[Lotus7]

POST DELETED

[smarm]

Just wondering where you've sourced your times from?

Upshifts with the VAG DSG gearbox are often quoted at 8ms upshifts. Fair few tech docs supporting this. As impressed as I am with the X3's box, it's still IMO not comparable with a dual clutch system.

[Bustofa]

Very interesting. Thanks Lotus.

[Max3Factor]

Also used in the latest 7 series and Rolls Royce Silver Ghost my dealer said.

[Filski]

Originally Posted by smarm

Just wondering where you've sourced your times from?

Upshifts with the VAG DSG gearbox are often quoted at 8ms upshifts. Fair few tech docs supporting this. As impressed as I am with the X3's box, it's still IMO not comparable with a dual clutch system.

Interesting you say that. My wife says she preferred the Q5's transmission. I told her she had rocks in her head, but since I've yet to try the X3 I can't say for sure.

[smarm]

Originally Posted by Lotus7

I believe the Q5 uses the Getrag 8-speed Tiptronic in the 2.0 cars and a 6-speed in the 3.2 cars (not DSG). Both are nice transmissions and are also used in some Mercedes cars. Since they're all electronically controlled these days, the transmission shift smoothness can be taylored to the specific vehicle trim. Most people judge a transmission by how transparent the shifts feel. Full throttle "fast as possible" shifting is another situation entirely and would probably rattle any rocks in anyone's head quite a bit.

In Australia, they all use the DSG box, "s-tronic" in audi speak. Thanks for the PDF as well, having good read of it now.

[smarm]

Originally Posted by Lotus7

smarm,

Thanks! Although I really try, I'm too often guilty of forgetting that different countries have vastly different versions of cars with the same names, and that car manufacturers sometimes seemingly, without any obvious reason change configurations at will.

One of our US car rags, "Car and Driver" (May, 2011) just published a comparison road test of the Audi TT RS, the BMW 1-Series M Coupe and the Infinity IPL G37. The Audi ran away with the 0-60 mph acceleration segment with a time of 3.6 sec. (BMW was 4.5 and the Infinity was 5.4). However in the fine print of the article, C & D stated that the Audi was a European model with a DSG transmission with Launch Control. They then go on to state that the US version won't be available with either the DSG or Launch Control, completely negating all of their acceleration comparisons. Oh well.

Heh, and just to add to confusion, if you order my current car (135), there's manual, DCT and automatic! How's that for choice!

[WAY]

I didn't think you could get auto anymore on the 135i. It's manual or DCT only?

Lotus, you forget that BMW starts building the X3 30D this month using the exact same transmission, with 560nm/413 lb/ft.

As for Porsche, they were the inventors of dual clutch gear box (not sure in conjunction with which transmission specialist) for their 962 race car. It was absolutely brutal though and it took 20 years for electronics to catch up for it to be possible to use for road cars.

[BXM3W]

Originally Posted by Lotus7

I believe the Q5 uses the Getrag 8-speed Tiptronic in the 2.0 cars and a 6-speed in the 3.2 cars (not DSG). Both are nice transmissions and are also used in some Mercedes cars. Since they're all electronically controlled these days, the transmission shift smoothness can be taylored to the specific vehicle trim. Most people judge a transmission by how transparent the shifts feel. Full throttle "fast as possible" shifting is another situation entirely and would probably rattle any rocks in anyone's head quite a bit.

I'm pretty sure the Q5 uses the ZF transmission, too. Here's one source...

"Audi will widely use an eight-speed automatic transmission produced by ZF, instead of a six-speed unit on cars sold in the United States, according to AutoWeek. The periodical cites the new 2011 dealer order guide when it says that roughly 70 percent of vehicles sold in the U.S. will feature the transmission.

Amongst these are the 2.0-liter turbocharged versions of the Audi A4 four-door and Avant, A5 coupe and cabrio, and the Q5. All versions of the Q7, along with the A8 and A8L will also be sold with the ZF eight-speed."

Read more: http://www.worldcarfans.com/11005132...#ixzz1JE0w9xoV

[sfax]

The Q5 uses 7 speed S tronic for all the diesel models

[Insider]

Does the X3 blip the throttle on downshifts?

[halohead52]

This is all fascinating. The transmission has taken some getting used to but I really like the way it feels. Especially appreciate the insights into the deceleration, as it is quite striking.

[bekind]

I've heard rumors that some of the 2012 chrysler products will have a slightly tweaked version of this zf 8 speed. They mentioned this for both their cars and suvs.

[sand99]

Great info Lotus!

I'm curious, which ZF 8-speed tranny is BMW using in other vehicles like the RWD 528i/535i? I was really impressed by the shift speed of these when I drove them as well.

[bekind]

They need some serious help! We actually cross shopped the new Grand Cherokee and the transmission certainly was a weak point. It's a shame too because the ML sourced chassis if very composed. I feel the tranny is really the only major thing holding them back. The 8 speed will go along way in improving that suv.

[weiweiwei]

Does it have downshift rev matching as the previous ZF?

[Insider]

Originally Posted by Lotus7

No, and a few people on this forum have complained that they really don't like to feel the slight deceleration "surges" as the transmission downshifts through each gear. The X3 seems to stay in a fully locked torque converter mode until the engine drops below 950 rpm so you can “feel” every downshift as opposed to vehicles that let the converter unlock and cushion or decouple the downshifts. A throttle blip might help a little, but would probably violate BMW’s attempt at squeezing every possible btu from each pound of fuel.

I haven’t found it to be at all objectionable, but then I’m used to driving 3-pedal manuals much of the time and it seems natural to be able to feel the engine compression slowing the car down.

Well that's too bad. I was hoping it would rev match like my current 335i auto does. Must be for fuel economy reasons.

[MA78]

Originally Posted by Lotus7

I haven’t found it to be at all objectionable, but then I’m used to driving 3-pedal manuals much of the time and it seems natural to be able to feel the engine compression slowing the car down.

I guess this is why I haven't been bothered by this. The X3 is my first automatic.

[LEDZEP]

Good thread.

[Ant Man]

great post Lotus7. Also another interesting fact is different brands of cars sharing the same ZF gearboxes but due to different software, feel and perform completely differently.

[Nahoa]

I don't see any notable difference in the downshifts between the X3 and my 330i.

[frankwin]

Originally Posted by Lotus7

Another interesting feature of the 8HP is its ability to execute shifts under full power very quickly. It’s in the same ballpark as the most sophisticated dual clutch manual transmissions and only transmissions used in much more expensive, very high performance sports and racing cars are significantly faster.

Single gearshift speeds (milliseconds)

Ferrari 575M 250 mS
BMW X3 35i 200 mS
Ferrari F430 150 mS
Ferrari 599GTB 100 mS (fastest shift speed achieved in a production “street’ car)
Ferrari 2010 F1 race car 50 to 60 mS (state of the art)

For reference, a very good driver using a conventional H-pattern manual transmission with good syncros, and a fast-acting manual clutch can perform a manual shift in 500 to 600 mS. A sequential, dog clutch racing manual gearbox might improve that to 300mS.

Finally, the 8HP is one of the few transmissions that can execute downshifts that “skip” going through most intermediate gears. With one shift it can jump from 8th to 2nd. or from 5th to 1st.

For more info about the speed range in each of the (8) gears in an X3, please see this previous thread:
http://x3.xbimmers.com/forums/showth...ighlight=speed
Attached is a pdf with more details about the engineering behind the 8HP transmission.

These numbers are great and agreed this transmission seems fantastic but do you know the power lost compared to a manual transmission? I would be curious too see if the quick shifting compensate for the higher power lost at the wheels during maximum acceleration.