Used Truck Review: Kenworth K104G

The Aerodyne cab, first rolled out of Bayswater on April 4, 1980
Many regard the K104G as the last of the real cabovers
K104G interior

More than any other country, Australia has an abundance of used trucks rolling up and down the highways. Matt Wood revisits Kenworth’s durable K104G


Love it or loathe it the cabover Kenworth has a special place in Australian transport history. There’s probably no other truck on the market today that will bring out a more passionate response, positive or negative, among drivers than the K series Kenworth.

It becomes hard to avoid clichés like ‘iconic’ or ‘legendary’ when talking about this particular vehicle but then again there wouldn’t be many drivers on the road today that haven’t set foot in at least one, at some stage in their career.

The birth of the K125CR way back in 1971 may have started the ball rolling, but it was the emergency of the Aerodyne cab, which first rolled out of Bayswater on April 4, 1980, that really caught the imagination of drivers and operators alike.

With its streamlined, high-rise sleeper, complete with tinted glass in the roof, the Aerodyne represented a quantum leap forward for long haul prime movers in Australia. Here was a cab that drivers could stand up in, admittedly, by standing on the bed, which also provided extra storage cupboards and room for life on the road. In short the K100 Aerodyne was an American style cab a driver could live in.

The K100E emerged in 1986 with an interior and dash redesign, plus revised cab suspension, but it was the industry-wide adoption of B-doubles that really thrust the K100 into the limelight. When the K100G Aerodyne appeared in 1995 the trucking industry pounced on it with enthusiasm for a number of reasons. For a start it fell within the 25-metre B-double envelope easily; secondly, there was still the full range of driveline choices from Detroit and Caterpillar to Cummins and, thirdly, the prime mover weighed in at between 8 and 8.5 tonnes.

There was little else on the market at the time that could tick all the boxes for an east coast, multi trailer operator. But it was the K104G which appeared in 1999 that really cemented the cabover as B-double king. None of the competing brands could play the B-double game and still have room for 1,400 litres of fuel on the chassis as well as keeping to the legal steer axle limit of 6 tonnes. The K104G was also now available with 600 plus horsepower, as well as the option of Eaton’s Auto-shift gearbox.

I’m sure I’m not alone when I say that on more than a couple of occasions I found myself clutching my bleeding scalp, weeping quietly while rocking back and forth in the driver’s seat of an Aerodyne, after forgetting to duck during an overly-enthusiastic cab entry. And I’m sure that there are plenty of people out there who’ve attempted to get changed, dog tired after a big night at the wheel, standing on the mattress and looking for all-the-world like someone squashing grapes at a wine festival as they try to get their trousers off without falling over and braining themselves.

The Aerodyne’s detractors have likened the driving position to sitting in a bucket with a gear stick jammed against the left leg and a driver’s door jammed into the right elbow. Fans of the cabover will counter by saying that the gear stick is within easy reach and that everyone knows that a real truck driver always drives with his or her elbow out the window anyway.

Switching switches

The K104G certainly wasn’t short of idiosyncratic charm; there was no standard positioning of gauges and switches, meaning that no two trucks seemed to have the same switch layout. This made for some interesting switch-flicking exercises, especially in the dark when jumping into an unfamiliar truck. Gauges seemed to develop a mind of their own after a few hundred thousand kilometres, often leaving only the speedo and tacho reading with any real accuracy. But by this stage in the model’s evolution, the engine manufacturers had their own RoadRelay units fitted inside the cab, meaning that most relevant engine information was available anyway.

The aluminium construction of the cab gave the prime mover an enviable tare weight and also meant that corrosion was never really much of an issue. The downside however, was that you would be pushing to find an example that doesn’t leak somewhere. In extreme weather you could be guaranteed to find a pool of water somewhere in the cab, either along the base of the fire wall, under the foot well mats or more often than not trickling along the dashboard.

K100 drivers soon learned never to leave paperwork sitting on the dash against the windscreen. And of course no discussion of the Aerodyne would be complete without mentioning the engine ‘hump’ that divided both the cab and opinions on it alike. For some it was an annoying obstacle to live with; for others it was a place to have your fridge in easy reach, a place to leave your street directory open and accessible, and, a place to slump if you just couldn’t be bothered dragging yourself out of the seat and into the bunk.

Driving the K104G is best described as an engaging experience, much in the same vein as its predecessors; and again detractors will complain that the ride was harsh and choppy, especially as a 25-metre B-double prime mover. But fans of the flat-faced Kenworth will say this was a small price to pay for the rig’s highway road manners. With two stacks behind the cab singing a sweet diesel tune, a gear stick at hand and some horsepower underfoot, the Aerodyne could be a very enjoyable beast to pilot.

On the whole the K104G was a great truck on the open road with excellent feedback through the wheel, the prime mover behaved predictably with multiple trailers, or even just one. The steer axle positioning, which tended to compromise the ride, the driver was effectively positioned on top of the steer tyre, also contributed to its manners at high speed. But, when it came to manoeuvring B-doubles at low speed, especially when reversing, the K104 was hopelessly outclassed by other competing cabovers on the market by this stage, namely Volvo’s FH and Freightliner’s Argosy.

The highway roadholding characteristics of the Kenworth were a trade off against the slow-to-react and even slower-to-chase traits of the prime mover when reversing.

The move to 26-metre B-doubles meant the end of a golden era for the K104G; the playing field had been levelled and now other manufacturers were able to compete for a slice of the market pie. While this didn’t serve to dent sales of the Aerodyne markedly, it meant that Kenworth could now stretch their wheel base out, moving the turntable and fuel tanks back on the chassis and smoothing out the notoriously ‘choppy’ ride of its previous 25-metre incarnations.

Recent updates

In 2006 Kenworth released the K104B, which featured improved cab access and another dash redesign. And in 2008 the K108 followed, the first significant upgrade of the cab since its inception. With new emissions laws in place the K108 cab was mounted higher to allow more air flow and deal with the higher running temperatures of the exhaust gas recirculation (EGR) engine. But it was the release of the K200 in 2011 that represented the first major redesign of the K series cab in 40 years.

The new cab featured a flat floor, another interior redesign as well as major exterior changes. With the absence of Caterpillar and Detroit from the engine options list, Cummins was now the only power source, while Eaton’s Ultrashift-plus AMT was now a transmission option as well as the traditional manual shift.

The sheer amount of K104G Aerodynes still on the road in any number of roles is testament to the durability and drivability of the prime mover. Whether by accident or by design, the cabover has proved itself to be a modular design, with many happy to rebuild or repower the vehicle when required. The desirability of this model has seen resale values remain high, even taking into account that many of these trucks have now covered over 1.5 to 2 million kilometres.

I discovered the example pictured at Brad Drew Trucks in Fyansford, Victoria and it’s typical of the breed: Cummins Signature at 600hp (441kW), 18-speed Road Ranger and a GCM of 90 tonnes.

Many regard the K104G as the last of the real cabovers, representing a time when a full range of engine manufacturers were available and before the uncertainty of new pollution technology. Given the Aussie way of squeezing every last drop of viability out of a commercial vehicle, I doubt the K104G will be disappearing from our highways anytime soon.

Find Kenworth K104 trucks for sale.

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