As a 5+year EC owner with the 4.9 litre engine and the 5 speed manual transmission, I'm pretty familiar with the pros and cons of that combination. however, I was asked on the EC owners forum some months back about the new Duonic transmission (paired with the new 3 litre engine), and this was my response FWIW (in terms of the transmission; I had a separate epistle on the 3 litre engine, which also looks great).
The situation at the time was that the Canter FG was no longer (temporarily) available in Australia with dual range gearbox (only high range; it is now back on the market with dual range transfer), plus we had a number of US owners buying ECs and they "only" had the 3 litre engine and Duonic gearbox option.
High range only manual transmission
In terms of the existing 5-speed manual transmission, it is really a 4-speed manual transmission with a crawler gear. The reason for this is that there is no “synchro” on 1st gear (or reverse), so that it is simply not practical to “change down” into 1st gear if you run out of puff in 2nd. You must completely stop the vehicle and then change into 1st. Actually, I have tried double de-clutching into 1st and it is possible, but I would never attempt this doing (say) a hill climb. It would be far too risky.
A second point to note is that the 4.9 litre engine is that while the 4.9 litre engine has more torque than the 3 litre, the 4.9 is electronically limited to 380 N.m of torque in 1st gear (and reverse) compared to the 3 litre engine which has 370 N.m available in all gears.
I’ve done quite a lot of bush work in EC4 now and have never used 1st gear for a hill climb EXCEPT where I need to literally “crawl” over boulders or climb onto (or off) a rocky ledge. In these situations, I am using 1st (low) to allow me to “inch” my way through or over an obstacle, rather than for any other reason (such as the steepness of the hill). It also means I don’t need to slip the clutch as much (which is tricky to control in very rough work and wears the clutch shortening its life).
So in most circumstances, you are not going to use anything lower than 2nd low for steep hill climbs. 2nd low is equivalent overall ratio to 1st high in the manual transmission in terms of overall gear ratios, so on most steep climbs, 1st high would be OK.
I don’t ever recall using 1st low for a descent, except in the same circumstances above where I need to “inch” down a slope due to its roughness not its steepness. Bear in mind the engine exhaust brake on the 4.9 litre engine is brilliant and is worth (for hill descents) at least 1 extra (lower) gear, probably 2 in many circumstances, compared to an auto box or “petrol” (gasoline) engine.
So for most purposes, the lack of a low range probably won’t have too much impact on hill climbs or descents and most drivers would, I think, adjust to it fairly well. Where the lack of low range will be important is in “inching” up or down rocky ledges or gullies etc. In this case, without low-low, you are left with needing to either go faster (not always good) or trying to slip the clutch (difficult or impossible in some cases). As an aside, one of the most common uses I have for low-low is “lifting” EC4 up onto blocks to level up the vehicle at a camp site. In this case, I don’t bother to put the free wheeling hubs in, I just put it into low-low and edge up onto the blocks. Low-low gives me that sort of control.
It will be an inconvenience on rough bush tracks not having the “closer” spacing of four gears in low range, which means probably having to use just 2nd gear high range for much of the bush work, but 2nd and 3rd high are very very flexible gears in the manual. And of course, whilst 1st high is equivalent to 2nd low in terms of overall ratios, 2nd low has synchro whereas 1st high does not, which means if you run out of puff in 2nd high, then you will have to completely stop the vehicle to change into 1st high (in the manual). These are important issues but perhaps for many owners not intending a lot of serious “technical” 4WD work, the low of the low range isn’t a major issue. For those who do want to cross the deserts or go down serious 4WD tracks, then the loss of low range with the manual transmission is certainly something to ponder.
Now to come to the issue of the 6- speed Duonic transmission.
Whilst this tranny has a "fully automatic mode", it is not a conventional “automatic” transmission at all. In fact, it is called an “automated manual transmission” (or “AMT”). Note “automated” not “automatic”. A conventional automatic transmission has a torque converter in it with transmission fluid. The AMT is in fact a computer-controlled manual transmission. But more than that, it is actually two complete manual transmissions running in parallel. One “side” (gear train) handles Reverse, 1st, 3rd and 5th, and the other side handles 2nd, 4th and 6th.
Each “side” has its own input shaft from the engine, its own clutch and its own output shaft. This means two input shafts, two clutches and two output shafts.
A computer chip monitors engine load, RPM, throttle position and all the things that any driver would if driving the vehicle manually.
Let’s say you are in 3rd gear and applying throttle and picking up speed. The Duonic will have the clutch for the gear train that handles 3rd gear “engaged”. BUT it will already have the parallel gear train engaged in 4th gear, just with the clutch disengaged. When the engine decides it is the exact right moment to change up to 4th, it simply disengages the gear train with 3rd and engages the gear train with 4th. That’s the beauty of the two input shafts, two clutches and two output shafts.
It can do this in around 0.03 seconds, i.e. much faster even than a traditional automatic transmission.
And of course, because the Duonic has no torque converter or transmission fluid, it has the towing capacity of a manual transmission rather than the de-rated towing capacity of an equivalent fully automatic transmission. It also has better fuel economy.
Plus it is a genuine 6-speed transmission, unlike the manual which (as noted earlier) is really a 4-speed tranny with a crawler gear.
This means the 6-speed Duonic can ensure the 3 litre engine is operating near its sweet spot much better than a 4-speed manual tranny can.
And if you are doing a hill climb and need to change down gear, the Duonic will do it in about 0.03 seconds. Compare that to the manual transmission, where I have timed myself and it takes somewhere between 1 and 2 seconds to change down gears, depending on the circumstances. This is a real issue in hill climbing because the Canter service (foot) brakes (drums all round) will NOT hold the vehicle on a very steep hill, so that changing down gears on a steep climb is fraught with danger. In many cases, it is better to stall the engine. But then the only option is to stall-start it in reverse and go back down the hill—sometimes a tricky operation and will be much trickier with no low range as the downhill speed (in reverse) will be that much higher.
And of course, if you are driving through sand and engine revs are dropping and you desperately need to change down gears, then with the manual transmission, as soon as you depress the clutch you’re stopped—and probably stuffed! However, the Duonic has no such problem as changing down is seamless. It will be a joy to drive in sand.
The Duonic has a fully automatic mode or the “semi-automatic” mode now the norm in automatic transmissions, where the driver can simply tell the vehicle to change up or down gear when he/she wants it to.
This means the Duonic is a very flexible transmission.
Another important point about the Duonic is that it has a “crawler” mode. In this mode, the vehicle will crawl forward (or backwards) and the driver controls vehicle speed via the foot brake. I’m not exactly sure how this option works, but as there is no separate crawler gear in the box, it is probably by computer control of clutch slippage. I’m not sure if this feature could be used for climbing over boulders or rocky ledges. If this is OK, then it would be a big plus. But Fuso would need to advise or the clutch could be burnt out.
Interestingly, in the USA the Duonic in the 4WD Canter has a choice of two diff ratios: 5.714 and 5.285. This gives US owners some additional potential for bush work, at a minor expense of highway driving speeds and fuel economy. And there is also the potential in the USA to fit an after-market transfer case with low range in it. For the very keen, this could be done either at initial purchase or afterwards.
I can see some downsides to the Duonic AMT. One is that as it has no conventional automatic box torque converter with automatic transmission fluid in it, then the engine will stall if too much torque is demanded from it. A normal automatic transmission won’t stall the engine (the transmission itself will stall, but the engine won’t). Secondly, because the AMT doesn’t have the traditional automatic transmission system, it doesn’t have a torque converter in it, with the great “torque multiplying” effect that we are all familiar with in auto boxes, which will be more of an issue with no low range transfer case than otherwise.
But apart from those two points, I think the Duonic, at least on paper, is an outstanding option for a 4WD truck—however, bear in mind I still haven’t driven one (as they are not available in the 4WD version of the Canter in Australia).
As a footnote, our EC has been over a weighbridge TWICE and each time I have had the front and rear axles weighted separately. It has an almost exactly 50/50 weight distribution (ours is a SWB). If you look at Howard's video, you can see how supple the suspension is, and that combined with the great weight distribution, along with the engine, transmission and 4x4 traction and absolutely brilliant LSD in the back axle (along with the ground clearance and approach/departure angles), does make these machines absolutely formidable vehicles off road.
rick
