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American Axle introduces EcoTrac disconnecting all wheel drive

American Axle & Manufacturing (AAM) announced the introduction of the automotive industry’s first disconnecting all-wheel-drive (AWD) system. EcoTrac is featured on the all-new 2014 Jeep Cherokee (rear-axle disconnect).

The EcoTrac Disconnecting All Wheel Drive takes a new approach to minimizing the effect of inertia and drag on a vehicle’s driveline system by disconnecting many of the rotating components from the driveline when they are not needed. These components include both the PTU and RDM hypoid gear sets, the bearings associated with the gear sets, and the driveshaft.

EcoTrac allows the AWD vehicle to utilize its primary drive system, the front wheels, when AWD is not needed; EcoTrac disconnects at the power transfer unit (PTU) and the rear drive module (RDM), allowing large portions of the driveline to discontinue rotating while in front-wheel drive.

When the vehicle senses that AWD may be necessary due to conditions, the system will passively and automatically engage. Utilizing a wet clutch in the RDM to gently bring the driveline to proper speed, the PTU will be quickly synchronized and will engage and begin delivering the appropriate amount of torque.

When conditions allow, the vehicle will revert back to an economical mode. The result, says AAM, is the benefits of an all-wheel-drive system without the sacrifice to fuel economy and emissions.

2WD Economy Mode. Click to enlarge.
AWD On-Demand Mode. Click to enlarge.

Traditionally, when adding all-wheel-drive capability to a vehicle, it results in an automatic one to three mile per gallon fuel economy penalty. We set out to find a solution to offset this, and that is exactly what our EcoTrac Disconnecting AWD does.

—Philip R. Guys, AAM Vice President Product Engineering

AAM’s EcoTrac Disconnecting AWD can be engaged with driver input or when Automated Transition Events (ATEs) occur. These ATEs are 100% customizable and include both environmental and dynamic events such as lower temperatures, rain detection and changes in slope among others.

Upon receiving the signal from the AAM electronic control unit to engage AWD mode, EcoTrac engages all-wheel drive seamlessly without noticeable shifting to the driver.

AAM says that its EcoTrac technology consists of many industry firsts, including AAM’s patented RDM with a side mounted Torque Transfer Device (TTD). Thus far, a total of five US patents have been assigned to AAM for EcoTrac. There are nine US patents pending relative to the technology.

EcoTrac is being manufactured at AAM’s Three Rivers Manufacturing Facility in Three Rivers, Michigan. In support of this new program, AAM has invested more than $100 million in the facility and has hired more than 550 new associates in 2013.


Michael Weindl

I had a VW Multivan SYNCRO which did the same thing 15 years ago..or is there a difference between Syncro and EcoTrac?


The difference is that this system disconnects the central driveshaft and the rear differential. Earlier systems kept the driveshaft spinning, either powered by the gearbox, or by the differential (which is powered by the rolling wheels).

This system is similar in concept to earlier "part time 4wd" systems on trucks that required locking the front hubs and engaging the central transfer case.The main difference is that this system is fully automated, and that it can disengage even in 4wd mode if traction is good.


If I was designing a system like this for a vehicle similar to the Jeep Cherokee, I would drive the rear wheels in 2WD mode. On relatively high traction surfaces, rear wheel drive is better balanced as the front tires provide much of the braking and all of the steering.


SD, the reason they didn't do that is multiple, but fuel economy is most important and disconnecting the drive shaft et al saves more than disconnecting the front drive axles. Also, fwd is easier for neophytes than is rear wheel drive.

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