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Choosing the Right Chassis




Choosing the right chassis

Steyr vs Mercedes

When choosing the vehicle brand, there was no discussion for me. I’ve had enough bad experiences with old Ivecos, Steyr’s are too exotic for me, I don’t want MAN (keyword injection pump), so it’s Mercedes.

When choosing the base vehicle, you can go for the RV dealerships the focus was not on the price and the availability of spare parts, but on important details such as final drive ratio, transmission, permissible axle loads and, of course, performance. These are the points that I am constantly confronted with later in everyday travel and they are points that cannot simply be changed.


In soft sand and in the mountains, engine performance can never hurt. Naturally, aspirated diesel provides the power immediately without delay and also has no turbo lag. Unfortunately, they only have a small amount of horsepower per liter of displacement. But with enough displacement, even the most tired naturally aspirated diesel will perk up.

With 1.8l displacement per cylinder, the V8 mobilizes 26hp and 96Nm per tonne, which leads to halfway “normal driving performance” and that completely without turbo. The power is always available without delay! It’s still not a race car, but you can take a leisurely stroll and cruise and not get stuck on every mountain.

failures so far

I have now driven more than 12,000 kilometers through half of Europe. Since then I have had to replace a low beam bulb and tighten a number of screws. Once a potter wasp had clogged a vent hose with a nest. The cover of the front differential housing is sweating – I would have expected some leaking oil seals on the axles and gearboxes.

Planned Optimization

The driving noise with the coarse off-road tires is quite loud. In the driver’s cab, we reach 80dB, depending on the surface. That’s why I’m going to rework here and soundproof the driver’s cab accordingly.

I will also have the exhaust system rebuilt. Back then, people still thought that you had to hear a V8. That’s true, but please not three kilometers before.

How much does it use?

Everyone who drives a larger car knows the question. I’ll put it this way: It consumes the same amount per tonne as the Vario. 2.35 liters seems to be a realistic approach in the weight class between 7 and 15 tons. A 10-ton 1222 V6 consumes 23.5l/100km and with the 11.5 tons, we are at 28 liters.

At 100% Autobahn, the consumption is 25-26 liters.

The mix of 1000 kilometers of off-road, 500 km of motorway, and 4500 kilometers of country roads (including France with hundreds of roundabouts) resulted in consumption of 29.3 l/100 km.

So it was to be expected given the circumstances.

Refueling in Morocco

The two diesel tanks with a total of 900 liters bring a range of over 3000km. Whether you need that, or whether 500l would be enough? I don’t like filling up, it’s always so expensive. That’s why I like big tanks. In times of Corona and border closures, it is also very useful if you have a lot of cheap diesel with you and don’t have to fill up with the expensive Portuguese diesel.

Nice to have

Also very popular with dogs: air suspension seats

Since I couldn’t find a second air suspension console for the passenger seat during the expansion period, I exchanged both seats for Grammer air suspension seats. Exactly the health seat Amarillo-Profi. In addition to the standard seat, this also has damping in the longitudinal axis. This means that you can easily move the seat forwards and backward. It may sound strange, but I don’t notice it while driving and it has reliably protected me from back pain ever since. If I switch off the longitudinal damping, I quickly get back pain, especially off-road. This was a chance hit that I can only recommend today.

tire choice

A four-wheel-drive RV needs off-road tires! Or?

On the Autobahn I dream of street tires with a construction site profile – at the gas station too. I would also love to switch to construction site tires if I could find any with a rolling circumference of 3600mm. The noise level of Michelin XZL tires is unbelievable – especially when they’ve driven 20,000km.

But the combination of gearing, weight and the tires is just perfect. Many owners of such old vehicles dream of 1550 revolutions at 80 km/h. And as bad as the tires are on the road, they are great off the road.

With 0.9 bar in the tire, the contact surface is 60cm long!

The possibility of being able to drive the 20-inch tires with extremely low air pressure and thereby increasing the contact area by 60% have saved me from getting stuck several times. Or I was able to free myself after getting stuck by releasing the air.

The high tire walls also spring much better, which not only has a positive effect on some road sections in Portugal but also on gravel and washboard slopes.

That’s why I will continue to stick with this tire size. Since the current tires are already 17 years old, I will soon switch to the hopefully quieter Michelin XZL2 tires. They combine the advantages of 20-inch tires with a slightly finer profile for better road characteristics.

The living room

The living cabin, with the 3mm GRP outer skin and 4mm aluminum angles on the edges, hasn’t been damaged by a tree yet. And there was already plenty of contact with trees, which can be clearly seen from the battle marks.

The firmly bonded KCT tempered glass windows with thermal insulation glazing have fully proven themselves. In winter I still complained when we had to heat the cabin despite the full sun. At 40°C in the shade, the windows are convincing all along the line, it stays much cooler in the living room. Now we no longer need to cover the outside of the panes with white sheets.


Let’s get to the important things of a residential RV, the floor plan. And here Tanja really did a masterful job. The planning of the floor plan is on your account. I only made corrections for technical reasons like weight distribution etc.

On the 1.40 meter wide longitudinal bed, with a latex mattress on the Froli-Travel sleeping system, you can sleep well. I have never slept better anywhere!

The benches, which are also 140 centimetres long, finally offer enough space to lie on comfortably or to offer two visitors a comfortable seat. The free space between the wood stove and the kitchen is also convincing. Four people can stand and talk here and it just gives the cabin an indescribable sense of space.

Even the bathroom is optimally planned in my opinion. Measuring a hundred times in advance and haggling over every centimetre has resulted in a perfect bathroom with a sink, shower and composting toilet.

You don’t know our floor plan yet? Welcome to the EIWOLA room tour:

We both agree: if we were to build a cabin of this size again, it would be exactly the same! Where we don’t agree at all is the quad garage hatch. I think she’s on the wrong side. 5 times out of 8 I would find it easier to unload the quad if the hatch was on the driver’s side. Unfortunately, we can’t change it now. And neither does everyone else who copied this floor plan :).


The wood used. Colombia poplar Ilomba plywood with CPL coating isn’t bad, but I wouldn’t use it again. Today I think that birch multiplex would probably be better. It’s simply more stable and the 100 kilos of extra weight could be saved on the diesel supply.

As a non-carpenter, I am particularly proud of the durability of my interior. So far none of the parts have given way, although the hut has been rocked through quite a bit.

power supply

November weather in Germany with almost zero solar yields.

Our journey started in November with a lot of rain. So an endurance test for the power supply. We left Germany with a battery charge level of 0% and have never been to an outlet to charge the batteries since. The solar charging current from 1600Wp on the roof has usually been sufficient so far.

24V folding module Exclusive to AMUMOT

For more independence, especially in winter or in shady places, a foldable solar module with 190Wp has been available for a few weeks. Since we have a 24V onboard network, I couldn’t simply take a foldable module from my range, but something new had to be developed.

The foldable module delivers another 1kWh extra per day

A foldable solar module with 72 cells was developed in close cooperation with the company SolarSwiss. This not only works particularly effectively but can also charge 24V and 12V batteries!

The new 190Wp foldable solar module is initially only available in my shop.

Why do you need so much solar power?

1600 Wp on the roof + 190Wp solar bag

Some people wonder what we do with so much electricity. I wouldn’t have thought so either, but the weather in central Portugal isn’t nearly as good as in the Algarve. On many days the sun can only be seen for a short time. On the many rainy days, the daily solar yield is almost zero.

When the sun shines, every watt of solar power counts to recharge the batteries as quickly as possible. Sure – you could also use a generator, but we don’t want that.

What’s even more difficult at the moment is that we’ve run out of gas. I forgot to fill up with gas on the last trip 6 weeks ago. I can’t drive right now for various reasons, so we cook with electricity. This backup with an induction hob was planned by me because of exactly such scenarios.

Now I’m glad that an empty gas bottle doesn’t immediately lead to an emergency and that we can continue our lives normally.

If you want to learn more about the power supply, I can recommend my blog article on the self-sufficient power supply and Tanjas Video recommends doing so.


Filling up with water at the fountain on the way

Actually, everything works as expected and has also remained 100% tight. The tank capacity of 420 liters of freshwater is certainly not oversized because of the washing machine. With the water filters, we are still very independent. The filters were already often in use in Morocco when we tanked water from the wells. This is not edible unfiltered. During the Corona lockdown in Portugal, there was only water from wells of unknown quality. After filtering we could drink it. And even on our property, the water filters for filling the tanks are constantly in use. Among other things, because of Corona and the many V&E stations that have been closed as a result, we are really happy to be able to fill up with water almost anywhere without hesitation.

The only optimizations were:

The 230V Kärcher garden pump is now doing what it was built for – in our garden. A Lilie 24V pump with 19l/min and 5.5 bar pressure now works as the pump for filling the tank, with or without a water filter.

24V pump in a storage box

The GROHE Premium bathroom fittings weren’t worth the money either. The disability is poor, which usually led to too much water flowing. Our water consumption has increased significantly compared to before. A ball valve in the supply line from the tap now limits the flow and saves water.

air conditioning

The one sent from Canada via Austria to Germany Mini Holzofen “Cub”works great. I love the stove and it has kept us nice and warm all winter. The telescopic stove pipe was also a brilliant idea. When retracted, it offers no point of attack for branches that scrape the roof and the construction can be dismantled by removing just one screw. All the soot that falls off stays in the stove and is not distributed in the living room.

But there is a catch:

The stove only heats the living room. The air in the cupboards stays cold. When it is cold outside, this inevitably means that the air in the room condenses in the coldest places and water forms there. It was particularly damp in the closet.

Luckily I ran heating pipes through all the cupboards during construction and can heat exactly these critical areas. Just not with the wood stove, but only with the diesel parking heater.

A heating circuit for all cavities and the bed.

The diesel heater was supposed to be just a backup for us. Initially, it wasn’t really usable for anything more, because it was abnormally loud and controlling the burner via the room temperature was total crap.

Radiator thermostat for switching off the living room heating circuit.

Over the last few months, I have completely rebuilt the heating system. The diesel burner and its water pump have now become significantly quieter. The heating is controlled via the return temperature of the heating circuit. A second, silent Vortex circulation pump continuously pumps the water around the circle during the heating season. The separate living room heating circuit was equipped with electric radiator valves, which are controlled by a wireless room thermostat. This means that the diesel heater can now be operated very comfortably.

With the burner control via the return temperature and the hot water boiler in the heating circuit, which now also works as a buffer tank, the heating now runs longer at full load and then stays off longer.

In normal operation, I don’t want to heat with diesel, but with wood. And when the stove heats up, it now also transfers some of the heat to a hot water heat exchanger. The diesel heater does the backup and only turns on when the return temperature drops below 22°C.

The heat exchanger on the woodstove.

With this solution, I can now always guarantee room temperature in the cabinets at the coldest point. So it will always stay dry here. The warm furniture also creates a buffer and ensures a very pleasant room climate. The heating is now perfect for the winter.

The next project is the installation of an air conditioning system. The space and, above all, electricity for this are available. Last summer we were often in places where there was no possibility to swim or where there was hardly any wind in the evening it didn’t get much cooler. I see 7kWh of unused solar energy every day and can’t sleep at night or think clearly in the shade at 40°C, which affects the workforce. So we’re testing a storage box air conditioner next year.


on the left is the homemade composting toilet

It took a few months for the composting toilet to work properly. But I guess I have it under control now. The toilet works according to the principle of nature’s head. Coconut bricks serve as the basic material that covers the droppings, binds odors immediately, and regulates moisture. The toilet works really well and allows 8-week emptying intervals from the solids bucket. After conversion, the urine is now stored in a 50L tank and now only has to be disposed of every two weeks. I still find this emptying interval tolerable. What I absolutely hate is having to empty something every day or every 3 days.

Mites had formed in the toilet in the spring. This happens in a damp but mild room climate. Such as when it rains or there is fog on Portugal’s coast. This problem should actually also have the owners of the purchase version. Since I modified the air supply and we have an even room climate thanks to the optimized heating, the toilet also works as desired.

Below is a picture of the rest, which is thrown away after 8 weeks of use – it’s just 15 liters in volume and doesn’t weigh much. If you consider that the toilet is initially prepared with a good 10 liters of coconut fiber and after 8 weeks of use by 2 people only 15 liters of compost are left, I think the system is super awesome.

15 liters volume after 8 weeks


The size of the kitchen is sufficient. The quality of the HPL coating on the worktop is inadequate. It is not scratch-resistant and only slightly heat-resistant.

The gas hob may look great, but it is difficult to clean. The pots protrude above the hob, the heat is reflected onto the worktop and the coating cracks.

The 5 kilo gas supply has proven itself well. Thanks to the possibility of filling up the small bottles at LPG filling stations, we are extremely flexible – especially since we only have to do this every 4 months. However, the day before yesterday it happened that the gas ran out. Nobody thought about the bottle anymore and when we drove for the last time 6 weeks ago. The backup, an induction hob, helps out now – until I have organized a full gas bottle.

My conclusion

I am glad that we implemented this project at the time. I’m happy that Tanja had such a good hand with the planning and that I was able to convert the 3D model into a real mobile home. Above all, I am very happy that after 13 months of continuous use, there are only a few points that need to be revised.

Our quality of life has increased significantly with the new cabin. On the other hand, comfort on the road has dropped – Traveling with a 4×4 truck is noisy, stubborn and extremely noticeable. But it’s still fun and at the latest when we’ve reached a goal that was unattainable with the previous vehicles, we know again why we drive such a car.




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