22 March 2002

SIX WHEELS ON

MY WAGON…

Wondering about swapping

your 4×4 ATV for a 6×6?

Andrew Pearce and

David Cousins go

mudlarking to check

the alternatives

IF nothing else, picking an amphibious six-wheeler ATV is fundamentally simple. Over here theres only two major makes on offer: a US-built Max or a Canadian Argo. And to make life simpler still, both pack V-twin petrol engines, drive all their wheels by chain and boast a 30-odd year pedigree.

So are they as peas popped from the same pod? Not quite. Model line-ups vary, the engines are at different ends and there are variations in load capacity and drivelines. The Whats On Offer? box expands on this and explains why we picked 18hp versions of the Max II and Argo Bigfoot to compare.

More interesting than spec sheets is the driving. Shelve what you know about pedalling a standard ATV and prepare for a different approach. The basics are easy – open the throttle to get rolling, steer on the levers – but it takes half an hour or so to recalibrate the mind to bouncing (or floating) along in a plastic bathtub.

Once thats over, several things become apparent, not the least that these things take a lot of stopping. Fallen trees, ditches, deep and wet gulleys, tight climbing turns across greasy ruts – terrains that would make most ATV pilots stop and scratch their head – are despatched by a scrabbling sextet of chubby tyres. And when crossing steep side-slopes youll swear that glue is involved.

But physics always wins. Bottomless ruts are best straddled because theres not much clearance under the broad bellies, while very steep climbs or drops need watching in case sudden weight transfer or unkind braking flips the outfit.

And, of course, traction finally runs out, not least because the harder you turn the more drive from the braked wheels drops away, which on difficult land means picking both the moment and place to change course.

Then theres the ride. Because theres no sign of springs, top speed is limited by how much hammering the pilot can stand, though around 25mph-30mph is on offer.

The pair have all this in common, so what splits them? Stand the two shoulder to shoulder and Argos Bigfoot is the bruiser. Bigger all round and weighing in at 414kg against the svelte Max IIs 340kg, its also a touch tidier-made. All of which helps explain the Bigfoots £1250 price premium, which expands to £1970 if you specify a roll cage and seat belts, goodies which the Max II has as standard.

Argo puts a 570cc, 18hp V-twin up front, while the Max II stows exactly the same powerplant in the stern. Polar opposites which, along with diverse transmissions produce a pair of very different characters.

These identical motors – built by Mitsubishi under licence from Briggs and Stratton – knock out plenty of torque so both six-wheelers feel quite lively, with plenty of instant steam for climbs, loads and towing.

The Bigfoots longer snout and front engine puts weight forward, which helps on climbs, harshens steep drop-ins and makes the light-loaded outfit float bow-down. It also sets up good balance when loaded, yet that big conk hides the terrain directly ahead.

The engine bay eats into foot room so the driver cant easily brace with the legs on rough going, but – critical for practicality – Argos layout allows a deep rear cargo compartment. And because its accommodation is 100mm (4in) wider than the Max IIs, theres substantially more room for passengers and load. Three can fit across the Argos front bench if all are on good terms, while the rear alcove can seat two small ones knee-to-knee, take several feed bags or a small bale or two… but not all at once.

The Max IIs engine-at-the-back layout gives better primary balance, so the outfit feels less harsh on drops and floats level in the water. The rear motor also allows for a stubby little nose and cavernous front footwell, both of which are significant plusses when the going gets scary. It also delivers a quieter, less fumey and less vibratory drive.

But load space suffers because theres no equivalent of the Bigfoots cargo well up front and the standard Silsoe-tested roll cage fences in the load space. ATV-style front and rear racks are an option on the Max, helping accommodate a 360kg payload – 33kg more than the opposition. But its 454kg towing capacity is a full 200kg down on the Argos. Theres less space for bodies, too, because the narrower tub can only hold two adults comfortably. For more seats or load space, look to the Max IV (£8229) or 20hp Buffalo pick-up (£9999).

&#42 Transmissions

These six-wheelers drive through a centrifugal clutch, a stepless belt/pulley set-up, a gearset, a diff and finally chains. Each wheel is carried by its own short stub axle. Drive is split into left and right wheel sets, with individuals in each trio linked by chain; the single diff sits between the sets. Outer bearings are sealed and grease-packed to keep the tubs watertight. But thats where driveline similarities end.

Argo uses the most recognisably conventional centre unit and sits the Bigfoot on 25in tyres to increase ground clearance. A small gearbox with high, low, reverse and neutral perches over a non-lockable differential, which drives mainly duplex chainsets from its output shafts.

Each shaft carries an outboard hydraulic disc brake, worked from independent handlebar-style steering levers and force-cooled by electric fan. The harder you pull a lever, the more that sides wheel set is braked and tighter you turn. Pull both levers and the Bigfoot stops.

Gears are swapped from a very reluctant horizontal lever below the front scuttle, though for most scooting about only low and reverse are needed – top gear isnt much of a step up. Shifting aside, the Bigfoot is a simple tool to use. Steering is progressive, braking strong and the twistgrip throttle easy work.

Maxs approach is quite different. It sits on 22in rubber, though the resulting small drop in underbody clearance doesnt seem to hurt. There are no gears beyond forward and reverse because all speed variation comes from the belt/pulley system and the centre drive unit is much more cryptic.

Inside it, friction bands linked to the steering levers brake input and output flywheels, contriving to send more or less torque down single-row chains to either wheel set. In their resting position the steering levers allow forward travel; pulling them back moves first to a no-drive position, then puts on the brakes.

This has several practical consequences. On the plus side, the Max IIs ultimate traction is better because it will keep driving even with one set of wheels waving in the air. In similar circumstances the Bigfoot comes to a stop because its open-centre diff sends power only to the spinning wheels.

On the minus side, the Max II is less intuitive to drive. Going forward is no problem as long as you dont ease back on the steering levers; do that and the bands slacken so youll stop on a hill. Want to reverse? First shift the under-seat lever (holding the steering wands back towards neutral to unload the gear teeth), then haul both levers right back to get underway. To steer in reverse, slacken pressure on one lever. Instinctive, this isnt.

&#42 Wading and other

business

Launching into deep water is a hoot. Release seat belt, ease in gently so the bow wave doesnt come to join you in the cockpit, add a little throttle to produce some forward motion. Steer by leaning the way you hope to go, which is harder to do in the wider, fatter-tyred Argo.

Then, as the opposite shore very slowly hoves into sight, pick an exit point… remembering that the rear-engined Max will duck its tail underwater if the climb out is too steep. If serious amphibious operation is on the cards, both six-wheelers will take an outboard motor.

Any other things to think about? The Bigfoots horizontal handlebars and more supportive seat deliver the more natural driving position, although once youve learned to exploit the Max IIs legroom and lean back on its bench, theres nothing to choose between them. Access is definitely easier in the Max – you simply step into it, whereas the Bigfoots deeper side rails are more of an obstacle.

&#42 Maintenance

Here, the Max II pulls a worthwhile fast one. A few minutes with the spanners sees the roll cage released and the body tub opened up like a clamshell to lay bare the oily bits.

The Argos shell is bonded shut, so access comes only through lift-off covers. It pulls back a little ground with automatic main chain tensioners, but overall the Max II looks easier to work on.

Both use O-ring roller chain which, if kept adjusted and fairly clean, shouldnt be too much of a worry. Service parts for the Briggs and Stratton powerplants should be easy to come by.

&#42 Take your pick

In this comparison, the Argo is the more expensive, bulkier and harder-to-get-into 6×6. Yet despite having the lower payload, it takes more bulk and people and has more towing capacity.

The cheaper Max II seems more leisure-biased. Its quieter and softer to drive despite the quirky transmission, slots through smaller gaps and is likely to keep pushing along where the Argo stops.

Our suggestion: Look carefully at spec sheets as model ranges from these companies overlap little. Pick the variant that suits your need and pocket, then try before you buy.

MAX IIFACTS

Model tested Max II 600-T.

Engine 570cc Briggs and Stratton Vanguard V-twin, air-cooled.

Output 18hp.

Transmission Variomatic belt plus forward and reverse.

Final drive Simplex chain.

Brakes Internal band.

Tyres 22×11.00-8.

Weight 340kg.

Towing capacity 454kg.

Seating capacity Two.

Payload 360kg including driver.

Warranty 12 months machine/ 24 months engine.

Price £6699.

ARGOFACTS

Model driven Bigfoot 6×6.

Engine 570cc Briggs and Stratton Vanguard V-twin, air-cooled.

Output 18hp.

Transmission Variomatic belt plus high, low and reverse.

Final drive Duplex/simplex chain.

Brakes Twin outboard hydraulic disc.

Tyres 25×12.00-9.

Weight 414kg.

Towing capacity 654kg.

Seating capacity Four on land, two on water.

Payload 327kg including driver.

Warranty 12 months machine/ 24 months engine.

Price £7950.

Whats on offer?

The Max and Argo model ranges arent particularly comparable, so we chose the closest match. The Max II is a two-seater with a shell moulded in polyethylene plastic and engines of 14hp, 16hp, 18hp or 20hp.

Prices run from £5249 to £7499. Beyond it are the bigger, more expensive Max IV four-seater and the Buffalo pick-up. Supplier is Westland Special Vehicles (01959-565513).

Argo has two models of comparable wheel number and power to the Max II. The £5950 Vanguard 2 has 16hp, while the the Bigfoot driven here shares its plastic bodyshell but gets an extra 2hp, a stronger chassis, underbody skid plate and sundry upgrades, all of which lift the price to £7950. Beyond it are 8×8 models. Supplier is Crayford Special Vehicles Ltd (01727-859222).

FOURWHEELS ORSIX?

We didnt set out to compare six-wheelers with conventional ATVs, but heres a few differences. Alongside a 4×4 ATV, the six-wheeler:

&#8226 Carries extra people.

&#8226 Costs more/hp.

&#8226 Has less ground clearance.

&#8226 Feels very stable, particularly on sideslopes.

&#8226 Needs a different driving approach.

&#8226 Goes to more unlikely places.

&#8226 Progressively neutralises half its driving wheels when turning.

&#8226 Is lighter to steer at slow speeds.

&#8226 Turns (much) tighter.

&#8226 Floats.

&#8226 Can take an outboard motor.

&#8226 Is slower.

&#8226 Is more uncomfortable at speed.

&#8226 Is potentially thirstier, but carries more fuel.

&#8226 Is harder to hop on and off.

&#8226 Is best with a long drawbar trailer.

&#8226 Wont tow dead weight round corners so easily.

&#8226 Has chains – lots of chains – to look after.