Unimog 404 Axles Under a '03 Silverado (Build thread)

[Korzenowsky]

Concept: Got tired of my slow “Do everything right” DOT Legal Cummins build, wanted something to beat on.
Not gonna be Linked or bagged or coiled, or double/triple/yota transfer cased to the nuts, I don't need fancy, Manitoba is flat, so lots of rad clogging mud and foliage, occasional creek run with rocks, nothing crazy.

Basic outline: full-size chevy truck, move the rad to the box, knock the front bumper, lights, and mirrors off. Boatside to get rid of typical rusted rockers and increase clearance. Torch the IFS crap out, eliminate the slip yokes. Swap in Unimog portal axles with some 66 inch ford rear springs and some anti-wrap bars, Simple.
Rear mounted rad and Boatsides are going to be a "stage two" scenario, for now I'd just like to get the solid axle stuff done.

I'm going to try and keep it as low as possible and not have the transfer case clocked way down, obviously the absolutely massive third member on the Mog axle can't share the same space as the oil pan, so I'm going to have to get creative in the front.

Couple Quick UNIMOG 404 Axle Specs-

-3.54 in the Center section
-2.13 in the Portals
-7.56 overal reduction
-Oil-bath hubs, ie No repacking wheel bearings after playing in water.
-Cable Actuated lockers
-Approximately 5 Inch Gain over stock axles in ground clearance

-205mm stud circle
-18mm studs (Lug Centric)
-161mm hub dia. (ISH)
(Some guys convert to eight lug with disk brakes, I'm probably just going to get custom steel centers cut)
-Drum brakes; M10 x 1.5 x 50mm jack bolts. (Brake adjustment with 19mm socket)
-Front brake cylinders are 1-5/8" and rears are 1-1/8"
-Stock mogs have 1/4" brake lines

-Front axle weight (dry): 530 lbs.
-Rear axle weight (dry): 485 lbs.
-Very large 3rd member, that really brings up some packaging issues:

Through a bit of research, and some word of mouth, I’ve come across some good tips on these axles.

-Lock the locker before you pull the shafts, so the locking collar doesn’t fall into the centre housing.
- check the bolts which keeps the 2 halves of the boxes together.
-bolts working loose between the boxes and the backing plates
- don’t put the portal boxes on the wrong side
- Wheel offset is what kills them. (suggested-face of the beadlock ring sits flush with the face of the big hub bolt)
-drums need to be indexed to the hub in the orientation they have been run long term or they’ll have runout issues.
-Drums have jack bolts, don’t try and wack/pry ‘em off of the hubs like one of the P.O’s of my axles did. Oops.
-suggested residual pressure valves in line


Little bit of Weight Comparison-
MOG-
4539 pounds DRY
11023.11 pounds GVWR

Chev-
5631 pounds Curb
9200 pounds GVWR

Rough comparisons with different options increasing weight or capacity, but I’m surprised, I honestly didn’t think that little Unimog could handle so much weight.

Anyway, for some further guestimations, 10.5 Corp in the Chev weighs about 500 pounds to be conservative, and about 300 for the front IFS paraphernalia, so about eight hundred in the negative, then fully wet Mog axles at the most are 600 each, so about a four hundred gain. I’m not going to include tires and wheels in this, purely estimating weight capacity of axles.
So 6031 pounds Curb with Mog axles , then about 100 litres of fuel at a rough conversion of .8 of a pound per litre is 80 pounds; 6,111 pounds as a very rough estimation. So about 4912 pounds of weight rating left for Cage/Cargo/Spare/People/Beer.

Again, Sand-f’in-paper rough estimations, obviously a unimog axle on a unimog wouldn’t see the loads like the ones on this Chevy will hitting logs and bumps and rocks, or those high single wheel loading conditions in extreme angles and holes, So I’m basically just taking a stab at the envelope for weight capacity here.

Sidebar- She’s gonna be a bit fat for a rig on 38x12.50s, Good gPsi to for good traction in some conditions….? LOL
Definitely going to see if I can find a wider tire that will fit with my scrub radius and WMS to frame clearance, maybe an Ag tire?

My 'eyecromiter' says this front suspension would be easier with a radius arm setup, but I'm gonna be stubborn.
Anyway, might as well put it on the internet so someone can learn from it

 

[YotaAtieToo]

Mounting the leafs under the axle?

 

[McBastard79]

Sounds interesting, I like it

 

[Korzenowsky]

Mounting the leafs under the axle?

Plan was spring over both front and rear, might switch to spring under in the front, especially because I'm not sure how easy it'll be to get an anti wrap bar in there that's not crazy long and cut down on belly clearance.
Rear is easy, all the room in the world on the passenger side when you run a smaller muffler.
IMO kinda prefer a spring over for this truck, leaves less to get caught up on things under the axle, and seems like a shame to waste that extra portal clearance.

 

[YotaAtieToo]

Spring over would be pretty retarded on a MOG portal, basically like running 6" blocks. Spring under will still have great clearance.

I think you'll have issues with a single wrap bar with that much leverage. You could run 2, but may as well go 4 link at that point.

 

[CDA 455 II]

Subscribed.

 

[Penetrode Offroad]

I'll be watching this.

 

[Korzenowsky]

Spring over would be pretty retarded on a MOG portal, basically like running 6" blocks. Spring under will still have great clearance.

I think you'll have issues with a single wrap bar with that much leverage. You could run 2, but may as well go 4 link at that point.

Oh definitely, You're completely correct. Maybe even more then six inches of block, around 9-1/2'' from where a non portal axle shaft would run, Seven inches roughly to the top of the axle tube from centre of the hub, then another 2-1/2" to the top of the stock bracket that I might use as a spring perch.

Plan "A" was spring over, and a large vertical spread on the anti wrap bar in the rear, and a large horizontal spread on the front, Sorta like an 80 series land cruiser front arm, But there's allot of good points for spring under too.

Spring under isn't a huge change, if I end up C-notching the rear to clear the axle tube at bump its not big deal, might even be able to use the same stock bracket style inverted.

And I could use a bolt pad like this image, wouldn't have too much drag. (Not my rig or my work)

In the front I'd have to do some f'in around with the crossover bar and steering arms, because the crossover is on the rear of the axle atm, and runs right through where the spring would run on a spring under, unless I make a super flush mounting pad.

Spring under is definitely more work, but does have allot of positives. Might put some thought into that, gotta see if it works with all my parts.

Definitely not fourlinking it, thought about it, but I've already got a "do it right" project with way too much damn scope creep LOL

I think I can keep the front low on Leaf springs with way less work, I'm attempting not to let project scope creep get ahold of me on this one.

Emphasis on THINK and ATTEMPT

 

[YotaAtieToo]

There is a company that makes some nice high clearance spua pads and plates. Basically a u shaped plate with either super short ubolts or just ubolt eliminators. Can't remember who, ruffstuff maybe?

Basically just a 1/4" below the leaf is all it hangs down

 

[M92PV4U]

There is a company that makes some nice high clearance spua pads and plates. Basically a u shaped plate with either super short ubolts or just ubolt eliminators. Can't remember who, ruffstuff maybe?

Basically just a 1/4" below the leaf is all it hangs down

I'm sitting here reading this thread trying to work out low profile su mounting options .

 

[posford]

There is a company that makes some nice high clearance spua pads and plates. Basically a u shaped plate with either super short ubolts or just ubolt eliminators. Can't remember who, ruffstuff maybe?

Basically just a 1/4" below the leaf is all it hangs down

Yeah thats Ruffstuff.

Deaver Long Travel Spring Under WIY Kit 2.5" Springs

Check out the deal on Deaver Long Travel Spring Under WIY Kit 2.5" Springs at RuffStuff Specialties

www.ruffstuffspecialties.com

 

[M92PV4U]

Why not make the leaf springs U bolts wrap the leafs?

 

[ANGRYBLACK]

How much uptravel are you aiming for?

 

[Korzenowsky]

How much uptravel are you aiming for?

Not a Bunch, Gotta sacrifice something to keep the centre of gravity down.
I'll see how many leafs I have to take out of the F350 rear pack, whatever rides good and lets them go a little negative, likely an inch or two, and move the hangers up/down to set bump there. Whatever that uptravel is, Thats what she'll be LOL, I've ran with a couple leaf sprung rigs but never seen anything with this long of a front spring, not much variety up here. We'll see how it does.

Rear Leaf springs I had kicking around are 43-1681HD Springs from a 08-13 F250. 3 inch wide, Equal Arc length front/rear, 66-1/2 Inches overall arced length eye to eye, 5-3/4 Arc height from a Six leaf pack. Supposedly its 5/447 with a 999 overload, for 4400 pounds of Capacity from one spring, with a stock tension shackle that’s about 4-5/8” long.

4400 for one pack, way overkill, gonna pull most of those leafs, Gm 47 x 2-3/4” Front springs are 2 Leafs for 1200lbs, 3 Leafs for 1400lb and 4 for 1900lbs, gonna shoot for something in that range.

Might go with a Six inch tension shackle in the front if i can get it in there, Depends where the leaf sits inboard in the frame.

Not too high tech, I don't have a specific number in mind. Any suggestions feel free, happy to use the community to make my life easier LOL

 

[OX1]

Just stumbled on this thread, actually looking for possibly another entire 404 steering axle.
Any updates on the build?

Anyway, I have been spring over on stock 79 Bronco springs with an add-a-leaf for almost 20 years now.
I did have a lot teething pains creating a traction bar that would hold up, but now have not broken anything
back there in 12-14 odd years.

Here is what I did for the rear traction rear bar
(I'm 3 link front, and still stock rear steer, so major compromises in that end too).

 

[Korzenowsky]

Just stumbled on this thread, actually looking for possibly another entire 404 steering axle.
Any updates on the build?

Anyway, I have been spring over on stock 79 Bronco springs with an add-a-leaf for almost 20 years now.
I did have a lot teething pains creating a traction bar that would hold up, but now have not broken anything
back there in 12-14 odd years.

Here is what I did for the rear traction rear bar
(I'm 3 link front, and still stock rear steer, so major compromises in that end too).

As far as an Update, I've been so busy with farming I haven't had a chance to do much, Working on collecting parts.
Took the door apart to see how high up I can boat side; filled the gap between the rear window and window frame with caulk, and discovered the frame is a diamond, y'know; just the little stuff

It seems like the previous owner jumped an approach, because all the crossmembers and body mounts on the passenger side are smeared backwards, and the front rad support, passenger fender, and the paint on the outside passenger footwell, all looks new.

Who knows, maybe he got distracted by the dash being en français.
Regardless, Not that this information changes my plans in the slightest, actually makes me feel way better about putting in under the knife.

Yeah it seems like 404 parts are few and far between on the used market, Expedition Imports has a Whole NOS Front the last time I looked, If that helps you any.

It definitely gives me confidence with low long your setup has lived under a full-size rig, Any Advice?

 

[OX1]

As far as an Update, I've been so busy with farming I haven't had a chance to do much, Working on collecting parts.
Took the door apart to see how high up I can boat side; filled the gap between the rear window and window frame with caulk, and discovered the frame is a diamond, y'know; just the little stuff

It seems like the previous owner jumped an approach, because all the crossmembers and body mounts on the passenger side are smeared backwards, and the front rad support, passenger fender, and the paint on the outside passenger footwell, all looks new.

Who knows, maybe he got distracted by the dash being en français.
Regardless, Not that this information changes my plans in the slightest, actually makes me feel way better about putting in under the knife.

Yeah it seems like 404 parts are few and far between on the used market, Expedition Imports has a Whole NOS Front the last time I looked, If that helps you any.

It definitely gives me confidence with low long your setup has lived under a full-size rig, Any Advice?

I ended up ditching the doors. Wheeling fullsizes in jeep cut trails on east coast, means doors were always getting smashed (and more important, door opening on body). I went tube door with inner lexan panel to keep most of the mud out. I run what "someone" nicknamed "shower curtains" in the rain/cold



I could write a book about mog axle install/usage/quirks, etc... First thing I would check before going any farther is front axle fit. No way I could do it without 6-8" lift, unless you move diff housing. I put it in the "Ford" spot, and had custom inners made. This was 20 years ago now, so not sure if anyone still making custom mog shafts. I tried just 2" front springs, but ended up with 4. So really I am at 9" or so lift and way too tall to wheel anywhere, that I can't ride bark, on really off camber spots.

Even with that, I was smacking oil pan with bracket I made for locker cable. I doubled up on oil pan, where it was hitting.

I finally put in air bumps in the front, just last year. Might even be able to lower it back down to the 2" springs now, But I like the height (under axles, and overall), being able to slip off a 3 foot rock, be pretty much turtled on it, but still get out of it. I do flip over a lot though, being so tall. (hence the full EXO)

I also disagree about having anything under axles. You go to all that trouble for 5" extra clearance, no way I am hanging things down below that axle. My lower front links are above the stock steering. Geometry is about as bad as it gets (and my links are pretty short by most std's), but I don't ever have to worry about hanging up on anything down there. Not a link, not shock mounts, rear leaves are WAY up there out of the way.
Lighter rigs can drag an axle with even a wheel off the ground over rocks, not so much on my 6200 lb pig.

If keeping stock steering or drag link, I recommend cutting 2", 1/4 wall in half, and welding to stock stuff. "tie rods' are pretty stout and rebuildable.
But the stock tubes on both are kind of weak. Adds crazy amount of weight, but they hold up to anything really.

Also, guy on Pirate used to make upgraded "bolts" for the kingpins. Really the only weakness in the knuckles. Not sure if anyone still makes them, but head of stock bolts is not all that. I bought 3, and still have my spare 15 years later.

 

[Korzenowsky]

I ended up ditching the doors. Wheeling fullsizes in jeep cut trails on east coast, means doors were always getting smashed (and more important, door opening on body). I went tube door with inner lexan panel to keep most of the mud out. I run what "someone" nicknamed "shower curtains" in the rain/cold........

First off, Can't tell you how much I appreciate the Veteran perspective, It definitely helps clear things up on my end, and I hope anyone reading this interested in portals can glean some information from your experience too.

That really is the name of the game for full-size, I'm hoping with my tube steel "boatside" I can keep my doors as whole as possible.
Because she's an extended cab I've got those two half doors to mess with too which might just get stitch welded shut
I've got another set of doors that I've been eyeing up to make half doors, IF I can keep the boat side stiff enough that I won't constantly be fighting the doors binding up.

I've known from the start I was gonna have to get creative on the fitment of the front axle, especially in trying to not get a really high COG, I'm not completely apposed to shoving the front axle out in front of the engine more, and with the thought of a rad relocate I do have the room for a little more up travel but that's not exactly possible with leaf springs without extending the frame way out, especially with my long ford springs. I still likely won't get around trimming my oil pan, the pinion snout is absolutely massive.

I think my best bet is just to compromise, Go with the benefits of clearance and just accept I'm gonna have a taller rig that's just a fact. And at the end of the day it's just metal, I can always change it.
It's a little bit like the battle some guys have with rockwells, they almost always end up taller than something with a conventional "Light truck" pinion setup, unless its a full buggy.

I like how you've mounted the steering cylinder behind the axle and used the stock steering crossover, there's a specific Youtuber with mog axles under a Zuk that welded a whole frame on the front side for a double ended ram, I mean if you're going full rock crawler and want all that weight down low; the world is your oyster, But My rig doesn't need any more weight LOL.

With all these Tips, I'm definitely keeping spring over, Gonna put an EXO on the List, tie it into the Boatside and see if that helps me Keep my full doors LOL

I'm also thinking I should put two or three holes on both eye and shackle brackets, to have static height adjustability on my leafs, Once I find a good balance I can always torch the low hanging hole off.

I'm thinking short up travel, more droop, and air bumps might be in my future, but I'll have to wait to find out.

I like that upgraded kingpin "bolt", What exactly is the fault on the standard Kingpin? Never Run Mog axles before so I am in the dark on that.
Also, Are you running a horseshoe brace on the portal box?

 

[OX1]

One option for the front, but it may go way beyond your $ limit, is go Mog/9. I traded a fully built D60/14 bolt
for a 406/9 setup. That would cure most of you front packaging issues.

I actually started building a whole new rig (based off a 74 bronco) with those, but then life and old age got
in the way. I've considered going back to them for portal box strength, but I have not broken any boxes yet. I even have the
braces welded onto two box housings, but never used or needed them. I do back out when she starts hopping or I'm getting
heavily denied. Also have a stock 400 (M) on propane, that's lucky to be it's original 140 HPish rating (so that helps)

I don't see how the front leaves are going to work. I remember when I first put the rear diff in with no traction bar.
(stock leaf springs and 2" add-a-leaf). All I did was put it in gear (in drive, at idle), and end of pinion rotated 3-4 inches.
Spring under might help, but that just kills packaging even more.

That's what I did on the taller rig. I'm @ right around 9' lift total, which is not totally insane with 43's, that are 99" outside to outside.
It's more stable then I think it should be slow crawling. But more unstable than I like in dynamic situations.
I would EXO the complete door frame. I just tagged the roof edge, even with an EXO tube there, I hit the drip rail.
No big deal right. Well it poured later in the day and the roof water funneled straight down on my left leg for about an hour.
I guess if you have actual doors, this won't be an issue. I guess it also depends on where you wheel, Not nearly as much an issue
out west where it is more open.

Just recently replaced that ram. Got hit by a couple rocks on the shaft over the years, and finally started leaking. But that was 20 years of abuse.
The ram tucked up there is HIGHLY protected. Same with steering behind axle. You can slam axle into rocks all day. Do have to weld in
protection for oil drain, and I did weld in skid for lower rear diff.

Also, I went to as many lengths as possible for things not hanging below the diff's (like rear custom upper shock mount X-member, so lower shock mount is not below axle tube). I've seen the 6G Bronco portals. Awesome stuff, but then you have rear shock mount still hanging 3-4 inches below axle tube. Not a huge deal I guess if you are running "faster" stuff, but can be a bitch running a 6K lb fullsize and hanging up on a shock mount (when you didn't have too).

The king pin bolt only uses a slightly tapered angled head. They eventually pull out and can start to ruin knuckle (and the knuckles are no longer available, I've been looking). You can see the stock bolt in the top of this pic. Not much "head" to it.

One other thing I did that I thought was pretty neat was using 205 shifters for the locker actuation. One of the things I hate about air lockers
is you never know if they are in or not. I wheel with plenty that have them, always seem like someone is having an "air" issue.

Having the ability to feel if locker is in or out, is really nice on tight trails (especially the front). You can "feel" it in, if front starts to spin a bit or right before a decent obstacle, then back out of throttle briefly, and pull it right back out. You can do this over and over during a trail, where an air locker, you never know if it's in or out and due to that, don't really want to actuate it 20 times in/out on a trail, usually.

Below is X-member for traction bar, that doubles holding locker shifter bracket arrangement (is a PIA when case has to come out, but with 205 case, no skidplate required, which again adds clearance).

Bad pick here, when I was finally getting my seats in, but you can see two rear shifters between seats (also confuses the crap out of people when they see 4 shifters )

 

[Stellaghost]

Hi
New to the forum
I was reading this primarily because I converted some 404 mog axles to go under a Landrover Lightweight
Diff nose can be shortened by several inches, fair bit of work but it can be done

You can see how I did mine at LR4x4.com, thread is mog 404 axles starting around page 11
Regards Stephen

 

[Stellaghost]

Meant to add it you look before page 11 you can see a different way of doing diff with flanges either way the pinion has to have threads and spline 're-cut after shortening
Regards Stephen

 

[Austin]

Also, guy on Pirate used to make upgraded "bolts" for the kingpins. Really the only weakness in the knuckles. Not sure if anyone still makes them, but head of stock bolts is not all that. I bought 3, and still have my spare 15 years later.

Nice! I'm talking to a machine shop now about making another batch of these.

You don't by chance have a spare set of knuckles do ya?

 

[No way]

Hi
New to the forum
I was reading this primarily because I converted some 404 mog axles to go under a Landrover Lightweight
Diff nose can be shortened by several inches, fair bit of work but it can be done



You can see how I did mine at LR4x4.com, thread is mog 404 axles starting around page 11
Regards Stephen

Buddy recently cut down this one for his buggy:

 

[Stellaghost]

I looked at doing it that way but had concerns about oil leaks and bolts coming loose, how much did he shorten it by, I managed 7 inches
Regards Stephen

 

[No way]

120mm iirc