Review: Kenworth T359

When the opportunity arises to drive a customer Kenworth, I usually jump at it. In any case, on this occasion Kenworth's T359 is a model in which I've previously done very few kilometres.

Prixcar Services is a joint car transport venture, equally owned by the Toll group and K-Line – the latter being the mob that owns the car-carrying ships chugging around Asia. My opportunity came about when Allison Transmission wanted to run one of its new TC10 linehaul transmissions in a real-world transport task, so it could test and evaluate local performance and gauge driver response.

The TC10 is Allison's first dual-countershaft 'box, and is designed to bring the advantages of a full automatic to the kind of applications that largely involve long-distance cruising – a field that, in the past, Allison hasn't counted among its strengths.

Prixcar was due to add another Kenworth to the fleet and the truck was duly ordered with a Cummins ISMe5 11-litre engine and Eaton UltraShift automated manual gearbox. It's standard fare for the application – there's no point in buying more power than you need and the Eaton AMT is a pretty decent kind of gearbox, especially with the bullet-proof Roadranger gearset at its heart.

But this truck had a different destiny. From the production line it was handed over to Allison, where the 'box was replaced with the new TC10 automatic, setting up the communications package so the shift points would suit the kind of cruising for which the T359 was intended.

I intercepted the truck in Queensland, just a day or so before the 2015 Brisbane Truck Show. Driver Martin Eales had loaded seven new cars on the single trailer, including a few Ford Rangers that bumped up the weight a bit.

Prixcar's standard trailer weighs in at a hefty 22 tonnes empty. The side frameworks have been designed to support hydraulics that allow the entire top deck to be lifted by at least two metres. The over-cab ramp also operates on lever arms to move a car back and then down to the trailer level. Add seven vehicles, and the truck was loaded pretty close to maximum GCM.

As with most of its current models, Kenworth’s T359 has benefited from some serious aero work, and is hampered only by the basic outline of a high cab, bonnet and mudguards. The 6x4 rig was spotlessly clean, despite already working hard on regular runs.

Whenever I drive a customer truck, I try to adapt myself to the seat, wheel and mirror set-up, rather than give the regular driver heartburn having to get everything back the way he likes it. But Martin and I are of a similar height and build, so everything worked for me as it was.

At the Brisbane Show, Kenworth announced new, larger cab designs across the range. This T359 was delivered before the change was made, so it retained the classic narrow feel and restricted road vision of its peers.

Kenworth does put a lot of effort into the driving position, though. After I told my brain that the seat and wheel were perfect for me, I almost never had to look away from the road while driving. My back and legs were well supported and I think I could do big miles in this setup without suffering the consequences afterwards.

The ominous presence of a car on a ramp over my head did restrict vision a little, but wheeling out of Prixcar's new Brisbane depot I had eyes on all the important bits – sides, mirrors, rear wheels etc – while being able to see the edge of the bonnet gave me a good idea of where the bumper was.

The Allison 'box made everything I did easy as far as moving the truck was concerned. I really just had to look and steer. The auto electrics juggled ratio and torque converter to keep torque going to the road even when I was figuring out what the gateman wanted me to do.

As we pulled out of the depot, Martin's warning came to my mind with a new clarity. The exit road had trees along the border.

"Watch out for overhead; I don't want a tree branch through a headlight," he'd said, meaning the Honda on top of the cab.

The Cummins 11-litre is a perfect match for this truck and application. Its 434hp and 1534Nm of torque was well inside the Allison's limits of 600hp and 2305Nm, but it was working with the heavy trailer and a full load of cars. Sticking half the load above a gap of fresh air meant that the centre of gravity was pretty high and road camber became my new best friend as we tooled around local industrial areas and arterials.

The T359 is an ideal rig for this task. A tight wheel cut means better-than-average turn-in so I never had to use all of the road at junctions, although a 90-degree intersection highlighted how the mudguard needed to be considered when going wide to get the truck safely through.

In the briefest possible terms, the TC10 lives up to Allison's claims. The only query I had was the operation of the engine brake. The TC10 changed down as normal to keep engine brake effectiveness at its peak, but inexplicably dropped the engine brake while the 'box made the range change. I thought that wasn't helpful, and I think Allison is going to look at it. There's no mechanical reason for it that I could think of, so it may be a matter of calibration.

As a company Allison Transmission tends towards the notion of 'under promise and over deliver', so I was surprised to see the claim in the technical brochure that the TC10 delivers a five per cent improvement in fuel economy.

This is backed up with the claim, "The TC10 achieves the best fuel economy, regardless of driver experience or expertise."

Neither statement has a disclaimer. As any half-decent fleet owner reading this knows his or her fuel bill for the month and year, this claim deserves a very close look indeed.

The TC10's 10 speeds are evenly spread to a direct-drive ninth, with 10th gear a 0.86:1 overdrive. The gearing spread allows this Kenworth to use a 3.08 diff, bringing highway cruising revs down to a lazy 1350rpm.

The methodology is pure Allison – a torque multiplier, or converter, is used for take-off, and then the transmission locks up, with changes facilitated by wet clutches to maintain full and uninterrupted torque from start to top speed. The initial lock-up on the TC10 occurs at walking speed, so there is no torque loss under power and always enough wear-free torque for take-off, even under full load and on the steepest slope.

All of that means there is zero friction wear on take-off, crawling and reversing – factors critical to this application.

So does the T359/TC10 combo work? Martin thought so. His comments were glowing and he confirmed that the fuel efficiency of the truck is several percentage points ahead of the AMTs he has driven during his many years of experience.

But putting transmissions aside, how does the truck itself perform? In short, the T359 isn't the most powerful, comfortable, quietest or most technically advanced metro and intrastate prime mover. But it probably doesn't matter. Because in the Australian market, the T359's European competitors lack one essential feature. None of them are Kenworths.

KENWORTH T359 SPECIFICATIONS (AS TESTED)
ENGINE: Cummins 11-litre ISMe5 in-line, six-cylinder, turbo-diesel
POWER: 434hp
TORQUE: 1534Nm at 1200rpm
EMISSIONS: ADR 80/03 (Euro 5)
EMISSIONS SYSTEM: SCR
TRANSMISSION: Allison TC10 10-speed automatic
CONFIGURATION: 6x4
BBC: 2795mm
BRAKES: Drum
CAB: Day
WEB: www.kenworth.com.au, www.allisontransmission.com