spicergear
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Well, here’s what’s been soaking up a lot of time for the past year or so, my 1977 Unimog 406. Originally it started life in the German Army with a bulldozer blade on the nose and backhoe on the rear. I feel pretty lucky that the truck has the heavy duty frame which wasn’t the most common option outside of the line of CASE Unimog trucks. It also had a fairly massive frame truss below the stock frame that ran from the backhoe’s large oil tank and mounting points to nearly the front axle at the front of the frame made up of a mid mount point and four, 2” solid steel round stock links. The truss, tank with mounting points, and offset drive for large Commercial hydraulic pump for the hoe were still on the truck. Blade and hoe were gone. I stripped the mounts and stuff off which was a LOT more work with frozen 1” pins at all link ends that a day under the truck with a sawzall and can of WD40 finally removed.
Truck had 14.5R 20 XL’s on it but I wanted a more open tread for my new European tractor. I really lucked out by knowing a guy that happened across a set of 90% Michelin XM-47’s in a 405/70R 20 (roughly 42.5”x 16”) high speed radials. Didn’t get them for a song…but still did well considering new one’s range from $1100- $1300 per tire. ßYeah, Michelin is REALLY proud of them.
The truck, body wise, was in really good shape with very, very little rust and just some fender flare abuse from previous owners that was able to be straightened with a hammer and dolly. The worst of the previous owner stuff came in two forms: 1st was the spider frame under the bad had been added to as the PO had a knuckle boom mounted at the rear of the truck so I had to undo some of that damage. 2nd was much worse- apparently I was the only one to ever check the oil in the front diff…which there was none. Instead, it was full of brown goop and water and a little over a year ago had me pulling the front axle out to replace ring & pinion (which is diff too in these Mogs) as part of a pretty costly rebuild. LUCKILY the portal boxes up front were not in need of rebuilding. One did have a little water in the oil but time and repeated flushing cleared that up. As a reference to how bad the diff was…the pinion support bearings had made it past the gear set INTO the BOTTOM of the differential housing- ALL OF THEM. I have a pic of one of the tapered rollers in my hand. I formed new brake lines while there to make sure all SIX brake calipers on the trucks 18” rotors would be clamping well for a long time. Yeah, two calipers per side on the front rotors then two more for the rear axle.
After that 7 week process and getting the axle back together with bunches of freshly imported (L) parts…that was back under the truck and the rear locker issue could be addressed. The 406’s and 416’s employ a mechanical air locker that is pretty darn slick. One axle has a longer section of splines out of the diff and has a sliding collar with a heavy face spline…sort of ‘love-joy’ coupler looking, that engages into the side of the side of the differential so that when it does, it locks that axle to the differential and with that axle not turning separately…the spiders can’t turn so it locks the other axle through the spiders. Really slick! Sounds like a lot of strain on the spiders until you see them…good luck breaking those!
The rear had a little merky oil in it and was able to be cleaned up but still had to disassemble. The one portal box needed rebuilt and I now know what a 140mm, $140 inside raceless roller bearing looks like…and that was a good price. The lower outer bearing and seal in the portal boxes are captive to Mercedes so you can get one from them, someone that happens to have some parts stocked, or import one from Europe. Fun-fun!
The electrical system of the truck was odd as certain lights lit and others didn’t for no apparent reason. I took the cover off of the narrow dash to be greeted with a fluff of copper and green and mouse poop as those little bastards had shredded 18 wires behind the gauge panel. Replacing wires through gauge holes and working via mirror and drop light took time off my life. On some of them there was only 1/8” of wire with insulation at the connector to identify where it had gone. Ugh…but got it. I also replaced the factory 24v headlights with a Hella conversion kit. Because the truck was factory outfitted with a blade it has mounts at the windshield and nice Hella halogens there. The wiring for the two lights was interesting as there were two 8 pin blocks on the firewall but one had no wiring. What you would do is swap your lighting harness plug for either the lower lights (no blade) over to the other block (blade on) and just swapping the light harness plugs manually was their trick. I bought a separate mulit-position rotary switch and wired the upper cowl lights into that so if I want I can run all four front halogens at once. I think I can melt snow in front of the truck now. J Even the flasher unit is complex- with the cover off of it (had to clean the points) it looks like the top view of a chemical plant or something!
The engine is an OM352 (5.7L) inline 6 Mercedes diesel that originally made a whopping 84hp. The 416 long wheelbase trucks made 110hp and they can be turn up around 130hp…but a pyro must be installed at that level. I installed a pyrometer, even though my upped ‘tune’ is well under real pyro needs, so I could get a baseline on the egt’s for when I bumped the power. The governor was raised to around 3,000rpm, fuel was turned up to around 100hp, and time was bumped ahead to help clean up the exhaust a little. All I needed was the truck to have just a hint more oomph on the road…it’s has all kinds of gear for pulling on the farm.
The truck had been parked for a while and took some time for the shifters on the tranny to loosen up but now are working really well. The tranny is a 6 speed, which is basically the 20 without the ‘cascade’ or multi-range box in front of it. The tranny has a single speed PTO (540) with factory standard front and rear drive flanges. I have a 2 speed waiting for some seals. The rear output is now spinning the worm of the 20,000lb Garwood I nested into the rear of the truck where the backhoe once resided. Four large ¾” machined plates secure the winch to the rear of the frame with a whole bunch of 5/8” grade 5 & 8 bolts. See why I was happy about the heavy duty frame. HA! That winch works really, really well too. I’ve already dragged a plethora of things and it’s proved it mettle time and time again.
Below the winch is the very unique pintle hook. The original mount had been hot wrench attacked by the PO and new ones are not available. There are also a couple used parts guys kicking around and they had never even had one of these in their possession. EuroTruck Importers in GA was able to email me an exploded view of factory mounts so I started making my own, with some added meat, so I could get the hook mounted once again. The uniqueness of these pintle hooks is that the heavy lower part that most of us know as the stationary part…actually drops down to disengage what hooked to it. Like say you’re stuck in the muck with your truck and trailer or implement being pulled you don’t have to break yourself in half to lift the drawbar up and out of the hitch, it drops out 90° so you can pull away. It’s really sweet and really, really beefy. I had a full white oak cut in half with both halves on the hook and on the way back up the farm winched a decent sized hickory off a bank and kept that on the winch…so all three tree hunks were behind the truck. My neighbor had wandered down when I got back up and told me he loved that truck. It’s also really fun getting groceries or hitting the local McDonald’s. J
On the heavy rear winch mounts I recently made up a lower mount for a light duty (like 600lb) jib crane my Pop had built a long time ago. Recently it worked great as it lifted about 260lbs into the bed with ease.
The current project is a 10,000lb front winch with hydraulic drive to take advantage of the factory hydraulic drops at the front of the truck. Hydraulic controls run up along the steering column so that part is taken care of already. The pinion has been flipped so it can be driven from the front and a heavy aluminum structural extrusion has been heavily modified on my milling machine to work with the winch, pinion seal, and hydraulic motor that will be mounted on the driver’s side of the winch. Winch will also be able to be pinned on and picked off.
SWEET !
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I sold the Viper to a guy that races in Telemark, Norway last year...um, actually and of '09.
