http://www.motorauthority.com/wp-content/uploads/GM/Chevrolet/79060.jpg
GM considers eight-speed gearbox

Posted on Wednesday 17 October 2007


Earlier this month information from leaked UAW documents revealed the Corvette may get a new dual-clutch transmission and now reports are claiming GM is also working on new seven and eight-speed gearboxes. The key now for GM is determining whether the improvements in fuel economy and performance would justify the cost of engineering them into a vehicle.

The executive director of GM Powertrain’s Transmission Engineering, Jim Lanzon, told The Car Connection that every possibility is being looked at including a similar gearbox design to the one used on the high-performance BMW M5. GM has the technology but as Lanzon explained, “there is more to making a seven or eight-speed transmission than adding more modules. You’ve got to be concerned about the parasitic losses that neutralize the fuel-economy gains.”

New computer design tools have sped up the development of GM’s recent gearbox technology. Where once it would take close to a decade to develop three or four new transmissions, with the aid of computerized tools GM has launched nine new six-speed transmission models in just four years.

Dual-clutch technology is slowly filtering to other companies after the Volkswagen Group first pioneered the gearboxes in their mass market vehicles. Mitsubishi’s Evolution X and the Nissan GT-R both get dual-clutch gearboxes and Ford is bringing it to market very soon. via motorauthority

I remember when playing the first Gran Turismo one of the cars (I think a GTO VR4) had a 8sp when you did the racing modification or something...can't believe it's true now.

I remember when playing the first Gran Turismo one of the cars (I think a GTO VR4) had a 8sp when you did the racing modification or something...can't believe it's true now.
Nissan Skyline GT-8 in GT4.

i.e. a G35 with 8 speeds.

Skyline 8 speed. I believe they sell them in Japan.

The key now for GM is determining whether the improvements in fuel economy and performance would justify the cost of engineering them into a vehicle.

The executive director of GM Powertrain’s Transmission Engineering, Jim Lanzon, told The Car Connection that every possibility is being looked at including a similar gearbox design to the one used on the high-performance BMW M5. GM has the technology but as Lanzon explained, “there is more to making a seven or eight-speed transmission than adding more modules. You’ve got to be concerned about the parasitic losses that neutralize the fuel-economy gains.”

Not only that, but you has to ask yourself whether any more than five or six speeds is just getting into overkill. Sure, you get into closer ratios and more efficiency, but you also put more wear and tear on the clutch and shifting mechanisms by shifting more often. And then, you run into a simple mathemetical ratio.....the more gears you add, the closer you get to the ultimate in efficiency to start with......a simple CVT, which a number of auto firms have NOW.

CVT's problem is they can't take good amount of Torque and HP.
Hopefully the tech will fix them soon.

CVT's problem is they can't take good amount of Torque and HP.
Hopefully the tech will fix them soon.

Yes, I know. The drive belts, with present technology, can only take so much.......but I brought the point up to illustrate that the more gears you add, the closer you get, in effect, to a CVT. The transmission just gets more and more complex when a simple drive belt will do the job more efficiently. But, yes, more engineering will have to be done with CVT's before they can be used across the board. And people will have to get used to a CVT transmission's different "feel".....come manufacturers already use artificial "shifting" of CVT's to falsely imitate the feel of a conventional tranny.

Having said that, though, with present technology, it is really hard to beat the twin-clutch VW-Audi DSG (Direct-Shift-Gearbox). Each time I have done a review of a DSG-equipped vehicle or have otherwise had a chance to drive one, it has put a smile on my face. IMO, no other transmission, manual or automatic, currently on the market, compares with it for everything combined......smoothness, refinement, efficiency, acceleration, mileage, and conventional shift/feel. It is, however, rather complex, and will be expensive to repair or replace if/when it fails after the warranty runs out.