By on July 18, 2014

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Now that the new GM 8L90 has made its way down to the C7 Corvette, it was only a matter of time before GM put the new transmission in their pickup trucks.

Starting in 2015, all of GM’s full-size, body-on-frame pickup trucks and SUVs will get the new 8-speed gearbox. Fuel economy improvements haven’t been announced, though GM claims that the new transmission will allow for numerically lower final drive ratios, which should have a positive impact on highway fuel economy.

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51 Comments on “2015 GM Trucks Get 8-Speed Transmission...”


  • avatar

    > lower final drive ratios

    Er….”Lower” final drive ratios are numerically higher by convention, and actually lower fuel economy. For example, if I move from a 3.55 to a 4.10 rear-end on a truck, I’m going to have a truck that revs much higher for a given road speed.

    /pedantry

  • avatar
    bball40dtw

    Is this a stop gap until the 10-speed developed with Ford makes it to the GM trucks? Ford needs to get the 10-speed out ASAP because even with a new truck, they’ll be behind GM and RAM in the transmission department.

    • 0 avatar
      carguy

      Weight will matter more than the marginal improvement of going from 6 to 8 gears – unless you are one of those guys that always buys the razor with the most blades.

      • 0 avatar
        bball40dtw

        The Gillette Fusion Proglide is the best razor I’ve ever owned.

        Yes the weight matters more, but the transmission needs to be updated on the F150 for CAFE and competitive reasons.

        • 0 avatar
          davefromcalgary

          bball, would you rather have a dimwitted 10 speed or a well programmed 6 speed?

          (serious question)

          • 0 avatar
            bball40dtw

            I’d rather have the 6 speed.

            However, poor programing of automatic transmissions is not limited to those transmissions with 7-speeds or more.

          • 0 avatar
            davefromcalgary

            Oh, I know that poor programming knows no bounds, I just picked two numbers for comparison sake.

          • 0 avatar
            bball40dtw

            I personally don’t see anything wrong with a 6 speed transmission.

            When we purchased our MKT, we also test drove a number of luxury/semi-luxury crossovers with 8-speed transmissions (new Durango, used Q7, used X5). The MKT still drove the best on the freeway, was the most comfortable to drive, and didn’t go hunting for gears like the Durango did. In that case, the 6-speed, even if it is a goofy Ford transmission with voodoo AWD, was my favorite. The 3.5EB engine certainly helped since there is power all the time.

          • 0 avatar
            davefromcalgary

            I think we are on the same page. You know I prefer manual transmissions, but when it comes to automatics, programming trumps number of gears.

            I often laud the performance of the 3800/4T60 combo, and everyone says, “duh, dat torque.” However, back in the day I also had a matching 4speed auto/2.2 ECOTEC Alero from work to match my 5speed manual/2.2 ECOTEC personal car. While it surely didn’t have the torque of the 3800, the transmission wasn’t lunging for 4th gear at sub 2000 rpm shift points, and while not exciting, it drove just fine.

            TL, DR. Better transmission logic, please!

          • 0 avatar
            bball40dtw

            My wife and I both prefer manual transmissions, but our current cars are not avialable with either.

            Derek’s public Fiesta ST lust, combined with my test driving of the vehicle, really makes me covet the Fiesta ST. My daughter is turned around in her car seat now, so it can work if we don’t have another kid for awhile. I love my C-Max, and Ford keeps sending me $450 checks to drive it. However, the Fiesta ST is special.

          • 0 avatar
            Toad

            I’d prefer a well programmed 10 speed. However, if I had to choose one or the other it is a lot easier to improve and update a transmission’s programming than it is to add gears.

            If a 6 speed can be programmed well, so can a 10 speed. I’ve been running 10 speed automated transmissions in 80,000lb trucks for over a decade and they work very well.

          • 0 avatar
            davefromcalgary

            I agree Toad, there is no reason any transmission can’t be well programmed, number of gears not withstanding.

            However, if I am buying a new vehicle, and I hate the way it shifts, “that can be fixed with a tune” isn’t really helping me. I don’t want to have to “improve” something on a brand new vehicle!

        • 0 avatar
          rockets

          Hey those Shave Club blades are surprisingly good…

      • 0 avatar
        Drzhivago138

        “…And the 27th blade polishes the jawbone.”

      • 0 avatar
        SaulTigh

        http://www.theonion.com/articles/fuck-everything-were-doing-five-blades,11056/

    • 0 avatar
      dantes_inferno

      I can see it now – “The Chevrolet Silverado delivers an EPA estimate of 30 mpg hwy 24 city with the optional 20-speed automatic transmission”

    • 0 avatar
      bts

      GM and Ford should still be developing a 9 and 10 speed together. The 9 speed is made for front wheel drive and the 10 speed for rear wheel drive.

      My guess is the 10 speed will appear in Cadillacs to differentiate it.

      I doubt the 10 speed will make a difference compared to the 8 speed. Doesn’t GM need to keep engine revs higher than Ford’s since they shut off half the cylinders on the highway?

  • avatar
    Andy

    Always wait at least a year on a new vehicle design… They waited a year with the last redesign (2007?) to go from 4 to 6 speeds. Now all the shiny new trucks have the “old” 6-speed. Well, maybe wait two or three years, so the bugs get worked out of the brand new transmission too… Forget it, only buy old trucks.

    • 0 avatar
      dwford

      Just got my Sierra yesterday with the “old” 6 speed auto. No thanks on the 8 speed. My 2013 Charger had the 8 speed and it’s just too many gears.

      • 0 avatar
        nrd515

        I’ve driven my friend’s Grand Cherokee with the 8 speed a bunch of times, and another friend’s Cherokee with the 9 speed, and I don’t understand the “too many gears” post at all. The 8 speed “Torqueflite” has been in the JGC’s for a while now, and I have no fear of “first year bugs”, and don’t see any other possible downside to the 8 speed. Better mileage, a little quicker, what is the negative here?

  • avatar
    Yesac13

    This news means that the 4.3 V6 GM trucks will sell very strongly in 2015.

    The 4.3 sold today is not the old 190 hp version that most people think of. It now makes 285 hp and 305 LBS of torque – the strongest naturally aspirated V6 available today.

    • 0 avatar
      mcarr

      Depends on how you measure “strong”. If you mean by the ability to accelerate to 60 mph the fastest, it’s not that. And actually, it felt a lot weaker than the numbers suggested in the one I drove. Passing on a 2 lane road unexpectedly took enough time to make me pucker.

    • 0 avatar
      dwford

      I drove the 4.3 while shopping for my Sierra. Slow, still bad gas mileage, and sounds like a blender filled with rocks.

  • avatar
    cartunez

    finally now lets just hope its reliable.

  • avatar
    celebrity208

    General Q for the B&B regarding this picture (and other transmissions): Why such a long output shaft? Or in other words, why doesn’t the transmission just end there (thus requiring a slightly longer driveshaft” instead of lengthening it with a “tail shaft” assembly?
    I mean, it looks like that output shaft is nearly 10″ long!

    • 0 avatar
      danio3834

      The particular transmission pictured is designed to accept a transfer case for a 4×4 vehicle. The splines on the output shaft will engage inside the transfer case. So instead of a full tailstock case as you’d see in a RWD version, it’s cut short to make room for the t-case.

      • 0 avatar
        jhott997

        no. The transmission pictured is for the Corvette.
        Rear mounted transmission/transaxle.
        The torque tube mounts at torque converter. The splined shaft goes into the differential.

    • 0 avatar
      IppoMakunouchi

      The transmission shown is for the Corvette – no bellhousing because of the torque tube attachment and a long output shaft for intefacing with the pinion gear in the rear differential. The 6L80 has the same shape factor.

      For trucks, you either have a 2WD slip yoke or a 4WD transfer case interface – notice how the rear bulkhead is interchangable. Most RWD cars usually have a fixed yoke.

    • 0 avatar
      Scoutdude

      The longer a drive shaft is the lower its critical speed. So either extend the output shaft and tail housing or you have to either put in a two piece shaft or make the shaft stiffer. See youtube for Mustang V6 with speed limiter removed to see what happens when a drive shaft reaches its critical speed.

  • avatar
    alexndr333

    “…made its way down to the C7 Corvette.”?? “Down” to the Corvette? How about “up” or just “to the Corvette”? There remains a sub-conscious anti-GM bias no matter how much TTAC tries to argue otherwise.

  • avatar
    DrGastro997

    Why 8??? It doesn’t seem to make sense unless GM can program it just right, meaning flawless operation. I highly doubt they’ll achieve it. I wonder who is the supplier for this 8 speed. Anyone know?

  • avatar
    canddmeyer

    Too many speeds. GM just needed to improve their 6-speed gear spacing and its programming, or buy it from Toyota’s Tundra.

  • avatar
    Jacob

    I remember the posters from +10 years ago who were predicting that all the 6-speed transmissions were going to explode in your face, because having one more gear than the 5-speed was going to doom it.

  • avatar
    Spartan

    1980s – 4 speeds, too many gears!
    1990s – 5 speeds, too many gears!
    2000s – 6 speeds, too many gears!
    2010s – 8 speeds, too many gears!

    Some of you are just never satisfied. We’d be stuck with three speed automatics that drop out of the power band with each gear change if some of you had your way.

  • avatar
    cgjeep

    Pickup trucks last/live forever. Transmissions don’t. Would hate to see the cost to replace this when truck is 10 years old.

  • avatar
    Jacob

    Instead of designing a new N+2 gear automatic transmission every few years, why not just develop a good CVT and be done with it?

    • 0 avatar
      Brian P

      Because gear-to-gear transmissions are stronger and more reliable than any CVT developed thus far. And, a lot of people, myself included, hate the way CVT-equipped vehicles drive.

      • 0 avatar
        highdesertcat

        CVTs are the wave of the future. They are far simpler than step-transmissions and cost much less to build, resulting in a greater profit margin for the manufacturer.

        I, too, prefer step transmissions and hope that Toyota will put that fantastic Lexus 460 8-speed automatic in the Tundra, behind that magnificent 5.7L V8. For me, that would be my wish come true in a pickup truck.

        SUV/CUV/Sedan-wise, CVTs are on the horizon for just about ever brand. Many have already switched over completely. CVTs are better today than just a few years ago and OEMs are trying fancy gimmicks like programming in faux shift points to fool the driver.

        But the main advantage a CVT has over a step transmission remains fuel economy in that the engine can be operated at peak efficiency while the infinitely variable transmission matches torque to the load. For many people fuel economy trumps everything else.

  • avatar
    IppoMakunouchi

    Current CVTs are limited in torque capacity and have a very specific shape (chainbelt cvts require two axis design). Most truck automatics are single axis and torque capacity is as simple as a diameter increase. I won’t say it is impossible for a high torque RWD cvt, but it is a huge challenge.

  • avatar
    CapVandal

    In heavy trucking, predictive cruise control is rolling out.

    “predictive cruise control feature on new transmission. Traxon software is tied in with GPS navigational systems to accurately track and predict upcoming terrain features, then adjust gear selection and shift patterns as well as throttle input to manage them effectively.”

    Seems like once this is fully developed it could squeeze out a couple or three highway mpg for light trucks.

    Once it is fully developed, the marginal cost of tossing in electronics is low. The idea that a chip and gps could do as much as Ford aluminum is interesting.

    Maybe it has been tested and discarded … I am hardly an expert on this. At least it follows the usual model of automotive improvement …. unlike google self driving cars.

    For a semi, 1 mpg is 10 to 20% improvement. Since they have single digit milage.

  • avatar
    Kevin Kluttz

    Listen…I see a major recall appearing on the horizon and closing fast! Either that or a lot of idiots doing a lot of beta testing.

    • 0 avatar
      highdesertcat

      Hah, the major recall appearing on the horizon is pretty much with anything GM you buy.

      A guy I know from church bought a Caddy new, 2011 or 2010 maybe, only to find out today that it will be recalled for one thing or another. My guess is the ignition switch, but he didn’t say so.


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