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Thread: No more manual transmissions in a Duramax - why?

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  1. #1
    Join Date
    Dec 2006
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    Absarokee, Montana
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    8

    Default No more manual transmissions in a Duramax - why?

    I currently own a Chevy Silverado Duramax HD 4x4, with a 6 speed manual transmission. Yet I am disappointed to discover the new 08 Duramax Diesels that GM is offering, you cannot order one with a manual transmission.

    I know there are fans of the Allison transmission out there, but I am a die hard manual transmission guy; all the vehicles I have ever owned had a manual transmission.

    If GM does not offer another Duramax Diesel with a manual transmission, I may be owning a Dodge Ram 2500 powered by a Cummins Diesel with a 6 speed manual transmission.

    Are there any thoughts as to what is going on at GM that would warrant their offering of the Allison transmission only and not having any manual transmission option available? Inquiring minds want to know.

    RKL

  2. #2
    Join Date
    Dec 2006
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    NJ
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    157

    Default

    the Cummins is a good choice, but im still not sure about the new ones, the 5.9Ls are known to be the million mile motor, this new one im not sold on yet. at least its not a mercedes, those cars, no manuals offered at all
    95 GMC Sierra 2500 4x4 6.5L turbo ext cab 6ft bed ( relocated NEW PMD with cooler, running so far so good) SOLD SOLD SOLD

    95 Chevy Silverado 1500 4x4 Z71 stepside 350V8

  3. #3
    Join Date
    Jun 2006
    Location
    Surrey, BC
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    Default

    I'm with you on this one. I specifically searched out a manual, and it was no easy task given their scarcity, so I guess therein lies the answer: people didn't buy them in sufficient numbers to warrant their production.

    The reason I prefer a manual is that I feel I have way better control than driving an auto, and I only use the brakes to come to a stop. Having said that, I would welcome the opportunity to try the 6-spd Allison with the gear select (arrow up or down) on the gear-shift arm. That way I could hold it where I wanted on grades and still have the ease of auto in town.
    Brett
    2005 GMC Sierra SLT Dually Crew, 4x4, stock
    71,000 kms

  4. #4
    Join Date
    Dec 2007
    Location
    Ardrossan, Alberta
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    Default

    My new service rig had an allison with the "manual" transmission option, and while I always drove the truck that way, it still didn't work like a real manual does.

    I personally won't be buying a new GMC becuase of that very reason. I'm not sold on the new Cummins either, so I may wind up behind the wheel of a new Powerstroke / 6 speed instead. I have a buddy who bought a brand new 6.7L cummins, and claims that it goes like crazy, but gets absolutely terrible mileage.

  5. #5
    Join Date
    Jan 2001
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    New Hampshire - Live Free or Die
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    6,057

    Default

    My guess as to why:

    Two reasons.

    First, I doubt if they sold enough manuals to warrant the costs involved in developing and certifying the emissions to make it profitable.

    Second, I expect emissions certification is a lot more difficult with the manual. With the automatic they can simply program out conditions that result in excessive emissions.

    Remember, too, the manual D-max is derated compared to the automatic, so there must also be some durabuility issues.
    The Constitution needs to be re-read, not re-written!

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  6. #6
    Join Date
    Apr 2007
    Location
    Alberta, Canada
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    Default

    Russell i think all the new diesels have terrible fuel mileage.....doesn't that come with the high HP numbers?

    aside from that, i think they like selling the automatic transmission trucks because they charge more. When i was pricing out my truck, i recall i could have gotten the 6 speed manual, but i was firmly told that it was damn near guaranteed to not last as long as the allison (when driven under normal conditions).......and of course 300 hp instead of 360. But i also remember the extra cash of around $3xxx for the allison transmission option.

    i could have put up with the 60 less horsepower, but it was the fact that i was trusting the guys at the dealer when they told me the allison will outlast the manual.

    i guess time will tell, and i settled for the auto anyways and have no real complaints other than leaky cooling lines.....but i would still rather enjoy driving a new diesel with a 6 speed manual. I won't settle for ford, and dodge hasn't won me over just yet
    2011 VW Jetta TDI, pretty well loaded without leather.
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  7. #7

    Default

    Hello, I am new to the forums. Not that new to diesels though. Apparently a local GMC Freightliner dealership told me that alot of Dmax's were tearing up the 6 spds. He also added the cost for redesigning a stronger unit and a less of a profit margin compared to the mark up on the Allison.
    08' 3500 Silverado Crew Cab LMM
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  8. #8
    Join Date
    Apr 2001
    Location
    Midland, Tx USA
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    236

    Default Miss mine

    I think you hit the nail on the head. Cost is the main reason for anything they do. Nowadays I really miss my ol '93 6.5 with the nv4500. Yea it was in the shop every 4 to 6 months for pumps (lift and injection) but I would gladly tolerate that for my 17 in town and 21 to 24 on the hwy mileage. Traded it for a 454 auto (couldn't find another standard) very reliable still got it at 203k but at a price 11 in town and 14 on the hwy both empty. Yip, I have a shouldu' had a v8 moment every time I fill up.....Hmm wonder where my ol' truck is today?

  9. #9
    Join Date
    Dec 2003
    Location
    SC
    Posts
    939

    Default

    I am not buying that the Duramax was tearing up many ZF's in 3/4 and 1 tons or bigger isn't it rated for up to close to 26000 lb gcvwr? Probably lots of clutch related failures though. GM doesn't make the ZF and didn't make the NV4500 either so petuie on cost of development. Funny how Southbend and a couple other manufacturers can develop a better clutch and has less money than GM too.

    The 5.9 Cummins gave the NV4500 5th gear and factory clutch a trial by fire and its a bit underrated for heavy towing but after they fixed 5th and put a better clutch with it its a pretty good tranny. Yeah, you get crazy snatching around a strong engine and a big trucks something has to give.

    Good point I agree more profit in selling auto's especially if you can streamline production lines and don't worry about manual options and having to credit back on sticker is really big.

    I do wonder about GM's grand picture of uniform bellhousing size and interchangeability across gasser trucks 3/4 ton through 2 tons. I think this time it really limited them in clutch disc size options and if thats what has always hampered them so. Especially in a platform engine like the 6.6 that can go in bigger trucks too. But dang I kind of question if they were giving $3000 back for manual trans vs Allison why they couldn't have come off the coin for a better clutch and still given some money back. Must have been Ford and Dodge manual truck price just beat GM's too much but I don't know never compared apples to apples. Plus Ford and Dodge's automatics were thier Achilles heel another reason they sell more manuals.
    97 5spd K2500 Ext Cab short Bed ~160K miles.
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  10. #10
    Join Date
    Dec 2001
    Location
    Yorba Linda, California
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    496

    Default

    I don't recall reading anywhere on the forums about the manual transmission itself being tore up by the Duramax engine. I believe it was the clutch. The reliability of the manual trans clutch was terrible relative to the Allison transmission.
    '02 Chev 2500HD EC/SB 4x4 D/A

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