Ford and General Motors Sign An Agreement To Work Together On Transmissions

H'mmmm I wonder just how far before friction renders the additional gears to be a moot point. Yet if it truly can handle the torque and move with greater fuel efficiency then more power to them.

No idea, but I do know that the 6.2L, 6 Spd trans, and 3.73 gears work great in my Silverado, and is a great combo!

It worked out great last time, and still, no one does a FWD transmission as well as GM.

I'd really rather have GM just do all of the automatic development for both FWD and RWD and Ford just license it.

I wonder how a 9 or 12 speed tranny will do with the smaller engines that have high horsepower but pathetic Torque much like the asian auto makers or european makers that build the pathetic DOHC Revers. I would think that the 9-12 gears would be optimized for fuel mileage and yet you would want a torque monster engine to allow those gears to really do their job.

I wonder how a 9 or 12 speed tranny will do with the smaller engines that have high horsepower but pathetic Torque much like the asian auto makers or european makers that build the pathetic DOHC Revers. I would think that the 9-12 gears would be optimized for fuel mileage and yet you would want a torque monster engine to allow those gears to really do their job.

Na, if anything more gears allows for less overall torque.

I wonder how a 9 or 12 speed tranny will do with the smaller engines that have high horsepower but pathetic Torque much like the asian auto makers or european makers that build the pathetic DOHC Revers. I would think that the 9-12 gears would be optimized for fuel mileage and yet you would want a torque monster engine to allow those gears to really do their job.

Na, if anything more gears allows for less overall torque.

I would normally agree with you except that I have experianced auto's that went into limp home mode and if they have more gears like this and if the tranny is not able to go into the bottom gears for a solid limp home mode, then your left with an auto that really will not move due to the lack of torque and yet the crazy gearing.

I might be one of the rare exceptions to have this happen to, but I have had it happen enough to have decided I would rather give up gas mileage and have more power and especially Torque.

What's really needed is a wider ratio spread than is currently typical of 6-speed transaxles. We really don't need more speeds. In fact, more speeds can actually hurt performance and economy.

Most 6-spds are ~6.0:1; the GM Hydramatic 6T70 is 6.04:1 for example. 7 and 8-speed autos currently achieve ~7.5:1. The ratio spread is the difference between the tallest and lowest gear in the transmission. A wide ratio spread allows for stout acceleration from stand still in first and low rpms on the freeway in top gear. Having more ratios only reduces the amount of rpm drop during an upshift.

With 6-speed transmissions we already have what is close to the ideal in rpm drops on upshifts. Let me give you an example... the current GM 6T40 transmission (Cruze Automatic) will see revs drop from the 6300 rpm redline to 4100 rpms in a 1-2 shift at the redline. In more leisurely driving, a shift at let's say 3800 rpm will see revs drop to 2500 rpm. This is quite optimal as is. Because a redline shift drops revs to near the 1.8 NA engine's torque peak of 3800 rpm. The 1.4T with it's wider torque spread doesn't even really need such a close ratio. In higher gears the gap actually gets narrow so there is even less rpm drop (as a percentage). A 5-6 shift at 6300 rpm sees a mere drop to 4700 rpm.

Too many speeds actually hurt for three reasons. Firstly, the engine's power is not being fully applied to the wheels during a shift, it is being wasted as heat into the transmission fluid. Hence, energy is wasted during each shift. Secondly, it makes the car slower partly because you are not accelerating during a shift and partly because the car accelerates fastest in any gear at the torque peak hence you want to drop close to that (simply dropping less isn't necessarily better). Finally, a 8-9 speed transmission often employs 3 planetaries instead of 2 -- more gears meshing around = more frictional losses. That going beyond 6 speeds gets you quickly diminishing performance and economy returns is evident in the fact that most 7 or 8 speed boxes "skip shift" routinely. That is they bypass a gear and move two steps up quite often in leisurely driving.

The problem with making a 6-speed box with a 7~8:1 ratio spread is that the planetaries get pretty big. So it may actually be easier to make a 9-speed with that kind of spread.

Dwight, doesn't this allow them that? They can use a lot higher top ratio and slightly lower bottom ratio and then have a really low differential ratio. Spritely performance around town, tall gearing for the highway, better driving with less power (assuming that's the goal here)

... and there is also replacements for the existing 1.4T and 1.8 coming in about the same time frame.

Dwight, doesn't this allow them that? They can use a lot higher top ratio and slightly lower bottom ratio and then have a really low differential ratio. Spritely performance around town, tall gearing for the highway, better driving with less power (assuming that's the goal here)

... and there is also replacements for the existing 1.4T and 1.8 coming in about the same time frame.

Yes, a 9~10 speed auto will get you to (or past) a 8:1 ratio spread.

My point was that the 9~10 speeds really isn't necessary and may actually hurt performance and/or economy. What's needed is the ratio spread and a 6~7 speed transmission with a wider spread will do just as well if not better.

I wonder how a 9 or 12 speed tranny will do with the smaller engines that have high horsepower but pathetic Torque much like the asian auto makers or european makers that build the pathetic DOHC Revers. I would think that the 9-12 gears would be optimized for fuel mileage and yet you would want a torque monster engine to allow those gears to really do their job.

You realize that most Jaguar, BMW, Mercedes and Audis have loads of low end torque.

And the GM 2.4 liter and 3.6 liter engines make similar torque to the Asians, often at even higher RPM.

But to your point, more gears should help to keep the engine in the sweet spot and get more out of it. The switch from 4-speed to 6 allowed for downsized engines, and the 4-cylinder replacing the V6 in many cars.

I remember reading a while back that Mercedes thought 9-speed was the ideal and that 10+ was of no benefit, but of course they are making a 9-speed so that could be a biased point. I will say that the Mercedes 7-speed is the best transmission I ever experienced, so I suspect their 9-speed will be great too. Infiniti's 7-speed though is one of those gear skippers and it hunts for 6th or 7th to save fuel then throws itself down to 2 if you get on the gas, it makes for a jerky car to drive.