Off Road Class C Motorhome and Extended Tray

RobertRyan wrote:
Still you can buy here vehicles with much better ground clearance,

I'll bet you can ... here in the U.S. too.

.... and how do the builders of these vehicles get the differentials, transmissions, engine pans, gas tanks, suspension components, etc., up high off the ground? They do it merely with taller tires and/or by also lifting the frame higher above the axles. Add a big tall (non-crank-up) RV living area box on top of the frame and you get the anti-offroad affect of raising the center of gravity even higher.

The real offroad engineering in the HumVee - being described here by the folks who know it - stands head and shoulders above the brute force methods of merely combining more and more steel with ever-larger tires. All these designs get you is high ground clearance at the expense of a higher than necessary center of gravity and (due to the narrowness of the tire track) a poor height-to-width lateral-stability geometry.

In an earlier post RobertRyan graciously provided the wheelbase length and track width for that photo of a (at first glance) mighty-looking expedition RV with a porch that he started this thread with. Here's the dimensions he provided:

RobertRyan wrote:
PNichols on the SLR Motorhome with Patio it is

Quote:

Wheelbase is 11.138 ft. Distance between the tires about 5.5 ft. This is on the non modified truck.

Note how tall (looking at the photo of it) and narrow (from the distance between the tires dimension, above) that very expensive expedtion RV is!

Finally ... to factually make my original point on comparative RV offroad lateral stability ....here's the wheelbase and (most importantly) track width of our modest little 24 foot Itasca built on Ford's ton-and-a-half E450 truck chassis:

E450 wheelbase = 158 inches (13 feet, 2 inches)

E450 front track width = 75 inches (6 feet, 3 inches)

E450 rear track width = 95 inches (7 feet, 11 inches)

Granted that those expedition vehicles have tremendous raw mechanical component ground clearance for mud/snow, road ruts, and rocks due to tall tires ... but I stand by my position that many of them are too narrow versus their heights for the best safety on offroad surfaces that may also tip the vehicle into aggressive angles. If they were built using drive system designs like that of the HumVee ... and if they had crank-up coach areas for lowest possible center of gravity ... then one would REALLY be getting something for the six-figure prices of them.

I will grant that their track narrowness does make travel with them in European cities easier, but why would wide-open Australia require unduly narrow RVs offroad in the outback? Wide and low is the name of the game.:C

From what I understand there were less than 400 of those LM002's made and they were all "boutique" builds. It would be cool to have a Lambo off roader, but parts would be ridiculous and being Italian, you KNOW it would need lots of work and parts to be reliable.

There are also companies like Banks that can "hot rod" a HMMWV, but when you start adding more engine electronics, 7 speed electronic trannies and dynamic suspension, it ceases being what an HMMWV was intended to be.

Now, I say a GREAT offroad RV would be built on a military spec HMMWV chassis. Imagine the ambulance version with a taller roof and extend it past the rear a bit with a rear kitchen/bathroom. Change out the full time 4WD for a selectable transfer case and you can have 2 wheel drive at RPM's that are reasonable for 65 MPH highway driving.

Jose

I may add to the above post the HUMMVV, with its 190hp diesel and initial 8000lb weight was no "speed chariot" Through its life it grew to 14,000lb making it awfully slow. The design was inspired by the Lamborghini 002, that was sold to some Gulf states. HUMMVV was made by AM General in The US.
Lamboghini 002

DaHose wrote:
The general specs of a real HMMWV are 16-inch ground clearance and 72 inches high. Full-time four-wheel drive, independent suspension, interchangeable hubs, inboard disk brakes, diesel V-8, 60 percent slope-climbing, 40 percent side slope and 60-inch water-fording. You can find videos on Youtube of a real HMMWV truck variant climbing over a flat 4 ft. wall and climbing its nose up and over a flat 6 ft. wall.

Now that would make the basis of a very good Off Road Vehicle, going by the specifications an Expeditionary Vehicle. Plenty of ground clearance, Independent suspension, 4WD, Diesel, great mobility.ie 60% slope climbing, water fording and very good Payload.
Price is a determinant though and there are vehicles much cheaper as capable available with much greater payloads.Still you can buy here vehicles with much better ground clearance, as I said vastly better payload and the ability to run considerable distances between refueling. By the Way you could buy refurbished Ex US Army Vehicles in Australia, but these were used mainly as "cars" or "rock crawling" not as the basis of a Motorhome.

In simple English, an HMMWV has an offset geared hub. The drive axle comes in at the top of the hub housing and internal gears move the output hub shaft lower down the assembly. Combine that with a design that tucks the engine, transfer case and transmission up into the chassis and you get something that is intended to work hard in combat.

The general specs of a real HMMWV are 16-inch ground clearance and 72 inches high. Full-time four-wheel drive, independent suspension, interchangeable hubs, inboard disk brakes, diesel V-8, 60 percent slope-climbing, 40 percent side slope and 60-inch water-fording. You can find videos on Youtube of a real HMMWV truck variant climbing over a flat 4 ft. wall and climbing its nose up and over a flat 6 ft. wall.

If you don't think an HMMWV is a good offroad vehicle, I have to believe that either you don't really know what a HMMWV can do, or you are a fan of silly oversized rock crawler looking things that stand 8 ft. high. We used HMMWV's in the Corps and I can tell you from first hand experience that they are impressive off road vehicles.

Jose

Mr Nichols, you failed to mention (probably didn't know!) that the MAIN reason why Humvees have such good diff clearance is that they have portal gearboxes in the hubs.

Charlie
U500 Unicat

PNichols wrote:
Robert,

Those high and narrow offroad expedition type rigs are expensive to buy and operate, as well as looking unstable on side-slopes.

In the Photo it looks more like a "Monster Truck" vehicle than an Expedition vehicle. Plenty of home made versions of Expedition Vehicle around, they do not have to be able to tow the Titanic to be an expedition vehicle. Many pathways in Africa, Asia and Europe can be tiny or non-existent. So a smaller vehicle can be more practical . Home made Expedition vehicle use military or mining vehicle bases that are extremely stable.
This is an OKA a mining based Vehicle that has been used as a Motorhome or Off Road Bus.using a Creek Bed as a Road