For a long time I’ve been known for going over the top on whatever I get engaged in, both good and bad. It’s part of life philosophy that has developed into just doing things in an Epic fashion.
I’m kicking off a fabrication project that’s been on the back burner for about 6 years now. But due to some pending real estate development I’ve got going on I’ll be losing one of my shops. This is forcing me to finish complete this project.
So here is the build of one of the most EPIC set of axles produced.
Maximally reinforced one of a kind Unimog axles to achieve unheard of clearance, including 4 wheel steering, & Central Tire Inflation.
First I imported unimog axles from Germany. If your not familiar with unimog axles they have an extra gear reduction box that fits in the wheel well. The gearbox also offsets the axle centerline to above the centerline of the wheel as well. It also reduces the size of the 3rd member(pumpkin) due to gear reduction between it and the wheel.
These happened to be factory reconditioned units that I immediately tore down. The stock unimog pumpkin location was slightly offset which doesn’t work for engine clearance reasons and also not optimal for the rear axle to be centered.
I cut down the tubes and rewelded them in the new locations to get the correct offset. I had to then slap the flange on the lathe and turn in down prep for welding to the new locations.
Next came the brakes. Stock brakes are massive 70lb drum brakes and also the bolt pattern for the axles is an oddball pattern only used in military applications. So I torched all that off along with the stock flange off the axle hub. Had new wheel mounting flanges CNC laser cut. Turned a new register on the hub and pressed them together. A friend Tig welded them together.
Then came drawing up and CNC laser cutting some brackets for the brake calipers. These brackets also reinforce the entire hub portal box. This is a weak area in the axle that needs this bracing to handle the 47” tires I had planned.
Here it is after mounting the standard chevy disc and the bitchin’ corvette 4 piston calipers I bought from the junkyards. There was a little grinding needed to fit them inside the wheels I have.
Then came adding link mounts to the axle. Notice how the outer link mount spans the tube to flange weld. Reinforcing this point and allowing force to transfer directly from the tires to the frame bypassing this failure point. That tube weld joint is a weak point compared to traditional axles due to the additional leverages placed by offsetting the wheel. Problem fixed here.
Upper and lower mounts done along with reinforcing and mounts for steering cylinders. The are custom double ended 2″ bore by 10″ stroke rams needed for the 45degrees of steering these axles have. They were manufactured with extra sealing and a few other features for rough offroad environment… unfortunately they are not mfg anymore.
And the front axle. Remember 4 Wheel Steering!
The front axle runs off a danfoss orbital valve while the rear is controlled with a joystick and simple manifold.
Final bracing on the box to make extra sure it doesn’t explode. I realize you can’t really tell whats going on but I basically used the stock cast gearbox as shell and built a steel exoskeleton around it reinforcing the front and back of the gear bearing areas. All the bolt holes are thru drilled so that the entire box and bracing system is clamped together.
Of course I needed some bad ass steering arms so these were CNC burned and formed before welding up. Double sheer on heim joint and they CLAMP the portal box to its mount making the stricter stronger. The pattern encircles the entire backing plate/portal box. It took me a few tries to get that bolt pattern and clearances perfect so that this would work.
Now unlike traditional solid axle vehicles I was able to achieve perfect Ackerman with this steering setup by plotting out the theoretical perfect location for the steering arms based on the width and wheelbase of setup. So each axle turns on its own turning radius…. and does so up to 45deg. You can see this below with inside tire at full lock while outside tire is on separate radius.
Now you may remember that I cut down the axle width. This means the stock shafts wouldn’t work. So I had CTM racing make new axle shafts out of 300M. That is specialty aircraft grade steel used in the landing gear on commercial aircrafts. Some of the toughest stuff around. Not many are capable of this.
I also took all the internal gears and joints and had everything Cryo Treated by the company that pioneered cryo treatment of metals. And why the hell not… build my own freaking Central Tire Inflation System??? Yes lets air up and down while driving. Designed and had my own custom hub bolt that integrates with a Dueblin rotating union to feed air to and from the tires while driving.
Now here is the really cool part. Because of the ultra-high clearance of the unimog axle combined with my strengthening to allow a 47” tire to be run the clearance underneath is unheard of. To gain this level of clearance you basically have to run 60” plus tires on very heavy duty axles ALA monster trucks. But then you don’t have a vehicle as light and mobile as what I will be building.
Here is a pictures of the axles on 47” tires. There is about 8” of clearance ABOVE that 5 gallon bucket before it hits the LOWEST point of the axle. Now combine 4 wheel steering and CTIS.
BAM! One of the most bad ass axle sets ever made. Saying they are the most badass ever made is likely an exaggeration but not by much.