car: automatic gearbox questions...

[VJ]

Just found this article:

http://www.fastlane.com.au/news/clevervw.htm

perhaps only available in Google's cache:

http://216.239.39.100/search?q=cache:0cAq1ukY1TMC:www.fastlane.com.au/news/clevervw.htm+VW+Polo+%22dynamic+shift+program%22&hl=en&ie=UTF-8

Apparently, it *is* a DSP (there also is some technical explenation in that article).

Well, I guess this more or less settles it: some DSP's don't allow for manual shifting...
(confusing though)


Jörg

[impact]

Should've chosen DSG tranny. It's a manual, except for the fact that the clutch (actually, both clutches, because there are two hidden in there) is computer-operated.

[VJ]

Well, I don't mind it being only-automatic, but it would have been nice to have a choice (I learned to drive a stick-shift, and liked it a lot; however problems with my back and left-hip make operating a clutch painfull).
A problem is that there is very little choice in automatic gearboxes in small cars. Mostly, one is lucky if the small car can be had with an automatic...


Jörg

[impact]

Word.

But VW promised to offer DSG in most models, starting with the Audi TT and Golf R32 this year, so perhaps eventually the Polo (and Lupo, which imho is a bit smaller and a lot cooler) will get one. Untill then, we can salivate.

[agallag]

The old style of automatic transmissions were all hydraulic. All shifts are made based on engine speed and throttle position, as well as a few other physical indicators. There are no electronics involved in the shifts.

Electronic controlled automatic transmissions replace a lot of the hydraulics with electronics that make the decisions on when to shift to a different gear. Originally, it was based on most of the same properties that hydraulic systems used, but was much simpler to manufacture, and usually more reliable.

What DSP adds is some intelligence to the shift program. It can tell when you're going downhill and braking, and will automatically downshift to use engine braking. It can do lots of other neat things to modify the shift program based on what the driver is doing, and what the road and conditions warrant.

Another advantage to DSP is that it's really simple to add in the "manumatic" shifting, since it's all electronic already. I guess in your car they just didn't want to put in the extra movement into the shift lever... cheap bums

[VJ]

Impact: VW told me the automatic version of the new Golf would come about a year after the launch of the new model. They couldn't say what type of gearbox it will be (and perhaps the R32 will come before the regular model), but suspected it to be a DSP as well...

Agallag: thanks for the info!

Originally posted by agallag
I guess in your car they just didn't want to put in the extra movement into the shift lever... cheap bums

Jörg

[impact]

Yeah, but that's for the Golf Mk5, the new one. The R32 is entirely different beast, it's the current Mk4 Golf with some goodies added (VR6, 4x4, and DSG transmission amongst other things).

Also the DSG tranny should eventually replace the DSP one so I hope the Mk5 gets DSG. Afterall, it is superior (it even achieves better fuel economy than manual, amongst other things).

[VJ]

Hasn't VW (audi) succeeded in making the first fully automatic gearbox with better fuel economy than a manual ?
(I seem to remember something along those lines) If so, it could be that that is the "multitronic" as is now available in the A4...


Jörg

[agallag]

I know audi has a nice CVT available in the A4 over here (continuously variable transmission). They're supposed to be quite efficient. It basically acts as if it's a normal automatic transmission that has an infinite number of gears (it's way more complicated than that though). It keeps the RPM at the engines most efficient point to help save gas and improve performance. Apparently they're a little boring to drive, since there are no cool engine sounds that you get from shifting gears. Just a drone of constant pitch.

Howstuffworks.com has some excellent articles on the various types of transmissions. Worth a read.

[Jammrock]

The Mini has a CVT

Jammrock

[impact]

CVT is very odd indeed. The rpm are constant and the only thing that changes when you accelerate is your speed.

Now DSG otoh, it even revmatches for you when shifting with all the appropriate sound effects.

for the technically inclined, here's a review:

First off, DSG is not a standard automatic transmission by any stretch of the imagination. DSG is something that has never been offered in production vehicles before and is a direct result of racing technology from 20 years ago coming down to consumer levels. Volkswagen has applied for numerous patents on this transmission and has plans to implement it as a third transmission choice in nearly every automobile model they offer in the future, even replacing tiptronic in some models like the Audi A3 or GTI. So you can expect to find DSG along side a manual six-speed in the next Golf V GTI and Audi A3/S3 models for example. VW is even offering DSG in their new Touran MPV and in TDI models in Germany.

Looking at the photo of the shift gate below you can see that at first glance it appears to look just like a regular tiptronic transmission with standard P,R,N and D plus an added "S" for sport mode with a gate to the right for manual shifting. "D" and "S" are both automatic modes much like an automatic transmission however they are drastically different in character - almost like having two different transmissions in the car.

Put the DSG in "D" and it behaves just like a regular automatic for the most part except that at a stop the car goes into neutral. When you start to ease off the brake, the clutch will smoothly engage just like a manual transmission. The current DSG programming for the "D" setting is conservative and shifts up through the gears very quickly if you are driving sedately around town to keep the fuel consumption reasonable. This may seem like a bad thing, but the transmission can make a 6th gear to 2nd gear change in .9 seconds - so when you put your foot down the transmission downshifts RIGHT NOW and immediately into the power band (and rev matches which is trick sounding with the 3.2l VR6). Normal upshifts are unbelievably quick and smooth with no jerkiness.

Drop the transmission in "S" for sport mode and you'll feel like you just swapped out the entire transmission with a complete race setup - the engineers that programmed this mode must really love to drive hard. The sport mode is still an "automatic" mode until you click one of the paddles. However it is very aggressive as it always tries to keep the car on boil between 4000 RPM and redline - imagine driving around like that all the time and you can see why it has its practical limits. Shifts are still VERY smooth between gears (almost too smooth in our opinion, but VW and Audi say they are looking into adjustments) and the transmission keeps the revs in the optimum power band. This setting is so hard core that it is really only useful for track events and driving on very twisty roads.

In sport mode the transmission utilizes fuzzy logic in the programming and is scary in how well it seems to anticipate your need to downshift - enter a straight-away, wind it out to redline, upshift and as you come into the next turn the transmission will rev-match and downshift into the meat of the powerband right about the time you want to down-shift. Since the computer already knows all the optimum shift points to keep the engine in the power band, the DSG will likely out-smart the driver. If you leave the transmission in "S" mode and don't touch the paddles, it will shift up and down through the gears automatically. At any time you can click the paddles and the transmission will assume you want to shift yourself from now on. And it will wait for your shifts - on the cars we drove you could bog it to death or run it clear into the redline and the DSG obeyed your command.
At a basic level DSG is a dual-clutch electronically controlled transmission that can be shifted manually via the shift lever or paddles on the steering wheel or it can be dumped into drive and used like an automatic - there is no clutch pedal. DSG utilizes 2 clutches, 2 main input shafts and 2 sets of gears - 1st, 3rd, 5th and Reverse on one shaft and 2nd, 4th, and 6th on the other. Because this is a wet system, there is an oil coiler and oil filter attached to the transmission.

DSG is completely different from BMW's SMG and Ferrari's F1 system in that it has two clutches instead of one. This means that DSG can fire off an upshift in .008 seconds whereas BMW's SMG takes .8 seconds to make the same shift.

Here's how it works (try to stay with us here): At a stop, the transmission drops into neutral. When you start to lift your foot off the brake, the clutch connected to input shaft 1 will smoothly engage moving the car forward much like a manual transmission except electronically and automatically. Input shaft 1 is now controlling first gear providing power to the wheels. While input shaft 1 is in first, input shaft two has selected 2nd gear in anticipation of the next upshift. When the transmission requests 2nd gear (either via the paddles, gate or automatically) clutch one opens up and clutch two engages in as quickly as .008 seconds. There is a certain amount of slippage in the clutches to ensure a smooth transition from gear to gear. In the event of a downshift, the transmission will request a throttle blip from the engine ECU to match revs and then shift down a gear - this happens in as quick as .6 seconds including the throttle matching. The transmission can even shift from 6th to 2nd gear without having to sequentially run down through every gear. In this case, DSG will switch input shafts from 6th gear going to 5th temporarily on input shaft 2 and then into 2nd with input shaft 1 while blipping the throttle to match revs - all in less than .9 seconds. Got that? Good.

The entire system is electronically monitored and controlled via a mechatronics module inside the transmission. This module communicates with the engine ECU and other electronic systems as well.

If you look at the photo above, you can see shift paddles on either side of the steering wheel along with what looks like a standard automatic/Tiptronic shift gate. The paddles are physically connected to the back of the wheel itself, not the steering column. That way they are always at the 9 and 3 o'clock positions. The left paddle is for down-shifts, the right paddle up-shifts. They are mounted close to the surface of the back of the steering wheel, have a very positive feel and have a very short and precise travel. Also, the R32 paddles are slightly larger and made of brushed aluminum, whereas the Audi TT paddles are black plastic and smaller.

Lastly, VW and Audi engineers have included a launch control feature - put the transmission in "S" mode, turn off the Electronic Stability Program (ESP), hold the brake pedal down with your left foot and floor the gas. The revs will rise to around 3,000 RPM and then quickly remove your foot from the brake pedal and the car will chirp the tires and launch HARD as if you revved a manual transmission and dropped the clutch. Pretty darn cool and a sure fire way to nail those stoplight launches.

The torque rating of the DSG transmission in the TT 3.2 and VW R32 is 325 newtons meters or 240 ft-lb - right about the torque rating of the 3.2l VR6. The DSG transmission weighs about 66 lbs. more than the standard manual MQ350 six-speed. However that includes an oil cooler, ECU, two clutches and more so it isn't exactly an apples and oranges comparison.

DSG utilizes a lot of components from the new six-speed MQ350/02M350 transmission including gears, syncros, sliders and more. DSG maintenance intervals have not been finalized, but it looks like a fluid and filter change about every 45,000 miles.

[impact]

You can find the whole review here: http://www.vwvortex.com/features/ind...irstdrive.html