Go to Windows 7 Insider GuideNissan developing new CVT with auxiliary gearbox tech
Nissan and JATCO are developing a new generation of CVTs.
(Credit: Nissan)Nissan's continuously variable transmissions (CVTs) have historically impressed us with their smoothness and efficiency. Nissan's latest announcement, in conjunction with its transmission supplier JATCO Ltd., could mean that its next generation of transmissions could be even more efficient.
Conventional CVTs work by pairing two variable conical pulleys with a belt to allow for infinitely variable gear ratios within the paired pulleys' ranges. However, due to friction constraints of the belt driven design, most CVTs have been limited to a maximum transmission ratio of 6:1.
Nissan's newest CVT combines the conventional belt-driven operation with an auxiliary gearbox for the top gear for an increased transmission ratio.
The new auxiliary gearbox raises the available transmission ratio from current 6:1 to 7.3:1, more than 20 percent higher than other CVTs. The upshot of this higher gear ratio is enhanced responsiveness on starting and acceleration. According to Nissan, "The 7.3:1 ratio is higher than the average conventional 7-speed automatic transmissions used on high-displacement engine-equipped vehicles, making it among the world's highest ratios for production vehicle use."
A positive side effect of the new transmission setup is a shortening of the overall length by 10 percent and a 13 percent weight reduction compared to conventional CVTs in its class. Smaller and lighter is always better when it comes to performance.
The new CVT is scheduled to appear in compact Nissan vehicles worldwide in the near future.
I've seen a few postings around the web from irked Nissan owners complaining about having to COMPLETELY replace their CVT boxes with rebuilt units @ 90k-100k miles...not exactly a longer living, cheaper, more consumer-friendly alternative to the old school automatic, if one were to ask me. I understand that the occasional transmission does prematurely wear out but still, a $5000 to $6000 hit to the wallet after only 100k miles isn't what I'd consider 'routine maintenance', either. Just curious if Nissan finally has anything to say about this; to date I've yet to find any official comments.