ZF 8 speed automatic

[SteveSRT8]

Originally Posted By: hattaresguy
Originally Posted By: SteveSRT8
Compare the shifting of an Audi versus a BMW. Both use the exact same gearbox above.

In the latest comparo I read in Car and Driver the Audi was a completely different transmission, never hunted between gears and drove transparently.

That's why it's programming. You just don't get it. Do you really think Bentley owners will tolerate any fuss whatsoever? Their 200 mph Flying Spur uses the SAME transmission!

Come with us into the future....


Those new Bentley's are not that good, over hyped VW's.

Now an Arnage...which cost a lot more than $200k and some change...those were nice cars.



Perhaps in your opinion. I recently drove one at an auto show and I can tell you that they are VERY nice, a nearly unbelievable combination of speed (over 200 mph) and ultra luxury. Highly capable chassis design as well as awd with 600 hp is definitely a sweet ride!

 

[asiancivicmaniac]

The Aisin 6 speed in the Miata shifts perfect.

 

[andyd]

7 spd , 8 or 9 speed autos. Another boy racer buzz word. In Drive, my 128 HP,3200 pound BMW is doing 88 MPH at 3K RPM. The de-tuned M 20 is just coming onto the cam at 3k . The ECU shuts off the injectors at 5.2K RPM.

 

[HTSS_TR]

Originally Posted By: JHZR2
A well geared 6-speed MT like in my 135i really cant be beat. Its got a useful enough 2nd gear that its super easy to drive in traffic, and a good 6th gear to get >30 MPG highway with a 300hp vehicle with full torque at fast idle.

I wish my S2000 has similar gear ratio. It has good transmission but for tracking/racing than for cruising on highway. It spins around 4500 RPM at 75 MPH, it should be around 3000-3200 RPM at that speed.

 

[Hokiefyd]

I guess this same, or similar unit, is used in this rental Chrysler 300 that I (still) have. I have an objective comment to make, and a subjective comment.

Well, maybe they're both subjective comments.

I share Steve's opinion that these will be much better with improved programming. I don't like how the transmission is programmed in the 300 at all. There's little performance from the engine unless you really step on it, because the transmission is always upshifting. Then you get too much when you floor it. There is also no user control over the gears, but that's Chrysler's fault, and not the fault of the transmission.

Subjectively, I don't like the delay as it downshifts to accelerate. You can perceive it counting down gears...it doesn't seem to be able to shift from, say, 5th to 2nd directly. Maybe it can and this is more poor programming. There's a good 1-2 second delay from when you push be gas pedal until you get the surge of power. Part of the problem is...back to programming...the dang thing is in 5th at 25 mph loafing along at 1,000 rpm.

I will say that I prefer fewer gears, with wider spacing. I'm an engine guy; I love to hear the engine rev and listen to it work. I know that an 8 speed will objectively make more use of the engine's power band, I know all that. It sort of feels too "sterile", with less emotion from the engine. I dunno...hard to describe.

Objectively, these are awesome units. Give me control over the gears (or program it better) and I'd be a happier camper.

 

[demarpaint]

Originally Posted By: Hokiefyd


I will say that I prefer fewer gears, with wider spacing. I'm an engine guy; I love to hear the engine rev and listen to it work. I know that an 8 speed will objectively make more use of the engine's power band, I know all that. It sort of feels too "sterile", with less emotion from the engine. I dunno...hard to describe.


+1 I drove an 8 AT in a rental for a week and it drove me nuts. 25 mph in 5th gear, give me a break, delays, what seemed to be a lugging engine. I didn't like it. I think 5 speed is my limit for an automatic transmission. Before I get flamed its only my opinion.

 

[mechtech2]

Originally Posted By: JHZR2
To add speeds, you have to add gearing ratios and their respective bearings and support hydraulics. For a given volume, the sizes of all this stuff (bearings most importantly, I guess) need to shrink.

Less bearing, more load from higher power engines = no good.

I fear longevity on 4 speed ATs, let alone these.

A well geared 6-speed MT like in my 135i really cant be beat. Its got a useful enough 2nd gear that its super easy to drive in traffic, and a good 6th gear to get >30 MPG highway with a 300hp vehicle with full torque at fast idle.


Why assume bearings shrunk? Maybe some are larger and better.

 

[hattaresguy]

Originally Posted By: Hokiefyd
I guess this same, or similar unit, is used in this rental Chrysler 300 that I (still) have. I have an objective comment to make, and a subjective comment.

Well, maybe they're both subjective comments.

I share Steve's opinion that these will be much better with improved programming. I don't like how the transmission is programmed in the 300 at all. There's little performance from the engine unless you really step on it, because the transmission is always upshifting. Then you get too much when you floor it. There is also no user control over the gears, but that's Chrysler's fault, and not the fault of the transmission.

Subjectively, I don't like the delay as it downshifts to accelerate. You can perceive it counting down gears...it doesn't seem to be able to shift from, say, 5th to 2nd directly. Maybe it can and this is more poor programming. There's a good 1-2 second delay from when you push be gas pedal until you get the surge of power. Part of the problem is...back to programming...the dang thing is in 5th at 25 mph loafing along at 1,000 rpm.

I will say that I prefer fewer gears, with wider spacing. I'm an engine guy; I love to hear the engine rev and listen to it work. I know that an 8 speed will objectively make more use of the engine's power band, I know all that. It sort of feels too "sterile", with less emotion from the engine. I dunno...hard to describe.

Objectively, these are awesome units. Give me control over the gears (or program it better) and I'd be a happier camper.


My latest experience with the 8spd was in a 2013 BMW.

328Xi, wanted to check out the 4 banger which was pretty good.

I had the same impression as you did with the 8spd, to many gears, to busy. When your going and get on it, its got to move threw a bunch of gears before anything happens. Kind of like turbo lag in an 80's car but not nearly as amusing. In an economy car like the 328XI that's fine, but in a performance car like say a 550I it would be annoying to say the least.

Only way to make it decent is to shift it manually and lock it into a few gears.

IMHO the 722.6 is a better gear box, beat it over the head and go, what was so bad about 5 speeds?

Porsche has a better auto if you must go with one, as does Mercedes. The latest 7spd 722.9 is tolerable, still to many gears but every one less helps.

 

[JHZR2]

Originally Posted By: mechtech2
Originally Posted By: JHZR2
To add speeds, you have to add gearing ratios and their respective bearings and support hydraulics. For a given volume, the sizes of all this stuff (bearings most importantly, I guess) need to shrink.

Less bearing, more load from higher power engines = no good.

I fear longevity on 4 speed ATs, let alone these.

A well geared 6-speed MT like in my 135i really cant be beat. Its got a useful enough 2nd gear that its super easy to drive in traffic, and a good 6th gear to get >30 MPG highway with a 300hp vehicle with full torque at fast idle.


Why assume bearings shrunk? Maybe some are larger and better.


Fine, maybe they didnt. What else shrunk then to fit more gear ratios into the same or smaller overall volume?

 

[PandaBear]

Originally Posted By: JHZR2
Originally Posted By: mechtech2
Originally Posted By: JHZR2
To add speeds, you have to add gearing ratios and their respective bearings and support hydraulics. For a given volume, the sizes of all this stuff (bearings most importantly, I guess) need to shrink.

Less bearing, more load from higher power engines = no good.

I fear longevity on 4 speed ATs, let alone these.

A well geared 6-speed MT like in my 135i really cant be beat. Its got a useful enough 2nd gear that its super easy to drive in traffic, and a good 6th gear to get >30 MPG highway with a 300hp vehicle with full torque at fast idle.


Why assume bearings shrunk? Maybe some are larger and better.


Fine, maybe they didnt. What else shrunk then to fit more gear ratios into the same or smaller overall volume?


The clutch packs

 

[Hokiefyd]

Originally Posted By: hattaresguy
Only way to make it decent is to shift it manually and lock it into a few gears.


Yes: give me some paddle shifters on the wheel or a slap shifter on the console. Too many cars, even non-performance cars, have slap shifters with the + and - on the console for a fully modern 8-speed transmission to not have one. Again, the fault of the automaker and not the transmission.

 

[JTK]

I'm sure there's applications where an 8sp AT makes for a great driving experience, but for most passenger vehicles? No way.

This makes me love my CVT even more.

Joel

 

[greenjp]

Originally Posted By: SteveSRT8
Jeff, you need to get out more. A recent test of Audi vs. Mercedes vs. BMW had the audi beating both HIGHER powered cars to 60 mph via its superbly programmed ZF 8 speed gearbox. It would not have been close with a 6 speed stick or slushbox. See Car and Driver for the details.

A small note: there is no "time lost" to shifting in a modern slushbox. Forward power is not interrupted to shift. That's why they are undeniably superior in a straight line. They are quickly becoming superior in economy as well.

Note this topic is NOT ABOUT MANUALS. They are still a driver's choice.

A few small notes of my own

I'm assuming you're talking about the S6 vs. M5 vs E63 AMG test here. An AWD Audi is going to have an advantage in a 0-60 contest against RWD cars regardless of transmission. Don't take my word for it: "A word about acceleration: While the M5 and the E63 are spinning tires on launch, the four paws of the S6 have already propelled it off the reservation, which is why it’s so quick to 60." (Car and Driver, July 2012). For the record, their 0-60 and -100 times are 3.7/9.2 (S6), 3.7/8.1 (M5), and 3.8/8.2 (E63).

The BMW in that test has a 7 speed dual-clutch automatic, the Benz has a standard type 7 speed, and the S6 has a 7 speed dual-clutch automatic. I double-checked the latter on Audi's website to be sure it's not the ZF 8 speed.

So no, that test doesn't prove anything about what more transmission speeds get you. It does prove that AWD provides superior launch and that an extra hundred or more hp will make up for it once you're at extra-legal speeds.

Per ZF's website, the 8 speed gives a 6% improvement in fuel economy compared to their old 6 speed. 6% of say 30 mpg is 1.8. I'll concede this is a little more substantial than marginal. They also suggest faster acceleration but provide no associated numbers. They do specify that shifts take 200 milliseconds. FWIW as the 8 speed is a conventional type automatic, there is in fact a delay in power transmission during the shift. Not too much but one more shift is 0.2 seconds lost. If this sort of thing matters in real life, which I'd argue it doesn't

I did find the August 2012 A7 vs 640i test, which does feature similarly powered cars (310 & 315 hp) both using the 8 speed ZF. The Audi wins that 0-60 by 5.1 to 5.4, and maintains it's lead through higher speeds. That's likely due to the superior AWD launch, similar hp, and 100 lbs less weight.

By all means, continue comparing tenths of a second and 1-2 mpg differences among the various automatic transmissions. I'm sure someone will chime in regarding CVTs at some point. I'll stick with sticks

jeff