The DCT in the PGT3 adds 70lbs to the wrong place on this car plus another 30lbs to steer the back wheels to keep it tame.

Here is the GTR layout. Wonder why the car is so heavy?




This is the GTR Xmission. A fragile unit that is plagued with problems. Don't keep it beyond the guarantee period. A clumbsy bit of engineering that needs plenty electronic intervention to keep it alive. Plenty lemon law claims.


It is not strong enough for the GTR but won't even fit in the ZR1 chassis which is close to the C7 design. AWD???


You could put the clutches behind the gearbox like in this Ferarri FF and add 100 to 150lbs.


You can add the FFs front wheel drive system if you can find the space, another 150lbs.


Careful what you wish for. check what Corvettes do arounf the Ring again.

 

Shaka, really nice shots, thanks

 

Let us know what your Ring time is the next time you drive that track...

 

Good article. GM has realized the need for an improved auto for some time now. Only problem I see with the staged upshifts is that there is no mention of a similar algorithm for the downshift. Probably not a big deal for some, but for others it would be noticeable, especially those who track their cars. For example, if the clutch fill time is already reduced in anticipation of an upshift, what happens when you jab the brakes and hit a quick downshift instead?


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A slow(er) down-shift I don't think would be a bad thing. Consider how much a botched downshift on a manual upsets the rear of the car for reference. The key is to have a throttle blip associated with the downshift to make it as smooth as possible, regardless of the time it takes to complete it. If memory serves correctly, when Ferrari released their DCT for the 458, some owners complained that it was "too smooth" with no jerk on up or down-shifts, as it was tuned to keep the rear planted under heavy acceleration and braking.

 

Ive done 12 laps there on two differnt occasions. How many have you done? 6 in a 928 and 6 in a ZR1. There are many other cars on the track and it would take a long time to learn it.

 

Let us know what your GT5 time is the next time you take your trololololololmobile for a spin

 

In your car?

What was your best lap time?

 

What's a GT5?

 

There is a world wide race going on to build the ultimate slush box. There are great tranny shops that will build you a fast changing auto that will beat any stick and DCT. Maybe not for iddy biddy engines.
This an American designed and built ZF 9 spped that will be used for a number of high performance cars.


The dual clutch technology requires to many parts, to input shafts and sometimes a split output or counter shaft. Heavy and expensive and unreliable. People suggest that this is the way of the future. No way. Look how compact and light you can get an auto these days. Short shafts can take much more torque and there is no redundancy in the tranny. Epi cyclic gear combos have the same drag as constant mesh.
Torque converters have advanced to such a degree that they smaller and lighter with their own internal clutch packs.
You simply can't make clutches work like fluid without a lot of wear.
The DCT was designed in the 30s for heavy armored vehicles to get thru sand and mud. They were heavy then, and they are heavy now.
Tadge said they have been working on a 4 speed auto that gives damn near DCT shift performance. The market requires at least 6 speeds. Also, it must pass GM's 100 hour durability tests.
ZF CEO Stefan Sommer as saying nine speeds are the “natural limit.” In Sommer’s words, “There is no hard line, but you have to consider the law of diminishing returns. The question is whether adding even more gears makes sense.”

That sentiment is echoed by Julio Caspari, president of ZF’s North American division, who believes that the race for more gears is driven by marketing and not engineering. As proof, Caspari says that there’s only an 11-percent gap in efficiency between today’s most-efficient gearboxes and a theoretically perfect ideal.

We’d be the first to point out that more gears equal more complexity, higher cost and, potentially, more points of failure. Unless someone can conclusively prove that ten speeds are better than nine, we say let’s turn our attention to other areas, like making more power from less displacement.

 

I like having more gears. Mechanical advantage for acceleration and big overdrives for fuel economy.

IIRC the original trans that came in the first model years of the GTR was garbage but since then they've improved it. Not to mention AMS's GTR broke into the 7's recently. It is using upgraded components from John Shepherd though.

 

Before anything, if GM was using a ZF 8-speed tranny, I don't think anybody would be complaining. Having said that, I believe Mercedes has the ultimate solution: the size and reliability of a planetary-gear automatic transmission, but with wet clutches instead of a power and weight-sapping converter.

They still do. But it was actually released on the California first, with the same complaint, even though it's more of a GT car. Have many miles on a 2010 Cali, and it feels boring. A friend has a 430 F1, and even though it shifts slower, it's a lot more fun, sounds like a manual driven by an expert, you get a big push at every shift, like a manual, and it blips the throttle on downshifts, which sounds awesome with the valves permanently opened. The only instance where the DCT beats the F1 is it jerks less when starting slow, like in heavy traffic. The F1 is actually the same Graziano manual transmission but with an electro-hydraulic clutch actuator and gear changer. VERY complex and heavy.

To me it does. In fact, I'd put that limit at 8 myself. Any more and you might as well get a lighter CVT, because it'd feel basically the same (which is 'like crap' to me ).

 

LOL

 

I can say definitely that a slower downshift is not what I want to try to adapt my driving around. It's not a huge deal on the street, but on the track I'd rather not have to plan for the added engine braking coming in late after my intended shift, as I could already be turning in when this happens. Even with a perfectly smooth shift, you have to deal with the engine torque in the lower gear when it engages. If you know the track you could adapt around it, but I think most of the folks who track their cars would be much more precise with a fast smooth downshift, versus a slow smooth downshift.


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The engineers at lexus purposely didn't put a DCT in the LFA because it was "unnatural"

 

Nice point!!! Some people need to call Weismann transmissions and ask them what one of their built autos are capable of! Inferior, NOT!

 

This may be sImiliar to what gm is planning for DCT convertor combination for future transmissions

Scroll down to see the convertor dct in real life..ldifferent application but reviews have been positive with regards to fun to drive relevance.

 

http://mazda.ca/MciWeb/skyactiv.action

 

The new GT3 trans. And quotes from Porsche..lol.
At Porsche we all love to shift gears manually, but what we love even more is being the fastest.”

Still, it’s a relief to note that we’re not dealing with any ordinary “Porsche Doppelkupplung” in this instance; instead it’s the amped-up adrenaline junkie of the family, the one that achieves top speed in top gear and packs closer ratios. It’s easy enough to say that shift times are down to just 100 milliseconds, but do you know what that means? The GT3 comes with Sport and Race Track transmission modes, and in the latter the up-changes are so fast it’s almost as if the car is prepared to break itself in the effort to please you.

Literally, it’s like an electric handclap – BAM – and you’re accelerating hard into the next gear. Porsche calls this a “lightning shift”, and the process is supercharged by a “torque overshoot” feature that hurls the engine into the new ratio. Down-changes are similarly dispensed with no pause and no mercy; you get exactly what you want at exactly the right time.


Techno, techno, techno, techno…

Even the paddleshifters have a 50% shorter action in the GT3, but if you do crave greater interaction you can always use the lever – which works superbly with Porsche’s ambitious but successful attempt to replicate the feel of a sequential racing transmission.

This combination of supersonic engine and whip-crack gearbox is utterly mesmerizing. If the manual transmission has got to die, this is surely the way it wants to go – vanquished to the point of irrelevance. But this wouldn’t be a GT3 without a chassis that also does extraordinary things to your nerve endings, and this car is in no mood to disappoint.

 

Excellent posts by Shaka, debunking a lot of the DCT hype and myths.

Thank you for posting!