I've become more interested in such a transmission because I'd like to buy a Vette one of these days but have all but given up on the wife learning how to drive a manual. A DSG transmission would be a great compromise for the two of us, but right now it seems to be a german/european-only technology.

Is GM going to go that route eventually or is there a reason why they won't?

 

DSG? What dat? I test drove an 06 C6 with the 6-speed auto and paddle shifter last month. Hoo boy, that's the ticket.

 

Read about 3 threads above...

 

The new six speeds are "clutch to clutch" planetary setups (unlike the clutch/band setup in the Hydramatics, like the 4L60E). Not the same layout as the shaft type DSG (from Audi/VW) that have the concentric dual clutches, but I think the net result is pretty much the same. The engine is still pulled down in speed by the releasing of the currently engaged clutch and the application of the next clutch (engaging a different portion of the planetary setup, and changing the ratio).

The DSG might be a little quicker, but otherwise the effect is pretty much the same. Manual control of gear changes without the clutch pedal.

 

But the .pdf makes specific mention of a clutch in this particular GM transmission setup. I am wondering if it is going to be one of those deals where you need the clutch to get moving, but after that it is unnecessary.

 

So how quick are the shifts on the new 6-speed auto that's currently in the Vette and what is the parasitic loss akin to? More like an auto or more like a manual or somewhere inbetween?

That's the average difference in performance between the 6-speed auto and 6-speed manual Vette with a properly skilled driver in both?

That appears to still have a clutch, though.

 

I was reading a little thing that MT had on the new 6spd autos, and they really liked it. The paddle shift was fast, but they cried about the placment and fuction of the paddles more, and the whole function of the transmission and opperation was lost in the review.

 

Wow, there's a surprise. I swear, MT is absolutely pathetic.

 

But doesn't the new 6-speed auto still use a torque converter? The Audi DSG, if I understand correctly, is not saddled with a torque converter (or the horsepower it uses).

 

Correct, but I *believe* it will go into lockup in almost all of the gears. For example, the Allison six speed autos start off in converter mode (non-lockup) in first gear, to launch the vehicle. It stays in converter mode during the 1-2 shift and through most of second gear. Then it locks up, and stays locked up for the rest of the gears (even during shifts). I would guess the new car/truck six speeds will be more or less the same. Hell, they can even be calibrated to go lockup in first (after the vehicle has launched and gained speed), so that you are basically only using the torque converter to get the smooth launch with torque multiplication. But I don't know how the car six speeds are/will be calibrated.

One nice thing is that a torque converter is a better mechanism than a clutch to get a vehicle launched. Once the TC is in lockup mode, it (by itself) doesn't really rob power. However, the automatic will still have a slight disadvantage because it is always pumping fluid to maintain hydraulic pressure at the clutches. Plus, I think the spinning planetaries (and the TC, which is likely a little heavier than the clutch, since it is filled with fluid) create more spin losses than the shafts and gears in a typical manual. But from the perspective of the ability to manually control shifts, it might be quite comparable to a DSG.

 

DSGs have hydraulic pumping losses, too, since they have normally-open clutches that require pressure to be applied in order to transmit power (otherwise, a power failure would result in both clutches being applied at the same time, which would be A Very Bad Thing).

As myself and several of my co-workers have been saying for a while now, the lines between "automatics" and "manuals" is becoming ever more blurry, and the situation isn't going to get any easier to understand. Eventually, there will be several different automated gearbox types, and the terms that are currently familiar will really depend on the X-by-wire user interface. Cool stuff, in my opinion.

I don't get the fascination with clutch pedals, but hey, I bet that there were plenty of guys in the 40s who lamented the loss of manual timing adjustments

 

I wondered about that as I was typing, but my recollection of how the DSG is set up was far to fuzzy to claim it, and I didn't feel like searching for it. And yes, both clutches being applied at the same time would be A Very Bad Thing. We call that "tie up" around here, though in our case it would be when 3 clutches are applied...

I've wondered if the new six speed autos would convince me to go auto for a DD. I've driven a Grand Prix GXP, and the tapshift seems not so useful with only 4 gears, especially when 1st will hit 60 and 2nd will hit ~100. The five speed autos in the Cadillacs offer another gear, which is better. I haven't had the pleasure of a new Vette with paddle shift six speed auto. I did briefly get to try an XLR-V, but I used the shift lever to tap, and I was too interested in playing with the power of the s/c Northstar to note very carefully how it shifted (plus the transmission was in early stages of calibration at the time).

So far I still like the clutch...

Weren't you working on a mechanism to tap shift your T56 in your Impala?

 

Ah, yea, that's the term I've heard from transmission engineers.

I'm OK with one, too. I think that the manual transmission is a bit of an anachronism, but then again, I still feel like there's a place for such a simple mechanical system in our ever-more-complex world.

Rumor has it that something like this is going on I'd be lying if I said that there was any meaningful progress, as I'm struggling just to keep the transmission intact.