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ADVANCED TRANSMISSIONS MORE TROUBLESOME, SAYS CONSUMER REPORTS

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2016-01-08 11:26
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2016 Honda eight-speed DCT: overcomes traditional DCT drivability issues and outshines ZF’s nine-speed planetary.

2016 Honda eight-speed DCT: overcomes traditional DCT
drivability issues and outshines ZF’s nine-speed planetary.

 
 
 

New types of multi-speed automatic transmission come in for significant criticism in the latest survey published by Consumer Reports (CR) in North America. Indeed, says the organization, teething troubles with advanced transmission designs are threatening to drag down the high reputations of several premium-brand automakers, with Honda’s Acura premium nameplate singled out for particular mention.

CR’s Annual Auto Reliability Survey for 2015 took in data from some 740,000 vehicles aged up to four years. Normally, says CR, problems with infotainment and connectivity systems come at the top of vehicle owners’ complaints; now, however, the organization has identified an “emerging trend of increased troubles” with new transmission systems. These systems, observes CR, have been introduced in order to improve fuel economy.

This year, notes the Report, Acura becomes the latest brand to see its overall predicted-reliability ranking drop sharply (down seven places from last year) due to problems with in-car electronics and transmissions for its newest RLX and TLX sedans.  CR has already seen these trouble areas drag down overall scores for Ford, Nissan, Fiat-Chrysler and others.

Explaining further, Consumer Reports’ Director of Automotive Testing, Jake Fisher, said: “Whether it’s a complex system such as a dual clutch gearbox, a continuously variable transmission, or one with eight or nine speeds, we’ve seen a number of brands struggle with new transmission technology. Many vehicles require repair and replacements because of rough shifting among the gears and slipping CVT belts.”

Acura’s parent company Honda has been hedging its bets in the transmission field, developing a series of dual clutch units in-house as well as buying in ZF’s nine-speed planetary unit for its smaller front-drive models, including the TLX V6. Indeed, industry sources suggest that as one of the launch customers for the nine-speed, Honda — along with Land Rover and Chrysler — even helped support ZF’s development program. Both types of gearbox are available on the TLX. Among the innovations posted by the new eight-speed Honda DCT is the addition of a torque converter, a feature designed to answer the criticisms of poor drivability leveled at many DCT arrangements in smaller cars. Though CR’s publicly-available survey score for the Acura does not distinguish between the two different transmission types available on the TLX, CR’s own road tests appear to vindicate Honda’s approach, being effusive in their praise for the innovative DCT but much less complimentary with the showing of the off-the-shelf ZF nine-speed:

“The eight-speed dual-clutch automated manual smoothly delivers quick, direct shifts,” says CR. “Occasionally, when starting after a brief stop, the transmission will hesitate before putting itself in first gear. But the TLX’s torque converter, an unusual component for this transmission technology, helps eliminate most of the low-speed stumbles and vibration found with other automated manuals.

“The nine-speed automatic that comes on V6 versions is neither smooth nor responsive. Most shifts come with a noticeable shock, reminiscent of transmissions from decades past. Part throttle kick-down is not always readily available and requires a deliberate prod of the gas pedal. V6 versions also have an electronic shifter consisting of buttons and lifters which is much less intuitive and requires looking down at it with every parking maneuver.”

The ZF-sourced nine-speed planetary automatic is also used by Chrysler Jeep in the 2016 Jeep Cherokee, which finishes in fourth place in the listing of the 20 least reliable models — the Acura places 17th. Regrettably, however, the feedback from Jeep owners has much in common with that posted by Acura drivers. Comments included, “Rough, jerky or erratic shifts. Transmission needed reprogramming, sometimes more than once, or replacement. Engine computer reprogrammed or replaced.”

CR’s road test verdict echoes those popular complaints, noting that early versions of the Cherokee did not get the transmission calibration right; later models, says the organization, are better but the transmission still feels underdeveloped.

While the disappointing showing of the ZF planetary transmission is perhaps surprising, negative feedback continues to surround the in-house dry dual clutch set-up on the Fiat 500L (plus some Dodge and Chrysler models) and the Getrag-Ford DCT on the Fiesta and Focus. Fiat has announced it will be replacing the twin-clutch transmission with a conventional six-speed automatic. Ford’s plans are as yet unconfirmed, but at September’s Frankfurt Auto Show Getrag released a new generation of small wet clutch DCTs that may help solve the drivability issues.

Not all DCTs come in for such harsh words. CR praises both BMW and Audi, the latter including many DCT models in its line-up and reaching third place overall for reliability. CVTs are generally noted for their superior smoothness — and indeed this is the case for most Japanese brands, especially Toyota and Lexus, which top the overall Survey standings. Nevertheless, there is an exception — Nissan, or more specifically the new Jatco CVT fitted to group models such as the Infiniti QX60 SUV and the Nissan Pathfinder crossover (X-Trail in Europe). Owners of both these models complained of jerky drivelines, vibration and transmission slipping, although these comments are not echoed in their more positive CR road test assessments.

A further surprise in the CR Survey findings concerns Tesla. The Model S was the highest ever scorer in CR’s own road test assessment, but feedback from around 1,400 owners reveals a pattern of complaints that prompt CR to give the model a worse-than-average predicted reliability score.

 

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