I didn't preheat it for the first pass while it was in the lathe, but did when I finished with the TIG welder.  I was worried about putting too much heat into the shaft and making it brittle.  It is my understanding that a properly heat treated shaft is only hardened to the depth of the splines so that all of the contact areas are hardened, but the rest of the shaft is not (to permit some twisting under shock loads).  I've never done anything quite like this before, so it may or may not work...

Impressive work. 
With the massive hp you are using, you might get away with the welded axles, but I fear they will break at the welds.  It would have been better to cut and have them resplined, as it appears the splines are smaller than the shafts.  No loss in temper then.

There is a company that custom makes axleshafts for these axles ($600 per shaft)...but I cannot have my existing ones resplined.  It is hard to tell in the pics, but the splines actually rise above the body of the shaft by about 1/8" so there is no way to respline them.  I know that my axleshafts aren't ideal...but I have found some other people running welded shafts successfully behind v8 power and 47" tires so I thought I would try it first (it is free).  In fact, Exaxt 4wd www.exaxt.ca actually shortens these axles the same way I did, but without the sleeve.  I don't know how many of these they have done, but was told that they have only had a very small percentage of failures.  With the sleeve I added, mine should be even stronger.  And, this isn't a daily driver.  If I break a shaft I'll just limp it home and pay for the custom ones.  But I think they'll work fine...

I think your half shafts should hold up just fine, assuming your welding skills are on par with your photography skills Your welds on the housings look very good.

I am not sure about the sleeve idea.  We have never done this.  Half of me says "more is better" and half of me says "more is less" because you are adding more places where stress can build up.  I'll blab a little more about the shafts in general and get back to the

All of the half shafts in a set of axles are a different diameter.  Rear shafts are thicker than the front and longer shafts are thicker than shorter shafts.  The shaft material is torsionally very springy and the shafts twist under load and spring back.  I think the engineers were trying to have equal twist factors on either side of the vehicle, and allow for more torque on the rear axle than the front.

The added sleeve may prevent the center section of the shaft from twisting.  When the welded shafts fail, they twist off in the original material just outside the weld.  The sleeves may carry some of the torque across the weld to the other side.

We usually use a donor shaft from the RHS to make a shaft for the LHS in the front.  They are a larger diameter and it was our hope that the extra beef would compensate for the weakness introduce at the weld.  We also do some stress relief and tempering around the weld area.  The tempering was a bit of a guess since the rod material is different from the shaft material and we have no idea what the original tempering specs were.

We usually consider 3 factors when deciding how or if to build 404 axles for a project:
1) Vehicle weight
2) Power plant
3) Tire size and weight

I don't remember the planned tire size in this thread but given 1) and 2), we would recommend using cut and welded shafts for this project.  They are economical and would not move the axles out the "bulletproof" category.  Your welded shafts should hold up just fine.

Thanks for the insight Mac; my new front shaft is made from a shortened long side shaft because it was a bigger diameter (as you discussed) however I didn't do the work on this one (bought it from Kabuki).  So, I'm not sure about how all of the welding and sleeving was done on it.  However, I did do all of the work on the rear shaft.  When I welded the sleeve on I didn't use much heat and welded it fairly quickly, thinking that this would prevent the heat from hardening the steel too deeply into the shaft. 
My thought in using the sleeve was twofold:  First I figured it would distribute the load over more area on the shaft (as you mentioned), and second I thought that it would essentially hold the welded section of the shaft together (assuming that as the weld twisted it would tend to expand).  The sleeve is machined to be a very tight fit; I had to polish the shaft and heat the sleeve to press it over the welded area. 
This is new territory for me; I'm not a machinist, welder, metallurigist or anything like that.  I just got tired of all the broken axles in my Samurai, and decided that these 404's would solve that issue with my new rig.  Hopefully my ideas work, but if they don't I'll know what not to do when I fix what broke.

Got the hub conversions done tonight.  Basically, the stock unimog hubs were turned down in the lathe.  The original unimog wheel flange was machined down for the rotor to fit over, but enough was left to cover and protect the seal on the portal box.  The end of the hub was also machined to fit the ID of a wheel flange that was laser cut with a standard 8x6.5 lug pattern.  Then I pressed the flange on the hub and welded both sides.  At that time, I didn't have access to a lathe so I just got them as straight as I could (they were very close because the hubs were machined true).  However, after assembling everything I put a dial indicator on the rotors.  Both rears are about .020" out (they look perfectly straight).  That's .012" out of spec according to a Haynes manual I have for chevy pickups, but I figure it will be fine for me.  If the pedal pulses too much for my liking, I'll true them up later.  The rotors are front rotors off of a 3/4 Ton chevy pickup and were $24 each.  They fit behind the wheel flanges and center on the wheel studs, which are pressed into the new wheel flange. 
In the pic with the hub, I'd like to point out the size of the wheel bearing; compare it to the size of the measuring tape sitting next to it 
Check out the ground clearance under the axle...with the 35 that's on there now, I've got more clearance under the diff than a rig with 1-ton axles on 44" tires.  I can't stop looking at that pic...digs, anybody?

On to the brakes...
One of the more common failures of the unimog 404 axles is the portal boxes breaking under load.  There's a few reasons I've found for this...overheating, improper gear orientation (gears are helical cut and if installed on the wrong side will push the box apart), loose studs, and some other theories I'm not so sure about.  So, (again thanks to Kabuki) I had a set of box braces cut out with caliper mounts integrated into them.  The braces are welded to the boxes and fully encircle them, adding strength. 
The calipers are 4 piston units from a 1965-1982 corvette.  They are EXPENSIVE if purchased from a parts store...I was looking at $200 each at my local Napa (couldn't swallow $800 for calipers).  I got lucky and found 4 rebuilt ones with new stainless sleeves from a corvette wrecking yard for $35 each.  The 4 piston design provides some good solid braking over a single piston design, and it also allows the caliper to be solid mounted (without slides).
I am planning on running 16.5" or 17" wheels...but the one in the pic is a 16.  The caliper fits with at least 1/4" clearance all around.  It may require some grinding with wheels that have a flatter center, but I'll cross that hurdle if it comes up. 

One of the reasons I chose these axles (besides the obvious ground clearance advantage and their heavy-duty design) is the gear ratio.  The 404's have a 7.54:1 overall gear ratio (3.54:1 in the diff, 2.13:1 in the portal boxes).  For those of us running high-revving import engines, you just can't get a low enough ring and pinion for Toyota axles if you're running larger than 33" tires.  And, the gears get progressively weaker the deeper you go.  By my calculations (assuming 40" tires) I should be running roughly 2700RPM in 5th gear at 65 (don't know if this speed will be possible yet).  This is pretty close to the stock vitara gearing.  The 2.0 starts to make good power just before 3000 RPM, and really pulls good at the higher RPM's.  That 7.54:1 should be perfect for this engine...

subscribed...  Looking to see more about the toy tranny swap!

subscribed...  Looking to see more about the toy tranny swap!

That's coming soon...waiting for the rest of the parts to arrive.  I'll go into good detail with that as right now nobody makes a kit to swap the toy tranny to the 2.0, but it can be done with mostly all off the shelf parts (if my plan works out) and a minimum amout of machine work.  Good option for the guys running the 2.0 in their Samurais...there are TONS of options for tcase gears, doublers, etc. with Toyota stuff. 
Speaking of which...I have the transfer case from my Vitara up for sale right now with the Trail Tough gearset in it...somebody buy it so I can keep working on the unimooki!
http://www.zukiworld.com/forum/index.php?topic=22564.msg186859#msg186859

Got the front mostly assembled yesterday; tooks hours of cleaning before it was ready to go back together.  The axles had grease in every nook and cranny, covered with a layer of sand and mud, and the previous owner had helped things by spraying a coat of orange paint over the whole mess to lock it all together.  Last week, I ran into a snag during the reassembly; while pressing the crosspin back into the shortened axleshaft, it made it all the way through the eye but not quite far enough through the CV joint and then got hung up.  Don't really know why; I thoroughly cleaned and lubricated it before pressing it back in.  Maybe there was a burr I overlooked, maybe a piece of metal accidentally got pressed in there...I'm not really sure.  At any rate, my press wouldn't move it anymore.  I tried heating it, I placed the whole assembly in the freezer overnight and then heated it while it was in the press and it still wouldn't move.  I mailed it to a friend with access to a 45 ton press...he couldn't get it out either.  I found a local manufacturing plant with a 100 Ton press; going to see if they will try to press it out for me this week.  If they can't get it, I'm going to have to buy a new axleshaft and CV joint...
Fortunately, I can reassemble everything without the shaft. 

   this thing is gonna be sick.

I started breaking down the Vitara tonight...but then the UPS guy showed up with my air rams and solenoid so I got distracted building the air locker setup.  The ram is more exposed than I would like, but they are really cheap so I'll carry a spare at first.  If I end up breaking them more than once I'll build some kind of little cage to protect it.  It works great; check out the video here:

LOCKER VIDEO

All of the parts coming off of the vitara are going up for sale...PM me if you're interested.

I got most of the drivetrain pulled from the Vitara last night; it looks like it's going to be another long day with the plasma cutter and grinder 
I took a pic of the stock vitara tranny/transfer case along side the toyota case I'll be installing (the suzuki stuff is to the right of the toy stuff).  I don't have the new bellhousing, adapter, billet case, gears, flywheel, or clutch yet for the setup but it is on its way to my house now.  So, I can't really measure exact distances but I can come close.  The new toy combo has the rear output about 1" forward of the zuk output, and the front is about 3" behind the zuk output.  This is good!!  Helps to counter the long pinions on the unimog axles.  Looks like my rear driveshaft will end up being about 36" long, and the front maybe 30" or so.  This will change if I decide to go with dual cases.  One obvious issue is the location of the shift levers; the toy ones are about 8" forward of the stock ones.  Gonna have to do some cutting welding and bending for sure...

think you going to get it done by POWERFEST




Ryan

think you going to get it done by POWERFEST

I'd really like to but unless I have no work for the next month I just don't see that happening.  It isn't out of the realm of possibility though...

One of the problems is that some of the parts I have ordered are a month or so out.  Kinda hard to finish the build without the parts 

If I do have it running, it will probably be without a lot of the details...like exocage, bumpers, air system, etc.  But I suppose I could always run with the stocker group...that is, after all, where I drove the vitara last year