes, and 3.73 limited slip carriers.

[ex-tyke]

Here's what Moser Engineering has to say:
A. The axle shaft has to be the same size or bigger as the original spline OD where you need it cut.(They can NOT be smaller )

B. On the original axles you need to be taking off at least 3 1/2″ to get past the original spline area.

[minorv8]

I narrowed a TR7 rear end 20 years ago, a total of 5 inches. Axles are of different length so LH axle was just perfect when fitted to RH sidd (or vice versa...) Anyway, this left only one axle to be shortened. Diameter was not a problem. But, the axle was induction hardened deep and too hard to have new splines cut. So I was left with 5 in shorter axle without splines. It took some time but I finally found a guy who had proper tools (boron nitride)  and I got my splines. IIRC the axle was heat treated along its complete length.

[tr8todd]

Talked to my machinist buddy and he says that trying to get the cutter to line up perfectly with the existing splines is extremely difficult and just not worth the effort to even try.  Cut them off completely and start again or buy new ones seems to be the only options.

[BlownMGB-V8]

Cutting splines is a slow process. You can do it with a mill, a dividing head, and a single point carbide tool in a fly-cutter if you have the machine time available, but buying the axles ready made is a better option.

Jim

[Orange Alpine]

The factory splines are rolled into the axle.  This requires the axle to be turned undersized, as the rolling process displaces steel and increases axle diameter.  If you examine your old axles, you can see the splines are higher than the turned diameter of the axle.  The custom axle guys do not roll spines.  They cut them, so they need final spline diameter axle.   That means cutting off the turned portion of the axle.

Bill

[BlownMGB-V8]

Also. there is a sight strength advantage to rolled splines due to work hardening of the metal, and surface quality is usually a bit better. Provided adequate spline engagement this is usually not an issue.

Jim

[roverman]

FWIW., I have also heard, some production axle shafts were "female broached". Might want to be leery of swapping axles, side to side, in high powered applications. Axles can take a twist, set and don't like to be un-wound.  Good Luck.  art.