6T75

[MGZ06]

It looks like GM has finally found a solution to powertrain diversity, I saw this transmission at NAIAS and was surprized to see how small it was. Main reason is the is no drive shaft assembly, now this transmission can easily be mated to a FWD or AWD without any problems. I have pics and will post them soon.

[dwightlooi]

It looks like GM has finally found a solution to powertrain diversity, I saw this transmission at NAIAS and was surprized to see how small it was. Main reason is the is no drive shaft assembly, now this transmission can easily be mated to a FWD or AWD without any problems. I have pics and will post them soon.

What do you mean it doesn't have a drive shaft? I am pretty sure that it has shafts in there to locate the gears. In a transverse automatic it is common to arrange sun-ring-planetary sets in parallel rather series. This is similar to 3-shaft manuals which has one input but two output shafts in parallel. The objective is naturally to shorten the width of the transverse mounted gearbox so it can be mounted beside the engine rather than having to sling it in a "L" arrangement to put it behind the transverse engine.

Unlike longitudinal RWD trannys, the transverse transmission for FWD applications typically has the differential housing integrated into it and driven directly with a gear coupling. In AWD adaptations the transfer case is usually attached tangent to the differential housing and driven off the differential's ring gear. This is normally decoupled, but when fully coupled transfers 50% of the available torque to the rear wheels. The mechanism for coupling can be viscously controlled (typical viscous LSD type setup), electronically controlled via clutch packs (ala haldex) or by using a torque biasing type arrangement (either Torsen style worm gears or Quaife style helical pinion gears).

Transverse FWD setups are lighter, more compact and more efficient than longitudinal drive trains. They also tend to have less "slop" and less vibration issues related to the shaft connecting the transmission and the rear differential. A transverse FF tranny tend to have around 10% drive train loss vs about 15% for FR setup with separate transmission and differential axle. This is one of the original motivations for going FF. Manufacturing costs and weight reductions being the other major factors.

Edited January 20, 2007 by dwightlooi