Topic: Rear axle shafts--Is it safe to swap sides?

[schadenfreude]

Hello all, this is my first post.  I just sold my FZJ80, and now I can dive wholeheartedly into my 83 pickup that I've had sitting around.  I've already rebuilt the front axle, adding a high steer and V6 brakes, 5.29 gears and an air locker.  Now I'm moving on to my rear axle.  I put the third member in yesterday, and am waiting to install the axle shafts until I get the motivation to pound out and re-install all 12 wheel studs haha.  The diff I pulled from the truck was welded, so I inspected the axle shaft splines for wear, and figured I would probably swap sides to get a little more life out of them similar to swapping birfs.  They're not destroyed by any means, but you can certainly tell which side had more force against it.  Figured I would check if this was a safe practice before I break something else and cost even more money    Thanks for your assistance! Looking forward to learning more about this side of Toyota.

[blackdiamond]

That's actually an interesting question from a metallurgical perspective.  I probably should have some insight into the subject given my engineering education, but I can't say that I do.  I'll contact a materials guru that I know and see if he has any insight...

If you describing the physical contact (i.e. exterior marks) on the splines then it would make sense that putting the force on the opposite side, but where it gets interesting is if the splines have been pushed beyond yield and have actually deformed (i.e. twisted) then I'm not sure that turning them around could be of benefit and they should probably just be replaced all together.  This same thought would go for the twisting of the axles.  It's normal for them to twist in as long as the stress doesn't exceed  yield, and once they have been pushed beyond that they should probably be replaced as the physical properties have been changed.  I would guess that they would become more brittle.

I'm curious now...

[mdtrail-toy]

As far as the actual shafts themselves, you said there dosnt seem to be any unusual wear on them. so swapping side to side will slide right in no problem. But only talking the shafts, were you may have a difference is the backing plate / brake assembly. Pretty sure the parking brake lever sits on the back side of the axel on either side. meaning if you flipped the whole set up that wouldn't work. you could press the backing plates off and switch to the opposite shaft. Good luck

[OTO Phil]

Never considered this... Interesting concept... if everything has the same P/N, then they would definitely fit..

[schadenfreude [OP]]

Well, they definitely fit back together.  I brought this question up because I was installing 1.5" spacers and wanted to replace all the wheel studs for peace of mind.  Meaning I had to completely remove both shafts anyways, so I figured I would pose the question.  From an engineering perspective, as black diamond was talking about, it is an interesting point.  I feel whether intentional or not, the splines would shear/fail before the actual shaft reached its maximum tolerance for torsional forces, but who knows?  I have a blown head gasket and what feels like a collapsed steering column to sort out, plus an exo cage to farm out, so it'll be awhile before I can update.  If and when I break a rear axle shaft, I'll update with pictures and we can try to see if flipping sides contributed or not.  I will say I backed the rig out of my garage to clean up my mess, and it drove down the block, u-turned and re-parked just fine.  Now it's time to wire up the air compressor and plumb my lockers while I wait for my new head to arrive.