By on November 7, 2012

Wondering when the automatic gearbox arms race will end? 8 speeds? 9 speeds? Even 10 speed gearboxes have been thrown out as grist for the automotive rumor mill, but one exec apparently has the answer.

The CEO of ZF transmissions said that 9 speed gearboxes will be the zenith of transmissions – anything more will be too complex and heavy to produce any efficiency gains.

Stefan Sommer, ZF’s grand fromage told Automotive News Europe that 9 speeds is the “natural limit” for gearboxes, and anything beyond that invokes the law of diminishing returns. Chrysler is expected to be the first to adopt a 9-speed automatic, but don’t look for anything beyond that, says AN

Earlier this year, Julio Caspari, president of ZF’s North American operations, hinted that a “Can-you-top-this?” race to add gears may be driven by marketing considerations rather than fuel economy.

That’s because there is only an 11 percent gap between the most-efficient transmissions today and a theoretically perfect gearbox


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53 Comments on “ZF CEO: 9 Speeds Is Enough...”

  • avatar

    Hey, new design! I like the change. Now if only the menubar up top would change stories (it’s been the same ones since the beginning of time it seems).

    • 0 avatar

      +1 it seems easier on the eyes

    • 0 avatar

      It’s pretty good, I agree. Now, if only the logo-that-no-one-liked can get voted off the island.

      I wonder if it’s better on mobile?

      • 0 avatar

        It is quite a bit better on mobile. I was using my phone when I noticed the change this morning. Good on you, TTAC, for having a nice website. Now it will be even easier for me to be distracted in class!

    • 0 avatar

      I agree, nice design. However pinch to zoom does not work on my tablet anymore. And could you, please, do something about being logged off every few days and also if I hit “Comments” button could I be redirected to the comments and not to the beginning of the article. Thanks.

      • 0 avatar

        Bimmer wrote: “… pinch to zoom does not work on my tablet anymore …”

        I hope this gets addressed quickly too. The other improvements are for naught, if I can’t comfortably read the site.

  • avatar
    el scotto

    Yep, marketing. ZF will build a 10 or 12 speed gearbox if someone pays them.

  • avatar

    Sure, they may build a 24 speed gearbox, but that’s it, because 24 is the highest number.

  • avatar

    Well, at some point it has to be mechanically simpler to just throw a narrow-range CVT in front of the slushbox than to add more gears. Maybe 9 is it?

    • 0 avatar

      Or go the bicycle route of using two gearsets to create a hella-lot of gears.

      • 0 avatar

        Actually, the planetary gearset transmission went the bicycle route when moving beyond 2 forward speeds. Each gearset can provide 2 forward and 1 reverse ratio. So, if you have 2 gearsets back-to-back you would easily have 4 forward gears (2×2) but actually can get a 5th forward gear by running both gearsets backwards, as two wrongs make a right! The added complexity of coordinating switching 3 gearsets simultaneously held things down until computers started operating everything; then we went to 6, 7, 8, and (soon) 9. At some point, switching so many gearsets around, even with electronic controls, becomes more of a hassle than the benefit.

        Check out this website:

      • 0 avatar

        I recommend the book called Changing Gears by Philip Gott. It covers the history of transmission design and development until just before the LePelletier 6 speed (now everywhere), and the automated layshaft (dual clutch) transmissions. He does a good job of humanizing the stories which keeps it from getting too dry.

  • avatar

    I suppose they can’t reach Infinity with brute force that CVT yields.

    (I know I’m making a dumb joke).

  • avatar

    If it costs $2,500.00 to $3,000.00 to rebuild the typical 3-4 speed automatic, does anyone know the cost of rebuilding the new 6-8 speed automatics? I suspect a LOT more. With these new automatics, are separate oil coolers standard equipment?

    • 0 avatar

      I think your right about the cost. However, since the 6-8 speed transmissions have smaller steps between the gear ratios and clever computers controlling the switching, they will hopefully wear out more slowly.

    • 0 avatar

      It’s not that much more expensive. The extra clutches and steels don’t cost that much more, and that is all that’s usually replaced in a basic rebuild. A Mercedes 7 speed trans is about $4000, and that is at the high mark up of a Mercedes OE part.

  • avatar

    This whole thing reminds me of the razor “blade wars” that have been going on for the past 30 years (but really took off in the 1990s). Search for the SNL Triple Trac razor ad from the 1970s – and life imitated art many years later!

    How many blades are we up to now? Five?

    BlueBrat – you beat me to the CVT joke! Gearbox makers unite: To Infinity and Beyond!

  • avatar

    I’m not buying a car with fewer gears than my bicycle. 27 speeds MINIMUM, ZF. You guys have to test your theoretical limit. Maybe every gear over 9 adds efficiency beyond 100%.

  • avatar

    640k also ought to be enough for anybody, right?

  • avatar
    bumpy ii

    Add a 2-speed differential and BAM! 18 speeds, beeyotch.

  • avatar

    I admit that I haven’t driven an automatic with more than 5 speeds, but I’ve heard that the 6, 7, and 8-speed units sometimes “hunt” between two gears. It sounds like a software issue that could be solved in time, but who knows?

    • 0 avatar

      This week’s rental is a 8-speed Chrysler 300 and the workings of the transmission are absolutely imperceptible. You accelerate obviously, and you see the tach move indicating that the transmission is doing something but you don’t feel any gear changes.

    • 0 avatar

      It depends on the goal of the car. For instance, the 8-speed ZF units in the Mercedes S class, Audi S8, and BMW 7-series are very good at making the shifts mostly imperceptible, and basically being close-ratio 5-speed’s with three overdrives for economy on the highway. They generally start from second gear unless you go full throttle, and with the twin-turbo engines in these cars, use the lower end torque to keep the revs as low as possible when you don’t have your foot in it. Plus, they can skip-shift really well, so if you’re doing 60 mph in 8th gear and want to make a highway pass, they will skip right to 4th or 5th, which hides the fact that there are so many gears really well.

      On the other hand, you have cars like the C63 and Lexus IS-F. The IS-F is particularly annoying in that it’s an 8-speed with very close ratios and an engine that likes to rev. So when you’re using the paddles on the track or in the canyons, you have to do a ton of shifting. If you’re going from a long front straightaway into a hairpin turn, you may realistically have to make 5 or 6 downshifts in order to be in the proper gear.

      IMO the 8 or 9 speeds are good for luxury cars and trucks where you’re not going to want to shift yourself very often, and for a sports car, 7 is the absolute maximum, and I prefer 6 gears.

  • avatar

    NINE? The car in my avatar has an almost infinite amount of gears. Beat that.

  • avatar

    “…theoretically perfect gearbox”

    For me, that would be a 5-speed manual

    • 0 avatar

      You’re a good man (or woman as the case may be) gettysburg.
      I went out for a drive tonight to for my next car. There’s not much with a stick, that’s fun to winter drive, for a lad in the snowbelt.

  • avatar

    I can’t wait for the Hemi’s with the 8 speeds. They don’t hunt gears and I doubt the rebuilding costs will be hugely more expensive just because of a few extra planetary gears. I think they are huge wins for the consumers.

    The A4 2.0T does 0-60 in 5.4 seconds according to C and D. That’s pretty amazing considering the pathetic 211hp.

    • 0 avatar

      Are you sure you weren’t thinking of the S4?

      From what I understand, Audi’s 2.0Ts usually dyno quite a bit higher. I’m not sure what the incentive is now, but they had a reason to underrate it in the past because Audi’s 3.2 V6 had only 252hp, and they wanted a reason for people to “upgrade” to the V6 (in the US, the V6 model had more standard options).

  • avatar

    The old wisdom was that 7 was the magic number. At 7 speeds, the lowest gear ratio would be enough to ditch the torque converter in favor of a wet-plate clutch. I suspect, however, that torque converters have been progressing closer towards wet-clutches anyway, they seem to be getting thinner and have more aggressive lock-up programs. Smoothness is less of an issue since modern automatics also institute some kind of spark-cutoff during gear changes as well?

    • 0 avatar

      That’s correct. Computer-controlled automatics generally retard engine timing during gear changes. Some of the luxury brands started doing this in the 90s, and the smoothness has only gotten better since then.

      That’s also why “sport mode” shift patterns have harsher shifts. Retarding engine timing slightly lowers power, and in sport mode, they are more likely to keep more power on tap even during shifts.

  • avatar

    Bicycles go to 11 in back, with options of 1, 2, or 3 in front for up to 33 speeds, although 3×10 is the largest common setup. Also Rohloff hubs have 14 speeds but are mega expensive.
    There are some payoffs to multiple ratios since it keeps the engine at optimum speed but at some point complexity and weight hit a point of diminishing returns, which may be why the ZF guy said 9.

    • 0 avatar
      Felis Concolor

      Having seen how Rohloff mixes and matches ratios with a mere 3 planetaries to come up with 14(!) evenly spaced ratios, there would appear to be room for improvement; the automobile design I’ve seen uses 4 planetaries to achieve an 8 ratio spread, which indicates it’s not using all 3 possible modes a planetary gear can provide (ring, planet or sun driven).

      Are there any auto trans engineers in the house who can explain why that particular progression can’t be used?

      It would also appear to add a layer of redundancy, as modern engine designs tend towards producing broad, flat torque curves, which improves transmission flexibility by allowing a single gear ratio to be used over a wider range of speeds. A wider range of transmission gears should thus be more forgiving for engines with very narrow power bands, which would allow for tuning for very low BSFC in a specific operating range, although it would turn the throttle pedal into more of a light switch instead of a volume knob – and that that point, you’ve entered the realm of CVTs and extreme efficiency series hybrid topologies.

      • 0 avatar

        To get 14 forward ratios out of 3 planetary gear sets, you’ll have to run each combination of pairs of gearsets “in reverse” to get those extra 6 ratios over the usual 8. Switching from going forward to reverse while rotating at 6500 RPM may put too much stress on the gearsets. It might make more sense to add a 4th gearset instead of beefing up the existing three to take the extra abuse.

      • 0 avatar

        “Are there any auto trans engineers in the house who can explain why that particular progression can’t be used?”

        I’d imagine that some of the possible combinations are effectively duplicate ratios

    • 0 avatar

      i fact some dude slip in one of the old 3 spd hub in rear, so being 33 u can add another 3 more to 36!
      well this can render it redundant though.

      should your 8-9 tranny start to hunt around for gears then is neither fun to driver nor tranny.
      to ZF who makes them dont they all wish u be start ordering parts after u drove her for a few weeks?
      heard rumours during the space race or post sputnik era, NASA routinely plant computer bugs so the workers will never be to bored.

  • avatar

    I remember when Ford launched the A4OD 4 speed automatic overdrive in 1979.

    My 16 year old self, wondering what the upper limit might be for gears in an auto box asked my uncle (who retired from Ford some 15 years later as a V.P.) this. I recall he was dead certain that 4 was the upper limit, as “there is not enough space inside the case to add anyone gears.”

    Good thing that trans designers never asked my uncle for his sage advice, and probably a good thing for Ford that my uncle made his career in the Company in a function other than engineering.

    • 0 avatar

      You can get 5 forward gears out of that exact gearset if you can control it so that both gearsets run their backwards ratio simultaneously. Two wrongs make a right! That, in fact, is how some 5 speed transmissions work.

      • 0 avatar

        Maybe that was the concept used 15 years later for the 5R55 trans… I recall there was some trick being used to turn it into a 5 speed from what was nominally a 4 speed box.

  • avatar

    So, how many gears does a usual “semi” have?
    13 comes to mind, but half of those are engaged using a compression handle on the shift column.
    Having more than 9 gears is not an issue. You just have to keep your wits about you and not comb your hair or pick your nose.


    • 0 avatar

      18 was pretty common with the old Road Ranger gearboxes and I’m pretty sure there was a higher number available also. My uncle has a tractor with 36 gears (forward and reverse) and that was only because he didn’t take the option that would have given 72…

  • avatar

    I have a headache trying to figure out all these gear permutations. Think I’ll go for a drive in my Corvair. With a Powerglide.

  • avatar

    I like to think of myself as a gearhead. My default response is to fix it myself.I have changed Hudsonite – a whale oil emulsion that lubricated the cork clutch Hudsons in late 40’s and 50’s.Yet, modern electronic control and lockup boxes baffle me. And, seemingly, more than a few of the “experts” that claim to be able to repair them. I have recently had two different diagnoses on the same problem. Nine speeds? Make 5 work for 200k miles first, then go forward. I agree it seems to me more marketing ploy than a practical advantage.

  • avatar

    7 or 8 speeds already act a lot like CVTs. 9 might be overkill. With an 8 speed gearbox, upshifts are imperceptible and downshifts can plant you in the right gear, right now.

    But I wonder if they’re heading into the uncanny valley of gearboxes. If it smells like a CVT and tastes like a CVT… will it turn people off like a CVT? While these boxes are definitely not as slushy as CVTs from a roll, when you’re pushing hard, the seamless acceleration and short steps in an eight speed box are nowhere near as dramatically satisfying as a five or six speed.

    And by dramatically satisfying, I mean less dramamine for the missus and less of that heady winding through the powerband for you.

  • avatar

    I used to think 8 CD changer is superior over 6 . Not anymore. Who cares.
    EVs do not require transmission and that is the future of main stream.

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