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Automatic V manual transmission question

Discussion in 'Technical Chat' started by lhedrick, Jan 28, 2012.

  1. Jan 28, 2012 at 8:35 AM
    #1
    lhedrick

    lhedrick [OP] Active Member

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    Time to replace my 17 year old T100.

    I want a full size truck but none are available with a manual transmission with one exception, the RAM diesel for 50,000 which is not what I need.

    The Tundra is automatic only. I will not buy an automatic transmission truck.

    My only choice is to downsize to the Tacoma which is available with a 6 speed manual.

    These MPG numbers are from Toyota.
    5 speed Automatic 16/21 MPG
    6 speed Manual 15/19 MPG

    Both with the same V6. How can this be? If both are cruising on the interstate and both are in lockup mode, one with a clutch the other with a locked torque converter and the automatic which will be heavier gets 2 MPG more? If both are locked the transmission should be acting like a solid drive shaft.

    I smell a rat. What is going on here?

    My 1994 T100 full size with a 3.0L V6 gets 19 MPH highway and it's almost 20 years old.

    As for the manual transmission Tacomas, are they available with unlocking hubs on the front end?
     
  2. Jan 28, 2012 at 11:18 AM
    #2
    Fightnfire

    Fightnfire Recklessly tired

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    I love a stick as much as the next guy (sports car) ... but time and time again I fail to see or understand the reasoning behind a stick shift in a truck, mid size or full size. This isn't 1985 or 95.

    The AT in the Toyota, and pretty much every other truck manufacturer, is better than the MT in almost every possible scenario.

    :deadhorse:

    That might be a tad strong, I know, but when everything so clearly points to the AT being superior I guess I just don't understand all the disbelief.
     
  3. Jan 28, 2012 at 11:22 AM
    #3
    easyeatlanta

    easyeatlanta Artificial Intelligence beats natural stupidity

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    i agree with the op it may not be that it is better or not and im not going to get into that but none the less I am bored when driving automatic
     
  4. Jan 28, 2012 at 11:24 AM
    #4
    Fightnfire

    Fightnfire Recklessly tired

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    That's a perfectly reasonable reason to like a MT.

    I would just feel like I am giving up WAY to much for a little boredom.
     
  5. Jan 28, 2012 at 11:26 AM
    #5
    09tacorunner

    09tacorunner Well-Known Member

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    someone correct me if I'm wrong but Im pretty sure there is a member on here that has a "shiftable automatic 6 speed" transmission Tundra. not sure if that makes sense at all but that sounds closer to what you would like.
     
  6. Jan 28, 2012 at 11:28 AM
    #6
    easyeatlanta

    easyeatlanta Artificial Intelligence beats natural stupidity

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    yes the automatics in the larger trucks/suv toyota has a shiftable automatic which provides a little more control but still not full control
     
  7. Jan 28, 2012 at 11:29 AM
    #7
    09tacorunner

    09tacorunner Well-Known Member

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    okay cool thanks for clarifying that! I just though that would be an option for the OP being that it is a full-size with some sort of control that he is looking for!
     
  8. Jan 28, 2012 at 11:30 AM
    #8
    09tacorunner

    09tacorunner Well-Known Member

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    just thought that could of been an option for OP!
     
  9. Jan 28, 2012 at 11:36 AM
    #9
    Fightnfire

    Fightnfire Recklessly tired

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    5. A car with manual transmission will always get better mileage than one with an automatic.


    Reality:
    Newer automatic transmissions can get the same highway mileage as a manual transmission (or even slightly better).


    Following previous oil embargoes, there was a rush on cars with manual transmissions because they got better mileage than automatics. But that’s less true today, especially at highway speeds, says Gabriel Shenhar, senior auto test engineer for
    Consumer Reports. Older three-speed automatics had to work a lot harder at highway speeds than today’s four- or five-speed automatics. And the new automatics produced in the last few years have an “overdrive” top gear that reduces engine rpm’s at higher speeds.


    In city driving or mixed city-highway driving, a manual still tends to get better mileage, Shenhar says. But on the highway and long driving trips in particular, your automatic may get as good or even slightly better mileage than the manual.
     
  10. Jan 28, 2012 at 11:55 AM
    #10
    lhedrick

    lhedrick [OP] Active Member

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    I really can't agree with your auto is better comment.

    They are bigger, heavier and much more complex and will not last a long. Every manual transmission I have ever owned has gone between 250 and 350 thousand miles with no troubles. I have never even replaced a clutch. The cars and trucks rusted out before any transmission issues.

    I have worked on planetary gear drive systems. They need many sensors and hydraulic systems to engage them. They easily add 1000 dollars or more to the price of a truck and will cost thousands more when a rebuild is needed.

    With the auto systems every thing is moving. Why turn front differential gears, CV joints and axles on dry road. I could possible be wrong on this one if the new automatic systems now disconnect the front end but I doubt it. If someone knows fill me it.

    For those who want an auto trans that's fine but I will keep my old truck if automatic is all I can get today. If you like an automatic transmission I can understand but I don't and they certainly are not better then a manual system.

    Simple is always the best. Look at a simple aircraft engine. Nothing automatic. Spark fired by magnites, fuel mixture controlled by pilot adjustment air cooled. No water pumps, no belts. Nothing to fail. Vacuum pumps for controls. No automatic systems which can fail causing a crash

    My old T100 has the ADD. It was nothing but trouble. Almost anything automatic costs more and causes problems. My ADD would not unlock when the temps went below 10 degrees F. I got old manual locking hubs from an old 4Runner and disabled the vacuum system and got ride of all the functions of the ADD and my T100 is now an old time manual 4WD system with hubs and it always works.

    The auto can never be as efficient as a manual unless the torque converter is locked all the time like a clutch and that does not happen. TC loses mean an automatic must always be some percentage less efficient then a clutch which is 100 percent locked at all times. It is a myth that modern automatics get better millage then a locked manual system.
     
  11. Jan 28, 2012 at 12:02 PM
    #11
    lhedrick

    lhedrick [OP] Active Member

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    The Tundra is automatic trans only.

    You may choose to shift it manually but, the mechanics are the same and I doubt the torque converter is ever locked up in anything but gear 6.

    Shift form 5 to 6. Watch the tech and you will see the RPM roll down on the up shift followed by another slight RMP drop when the torque converter locks up.

    No shift back down from 6 to 5. Watch the RPM go up but I doubt you will see a following RPM drop. This means the torque converter is not locking. Any time the TC is not locked we have about a 10 percent loss due to fluid heat generation in the TC.

    So, it is not possible for any automatic system with the same engine to be as efficient as a manual when there is a 10 percent loss in the TC. No doubt they are getting better but not that much.
     
  12. Jan 28, 2012 at 12:14 PM
    #12
    iroh

    iroh Well-Known Member

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    The mileage difference is the difference in top gear ratio:
    RA60(AY6) manual, 6th gear: 0.84:1
    A750E(2WD)/A750F(4WD) auto, 5th gear: 0.716:1
     
  13. Jan 28, 2012 at 1:10 PM
    #13
    lhedrick

    lhedrick [OP] Active Member

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    Thanks, that is very good information about the Tundra 6 speed auto.

    If the torque converters locks up in the higher gears than the automatic should get about the same milage as a manual. I wonder about the long term durability? The Trunda really became a monster compared to my old light T100. It's just too big and heavy which is another reason I may move to the smaller Tacoma.
     
  14. Jan 28, 2012 at 3:48 PM
    #14
    MountainEarth

    MountainEarth Well-Known Member

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    Old thinking. As others have said, the automatic in the 2nd gen V6s is a beast that has been around since 2003 (in the 4Runners) with a miniscule failure rate. Just as computers are better than they were 20 years ago, so too automatic transmissions. Especially the German and Japanese engineered ones. And yes the auto bests the 6-speed in MPG, not just because of it's gearing, but because the computer can outshift you anyday. That's why it's better MPG both city & highway. I used to think exactly like you, OP. But the world of transmissions is turning upside down. And CVTs are going to revolutionize it even more.

    EDIT: Also if you really hate all things "automatic system" you'll hate the fact that the 6-speed manual is also a drive-by-wire system.
     
  15. Jan 28, 2012 at 8:26 PM
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    lhedrick

    lhedrick [OP] Active Member

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    Drive by wire? By that do you mean it's the same transmission as the 6 speed auto but with a manual shifter and clutch. A 6 speed planetary as opposed to a main/lay shaft setup. Are you saying they are the same transmission with just an electric manual shifter?

    All interesting stuff.

    By the way I will accept a milage driver off any day with identical engines and gearing. I can beat an automatic every time.

    Funny thing the rest of the world still uses manual transmissions with small diesel engines. Only here in the US is a 4.0L V6 a small under powered motor. Many places use 150 HP 6 cylinder diesel engins in trucks hauling 10000 pounds. In the us many think a 5.0L V8 it still too small.

    Thanks for the tip on the 6 speed manual I will look into how it works. Very interesting. Always lots to learn.

    My T100 3.0L V6 is only about 150 HP and it has been fine. Slow at times on long grades but not a problem. I just can't do 60 when pulling my light drift boat and trailer.
     
  16. Jan 28, 2012 at 8:37 PM
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    KenLyns

    KenLyns Lord of War

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    It's throttle-by-wire to be exact. The butterfly valve on the throttle body is driven by an electric motor, with no mechanical connection to the gas pedal.

    The Tacoma is faster to 60 mph and in the 1/4 mile with the auto, according to Car and Driver testing, again because of the more "appropriate" gear ratios.

    The clutch throwout bearing shaft on 6-spd is known to wear prematurely. This was fixed last year. If you buy a new '12 truck, it should have the improved design.

    The 5-spd auto was sized for the previous gen. Tundra's 4.7L V8, so it's overdesigned for the 4.0 application and very reliable.
     
  17. Jan 28, 2012 at 11:34 PM
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    MountainEarth

    MountainEarth Well-Known Member

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    But they're not geared the same way. The auto and manual are geared differently. I've read that Toyota did it because they were having problems getting the same tow rating on the manual. Whether that's true, I don't know. And because of that, you'll see that almost universally the auto does 2-3mpg better than the stick, no matter who you are. Now if you drive mostly rural between 25-65, you might do better with the stick. But in stop and go, and over 65, MPGs get killed.

    Trust me... a lot of us would have liked to see Toyota do better with the manual on the 2nd gen. As an all-manual guy for 20 years, I didn't believe the automatic did better either. But if you look at the real world MPG that people report on this forum and others, the EPA numbers are pretty right on for a stock truck. I've driven botha 2009 6-speed and a 2010 auto, and seen it for myself.
     
  18. Jan 29, 2012 at 8:58 AM
    #18
    lhedrick

    lhedrick [OP] Active Member

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    Thanks everyone.

    We have kind of beat this one to death. Got some good new technical information I did not have before on this subject.

    It might sound crazy but I miss the old days with my tiny 4 cylinder International Scout 4WD. 3 speed on the floor. 3 control levers. 1 to shift the transmission, 1 to shift in the transfer case and the last lever to select high or low range. Limited slip front and rear differentials and I still got is stuck crossing a stream one time. Vacuum wind screen wipers would stop when you went up hill and opened the throttle pushing up the manifold pressure.

    Those were the days. I think the little thing got 12 MPG and only went 55 MPH wide open. Might have been around 75 HP. Never had a top for it. Most fun I ever had with 4 wheels.

    Thanks again.
     
  19. Jan 29, 2012 at 11:27 AM
    #19
    lhedrick

    lhedrick [OP] Active Member

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    The one I had was something like a 1960 model. I have not seen one for over 30 years. I later had a 1970 Ford Bronco 302 V8. Even those are becoming scarce.

    --
    One thing I forgot. With all this discussion of 5 and 6 speed transmissions I am getting the impression the dual range transfer case my be a thing of the past. I have not been in one of the new trucks. Is it now just 1 set of gears only or do the still have a high and low range?
     
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