Advice needed on 6x6 project?

Steelsopr

New member
Hello. I am looking in to starting a build project. As a base I want to use a sprinter van, but I never owned one in the past and would appreciate any advice or feedback on the feasibility of my project. I want to make myself a bit unusual camper van with six wheels. Idea is to replace the rear axle with a turning one same as in front, sinc them so they turn in opposite to each other. Then add the rear axle in the middle of the van between the others. This will require welding the side door shut and adding new wheel arches.

There are some 6x6 Sprinter truck projects, but there extra axel is none turning one and basically acts as support for the rear one. In my project aI want them to be more or less evenly spaced and independent of each other.
I am not sure about the space available under the van to fit everything. Should I pick a van or truck version as a base?
What are your general thoughts about this idea?
If anybody has any links or information about transmission modification of the sprinter, please share. Maybe someone did a 2 wheel drive to 4x4 conversions that can be used as a start?
 
Find a working 6x6 and put a Sprinter body on it. haha Hard to imagine our vans with all those axles.

MB makes a 6x6 for several hundreds of thousands $ and there is a video of it driving in the dunes in Saudi Arabia. Kind of fun to watch but the mileage, what mileage? Lower single figures would only be the beginning. It did seem capable to go just about anywhere. I think it had a gas engine, but could be wrong. Keep us in the loop.
 

BrennWagon

He’s just this guy, you know?
The engineering challenges of making a 4 wheel steering system are significant, and the idea of adding another axle midship would require a whole lot of reinforcement. The chassis can version is really the only option for such an ambitious project, and even then the challenges are more than significant
 

Kajtek1

2015 long/tall limo RV 2.1l
x2 on cab & chassis body, that comes with frame.
I converted my long bus into small RV and could not help to notice how fragile the unibody is.
Wood tools work on this mild steel just fine.
 

Steelsopr

New member
Steelsopr.
Interesting idea but a lot of problems. Where are you located and what is your background? Eric.
I am in Melbourne Australia. I am a robotics engineer, my experinese with car tuning is limited to offroad customisation, mostly jeeps and ford ranger. I never worked on a van before.
 

Steelsopr

New member
Find a working 6x6 and put a Sprinter body on it. haha Hard to imagine our vans with all those axles.

MB makes a 6x6 for several hundreds of thousands $ and there is a video of it driving in the dunes in Saudi Arabia. Kind of fun to watch but the mileage, what mileage? Lower single figures would only be the beginning. It did seem capable to go just about anywhere. I think it had a gas engine, but could be wrong. Keep us in the loop.
That is actually easy to do. There are tons of standard 6x6 vehicles here. Taking a van body and sticking it on an old defender or nissan 6x6 is not that hard. They cost from 5kAUD to 30KAUD used, it is really not hard to get them here.




Issue is that they all have the double back axles none steering ones. They handle like limo, I am after something that is more mobile and can squeese in tight spaces on the track and can get over bumps and rocks.
 

Kajtek1

2015 long/tall limo RV 2.1l
When I admire your drive for the project, having 2 steering axles on vehicle brings lot of headaches.
From my observation when they are handy in narrow turns, at high speeds lot of things start wobbling.
I used to own Prevost bus, who had tag axle to carry the weight and help with stabilization. At low speed I could lift it, what allow for smaller turning circles. Pretty popular design on big vehicles in USA.
Let me rephrase it. My first ClassC mothorhome was build on small Toyota pickup. To help in carrying 20 foot body, the converter added tag axle on it with electric brakes.
 

Midwestdrifter

Engineer In Residence
Dual steering axles? On a unibody van? It sounds like a pipe dream for someone who has never built custom rig of that complexity.
 

Eric Experience

Well-known member
Steel.
Something to consider, With an axle in the centre if you were to go over a hump the centre axle has to be able to travel up the full hight of the hump or take the full weight of the vehicle as it passes the balance point. Both tricky problems. I am in Melbourne and would like to talk about your ideas . The dual steering is the easy part. Eric
 

Midwestdrifter

Engineer In Residence
Is there a specific reason why you want/need such a vehicle? I am sure it can be done with enough time and money, but remember that unibody vehicles use the skin and floor as load paths, and interrupting those will require significant engineering to restore integrity.

Also note that every sprinter 06+ is Aus has stability control, and most require wheel speed feedback for the auto transmission to work. So if you are planning to use the sprinters drivetrain, you are looking at a lot of hurdles to overcome, many with software.

Sprinters use a McPherson Strut setup in the front. This uses a rack and pinion steering setup, all mounted to a subframe assembly.
 

autostaretx

Erratic Member
If i read your description correctly, you were planning to (still) have only the solid "rear" (now middle) axle as the powered set of wheels?
So the two end wheel sets would be steering, but only the middle would provide "push"?

If that's so, then perhaps buying two Sprinters, chopping one just behind the rear axle, and the other before the rear axle, and then welding them together tail-to-tail?

PushMePullYou.jpg

If you want the (new) rear steerable set *also* powered, then perhaps start with one 4x4, and use it for one of the "ends".
(edit due to Cheyenne's 6x6 reminder: Start with *two* 4x4s ... or look at Ford Transits or Fiat Ducatos which offer front-wheel drive)

--dick (that's two 118 inch wheelbases, so 24 feet (about 8 meters) between the end axle sets)
You could remove the "trailer" unit's sliding door section to shorten the mess by a meter or so.
 
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Cheyenne

UK 2004 T1N 313CDi
If i read your description correctly, you were planning to (still) have only the solid "rear" (now middle) axle as the powered set of wheels?
Dick,

6 x 6 implies ALL 6 wheels driven or else it would be 6 x 2 or 6 x 4.

I don't see how the three axles would track, going round a bend the front and rearmost axles would try to take a different radius to the centre axle and scrub the centre tyres sideways, or am I missing something?

Keith.
 

autostaretx

Erratic Member
Yes, i spaced on the thread's "6x6" title ('twas a quick post before a half-hour obligation).
Seattle has 6-axle public busses that have a switchable "track" mode.
In normal situations, the tail set is "just a solid-axle trailer" ... but for tight turns or other confusions, the tail wheel can be told to mimic the front angles. This avoids "short-cutting" across middle-of-intersection round-abouts.

There's also the good old example of the "hook-and-ladder" fire truck with the rear steersman.

To visualize how it might work, mentally think of the "front two axles" in a normal sense,
then shift that solid-middle-axle to participating in a mental picture of the "back two axles" being a conventional vehicle backing up. Yes, it's difficult to avoid over-steering, but that's what sneaky control systems are designed to handle.

And then there are the "very heavy goods" transporters, where *all* of the many axles are powered and steerable (in a variety of ways ... including move vehicle sideways, perpendicular to its length)

ManyAxles2.jpg

Where to buy them (with a fascinating catalog ... order by number of steerable powered axles):

--dick
 
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