Why the 2022 Toyota Land Cruiser 300 Series' 10-speed automatic transmission might not be such a good idea | Opinion

There’s no doubt that automotive powerplant technology has been on a steep trajectory in recent years as car makers chase more power and torque from each drop of fuel.

But it’s also true that the development of the transmissions that take that power and torque to a car’s wheels have also, recently, been on an equally steep tech-curve. Perhaps even steeper.

That has brought us to the point today where a vehicle’s transmission has at least as big a role to play in overall performance and efficiency as the engine itself.

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In fact, in some cases, we’re even seeing new-tech transmissions giving older, less advanced engines a second chance.

Witness the fact that General Motors and Ford (who joint-developed a 10-speed automatic last decade) have both been able to use that transmission to eke more life out of their large-capacity V8 engines.

Without the efficiency (read: fuel economy) gains of this transmission, it’s possible neither car maker would be able to justify the booming V8 engine in such volumes as they’re currently built.

The rise of the smart transmission is an across-the-board trend, even to the point of full-sized off-roaders sporting the sort of sophisticated, multi-ratio transmissions that were just a short time ago the preserve of luxury cars.

And into that landscape will soon come the all-new Toyota LandCruiser, the 300 Series, complete with its equally new V6 turbo-diesel engine and a 10-speed automatic transmission.

But Australian consumers of off-road four-wheel-drives are nothing if not conservative. And there’s an acute awareness that something different does not automatically confer something better.

Perhaps the first question when it comes to a 10-speed automatic transmission in an off-roader is `why?’.

Given that we know the new LandCrusier will have a massive 700Nm of torque from its V6 turbo-diesel engine, why on earth would it need so many ratios? The answer, as usual, comes back to efficiency.

When you look at the way a modern 10-speed transmission works, it’s not like an older, four or five-speed unit.

Instead of climbing up through each as the vehicle accelerates, a 10-speed can, in part-throttle conditions, skip whole ratios - a concept called double-step shifting – on its way to top gear or whatever ratio is deemed spot-on by the car’s brain.

Many Australians first saw this for the first time on the Ford Explorer of 1996. The off-roader would shift to either second or third gear from first depending on throttle position and the load on the engine at the time.

And when you have 10 ratios to play with, that strategy can become very complex but very rewarding in terms of saving fuel and reducing emissions.

Having 10 ratios also means there’s a gear for every situation and load, something that should prove a positive for those who tow heavy boats or caravans.

The use of eight-, nine- or 10-speed automatics recently has also allowed some manufacturers to do away with the low-range gearset in their off-roaders.

Several vehicles from VW, Jeep and Land Rover (to name a just three) now no longer bother with a low-range reduction-gear, instead relying on the super-low, high-range ratios that such a transmission can provide while still offering enough legs in the taller gears for relaxed highway driving.

Improved engine management including much reduced turbo-lag and computer-control of the torque-converter helps it work in the real world.

Would Toyota ever dare to eliminate low-range from its LandCruiser in any of its full-sized forms?

Almost certainly not, and buyers probably wouldn’t cop it if it did.

There’s a sense in the off-roading community that using a low first gear (with the option of slipping the torque-converter for a little more flexibility) is not the way a proper off-roader operates.

There are concerns over the amount of heat produced by such a mechanical strategy (torque-converter slip creates enormous heat) and how that will affect performance in the short and long term.

There’s more than a little science to it, also, and any automatic transmission specialist will soon reveal that it’s heat that kills automatics.

For those who subscribe to that view, low-range gears are pretty non-negotiable. And if that’s the case, then we’re back to the original question of why a vehicle, even a 2.5-tonne one, needs 10 forward ratios AND low-range.

We’ve already seen instances where a vehicle technically has too many ratios, including early examples of the current LandCruiser 200 Series, with its six-speed transmission refusing to select top gear at less than about 115km/h.

Toyota soon developed a re-flash for the onboard computer, which allowed the vehicle to select top gear at closer to 90km/h.

Clearly the original shift strategy was designed with markets like the Middle East in mind, where average highway speeds are much higher than here.

Even so, it left a lot of LandCruiser owners wondering why the vehicle need six gears if it wasn’t going to use them all.

It wasn’t just Toyota that experienced this problem Down Under, either: other makes and models have also vexed owners with their refusal to select the highest gear at legal Australian highway speeds.

But even if the forthcoming 300 Series can use all its gears at 100km/h, doesn’t a 10-speed automatic mandate greater complexity and, therefore, potential reliability issues than a simpler five- or six-speed unit?

The short answer is yes, but it’s a qualified yes: any vehicle that is poorly designed and badly built, regardless of how simple it is, is more likely to give grief than a complex one that has been designed and constructed to a high standard from quality materials.

And it’s the latter camp that Toyota’s fanbase and the brand itself sees itself in the overall scheme of things.

It’s a difficult argument to counter, too, and there’s absolutely no doubt that, weight-for-weight over the years, the Toyota brand has the drop on the others in reliability and durability terms.

But there have been the sort of hiccups that any manufacturer experiences over the years, and it’s also true that no brand – not even Toyota - has a perfect reliability track record.

In the world of ten-speed autos, the unit in the 2.0-litre bi-turbo version of Ford’s Ranger has been recalled for failing pump gears that could lead to catastrophic failure, and the 10-speed unit that was a joint-project between General Motors and Ford has also seen its share of gremlins.

Codenamed the 10R80, the latter transmission has been beset with valve-body problems causing harsh shifting and complaints from owners. More recently, the unit has come in for criticism for failures of the pump-dive gear.

Two-piece valve bodies and vastly more complex mechanical layouts could both contribute to in-service failures, particularly in a vehicle working as hard as an off-roader is expected to.

For instance, compared with an old-fashioned four-speed automatic with two planetary gearsets and just two or three friction surfaces (clutches or bands), the typical 10-speed automatic uses four planetary gearsets and anything up to six bands or clutch-packs.

And where the four-speed has a single fluid pump, the 10R80 10-speed uses a conventional input-shaft-driven pump and a secondary, electric pump.

Even the viscosity of the fluid required for a modern transmission might raise eyebrows among the off-road set: where older transmissions use fluid with a viscosity of between six and 7.5 centistokes (the accepted physical metric for kinematic viscosity) a transmission like the 10R80 uses fluid with a viscosity of 4.5 centistokes; much thinner, in other words.

Heat in most fluids reduces viscosity, meaning that getting transmission fluid that is already thin, really hot is a great way to make it break down and stop protecting the transmission’s wearing surfaces (in extreme situations).

Ands that’s before we start talking about a valve body capable of effecting shifts for 10 forward gears or the electronics required to control that valve body.

Again, there’s an industry-wide awareness that Toyota tends to get this stuff right more often than some of its competition (and Toyota has had a 10-speed auto on sale since 2016 in the Lexus LC500) but hardcore off-road fans and those who enjoy remote area travel will be following the new LandCruiser’s introduction very closely.