BUYERS GUIDE - HEAVY DUTY
It’s always amazed us that working-4×4 ute and light truck makers have stuck with manual transmissions, when all earthmoving gear and most heavy all wheel drive trucks have automatic transmissions. Thankfully, that scene is changing and there were three self-shifting light 4×4 trucks available in 2019.
The immediate choice is Isuzu’s market-leading Isuzu NPS300 4×4 that was released with the company’s automated manual transmission (AMT) in 2019. AMT models normally attract a RRP increase in the $3000-$4000 band.
Another factory-fitted AMT 4×4 light truck came from Iveco, in the form of the 2019 Daily 4×4. Unfortunately, the 2019 model was delayed by transfer case issues and wasn’t readily available until 2023.
The third entrant into the self-shifting 4×4 light truck market is Hino’s 817 4×4, but there’s no factory-auto-fitment for this truck as yet. However, there is an Allison after-market automatic transmission kit available from Penske.
First up, some background into 4×4 light truck two-pedal drivelines.
Why AMT and not full automatic
Isuzu and Iveco have adopted automated manual transmissions for their 4×4 light trucks for two main reasons: lower cost than a torque-converter transmission and reduced torque loading in the driveline.
Torque loading is a significant issue with 4x4s, because the transfer case low range ratio multiplies transmission torque by up to 3:1 in most cases.That’s a lot of torque loading going into propeller shafts, differentials and half shafts.
In the case of a torque converter automatic transmission, such as the Allison, there’s additional torque multiplication by the fluid coupling’s stator – typically 2.5:1 – and the transfer case may not have the torque capacity to handle that additional torque loading.
Most automated manual transmissions don’t have that torque multiplication. In the case of Isuzu’s NPS300 AMT that does have a fluid coupling there’s no stator in the coupling, so there’s no torque multiplication.
The Hino 817 4×4 is a different beast from its competitors, in that it employs the large transfer case from the company’s GT, 13-tonnes GVM truck, so there’s ample torque capacity in the transfer case to handle more than double the 817’s engine torque peak of 464Nm. Hence, it can accept a torque-converter fully-automatic transmission.
We’ve tested the Hino Auto and covered our findings in our main Hino 817 4×4 report.