By on December 23, 2014

 

Ford 10 speed transmission cross section design pieced together from various patent disclosures

Ford 10 speed transmission cross section design pieced together from various patent disclosures

If a transmission has 5 clutches and for the realization of a gear ratio 3 out of the 5 clutches have to be engaged, there are a total of 10 possible combinations. The ZF 8HP and GM 8L transmission families have 5 clutches of which 3 are engaged for any gear state, but only have 9 out of these 10 states are present and accounted for (8 forward gear ratios along with 1 reverse gear ratio). The 10th combination leads to a situation where the transmission would want to turn in forward and reverse direction at the same time, i.e. the transmission would lock up the output shaft and potentially self destruct.  The Ford 10R transmission design has 6 clutches and 4 are engaged for any given gear ratio. This gives us 6C4 or 15 possible combinations, 11 of which are used to yield 10 forward gear ratios and 1 reverse gear ratio. The 4 other combinations do not yield a functional transmission gear state or put the transmission in Neutral.

In the last article on the Ford 10 speed transmission we looked at some of the design details of the Ford 10 speed RWD automatic transmission without going into the details of the actual power flow for the various gears. In this article, a detailed analysis of the power flow is presented along with the gear ratio calculations and shifting operation of the transmission. Just like the last article on the subject, the information is based on invention disclosures by Ford. The most relevant patent for the purpose of understanding the power flow is US Patent #8545362.

 

The casual reader is advised to go through the basics of planetary gear sets from the earlier saturation dive articles before wading into this detailed analysis. The simplified representation of the 10R design or the “stick diagram” of the Ford 10R design is presented below

10R80 stick diagram

10R80 stick diagram

The output shaft of the torque converter is the input shaft to the transmission. The output shaft (Gear set 4 planetary carrier) is connected to the rear wheels through a prop shaft.  All 4 planetary gear sets are “simple” planetary gear sets, for the definition of a simple planetary gear set please refer to the ZF 9HP transmission saturation dive. The 4 gear sets have the following rigid links

  1. Planetary carrier of gear set 1 is rigidly connected to the ring gear of gear set 4
  2. Ring gear of gear set 2 is rigidly connected to the sun gear of gear set 3
  3. Planetary carrier of gear set 2 is connected to the input shaft
  4. Ring gear of gear set 3 is rigidly connected to the sun gear of gear set 4
  5. Sun gears of gear sets 1 and 2 are rigidly connected.

The function of the shift elements is as follows

  1. Activation of brake A grounds the ring gear of gear set 1
  2. Actuation of brake B grounds the sun gears of gear sets 1 and 2
  3. Engagement of clutch C causes the ring gear of gear set 2 and the intermediate shaft to rotate at the same speed
  4. Engagement of clutch D causes the planetary carrier of gear set 3 and the intermediate shaft to rotate at the same speed
  5. Engagement of clutch E connects the sun gear of gear set 3 and the ring gear of gear set 4 to the input shaft
  6. Engagement of clutch F causes the ring gear of gear set 4 and the planetary carrier of gear set 1 to rotate at the same speed.

The astute reader will note that there are several similarities between this design and the ZF 8HP design in terms of gear layout as well as brake A and B layout. Of course there is one additional shift element (a rotating clutch), and there is an intermediate shaft that is not directly connected to any gear set element unlike the ZF 8HP design. The 5 rigid links between the gear set elements are in fact exactly the same as the ZF 8HP design. Please refer to the ZF 8HP transmission saturation dive for the ZF 8HP stick diagram and CAD renders. A CAD render of the Ford 10R may therefore appear very similar to the ZF 8HP CAD render to the casual observer.

For the 4 simple planetary gear sets, the gear tooth counts are estimated to be

  1. Gear set 1: Sun gear S1 = 45 and Ring gear R1 = 99
  2. Gear set 2: Sun gear S2 = 51 and Ring gear R2 = 89
  3. Gear set 3: Sun gear S4 = 63 and Ring gear R3 = 101
  4. Gear set 4: Sun gear S4 = 23 and Ring gear R4 = 85

 

First gear

First gear is achieved by engagement of brakes A and B, along with actuation of clutches D and E. A simultaneous actuation of brakes A and B causes the sun gear and the ring gear of gear set 1 to be grounded, thereby causing the planetary carrier of gear set 1 to be grounded. By the virtue of a rigid link, the ring gear of gear set 4 is also grounded. Clutch E connects the input shaft to the sun gear of gear set 4, while the planetary carrier is the output. The figure below explains the speed states of the various members. The power flows through Clutch E to the sun gear of gear set 4, the ring gear of gear set 4 provides the reaction torque which flows back to brakes A and B. Clutch D need not be engaged for the first gear to work, but it is engaged because it is required for a shift to 2nd gear or to reverse gear. Clutch C is open and sees a relatively small amount of relative speed, while clutch F is open and sees a large amount of speed difference (slightly higher than input speed).

10R80 1st gear kinematic state

10R80 1st gear kinematic state

In the figure above, all elements that are color coded orange spin at the input speed, and the beige color denotes 0 speed. The blue colored elements spin faster than the input and the purple colored elements spin faster than the input but slower than the blue elements. This sets up an under-driven gear ratio of

 

(1) 1st   = S4+R4


S4

= 4.696 

Second gear

A shift to second gear is accomplished by releasing clutch E and engaging clutch C, while shift elements A, B, and D stay engaged. This causes gear set 2 to act as an overdrive because the sun gear is grounded, the planetary carrier is rigidly connected to the input shaft, and the ring gear is the output element. Since clutch D is closed, the planetary carrier and the sun gear of gear set 3 are forced to turn at the same speed as the ring gear of gear set 2. Therefore, gear set 3 spins as a unit, i.e. all 3 members are turning at the same speed. The power flows from the planetary carrier of gear set 2 to the ring gear of gear set 2  to the sun gear of gear set 4 to the output shaft. The reaction torque is provided by brakes A and B through the ring gear of gear set 4

10R80 2nd gear kinematic state

10R80 2nd gear kinematic state

In the figure above, the orange colored elements spin at the input input speed, while blue colored elements spin faster than the input. The beige colored elements are stationary. Clutch E is open and sees a low  speed difference, while clutch F is open and sees high speed difference at approximately 1.5 times the input speed.  The overall ratio between the input and the output is a net under-drive with the following ratio

(2) 2nd   = (S4+R4)R2


S4(R2+S2)

 =  2.985 

Third gear

The shift to 3rd gear is realized by disengagement of brake B and engagement of clutch E. A simultaneous engagement of clutches C, D, and E causes all 3 elements of gear sets 2 and 3 to spin at the same speed as the input. Since brake A is still engaged, the planetary carrier of gear set 1 and therefore the ring gear of gear set 4 is under driven with respect to the input. Meanwhile the sun gear of gear set 4 spins at the input speed. Brake B sees a high speed difference across it (since the inner plates of the clutch are spin at input speed), while clutch F has a relatively low relative speed.

10R80 3rd gear kinematic state

10R80 3rd gear kinematic state

In the figure above, the orange colored elements rotate at input speed, beige colored elements are stationary, and the red colored elements are under-driven. In this state, gear set 4 acts as a mixer module with an under driven ring gear and a sun gear that rotates at input speed. Since the speed of the carrier is always a weighted mean of the speeds of the sun and the ring gear, the ratio is as follows

(3) 3rd   = (S1+R1)(S4+R4)


R1S4+S1(S4+R4)

 =  2.179  

Fourth gear

Fourth gear is achieved by opening clutch E, and closing clutch F. The simultaneous actuation of clutches C, D, and F causes the following

  • Clutch C and D closed implies the sun gear and the ring gear of gear set 3 rotate together, which means the ring gear of gear set 3 and consequently the sun gear of gear set 4 also turn as the same speed as ring gear of gear set 2.
  • In addition to the constraint above, closing clutch F means that the ring gear of gear set 4 also rotates at the same speed as the ring gear of gear set 2
  • Therefore gear set 3 and gear set 4 spin as a unit at the output shaft speed
10R80 4th gear kinematic state

10R80 4th gear kinematic state

In the diagram above, all elements that are color coded green spin at the same speed as the output, while the orange color denotes the input shaft. The blue colored elements spin at a speed that is faster than the input. Therefore the gear ratio only depends on the gear ratios of gear sets 1 and 2. The exact formula for the gear ratio is

(4) 4th   = S1(S2+R2)+R1S2


S1(S2+R2)

 =  1.801  

Fifth gear

The shift to fifth gear is realized by opening clutch D and engaging clutch E. This change in clutch actuation does not alter the kinematic behavior of the first 2 gear sets. Therefore the ring gear, the sun gear, and the planetary carrier are still rotating 1.801 times slower than the input. The speed difference across the open brake B is identical to fourth gear as well. The carrier of gear set 3 now rotates slower than the input, and gear set 4 is acts as a mixer module.

10R80 5th gear kinematic state

10R80 5th gear kinematic state

The orange colored elements rotate at input speed, the red colored elements rotate 1.801 times slower than input speed, the blue colored elements turn faster than input, and the purple colored element is slower than input. Therefore the gear ratio is defined by the gear ratios of gear sets 1, 2, and 4. Since the ring gear of gear set 1 rotates at 1.801 times slower than input, and the sun gear is connected to the input, the overall ratio is an under drive

(5) 5th   = (S1(S2+R2)+R1S2)(S4+R4)


S1(S2+R2)(S4+R4)+R1S2S4

 =  1.539  

Sixth gear

Sixth gear is achieved by releasing clutch C and engaging clutch D. The resulting kinematic arrangement forces the following speed relationships

  • The sun gears of gear set 1 and 2 spin at 1.291 times the input shaft speed (color coded blue in the figure below)
  • The ring gear of gear set 4, the planetary carriers for gear sets 1 and 3 all rotate 1.397 times slower than the input shaft (color coded red in the figure below)
  • The ring gear of gear set 2 and the sun gear of gear set 3 rotate 3.841 times slower than the input shaft (color coded purple in the figure below)
10R80 6th gear kinematic state

10R80 6th gear kinematic state

Therefore gear set 4 still acts as a mixer module, and since the ring gear speed is 1.397 times lower than the input shaft speed, the overall ratio is an under drive. The formula below shows that tooth count of all 4 gear sets result in the over all gear ratio.

(6) 6th   = (S4+R4)(S1R2(S3+R3) + S1S2S3 + R1S2S3)


(S4+R4)((S1R2(S3+R3) + S1S2S3)) + R1S2S3S4

 =  1.288  

This gear ratio calculation was a real bear, it took me 4 of my most productive hours to finally arrive at the pithy equation above. But as we have seen before, the numerically small under drives of these modern automatic transmissions are generally quite complicated in operation.

Seventh gear

The shift to seventh gear is accomplished by releasing brake A and engaging clutch C. This means all members of all 4 gear sets turn at the same speed as the input. The ratio is therefore

(7) 7th   = 1


1

 =  1.000  

Simplicity is nice, once in a while. The 3 remaining gear ratios are all overdrives.

Eighth gear

The shift to Eighth gear is realized by releasing clutch C and engaging brake B. Since the sun gear of gear set 2 is now grounded, and the planetary carrier is connected to the input shaft, therefore the ring gear of gear set 2 rotates faster than the input shaft. Gear set 3 acts as a mixer module, since the ring gear is tied to the input shaft through clutch E, and the sun gear is tied to the over driven ring gear of gear set 2. The planetary carrier of gear set 3, rotates faster than the input, but not as fast as the ring gear of gear set 2.

10R80 Eighth gear kinematic state

10R80 Eighth gear kinematic state

The orange colored elements rotate at the speed of the input shaft, the dark blue elements rotate at 1.57 times the input speed. The light blue colored elements spin at 1.22 times the input speed. Therefore gear set 4 acts as a mixer module since the ring gear rotates at 1.22 times the input speed and the sun gear rotates at the input speed with a ratio of

(8) 8th   = (S4+R4)(S3+R3)R2


(S4+R4)(S3+R3)R2 + S2S3R4

 =  0.852  

 

The ring gear of gear set 1 rotates at 1.775 times the input speed. Therefore the relative speed difference across brake A is 1.775 times the engine speed assuming that the torque converter is locked up.

Ninth gear

The shift up to the Ninth gear ratio is achieved by closing clutch C and opening clutch D. This simplifies the kinematic state of the transmission and takes gear set 3 out of the equation. Now the ring gears of gear sets 2 and 4 are connected, and are over-driven with respect to the input shaft. The light blue colored elements in the figure below rotate at 1.57 times the input speed instead of 1.22 times the input speed in Eighth gear.

10R80 9th gear kinematic state

10R80 9th gear kinematic state

In a manner very similar to Eighth gear operation, gear set 4 is a mixer module with a ring gear rotational speed 1.57 times faster than the input while the sun gear rotates is coupled to the input through clutch E. This sets up an overdrive ratio of

(9) 9th   = (S4+R4)R2


(S4+R4)R2 + S2R4

 =  0.689  

Tenth gear

The shift to the the 10th and final forward gear is achieved by releasing clutch E and engaging clutch D. This kinematic state is a pretty simple one, gear sets 3 and 4 now spin at at the same speed as the output shaft, while gear set 2 acts as an overdrive.

10R80 10th gear kinematic state

10R80 10th gear kinematic state

The sun gear of gear set 2 is grounded, the planetary carrier is the transmission input and the ring gear is effectively the transmission output. This sets up a straightforward overdrive ratio of

(10) 10th   = R2


S2+R2

 =  0.636  

The relative speed across clutch E is 0.36 times the input speed, while the relative speed across brake A is 2.28 times the input speed. This is a very high efficiency state with a locked torque converter, much like the top gear operation of the GM 8L family or the ZF 8HP family.

Reverse gear

Reverse is achieved by engaging shift elements A, B, D , and F. Simultaneous engagement of these 4 shift elements locks the carrier of gear set 3 to ground, turning it into a reversing unit. For reverse gear operation, gear set 2 acts as an overdrive, gear set 3 acts as an under drive and the reversing gear set, while gear set 4 acts as an under drive.

(R) Rev   = -R2R3(S4+R4)


S3S4(S2+R2)

 =  -4.786

The first gear ratio and the reverse gear ratio are numerically quite close to each other, which is not possible with the power flow of the ZF 8HP. The ZF 8HP is yet to show up in a RAM 2500/3500 application, and I suspect that for heavy duty user cases, e.g. snow plow operation,  numerical parity between first and reverse gear ratios is important.

 

Closing remarks on the Ford 10 speed transmission design

The gear ratio numbers presented here are estimates based on the patent filings, the actual gear ratios when the 10R transmission family sees the light of day might very well be slightly different. As noted in the last article, this transmission is unlikely to meet the gear ratio spread of the 9G-Tronic, but the spacing between the gears is pretty much spot on. In my humble opinion, the ground the Ford design gives up to the 9G-Tronic in gear ratio spread, it will probably make up in efficiency because of 1 less open shift element in any given gear.

The genius of this design is the use of an intermediate shaft which is connected to 3 of the 6 shift elements. This intermediate shaft allows for 10 well spaced ratios between the highest and lowest gears, and also simplifies the hydraulic system of the transmission because hydraulic power for half the shift elements goes through one rotating shaft. This kind of design is far too complex to be totally invented by a human because there are simply too many permutations and combinations to consider when evaluating a power flow. Therefore candidate designs are typically brute forced by computers and subsequently short listed and refined by carbon based life forms. The use of such an intermediate shaft that is not directly connected to any of the planetary gear elements is truly unique, and leads me to believe that the transmission synthesis software used at Ford is a step or two ahead of the transmission synthesis software used by the other big boys of transmission design. There are patent disclosures out there from ZF with 4 gear sets and 6 clutches that do yield 10 forward ratios and 1 reverse, but the ratio spacing is rather less than optimal. In US Patent #8465390, ZF has disclosed a power flow which has ten forward ratios, but 5th and 6th gears ratios are practically equal to each other, and so are the 8th and 9th gear ratios. Additionally there are 3 open shift elements for any given gear ratio, thereby the transmission concept disclosed in this patent would have a lower efficiency than the Ford design.

 

That is all I have to say about that.

 

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83 Comments on “Saturation Dive: Ford 10 Speed Transmission Power Flow...”


  • avatar
    TopJimmy5150

    I can’t wait until a few years from now when the stories of how these transmissions detonating into piles of metal filings are told.

    • 0 avatar
      Spartan

      I’m sure someone with your same logic said the same thing about those wretched 4 speed automatics. 3 speeds is enough! While we’re at it, hell 640K ought to be enough for anyone! Or better yet, I don’t need no car, where’s my horse?

      We’ve had 7 speed autos for some years now, along with 8 speed autos since at least 2007(?) with Lexus leading the way. No manufacturer is going to grenade themselves by releasing a transmission that’ll be “detonating into piles of metal filings”.

      • 0 avatar
        SC5door

        “No manufacturer is going to grenade themselves by releasing a transmission that’ll be “detonating into piles of metal filings””

        Have we forgotten the Chrysler Ultradrive mess? They still haven’t gotten rid of that horrid design with the 62TE still floating around. Hopefully it will die when they switch over to the 9 speed on everything.

        • 0 avatar
          bball40dtw

          Chrysler had horrible transmissions for years. They messed up 3 and 4 speeds just as often as 6 speeds.

          • 0 avatar
            CJinSD

            I have never encountered a problem with a 3-speed Chrysler TorqueFlite transmission. The cars they were in stopped being economical to operate well before 100,000 miles were reached, but the transmissions remained smooth as glass until the cars were sold for scrap value.

          • 0 avatar
            bball40dtw

            CJ-

            Fair point. I should have left it with 4-speed as I’ve had trouble with the 42LE and 44RE.

          • 0 avatar
            dal20402

            The reliability record of the 6-speed Chryslers, while not great, is much better than the old A604.

          • 0 avatar
            bball40dtw

            I’m just glad they use ZF transmissions now.

          • 0 avatar
            thornmark

            Chrysler simply made the best automatics for decades, the legendary Torqueflite.

            Even more than w/ engines, Chrysler led market.

      • 0 avatar
        RetroGrouch

        Talk to Fiatysler and their poorly built licensed copies of the ZF 8 speed.

      • 0 avatar
        Scoutdude

        Many of the early 4sp auto boxes didn’t live long lives. Eventually yes they did evolve into durable transmissions. Take the AOD on the earliest ones 100-120K was a common life expectancy. By the time it was ready to be switched to the AOD-E/4R70 it was not uncommon for them to last 3-400K with occasional service.

  • avatar
    Beerboy12

    I will take the 6 speed manual and deal with clutch replacements every 150K miles… Call me a curmudgeon.

    • 0 avatar
      pragmatic

      150K should be a minimum. More like 200K or more.

      • 0 avatar
        raph

        If you can get a stock 07-09 GT500 clutch to last that long in city driving I will gladly bow to your clutch work skills.

        • 0 avatar
          pragmatic

          Haven’t had anything with that much power so YMMV.
          My father bought an 1977 E150 that he drove to and from work in NYC the original clutch in that vehicle was changed at 180,000 miles because I was changing the transmission that failed due to a leaking seal that leaked out the fluid. Clutch was still good but I had already purchased the new one. Low power IL6 but heavy (in the day)vehicle with a high (numerically low) first gear (three on the tree) that required quite a bit of slip to get going. He also taught me and my brother to drive stick in NYC in that vehicle. So I think it can be done.

          In the interest of science lend me the car for 10 years and we will see.

  • avatar
    Fordson

    Very well done. These saturation dive pieces are great and really aid in understanding the possibilities of planetary gearsets.

    Also an interesting comment on Ford’s expertise in this area.

  • avatar
    Jeff S

    It does make me start to wonder when the number of gears reach the saturation point. At what point does the number of gears no longer become more efficient and yield better performance. Will eventually a better CVT be developed that performs better and lasts longer? I believe they will reach a maximum number of gears eventually where they can not develop these transmissions any further. The same I guess could be said for blades on a razor cartridge-first 1, then 2, then 3, then 5, and possibly 6. Will we eventually see razor blade cartridges with 10 to 15 microscopic blades at $5 or more a cartridge. How much better are 5 bladed cartridges than 2. Not dissing these 10 speed transmission just wonder when the maximum limit of gears is reached to where peak efficiency and reliability is reached. Where no more efficiency can be reached and where cost is prohibitive and reliability significantly decreases. Where is the point of diminishing returns.

    • 0 avatar
      bball40dtw

      Timur noted in his last piece about this transmission that current CVTs can’t handle the power the Ford 10R transmission is designed to. We are getting close to Ford putting down 500 ft-lbs out of the 3.5EB.

    • 0 avatar
      DenverMike

      10-speeds is a good place to stop at. But pickup trucks can use lots more, because of the wide spread of available axle, final drive ratios. Frequent towing, 4:10s to 5:13s can use lots more overdrive. Freeway gears, lots more underdrive.

      A 15-speed in a pickup truck would make it more versatile without the need for changing out axle gears, front and rear, when situations change. Say running bigger tires. Or owner change.

      For decades, companies like Gear Vendors have been great suppliers/installers of over/under auxiliary units, for those doing serious towing. These would be obsolete. Some call these “splitters”, and behind 6-speeds, that’s a 12-speed!

      Same with aggressively (rear end, axle) geared muscle cars, sports cars and street/strip. Or street/track where 15-speeds would be a godsend. Best of both worlds.

    • 0 avatar
      Beerboy12

      I think reliability will be affected by complexity rather than the no. of gears. The more gears the box has the less time each gear is in use and therefor, will last that much longer.
      There are an incredible amount of moving parts and electronics to make this gear box work and each part adds risk of failure.

  • avatar
    JMII

    Assuming the fastest your going to cruise around on some highway is 100 MPH then this transmission has a gear for every 10 MPH. This seems insane. However I guess the idea is that at any given forward speed, throttle position, hill grade, etc, etc, that the engine is using the most efficient ratio possible – and having 10 choices means two things: its either going to always be in the perfect gear or always hunting for a better one. Thus I assume the software making these choices must be pretty special. What is the application for this? Full size diesel truck? Anything else seems like a waste.

    • 0 avatar
      dal20402

      A transmission like this allows an engine to be optimized for a narrower powerband without sacrificing drivability — something that’s very useful with modern turbo engines.

      The first application of this transmission will be full-size trucks but I’m sure we will see similar designs in cars before long.

  • avatar
    panzerfaust

    Looks like a much better alternative to getting the most out of turbo charged small displacement engines than the one GM is using. I’ve driven three different 2014 Chevrolet models this year and found they all had the same issues of considerable lag/hesitation when slowing down and then re-accelerating, and always hunting around for the right gear in the 35-45 mph. This was particularly annoying with the Impala which is a heavy car with a 4cylinder engine, you find yourself in some scary split second moments waiting to see if your car is going to respond or not.

    • 0 avatar

      BMW has the same issue in their 6 speed automatics. the ones I’ve driven always feel like they are 10 steps behind, and actually make Fords wretched CD4E transmission feel like a champ.

      I used to get annoyed at 4 speed units, but I’m starting to think they are probably the best number of gears for a fairly torquey engine, granted the 4R55E in my Explorer is made of questionable materials but it has the right gearing my book, coupled with a 3.73 rear axle it gets the same performance as my 1977 Chevelle, while edging it out a bit in fuel economy by 2mpg in most driving conditions.

      • 0 avatar
        Scoutdude

        Well 5 and 6 speeds aren’t any more complicated than a 4sp. The 5R55x is really just a 4R55 where “2nd” is 1st + OD.

        A lot of the problem with the 4R44/4R55/5R55 transmissions is lack of proper service. If people do take them in for “service” it is usually at a monkey lube place that “flushes” the trans with a fluid exchange machine, using “universal” fluid and they certainly don’t adjust the bands. A common reason that the anchor on the band breaks is that it was not adjusted so it slams when it shifts due to excess clearance. Do a proper service by dropping the pan, changing the filter, adjusting the bands and only using Mercon V every 50 or so and the trans will usually lead a long life. The other reason they “fail” is a bad solenoid pack and shops sell a rebuilt trans for more profit rather than replace the solenoid pack. To be fair a lot of trans that could be fixed by replacing the bad sensor or solenoid(s) often get replaced by greedy or incompetent shops.

        • 0 avatar

          Mine’s failing due to a lame design flaw. the steel servo pins have worn out the soft aluminum bores, so it has a sloppy 2-3 and 3-2 shift. the original transmission lasted 225,000 miles but suffered a broken intermediate band, and was having shift quality issues even then for the 2-3 3-2. I serviced it every 50-60,000 miles and adjusted the bands then. the only band to really ever get out of adjustment has been the OD band. I did replace the EPC solenoid once, but its been a decent transmission, just gets angry when you get it hot in stop-n-go traffic, and the manual valve has issues when hot, that it slips in drive if you reverse then toss it into drive, without going past D to 2 and then back to D. It currently has 336,000 miles on that original transmission case. The shop I took it to kept asking me who installed that transmission – didn’t believe me that Ford did it at the plant and that it was the original one.

          Meanwhile I’ve killed one TH-350 with a sticky govenor, when I got the car, the fluid was as black as night and the filter was still the factory one – 34 years later! It lasted 5,000 miles and a year after I got the car and got it working in all 3 gears and reverse.

          I’m talking about ‘feel’ a 4 speed feels right, a 5 speed is ok, but 6 gets to the point that under light acceleration it feels like its just slipping and not actually doing anything useful, and then theres the dim-witted pause as the ECM figures out what heck you just did with a WOT setting that by the time it commands a downshift, you don’t need it anymore so you get a lurch.

          • 0 avatar
            Timur Apakidze

            While band brakes are light and don’t take up a lot of space, the problems you have had with band brakes is exactly why the use of bands is verboten in modern automatic transmissions.

          • 0 avatar
            Scoutdude

            Any decent rebuild of that family of transmissions will include sleeving the bore for those servos. In place of sleeving the bore on an in-service trans you can get servos that are machined to take o rings. The o ring will seal the out of round bore and eliminate the issue. The o rings do wear out but they are a cheap and easy replacement.

  • avatar
    DeadWeight

    I won’t be satisfied with automatic transmissions until there is one gear for every 100 revolutions per minute on the tach.

    Until there’s a 60 speed, don’t bother me.

    I’ll stick with my manual transmissions with foot operated hydraulic clutch forever, b!tches.

    • 0 avatar
      bball40dtw

      Hey, I’m busy shaving over here with my Mach35.

      • 0 avatar
        Lie2me

        DeadWeight will never be accused of being an “early adapter”

        • 0 avatar
          kjb911

          I’ve switched back to a safety razor and shaving gel and love the smoothness that one blade provides…why did we get away from this?!

          • 0 avatar
            Lie2me

            Get away from a single blade? When the multi-blade razor came along and made a once terrible choir easy and comfortable. At least that’s been my experience

      • 0 avatar
        DeadWeight

        I will give up my $40 Panasonic electric razor only when Gillette comes out with their 48 blade surround sound Plasma Warp Edge shaver refill head on a rotating 360 degrees & reversible direction handle.

    • 0 avatar
      Zackman

      Until there’s a 60 speed, don’t bother me.”

      May you be cursed with a Dyna-flow forever! 1 speed is good enough.

    • 0 avatar
      DeadWeight

      I long for an automatic transmission that hunts for & shifts gears 3,782 times during a 10 mile drive to the nearest Costco, with 800 of those gear changes happening while searching for a parking spot (I will not “short trip” any of my vehicles, so if Costco is only 4.6 miles away, I’m still driving 10 miles to get there, at least).

      • 0 avatar
        blppt

        Oh, I agree…even with my “relatively” calm 6 speed auto (well, dual clutch)—I find myself switching to manual mode a lot just to keep the transmission from hunting gears when it simply does not have to. The VW 2.0T has a lot of punch down low, but the transmission sometimes acts like its attached to a high-revving NA 4 cylinder with its downshifting at the slightest grade. Just dumb transmission programming IMHO. The 2.0T has more than enough power to maintain speed up the tallest Taconic Parkway grades @ 65mph in 6th without stress, yet, if I left the transmission in “D” it would downshift at nearly all of them.

        I grew up with my first 2 automatics were 3 speeds, so this era of more and more gears is really astonishing.

    • 0 avatar
      izzy

      DW – If you are as old as dirt like me, with a bummed left knee, you would appreciate an automatic transmission while getting stuck in traffic.
      These young guys! ….and get off my f’ing lawn.

      • 0 avatar
        DeadWeight

        I’m all banged up from football, soccer, accidents and many, many other activities, left knee included – it pops & makes a symphony of sounds along with my other joints, back vertebrae & other parts – but until they saw off my left leg and right hand, they will never take my freedom.

        • 0 avatar
          krhodes1

          @Deadwieght

          I’m with you. I can be predictive in my shifting, an automatic can only be reactive at this point.

          Even in heavy traffic, if you are shifting all the time, you are doing it wrong.

          I’ll also say that 95% of the magic in many-speed automatics is the software. In the past three weeks I had a ZF 8spd equipped BMW 228i for four days, and a ZF 8spd equipped Audi A4 for four days as rentals. Both 2.0T motors, the BMW being about 50X better in how it shifted, especially at low speeds. The Audi could not make up its mind, the BMW always seemed to do mostly what I would do if I was shifting the thing. Still some stupid there, like putting it in Sport locking out 8th gear unless shifted manually.

          The only automatic I truly like is ye olde ZF 4spd in my Range Rover. Mostly because it is in 4th gear with the TC locked at 35mph, and generally acts like a 1spd transmission most of the time. Of course, it gets 14mpg…

          • 0 avatar
            izzy

            To be honest, my next car will probably be 2016 Subaru WRX manual. I was just giving DW a hard time.
            I tried to shift as little as possible in traffic. Usually go from 2nd to neutral and coast and repeat.
            I do prefer manual car. Hoping the WRX’s shifter is close to that of the Acura Integra I had in terms of feel.

        • 0 avatar
          petezeiss

          “but until they saw off my left leg and right hand, they will never take my freedom”

          Too dramatic.. just wait till your hip bursae make words like “iliopsoas” and “trochanteric” part of your daily vocabulary.

          • 0 avatar
            pragmatic

            I don’t know about that. Four years ago I was diagnosed with RA. Before treatment became effective I couldn’t dress myself (even with help getting socks on caused tremendous knee pain), climb stairs or walk without a cane.

            The hardest part of driving was moving the shift lever (if it were an older automatic that required pressing a button I would have been out of luck), turning the key (I used a large hook so I had enough leverage), and getting in or out of the car (full size trucks were out due to high seat, Ranger was better than the Lincoln). Clutch work was never a problem. Its not down long enough to cause pain. Of course you may chose to live where stop and go traffic is the norm so the problem is not what you drive but where and when.

    • 0 avatar
      LectroByte

      Seems like a CVT is a much better answer, all these “umpteen speeds” and “gear changes” seem so last century.

      • 0 avatar
        Joe K

        As of today (tomorrow may change as we don’t know what people are working on) CVT’s have a limit as to how much power they can handle since they don’t use gears to transmit power (Nissan’s system is a hybrid but still has the same issue). Geared transmissions can handle much more power, but it does beg to ask the question, where does the complexity and cost become worth it compared to the simplicity of a CVT.

  • avatar
    Zackman

    This is fascinating to me, but it may as well be Greek, because not only do I not quite understand how the finer points of a carburetor works beyond a basic aerosol can, I still can’t get a handle on how an old 2-speed Powerglide works!

    10 speeds? More stuff to blow up, that’s for sure! For now, though, my 6-speed Impala works wonderfully well and I can’t imagine any other transmission being any better.

    … I’m sure I’ll find out one of these days, though.

    • 0 avatar
      carguy67

      re: “… I not quite understand how the finer points of a carburetor works beyond a basic aerosol can …”

      That’s easy: the carburetor sucks, the can blows.

      • 0 avatar
        Scoutdude

        No really a carb “blows” fuel into the engine. The fuel is pushed out of the fuel bowl by the atmospheric pressure on it, into the low pressure area crated by FLOW though the venturi.

  • avatar
    PrincipalDan

    S0 when do 2 speed rear ends become mainstream? Then we could have 18 to 20 gear ratios no problem.

    • 0 avatar
      Timur Apakidze

      They are already quite mainstream if you buy a 4×4 F series, RAM, or a GM pickup truck. The 4×4 transfer case includes a 2 speed planetary that either operates in direct drive (1:1) or LO range (2.64:1 for some models, 2.72:1 for others).

      So if you bought a 4×4 truck with 3.73 rear end, you get two rear ends (3.73 and approximately a 10:1)

    • 0 avatar
      krhodes1

      I do find it interesting that the latest Nissan CVT also has a 2spd planetary gearset to give it a wider range and quicker downshifts. Neat!

      • 0 avatar
        Scoutdude

        Acura has a 2sp planetary combined with a 6sp dual clutch to make their 7sp

        • 0 avatar
          thornmark

          I think they added a torque converter, which makes it smoother and faster than others.

          Same w/ Honda’s CVT. Most reviewers agree that Honda makes the best CVT and they do it w/ a torque converter.

  • avatar
    Jeff S

    Why stop at Mach35 blade, how about Mach50 for an even closer shave, a shave comparable to a guillotine. As for transmissions I want at least a 120 speed transmission-1 speed for every mile per hour I go.

  • avatar
    Jeff S

    Ok, Denver Mike we will give you that 15 speed auto for trucks but I still want that Mach50 blade razor. You could multipurpose the blades as cheese graders.

  • avatar
    Onus

    I like the super low 1st gear. But, i see a huge spread between first and second.
    Do you foresee that this transmission will start in second instead of first in normal situations? I like the ratios after that.

    • 0 avatar
      Timur Apakidze

      In “Eco” mode this transmission probably can start out in second gear without any problems.

      As far as the spread between the first and second gears, there is an important point to not. If you look at the equations for the second gear and tenth gear, you would notice that first gear ratio times the tenth gear ratio (4.696 multiplied by 0.636) gives you the second gear ratio (2.98). Therefore the spacing between the first and second gear cannot be chosen independently of the 10th gear ratio.

      Therefore the spacing between first gear and second gear ends up being a tad wider than optimal, but as you note the ratio spacing after that is spot on. This is also true for the ZF 8HP design, the spacing between the first and second gear is especially large for the second generation design.

  • avatar
    STRATOS

    These technical details are great but they all lack the physical dimensions and weights.There is never a comparison to the transmissions they are supposed to replace.In that context these details are meaningless.

    • 0 avatar
      James2

      The author can only go by what info Ford provided in the patent filing(s). But, I imagine the new gearbox will largely fit in the same space as the existing 6-speed. As for weight… unobtanium casings, anyone?

    • 0 avatar
      Brian P

      It has 4 planetary gearsets and 6 clutches, which are partially nested. Most 6-speed auto-boxes have 3 gearsets and 5 or 6 clutches. It will be long (so is the ZF 8-speed) but not exceptionally so. The vehicles that these transmissions are going into have the length available. (The transverse 9-speed is the true marvel of space efficiency.)

      The neat thing with planetary gear-sets is that each extra gear-set and clutch increases the number of possible combinations almost exponentially. The old-fashioned 3 speed automatic had 2 gearsets and 4 clutches. Sure, this new transmission has more bits and pieces inside it than the old skool transmissions – but not by nearly as much as one might think.

      • 0 avatar
        Scoutdude

        Yeah for example a 4 5 and 6 speed trans can be made with the exact same number of components. In fact that is what Ford did to create the 5R55 series of transmission from the 4R55 unit. They just apply OD on 1st to get the new 2nd between the old 1st and 2nd.

  • avatar
    honda_lawn_art

    I can imagine the advertisement would feature the Hondells/Beach Boys, “1st gear, it’s alright, 2nd gear, I lean right……7th gear, grab a bite……10th gear, uh, Dolemite?”

  • avatar
    Joe K

    If I remember correctly on the Chrysler design, you only reach the top gear over 80 mph. If this is true, will these top gears ever truly be utilized by the average driver who doesn’t live in a state with high speed limits, or is this all just smoke and mirrors for EPA numbers.

    • 0 avatar
      Timur Apakidze

      It depends which Chrysler transmission you are talking about. The 8HP (Grand Cherokee, Charger, 300, RAM) has no difficulty getting into 8th gear at sixty mph. The 9HP (Cherokee, 200, etc) does not appear to shift into the top gear at less than extra-legal speeds.

      To answer your question – the ratio spacing of this design is such that all 10 gears will be useful at legal speeds.

  • avatar
    TrailerTrash

    These types of articles make me want to change to a seat in the far back of the classroom and hope I never get called on…

  • avatar
    smallworld

    The article was terrific enough to finally sign up. Hello, TTAC!

    Timur, when riding gear hub bikes, efficiency differences depending on number of engaged gear sets are very noticeable. Direct drives are great, 1 set already feels worse, you do not want to stay long in gears with 2 active and more are… just no.

    I see here 2 sets actively transferring in 9th, 3 in 8th,, even 4 in 6th etc.

    Don’t you think that, when chasing efficiency, automated double clutch manuals, with only one gear set engaged at a time and no drag from dog or dry plate main clutches, are better way to go?

    PS. Speaking of which, VW, in their new 10 (12 in fact) speed DSG, aborted this principle and re-used some gear sets.

    • 0 avatar
      Timur Apakidze

      Smallworld

      If you read the previous articles on the (https://www.thetruthaboutcars.com/2014/03/saturation-dive-zf-8-speed-automatic/)ZF 8HP or the (https://www.thetruthaboutcars.com/2014/04/saturation-dive-the-gm-8l90-transmission)GM 8L90, you will see that all 4 planetary gears are used for 5th gear operation, and that the overdrives use more than one gear set as well. So if the efficiency of ZF 8HP is good, the Ford design will be at least as good as well.

      You are right that direct drive state is the most efficient state, and the use of multiple gear sets reduces efficiency, the impact is not as high as it may be for a bicycle gear hub, because of better lubrication that is available in an automatic transmission. The bicycle gear hubs I am familiar with are all packed with grease, this transmission will use a specific ATF which will keep the frictional losses down to a minimum.

      As for DSG gear boxes, yes they are more efficient especially the ones that use dry clutches, the problem tends to be low speed behavior. A torque converter automatic provides very smooth launch from a stop but at low speed the DSG gear boxes are not as smooth. The average American driver who has no exposure to a proper manual gear box thinks that DSG low speed behavior is unacceptable.

      • 0 avatar
        TrailerTrash

        isn’t “A torque converter” at low gears and a type of DSG for higher kind of what the Mazda cars have been getting? The 6 and now the 3 have this set up…I believe.

        • 0 avatar
          redav

          No. Mazda uses a normal automatic, not a dual clutch. However, their design uses a small torque converter that is only involved at low speeds. After that, it uses lock-up plates to bypass the toque converter and give it that direct feel.

          They’ve said they do not intend to pursue higher numbers of gears. Their philosophy is that improving the engine instead accomplishes the same thing.

      • 0 avatar
        smallworld

        Thanks for all answers!

        Splurging gear sets will lead to efficiency penalty no matter the maker. Pity that an apple to apple comparison between double clutch and classic autobox in terms of power losses is next to impossible.

        Most gear hubs are indeed greased, but gears feel differently also on oil bathed Rohloffs. This perception of inefficiency was one of the key reason for gear hub market adoption failure and staying with good old derailleurs in anything but city bikes. So the losses imho are not negligible.

        Double clutch “quirks”: creep is not “spontaneous” and induced instead (by software slipping clutches), sets in after a brief moment. Spirited pull off also causes the engine backing off a bit for sparing clutch engagement under little load, then it really leaps forward. It never bothered me but some may complain. Torque converter auto is meanwhile a stomp-and-go device.

        Apparently these clutch slip games in ever congested Asian mega cities caused heat buildup, reduced service life and VW transmission troubles there. New 10/12 DSG design adds very low “crawler” ratio to avoid most of that slip. An additional torque converter to handle just that is the way Honda/Acura went. Mazda meanwhile afaik used multi plate lockup clutch to bridge the torque converter faster and more frequently in their regular autos.

        Worth noticing that natural creep of an autobox has its price. Without start/stop, the engine bears more load when idling, sloshing TQ oil around when the transmission is not in neutral.

      • 0 avatar
        pragmatic

        I hear complaints about the Focus getrag dry clutch automatics. We have ~20 of them as fleet vehicles. I think they are fine. They can be confused in some stop and go situations and there is occasional judder with some launches. Nothing I think is too bad. I’d rather have no creep at all. But then I’ve never owned and automatic and my be more forgiving of the faults with the computer controlled clutch.

    • 0 avatar
      Scoutdude

      Lower frictional losses are why there are so many automated manual transmissions currently. Every gear to gear interface results in some frictional losses due to the sliding action of the gears meshing. With a manual type transmission there are only two gears meshing and transferring power when there is a reduction or OD range selected. With a planetary gear set there are six or sometimes eight gears in mesh transferring power. Each of the planets is simultaneously meshing with the sun and the ring gear. However the design of the planetary gear set means that each gear is under less load and can be thinner. The meshing of gears tends to make them want to separate. So the interface between the ring and planet counteracts the meshing of the sun and planet. That extra friction of a planetary gear set is why Honda uses simple spur gears in their automatics.

  • avatar
    Joss

    The more gears you have the more often your shifting. My 3 speed bicycle is favorite round town. I often catch the 440hp at the next red…

  • avatar
    05lgt

    When a multi gear downshift is required do these things have to cycle through all the in between power paths or can they jump from 8 to 5? Is the quickest way down being to drop torque and cycle down through a large number of changes at no torque transferred why some newer vehicles have such a fierce case if “who, me” when poked while already moving?

    • 0 avatar
      bumpy ii

      These days most automatics can skip gears, but depending on the exact design, some gear jumps can take a moment or three to engage all the necessary brakes and clutches and get all the proper elements spinning at the correct speeds for the chosen gear ratio.

      • 0 avatar
        Timur Apakidze

        That is correct bumpy ii.

        @05lgt
        A downshift from 9 to 5 would be easy because all that has to be done is brake B would have to be released and brake A would have to be engaged. Similarly an 8 to 6 downshift would be easy because once again brake B needs to be released and brake A needs to be engaged. An 8 to 5 downshift would be a little bit longer because 2 shift elements need to be disengaged and 2 need to be engaged at the same time, takes longer to fill 2 clutch pistons than just 1.

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